Thesis

THERMODYNAMIC STUDY OF TERNARYREFRIGERANT EQUILIBRIA

A THESIS SUBMITTED

TO THE

UNIVERSITY OF MUMBAI

FOR THE DEGREE OF

MASTER OF CHEMICAL ENGINEERING

(PARTLY BY PAPERS PARTLY BY RESEARCH)

SUBMITTED BY

NILESH WAMAN GONNADE

UNDER THE GUIDANCE OF

PROFESSOR SUNIL S. BHAGWAT

INSTITUTE OF CHEMICAL TECHNOLOGY

UNIVERSITY OF MUMBAI

MATUNGA, MUMBAI-400019

JUNE 2010

STATEMENT TO BE INCORPORATED BY THE CANDIDATE IN THE

THESIS AS REQUIRED UNDER REGULATION FOR THE M. CHEM . ENGG.

DEGREE IS AS UNDER:

STATEMENT BY THE CANDIDATE

As required by the University Regulation No. R.2316, I wish to state that the work

embodied in this thesis titled “Thermodynamic Study Of Ternary Refrigerant Equi-

libria ” forms my own contribution to the research work carried out under the guidance of

Prof. Sunil S. Bhagwatat the Institute of Chemical Technology, University of Mumbai.

This work has not been submitted for any other degree of this or other university. When-

ever references have been made to previous works of others, it has been clearly indicated

as such and included in the bibliography.

Nilesh Waman Gonnade

(Research Student)

Certified by

Prof. Sunil S. Bhagwat

(Research Supervisor)

Department of Chemical Engineering

Institute of Chemical Technology,

University of Mumbai, Matunga,

Mumbai-400019.

Date:

Place: Mumbai.

CERTIFICATE

The research work presented in this thesis has been carried out by Gonnade Nilesh

Waman for Master of Chemical Engineeringdegree under my supervision. I certify

that, it is his bonafide work. The research work is original and has not been submitted for

any other degree of this or other university. Further, that he was regular student and has

worked under my guidance as a full time student at MUICT untilthe submission of the

thesis to the University of Mumbai.

Prof. Sunil S. Bhagwat

(Research Supervisor)

Department of Chemical Engineering

Institute of Chemical Technology,

University of Mumbai, Matunga,

Mumbai-400019.

Date:

Place: Mumbai.

Acknowledgement

Acknowledging people for their efforts and help is indeed a tricky job especially as

the feeling regarding someone can’t be expressed in words. Still it is necessary on my

part to express my thankfulness to some of the people, who have been kind to me and

sharing hands with me to show me the better way of life where the success lives.

Success is the manifestation of diligence, perseverance, inspiration, motivation, inno-

vation. I ascribe my success in this venture to my research guide Prof. S. S. Bhagwat for

his valuable guidance throughout the project work. His systematic approach to solve any

type of difficulty has helped me during research. His continuous guidance. inspiration,

support and co-operation in each and every respect made me tocomplete this work. I

am really thankful to him. It is my pleasure to acknowledge him for the freedom that he

has given to me to pursue the research work independently andfor his constant encour-

agement with critical appraisal on my work. His guidance helped me in all the time of

research and writing of this thesis.

I would like to specially thank my senior colleagues Sachidanad Satpute, Ramesh P.,

Nilesh M., Manish S., Chaitanya K. who had helped all the times with constant encour-

agement, valuable suggestions and for the stimulating discussions. All were the source

of inspiration throughout my work. I convey my deep sense of gratitude to Bhushan,

Rajesh, Sharad, Anant, Balu, Swapnil, Sarish, Anik, Gorakshnath, Vrushali, Meenakshi,

Amar, Kamalakar, Sachin and Abhijeet for their jovial nature that made lab atmosphere

always friendly, co-operation in thesis work and for all thefun we have had in the last

two years. I wish to thank all my junior lab mates Rohan, Vivekand Dattatraya for their

co-operation during preparation of my thesis.

I have thoroughly enjoyed my research tenure in ICT with Vinod, Ashween, Sachin

Jadhav, Prasad, Kiran Bhor, Amit Mhatre, Nitin, Pravin Tadkar, Somdev, Ashish S., Rahul

B., Mandar B., Nilesh K., Mr. Pravin Bhandari, Abhijeet Mestri, Siddheshwar, Ankush

.......who have made my research experience extremely enjoyable and help me in difficult

situation. I would like to thank them.

Its great having friends scattered in the various labs in ICT. I would like to thank

VGG, VKR, AVP, AWP and PDV lab mates for being friendly to me.

I would also thanks to my BATU class mates Sriniwas, Ganesh P.Kiran , Shriniwas

K., Ashok, Leeladhar and Rohit babu for their co-operation and friendly behavior.

My family members have played a major role. They have supported me during the

course of work in many ways. Without their support, i would not have seen this day.

I would like to thank all my family members Aai, Baba, Nishantand Jayant for their

inspiration, support and encouragement that always made meto accept new challenges

in the life and forge ahead to achive my goal in life.

-Nilesh

Contents

1 Introduction 1

1.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

1.2 Refrigeration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

1.2.1 Vapor Compression Refrigeration . . . . . . . . . . . . . . . . .6

1.2.2 Vapor Absorption Refrigeration . . . . . . . . . . . . . . . . . .7

1.3 Ammonia - Water Mixture . . . . . . . . . . . . . . . . . . . . . . . . . 8

1.4 Objective of the Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

2 Literature Survey 10

2.1 Literature Survey for Ammonia - Water System . . . . . . . . . .. . . . 11

2.2 Literature Survey for Ammonia - Water - Salt System . . . . .. . . . . . 13

3 VLE of Ammonia - Water System 16

3.1 VLE Equations for Ammonia - Water Binary System . . . . . . . .. . . 17

4 VLE Measurements of Ammonia - Water - Salt System 22

4.1 Experimental Set up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

4.2 Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

4.3 System Details . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

4.4 Result and Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

4.5 VLE of Water - Salt Binary Mixture . . . . . . . . . . . . . . . . . . . .26

4.6 VLE of Ammonia - Water - Salt Systems . . . . . . . . . . . . . . . . . .29

4.6.1 Effect of Acetates(CH3COOK, (CH3COO)2Cu) . . . . . . . 29

i

Thermodynamic Study of Ternary Refrigerant Equilibria

4.6.2 Effect of Ammonium Sulphate((NH4)2SO4) . . . . . . . . . . 33

4.6.3 Sodium Thiocyanate(NaSCN) . . . . . . . . . . . . . . . . . . 36

4.6.4 Effect of Nitrates(NaNO3, KNO3) . . . . . . . . . . . . . . . 38

4.7 Data Fitting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

4.7.1 Modeling of Ammonia - Water - Salt System by Redlich - Kister

Equation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

4.7.2 Modeling of Ammonia - Water - Salt System by NRTL Equation . 54

4.7.2.1 Modeling of Ammonia - Water - Salt System by Psu-

dobinary Method . . . . . . . . . . . . . . . . . . . . 56

5 Conclusions 65

6 Future Scope 67

Nomenclature 69

Appendix 71

References 84

Synopsis 87

ii

List of Figures

1.1 Block Diagram of Vapor Compression Refrigeration system. . . . . . . . 6

1.2 Block Diagram of Vapor Absorption Refrigeration system. . . . . . . . . 8

4.1 Block Diagram of Vapor-Liquid Equilibrium set up. . . . . .. . . . . . . 23

4.2 Vapor-Liquid equilibrium of Pure Water System. . . . . . . .. . . . . . 25

4.3 Vapor-Liquid Equilibrium of Ammonia - Water System. . . .. . . . . . . 25

4.4 VLE of Water - Potassium Acetate. . . . . . . . . . . . . . . . . . . . .. 26

4.5 VLE of Water - Copper Acetate. . . . . . . . . . . . . . . . . . . . . . . 27

4.6 VLE of Water -Ammonium Sulphate. . . . . . . . . . . . . . . . . . . . 27

4.7 VLE of Water - Sodium Thiocyanate. . . . . . . . . . . . . . . . . . . .28

4.8 VLE of Water - Sodium Nitrate. . . . . . . . . . . . . . . . . . . . . . . 28

4.9 VLE of Water - Potassium Nitrate. . . . . . . . . . . . . . . . . . . . .. 29

4.10 VLE of Ammonia - Water - Potassium Acetate in 10 Mass % Ammonia

Solution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30


Solution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31


Solution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

4.13 VLE of Ammonia - Water - Copper Acetate in 10 Mass % Ammonia

Solution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32


Solution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

iii



Solution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

4.16 VLE of Ammonia - Water - Ammonium Sulphate in 10 Mass % Ammo-

nia Solution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

4.17 VLE of Ammonia-Water-Ammonium Sulphate in 20 Mass % Ammonia

solution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

4.18 VLE of Ammonia - Water - Ammonium Sulphate in 30 Mass % Ammo-

nia Solution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

4.19 VLE of Ammonia - Water - Sodium Thiocyanate in 10 Mass % Ammonia

Solution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36


Solution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37


Solution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

4.22 VLE of Ammonia - Water - Sodium Nitrate in 10 Mass % Ammonia

solution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

4.23 VLE of Ammonia-Water-Sodium Nitrate in 20 Mass % Ammonia Solution. 39

4.24 VLE of Ammonia-Water-Sodium Nitrate in 30 Mass % Ammonia Solution. 39

4.25 VLE of Ammonia - Water - Potassium Nitrate in 10 Mass % Ammonia

Solution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40


Solution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40


Solution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

4.28 Parity plot for Bubble Pressure of Water - Potassium Acetate Mixture. . . 45

4.29 Parity plot for Bubble Pressure of Water - Copper Acetate Mixture. . . . . 46

4.30 P/(Pno salt(1 − xsalt)) for Water-Potassium Acetate Mixture. . . . . . . . 46

4.31 Parity plot for bubble pressure of Ammonia - Water - Potassium Acetate

Mixture. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

iv


4.32 Parity plot for Bubble Pressure of Ammonia - Water - Copper Acetate

Mixture. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

4.33 Calculated Bubble Pressure of Ammonia - Water - Potassium Acetate at

400C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

4.34 Calculated Excess Gibbs free Energy of Ammonia - Water -Potassium

Acetate at 400C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49


600C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

4.36 Calculated Excess Gibbs Free Energy of Ammonia - Water -Potassium

Acetate at 600C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50


800C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51


Acetate at 800C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51


1000C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52


Acetate at 1000C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

4.41 P/(Pno salt(1 − xsalt)) for Ammonia - Water - Potassium Acetate mixture

at 400C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

4.42 P/(Pno salt(1− xsalt)) for Ammonia - Water - Potassium Acetate Mixture

at 600C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53


at 800C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54


400C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57


Acetate at 400C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

v



600C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58


Acetate at 600C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

4.48 Calculated Bubble Pressure of Ammonia - Water-Potassium Acetate at

800C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59


Acetate at 800C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59


1000C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60


Acetate at 1000C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

6.1 Calculated mole fraction of Ammonia in vapor phase for Ammonia -

Water - Potassium Acetate at 400C using Redlich - Kister equation. . . . 72


Water - Potassium Acetate at 600C using Redlich - Kister Equation. . . . 72


Water - Potassium Acetate at 800C using Redlich - Kister Equation. . . . 73


Water - Potassium Acetate at 1000C using Redlich - Kister Equation. . . 73


Water - Potassium Acetate at 400C using NRTL Equation. . . . . . . . . 74






Water - Potassium Acetate at 1000C using NRTL Equation. . . . . . . . 75

vi

List of Tables

4.1 Redlich-Kister constants for Water - Salt . . . . . . . . . . . .. . . . . . 45

4.2 Redlich-Kister constants for Ammonia - Water - Salt . . . .. . . . . . . 47

4.3 Table showing values ofD0, D1, D2, and D3 at different Temperature

for Ammonia - Water - Potassium Acetate Mixture. . . . . . . . . . .. . 61

4.4 Table showing values ofE0, E1, E2, and E3 at different Temperature for

Ammonia - Water - Potassium Acetate Mixture. . . . . . . . . . . . . .. 61

4.5 Table showing values ofD0, D1, D2, and D3 at different Temperature

for Ammonia - Water - Copper Acetate Mixture. . . . . . . . . . . . . .. 61

4.6 Table showing values ofE0, E1, E2, and E3 at different Temperature for

Ammonia - Water - Copper Acetate Mixture. . . . . . . . . . . . . . . . 62

4.7 Table showing values ofD0, D1 and D2 at different Temperature for

Ammonia - Water - Ammonium Sulphate Mixture. . . . . . . . . . . . . 62

4.8 Table showing values ofE0, E1 and E2 at different Temperature for

Ammonia - Water - Ammonium Sulphate Mixture. . . . . . . . . . . . . 62


Ammonia - Water - Sodium Thiocyanate Mixture. . . . . . . . . . . . .. 63


Ammonia - Water - Sodium Thiocyanate Mixture. . . . . . . . . . . . .. 63


Ammonia - Water - Sodium Nitrate Mixture. . . . . . . . . . . . . . . . .63


Ammonia - Water - Sodium Nitrate Mixture. . . . . . . . . . . . . . . . .64

vii


4.13 Table showing values ofD0 and D1 at different Temperature for Ammo-

nia - Water - Potassium Nitrate Mixture. . . . . . . . . . . . . . . . . .. 64

4.14 Table showing values ofE0 and E1 at different Temperature for Ammo-

nia - Water - Potassium Nitrate Mixture. . . . . . . . . . . . . . . . . .. 64

6.1 P/(Pno salt(1 − xsalt)) for Water - Potassium Acetate Mixture. . . . . . . . 76

6.2 P/(Pno salt(1 − xsalt)) for Water- Copper Acetate Mixture. . . . . . . . . 76

6.3 P /( P no salt (1 − xsalt ) ) for Water - Ammonium Sulphate Mixture. . . . 76

6.4 P/(Pno salt(1 − xsalt)) for Water - Sodium Thiocyanate Mixture. . . . . . 77

6.5 P/(Pno salt(1 − xsalt)) for Water - Sodium Nitrate Mixture. . . . . . . . . 77

6.6 P/(Pno salt(1 − xsalt)) for Water - Potassium Nitrate mixture. . . . . . . . 77


in 30 Mass % Ammonia Solution. . . . . . . . . . . . . . . . . . . . . . 78

6.8 P/(Pno salt(1 − xsalt)) for Ammonia - Water - Potassium Acetate mixture

in 20 Mass % Ammonia solution. . . . . . . . . . . . . . . . . . . . . . . 78



6.10 P/(Pno salt(1 − xsalt)) for Ammonia - Water - Copper Acetate Mixture in

30 Mass % Ammonia Solution. . . . . . . . . . . . . . . . . . . . . . . . 79





6.13 P/ (Pno salt (1 − xsalt )) for Ammonia - Water - Ammonium Sulphate

Mixture in 30 Mass % Ammonia Solution. . . . . . . . . . . . . . . . . . 80

6.14 P/ (Pno salt(1 − xsalt) ) for Ammonia - Water - Ammonium Sulphate


6.15 P/( Pno salt (1 − xsalt)) for Ammonia - Water - Ammonium Sulphate


viii


6.16 P/ (Pno salt (1 − xsalt )) for Ammonia - Water - Sodium Thiocyanate

Mixture in 30 Mass % of Ammonia Solution. . . . . . . . . . . . . . . . 81

6.17 P/ (P no salt (1 − xsalt )) for Ammonia - Water - Sodium Thiocyanate


6.18 P/ ( P no salt (1 − xsalt ) ) for Ammonia - Water - Sodium Thiocyanate


6.19 P/(Pno salt(1 − xsalt)) for Ammonia - water - Sodium Nitrate Mixture in


6.20 P/(Pno salt(1 − xsalt)) for Ammonia - Water - Sodium Nitrate Mixture in


6.21 P/(Pno salt(1 − xsalt)) for Ammonia - Water - Sodium Nitrate Mixture in


6.22 P/(Pno salt(1 − xsalt)) for Ammonia - Water - Potassium Nitrate Mixture






ix

Chapter 1

Introduction

1


1.1 Introduction

Interest in absorption refrigeration systems driven by waste heat, as an alternative to

conventional power-driven systems has increased because of current energy and envi-

ronmental issues. The working fluids commercially used in the absorption refrigeration

system and heat pumps are water - lithium bromide and ammonia- water. Ammonia-

water system is well known absorption refrigeration working fluid which is widely used

in the industries in ammonia absorption refrigeration cycle for the generation of refriger-

ation. The standard Ammonia Absorption Refrigeration (AAR) cycle operates at a heat

source of 120 to 1400C. A significant amount of industrial waste heat is below 1000C

and can be made available for refrigeration. AAR cycle needsto be modified to run it

using low grade heat source. One of the ways to modify the AAR cycle is to change the

vapor-liquid equilibrium (VLE) of ammonia-water binary system.

H2O−LiBr operate under high vacuum conditions hence,H2O−LiBr are volumi-

nous and require air removal systems, do not operate below anevaporation temperature of

4 0C and crystallization and corrosion problems. However, theammonia - water system

needs rectification of the refrigerant vapor, operates at high pressure, high water content

in the vapor phase, resulting in, a necessary requirement for an expensive dephlegmator,

and resulting in the high vapor pressure at elevated temperature for theNH3 −H2O and

therefore requires resistant and heavy components [Salaveraet al. , 2005]. However, this

system can be air-cooled and can operate at evaporator temperatures below 00C.

Knowledge of salt effect is necessary in separation processes such as extractive dis-

tillation, azeotropic distillation, extractive crystallisation, biofluid processing, geological

formations and many such processes. These processes involve non-volatile salts, arise in

two situations. First, as an alternative to extractive or azeotropic distillation, salts may

be added to a system to alter the VLE behavior. Second, there are cases where salt is

generated in the process before final product purification [Booneet al. , 1976].

The addition of salt to any binary or multicomponent system may change the VLE of

system by changing the relative volatility, solubility, thermal conductivity, density, sur-

face tension and partial pressure etc. of the solvents because of the interactions between

2


the salt ions and solvent components [Lee, 1997; Darwish andAl-Anbar, 1997]. These

changes, if they occur, will result in altering the VLE of thesystem [Johnson and Furter,

1957; Darwish and Al-Anbar, 1997]. VLE of ammonia-water system can be effectively

changed by using the additives like NaOH and KOH [Brasset al. , 2000; Salaveraet al.

, 2005], LiBr [Peterset al. , 1994] and LiNO3 [Liboteanet al. , 2007]. The VLE data

available for ammonia-water-salt systems is inadequate. Astudy of the effect of various

salts on the VLE of ammonia-water system was therefore undertaken to suggest changes

in the binary ammonia-water system.

Decrease in the solubility of a non-electrolyte in the solvent caused by the addition

of a salt is called as salting-out effect and the opposite is called as salting-in effect. Both

these effects is useful in AAR cycle. The salting-out salts will be useful in the generator

where the vapor pressure of ammonia can be increased and salting-in salts will be useful

in the absorber where the solubility of ammonia in water willbe enhanced. The addition

of salting-out salt in the generator of AAR system will significantly increase the vapor

pressure of the system by reducing the solubility of ammoniain water. This salt will be

carried into absorber along with the weak solution from the bottom of the generator. The

presence of salting-out salt in the absorber of AAR cycle, will have adverse effect on its

performance. Hence we need to restrict the salt in the generator side. This can be done by

using membrane separation process and the pressure gradient between the generator and

absorber can be utilised for the said separation of salt fromthe ammonia-water mixture.

The pressure required for the separation of the salt, using membrane separation technique

will depend on the size of the salt molecule. Smaller the sizeof the molecule, higher the

pressure required for the separation. The presence of salt may cause corrosion problems

to the equipment and hence we may have to spend more capital investment for having

equipments made up of corrosion resistant material. Considering all the above mentioned

things, the criterion for the selection of salts to be testedon the VLE of ammonia-water

mixture was decided on the basis of its solubility in ammoniaand water, its molecular

size and its corrosivity.

The salts were selected on the basis of their solubility in water and ammonia inde-

3


pendently. If a salt is more soluble in water than in ammonia,then it will show more

interaction with water than with ammonia and hence the resulting effect will be salting-

out of ammonia. Similarly, if a salt is more soluble in ammonia than in water or if salt

is soluble in both ammonia and water, then it will show interaction with both and the

resulting effect will be salting-in.

Salting-in or salting-out effect are considerable industrial and theoretical importance.

It is observed that, the molecules of the more polar component are generally preferentially

attracted by the electrostatic field of the ions and hence thevapor composition is enriched

by the less polar solvent in which the salt is less soluble [Iliuta et al. , 1998]. On the

addition of salt to the binary system, if the total vapor pressure of the system increases

then it is called as salting-out effect and if the total vaporpressure of the system decreases

then it is called as salting-in effect.

The performance of AAR cycle can be improved by adding salt, which either in-

creases or decreases the solubility of ammonia in water. In tropical conditions like India

where both the condenser and absorber are operated at a temperature of around40 0C,

the use of low temperature heat sources is more difficult. If we want to run a standard

AAR cycle at a heat source of around70−100 0C, we need to add salting-out salt which

will give same vapor pressure in the generator as it gives at120 − 140 0C without salt.

We need such a salt, which shows salting-out effect at70 − 100 0C and salting-in at 40

0C or at least no effect or very less salting-out effect at 400C. So that the overall effect

of salt on the AAR cycle will be positive and there will not be any need to restrict the salt

up to the generator side.

Very few additives are tested on the VLE of ammonia-water system. Therefore the

study of ammonia-water VLE with different additives is important to suggest the changes

in the binary ammonia-water system.

The different additives studied includes potassium acetate, copper acetate, ammo-

nium sulphate, sodium thiocynate, sodium nitrate and potassium nitrate. All these addi-

tives were tested at ammonia concentration of 10, 20 and 30 mass% {mass of ammonia

/ (mass of ammonia + mass of water)} and at different concentrations of additives. PTx

4


data was generated for these systems. Rocked static VLE cellwas used to generate the

VLE data for ammonia-water system with additive. The salt concentration used in mass%

and is given as

Salt mass concentration =mass of salt

mass of salt + mass of ammonia + mass of water×100

The generated VLE data for ammonia-water-salt system was correlated using the

Redlich-Kister and NRTL equation.

1.2 Refrigeration

Maintaining the temperature below that of the surrounding is called as refrigeration. It

is the process of removal of heat from low temperature and rejecting it at higher tem-

perature. This process is opposite to the natural directionof heat flow. Second Law of

thermodynamics states that heat can not be transferred fromlow temperature to higher

temperature without expenditure of energy. Refrigerationis best known for its appli-

cations in air conditioning and in the treatment, transportation and preservation of food

and beverages. It also finds large scale industrial applications in manufacturing of ice

and dehydration of gases. Application in the petroleum industry includes in lubricating

oil purification, low temperature reactions and separationof volatile hydrocarbons. Gas

liquefaction process also requires large scale refrigeration. Generation of refrigeration

below the temperature of -1500C is called as cryogenics.

Types of Refrigeration Cycles

There are number of refrigeration techniques and their combinations, that can generate

cold condition for domestic and industrial applications. Vapor compression (mechanical)

refrigeration cycle and Vapor absorption refrigeration cycle are the most widely used.

The main difference between the two cycle is the type of energy source used for produc-

5


tion of refrigeration. Vapor Compression cycle needs mechanical work as energy input

while vapor absorption refrigeration cycle is a heat operated refrigeration cycle.

1.2.1 Vapor Compression Refrigeration

Currently, electric motor driven vapor compression refrigeration cycles dominate the air

conditioning and refrigeration applications. Figure 1.1 shows the block diagram for a

Vapor Compression Refrigeration cycle. The four basic components of the system are

the compressor, condenser, evaporator and expansion valve.

1 2Evaporator

Compressor

34

ThrottleValve

Condenser

Figure 1.1: Block Diagram of Vapor Compression Refrigeration system.

A working Fluid (refrigerant) is boiled off in the evaporator at pressure, low enough

to provide the cooling. A work driven compressor (usually electrical work) then increases

the pressure of the evaporated working fluid. The high pressure vapors are condensed in

the condenser by rejecting heat to the surrounding. The condensed working fluid is then

expanded back into the evaporator, (via an expansion valve)where it can again provide

the cooling. The cycle involves two pressures, high and low,to enable continuous process

to produce the cooling effect.

6


1.2.2 Vapor Absorption Refrigeration

The heat operated vapor absorption refrigeration technique employs a solute gas as the

vaporizing refrigerant and a suitable solvent for recovering and recycling the refrigerant.

Figure 1.2 shows the block diagram of Vapor absorption refrigeration cycle. The refriger-

ant is vaporized in the evaporator at low pressure to providethe cooling. The evaporated

refrigerant is absorbed in solvent liquid (absorbent) in the absorber. The heat of solution

released in the absorber is removed by cooling water. The rich solution produced in the

absorber is separated by application of heat in the generator. The refrigerant is boiled

off, producing a lean solution which is recycled to the absorber. The vapors from the

generator are condensed and returned as refrigerant liquidto the evaporator. The cycle

involves two pressures, high pressure side (Generator and condenser) and low pressure

side (absorber and evaporator). Refrigerant solution fromthe absorber is pumped to the

generator, where the absorption refrigeration cycle requires electrical energy. However,

the electricity required is much less compared to the heat required.

A large number of refrigerant-solvent combinations can produce refrigeration by ab-

sorption refrigeration technique. Some of the industrially important solute-solvent com-

binations are;

• Ammonia as refrigerant and Water or dilute aqueous solutionof Ammonia as ab-

sorbent.

• Water as the refrigerant and aqueous Lithium Bromide solution as absorbent.

Ammonia-water system is advantageous when compared to the water-lithium bromide

because the later can not operate below freezing point of water.

7


Condenser

Generator

Evaporator

Absorber

QB

QCQE

QA

RefluxTop product

Feed

weak aqua

Refrigerant

Evaporated Refrigerant

Figure 1.2: Block Diagram of Vapor Absorption Refrigeration system.

1.3 Ammonia - Water Mixture

Ammonia and ammonia-water mixtures attract more attentionto the usage as natural

refrigerant, supercritical fluid solvent and working medium in power cycles and refriger-

ation cycle. Power cycles with ammonia-water mixtures as working fluids have been

shown to reach higher thermal efficiencies than the traditional steam turbine (Rank-

ine) cycle with water as the working fluid. Ammonia is highly soluble in water. Its

high solubility is because of the hydrogen bond formation between water and ammo-

nia. While these bonds, are not exactly sharing electrons like Covalent bonding. The

hydrogen bond is an electrostatic force between covalentlybonded hydrogen atom of

one molecule and electronegative atom of another molecule.It is very week (strength

about 2-10 Kcal/mole) as compared to a covalent bond (strength 50-100 Kcal/mole).

The hydrogen bonding between water molecules is stroger as compaired to the hydrogen

bonding between ammonia molecules. This is the main reason,why water is liquid and

ammonia is gas at room temperature. Comparison of the physical properties of the am-

monia with that of water shows that ammonia has the lower melting point, boiling point,

density, viscosity, dielectric constant and electrical conductivity; This is due to weaker

8


H-bonding in ammonia.

Water and ammonia are natural fluids which do not harm the environment. There-

fore, they are also considered as an alternative refrigerant to replace chlorofluorocarbons

in some refrigeration applications. For design, simulation and optimization of such ma-

chinery, accurate description of the thermodynamic properties of the mixture for a wide

range of pressure, temperature and composition are needed.For this purpose, correla-

tions for calculating thermodynamic properties of binary mixtures have been presented

by researchers.

1.4 Objective of the Work

1. The first objective is to measure a set of pressure-temperature-total composition

data.

2. To study the influence of salt concentration on the vapor-liquid equilibrium behav-

ior of ammonia-water and to develop a fundamentally sound approach to correlat-

ing the influence of salt on the behavior of a system.

3. To estimate activity coefficients of the solvents from experimental data correlated

using Redlich-Kister and NRTL equations.

9

Chapter 2

Literature Survey

10


2.1 Literature Survey for Ammonia - Water System

TheNH3 −H2O mixture is receiving increasing attention due to the potential use of the

system as a working fluid in refrigeration and power cycles. The binaryNH3−H2O mix-

ture has a large technical significance in the fields of absorption refrigeration machines,

absorption heat pumps and heat transformers. Ammonia and water have been considered

as alternative organic refrigerants to replace chlorofluorocarbons (CFC) in some refriger-

ation applications to prevent the destruction of environment and natural working fluids.

NH3 − H2O mixture does not affect the atmospheric ozone layer nor do they contribute

to the green house effect. Therefore, the significance of this mixture in refrigeration

technology is strongly increasing. Refrigerating cycle with NH3 − H2O mixtures as

working fluids to reach higher coefficient of performance than traditional working flu-

ids. Thermodynamic modeling of a technological processes requires information on the

phase equilibrium and other thermodynamic properties of theNH3 − H2O mixtures.

The first attempt to obtain the VLE data on the ammonia-water system over the full

range of composition was made by Wilson, who measured the total vapor pressure VLE

data from 273.15 K to 364.15 K and up to 1.17 MPa. His study was further extrapolated

to 3.85 Mpa. Isobaric VLE of the systemNH3 − H2O are experimentally determined

at 14.69 and 65 psia in dilute solution of ammonia in water. The results obtained are

correlated in terms of the relative volatility [Polaket al. , 1975].

Vapor-liquid equilibrium data for the ammonia-water system over the complete com-

position range have been obtained at the temperature from 313.15 K and 588.7 K [Gille-

spieet al., 1987]. The total pressure method is used to obtain PTx data,and in a separate

procedure equilibrium vapor and liquid phase composition (PTxy data) are analyzed. The

PTx data is reduced to PTxy data using the Redlich - Kister activity coefficient expan-

sion with four parameter. The parameter of the Redlich-Kister expansion is obtained

by fitting the total pressure data using a least squares procedure. One PTxy is used to

evaluate the second cross virial coefficient. Relative volatility is calculated from the the

total pressure data, which are in good agreement with the values obtained from equilib-

rium phase measurements. The reduced data thus obtained is in good agreement with

11


the actual PTxy measurement, giving a thermodynamically consistant set of vapor-liquid

equilibrium measurements.

Syed et al. have measured the Isothermal vapor-liquid equilibrium data for the ammonia-

water system at temperatures from 306 to 618 K and at pressures up to 22 MPa [Syed

et al. , 1987]. The equilibrium temperatures, pressures, and the compositions of both liq-

uid and vapor phases are measured simultaneously and compaired results with literature.

The data is extended into the critical regions of the seven-phase envelopes at temperatures

between the critical points of ammonia and water.

Pressure-temperature-overall composition VLE data are determined for the ammonia-

water system at five temperatures between 293.15 and 413.15 Kand up to 500 psia

[Smolenet al. , 1991]. The measured data is correlated by means of Redlich-Kwong

equation of state modified to include Peneloux’s volume translation and a density-dependent

mixing rule. Different constants values in the vapor and liquid phases have used to achive

calculated vapor-phase composition with previous literature result.

The experimental data on phase equilibria in ammonia-watermixture are fitted on

basis of thermodynamic perturbation theory in the range of temperature (200 - 640 K)

and pressure (0.02 - 23 MPa) [Abovsky, 1996]. Data for the vapor-liquid equilibrium are

regressed by least square method. Effects of mixing on enthalpy and volume and some

deviations from one-fluid approximation is analyzed.

Mejbri et al. have model the ammonia-water refrigerant mixture by three different

approaches and compared with model [Mejbri and Bellagi, 2005]. The first is an empiri-

cal approach based on a free enthalpy model of the mixture considered as resultant of the

properties of its pure components and of an excess term corresponding to the deviation

to ideal solution concept. Secondly, a semi-empirical approach based on the PATEL and

TEJA cubic equation of state is considered. Finally, a theoretical approach formulated as

PC-SAFT (perturbed chain statistical associating fluid theory) equation of state is treated.

Comparison of these three methods proves the superiority ofPC-SAFT in predicting and

extrapolating the thermodynamic properties of the water-ammonia system up to very high

temperatures and pressures.

12


The PVTx properties ofNH3 − H2O mixture have been measured in the near and

supercritical regions. Measurements are made at temperatures from 301 to 634 K and

at pressures up to 28 MPa [Polikhronidiet al. , 2009]. Temperatures and densities at

the liquid-gas phase transition curve, dew and bubble-pressure points, and the critical

parameters for theNH3 −H2O mixture are obtained using the quasi-static thermograms

and isochoric break-point techniques.

2.2 Literature Survey for Ammonia - Water - Salt Sys-

tem

Vapor-liquid equilibrium data for the system ammonia - water and lithium bromide (LiBr)

at four temperatures, 303.15, 333.15, 373.15 and 423.15 K and pressures up to 1.5 MPa.

The salt concentration in the liquid phase was chosen in the range 5-60 mass % LiBr in

pure water [Peterset al. , 1994]. Similar type of experiments has done by Zimmermann

(1989) in the temperature range of 303 K to 423 K and pressuresup to 15 bar [Zimmer-

mann and Keller, 1989]. The analysis of the data obtained forthe two binary mixtures

ammonia-water and water- lithium bromide indicates, the static method to be useful to

measure VLE in theNH3 − H20 − LiBr system.

Boone et al. have explained the procedure for correlating the effect of non-volatile

salts on the vapor-liquid equilibrium of binary solvents [Booneet al. , 1976]. The pro-

cedure is based on estimating the influence of salt concentration of both components in

a pseudo-binary solution. Using this technique and Wilson parameter have determined

from the infinite dilution activity coefficients, precise estimation of bubble point temper-

ature and vapor phase composition is obtained over a range ofsalt and solvent composi-

tion.

Data for a number of alcohol-water system saturated with various inorganic salts have

been correlated by computing pseudo-activity coefficientsfor the volatile components

[Rousseauet al. , 1972]. Coefficient computed are readily correlated by means of the

Van-laar, Wilson and Renon equations.

13


A static method is used to obtain vapor liquid equilibrium data for the systems am-

monia - water - potassium hydroxide and ammonia - water - sodium hydroxide at tem-

peratures of 303 and 318 K and pressures from 0.1 to 1.3 MPa [Brasset al. , 2000]. The

salt concentration in the liquid phase is chosen in the rangefrom 2 to 60 mass % salt in

water. In both systemsNH3 − H2O − NaOH andNH3 − H2O − KOH, solid liquid

vapor equilibrium are observed. In theNH3−H2O−KOH system, liquid - liquid vapor

equilibrium is observed at 318 K and 1.1 MPa.

An equilibrium cell is used to measure thermal property of the ternaryNH3−H2O−

LiBr mixtures. The pressure and temperature data for their VLE data are measured at

ten temperature points between 15-850C, and pressures up to 2 MPa [Yuyuan and Tiehui,

2005]. The LiBr concentration of the solution is chosen in the range of 5-60% of mass

ratio of LiBr in pure water and ammonia concentration up to 0-60%. The VLE for the

NH3 − H2O − LiBr ternary solution is measured statically. The experimentalresults

show that the equilibrium pressures reduced by 30-50%, and the amount of component

of water in the gas phase reduced greatly to 2.5% at 700C temperature.

Vapor-liquid equilibrium of ammonia - water - potassium hydroxide and ammonia -

water - sodium hydroxide systems are measured by a static method from 293.15 K to

353.15 K. The experimental vapor pressure data has been correlated with temperature

and mass percent concentration using an analytical polynomial equation [Salaveraet al.

, 2005].

The vapor pressure of ammonia - lithium nitrate - water and ammonia - lithium ni-

trate mixtures is measured by a static method from 293.15 K to353.15 K in ammonia

mass fractions ranging from 0.2 to 0.6 [Liboteanet al. , 2007]. The equilibrium liquid

and vapor compositions are determined using the Redlich-Kister equation for activity co-

efficients of the liquid phase and the Redlich-Kwong equation of state for the modeling

the vapor phase nonideality. Vapor pressure, Temperature and liquid-phase composition

are correlated using an empirical equation. The capabilityof the electrolyte nonrandom

two liquid (E-NRTL) model to predict the VLE of the ternary mixture is evaluated by

comparing predicted and experimental data of the ammonia - lithium nitrate - water so-

14


lutions. The binary interaction parameters of ammonia - lithium nitrate needed for the

prediction of ternary VLE are determined from binary experimental data. The isobaric

data for the system methanol-water, ethanol-water and 1-propanol water, each saturated

with a inorganic salts is correlated by means of the Van-laar, Wilson and Renon equations

[Rousseauet al. , 1972]. Activity coefficients are calculated for each volatile component

using standard equation state for thermodynamic equilibrium.

The simultaneous solubility of sulfur dioxide and ammonia in aqueous solutions of

(ammonium sulfate or sodium sulfate) is measured by a synthetic method in the tempera-

ture range from 313.6 K to 373.2 K and at pressures up to 2.5 MPa[Meyeret al. , 2006].

The enthalpy change upon diluting aqueous solutions of sulfur dioxide, ammonia and

(ammonium sulfate or sodium sulfate) in aqueous solutions of the same salt is measured

in a batch calorimeter at about 313 K and 352 K. The experimental results are compaired

with predictions from a thermodynamic model for the vapor-liquid equilibrium and the

enthalpy of dilution of those chemical reacting systems. Inthat model, activity coeffi-

cients are calculated from Pitzer’s modality-scale-basedGibbs excess energy model.

15

Chapter 3

VLE of Ammonia - Water System

16


Vapor-liquid equilibrium, is a condition where a liquid andits vapor (gas phase) are

in equilibrium with each other, a condition or state where the rate of evaporation (liq-

uid changing to vapor) equals the rate of condensation (vapor changing to liquid) on a

molecular level such that there is no net (overall) vapor-liquid interconversion. Although

in theory equilibrium takes forever to reach, such an equilibrium is practically reached

in a relatively closed location if a liquid and its vapor are allowed to stand in contact

with each other long enough with no interference or only gradual interference from the

outside. Vapor-liquid equilibrium is at the heart of many chemical and envirmental en-

gineering processes and activities. Distillation, dryingand evaporation are all based on

VLE. For ideal solution, it is simple and we can separate any mixture of species with

different boiling points. For nonideal solution, the process is more complex, specially in

the case of ammonia-water mixture.

3.1 VLE Equations for Ammonia - Water Binary System

The starting point is the equality of the fugacity of each species in the two phases:

fi

V= fL

i

i = 1, 2, · · · · · · · · · · · · , N

where for the N-component mixturefi

Vis the fugacity of the component i in the vapor

phase andfLi is the fugacity of component i in the liquid phase. In the activity coefficient

approach the vapor-liquid equilibrium of ammonia-water system was calculated by using

the equation,

P φi yi = xi γi Psati φ sat

i exp

V Li (Pi −Psat

i )

RT

ff

(3.1)

Component 1: Ammonia

Component 2: Water

Correlation for calculating saturated temperature and saturated pressure of ammonia

and water are given as,

17


For Ammonia,

log P sat1 = 7.36048 −

926.13

T sat1 + 240.17

(3.2)

For Water,

log P sat2 = 8.07131−

1760.63

T sat2 − 233.426

(3.3)

whereP sat1 and P sat

2 are in mm Hg andT sat1 andT sat

2 are in0C

Equation of state analogous toRedlich-Kwongequation of state has been used, how-

ever, it also includes2nd and3rd virial coefficients [Gillespieet al. , 1987].

Z =V

V − b+

B − b

V+

C − b2

V 2(3.4)

where,

V molar volume

b,B,C Virial Coefficients

b is theRedlich-Kwongb, given as:

b = y1b1 + y2b2 (3.5)

where,

b1 = 21.11 andb2 = 15.0

Second Virial Coefficient (B):

B = y2

1B11 + 2y1y2B12 + y2

2B22 (3.6)

where,

B11 = 18.02

[1.898 −

(2641.62

T

)exp

(186210

T 2

)](3.7)

18


B22 = 0.926

[26.35 − 27.93

(exp

(725

T

)− 1.0

)](3.8)

B12 =1

2

[B∗

11

(Vc2

Vc1

)+ B∗

22

(Vc1

Vc2

)](3.9)

Vc1 andVc2 are critical volumes of water and ammonia respectively,

Vc1 = 56 cc/mol

Vc2 = 72.5 cc/mol

Here,B∗

11 meansB11 calculated from Eqn. 3.7, substitutingA12

Tfor 1

T. Similarly for

B∗

12

A12 = 0.944 + 0.0138(

1000

T

)2T < 405.9K

= 1.015 T ≥ 405.9K

Third Virial Coefficient (C):

C = y3

1C111 + 3y2

1y2C112 + 3y1y2

2C122 + y3

2C222 (3.10)

where,

C111 = 2097 (cc/mol)2

C222 = 4178 (cc/mol)2

3C112 = 2

(Vc2

Vc1

)C111 +

(Vc1

Vc2

)2

C222

3C122 = 2

(Vc1

Vc2

)C222 +

(Vc2

Vc1

)2

C111

Fugacities of Pure Species

Fugacity Coefficient of Pure Species,

Fugacity coefficient of pure species can be calculated by,

19


ln φi =1

RT

∫ V

∞

(RT

V− P

)dV − lnZ + (Z − 1) (3.11)

ln φi =

∫ V

∞

(1 − Z)dV

V− ln Z + (Z − 1)

substituting Z from Eqn. 3.4 in above Equation,

ln φi = ln

(V

V − b

)+

B − b

V+

2 (C − b2)

V 2− ln Z + Z − 1 (3.12)

Fugacity Coefficient of Pure Species in a Solution,

ln φi =1

RT

∫ V

∞

[RT

V− N

(∂P

∂Ni

)

T,V,Nj

]dV − ln Z (3.13)

For ammonia,

ln φ1 = (M1 + M2 + M3 + M4) − ln Z (3.14)

where,

M1 = log

(V

V − b

)

M2 =b2

V − b

M3 =− (b + b2 − 2 (y2B22 + y1B12))

V

T4A = 3y2

2C222 + 2y1y2C122F + y2

1C112F

M4 =− (b2 + 2bb2 − T4A)

2V 2

For Water,

20


ln φ2 = [M1 + M2 + M3 + M4] − ln Z (3.15)

M1 = log

(V

V − b

)

M2 =b1

V − b

M3 =− (b + b1 − 2 (y1B11 + y2B12))

V

M4A = 3y2

1C111 + 2y1y2C112F + y2

2C122F

M4 =(b2 + 2bb1 − M4A)

2V 2

where,

C111 = 2097 (cc/mol)2

C222 = 4178 (cc/mol)2

3C112 = 2

(Vc2

Vc1

)C111 +

(Vc1

Vc2

)2

C222

3C122 = 2

(Vc1

Vc2

)C222 +

(Vc2

Vc1

)2

C111

21

Chapter 4

VLE Measurements of Ammonia -

Water - Salt System

22


4.1 Experimental Set up

The use of rocket cell for ammonia-water system to study their equilibrium total vapor

pressure at varying temperature was initially measured by Gillespie et al. [Gillespieet al.

, 1987]. Similar type of setup with special arrangement of horizontal autoclave rotation

as shown in figure 4.1 was used for further research work. The volume of the autoclave

was 300 cm3 and the material of construction was SS 316. The digital pressure indicator

(Wika, Mumbai) with an accuracy of±0.25% was mounted on top of autoclave. The

autoclave has an arrangement for RTD sensor Pt 100 at the center. Temperature was

controlled and measured using a PID controller with an accuracy of 0.10C. Autoclave

was kept on oscillation, to attain better mixing and vapor-liquid phase equilibrium. The

oscillator stand was pivoted to motor with a rod connecting the flywheel which rotates

the autoclave to forward and backward direction.

T

P

M

G

F

H

A

PS

TS

C

B

Figure 4.1: Block Diagram of Vapor-Liquid Equilibrium set up.

(A, B = sampling tube; F = Flange; G = Gear box; T =Temperature indicator; PS =Pres-sure sensor; M = Motor; H = Casing containing heating coil; TS= Temperature sensor;V = Autoclave)

23


4.2 Materials

Ammonia solution (sp. gravity 0.89, 30% AR solution), potassium acetate (AR grade,

99.0% purity), and copper acetate (AR grade, 99% purity), ammonium sulphate (AR

grade, 99% purity), sodium thiocyanate (LR grade, 98% purity), sodium nitrate (AR

grade, 99.5%) and potassium nitrate (AR grade, 99.5% purity) were used for experimen-

tal work. All chemicals were purchased from M/S sd fine Chemicals Ltd Mumbai.

4.3 System Details

The vapor liquid equilibrium of ammonia-water mixture and water-ammonia-salt were

studied in 10K steps at varying temperature from 313.15 K to 403.15 K. Every set of

experiment were carried out for 45 minutes to attain equilibrium. The effect of differ-

ent concentration of salt additives on ammonia-water system was studied, as their small

presence in system exerts a significant effect on the relative volatility of the component.

Therefor the effect of salt on the VLE of ammonia-water system was studied at different

concentrations. The different salt additives as potassiumacetate, copper acetate, ammo-

nium sulphate, sodium thiocyanate, sodium nitrate and potassium nitrate at concentration

of 5, 10, 15 and 20 mass % was added to the mixture of water and ammonia at the con-

centration of 10, 20 and 30 mass% to study the ammonia-water-salt VLE system. Rocked

static VLE cell was used to generate the VLE data for ammonia-water system with addi-

tive.

4.4 Result and Discussion

Aim of the present research work, is to correlate the vapor pressure values obtained from

experimental data with Redlich-Kister and NRTL equations.VLE setup was calibrated

by using pure water, the obtained experimental vapor pressure values matches with the

literature values with 2% difference, as shown in figure 4.2.

24


90 100 110 120 130 140 150 160 170 180

Temperature 0C

0

1

2

3

4

5

6

7

8

Tot

al V

apor

Pre

ssur

e (a

tm)

Antonie EquationExperimetal

Figure 4.2: Vapor-Liquid equilibrium of Pure Water System.

30 40 50 60 70 80 90 100 110 120 130 140Temperature

oC

0

3

6

9

12

15

18

Tot

al V

apor

Pre

ssur

e (a

tm)

Pure water10 Mass% Ammonia20 Mass% Ammonia30 Mass% AmmoniaAntoine Equation for WaterGillespie et al.

Figure 4.3: Vapor-Liquid Equilibrium of Ammonia - Water System.

Vapor-liquid equilibrium data for the ammonia-water system over 10, 20 and 30

mass% composition, it had been obtained at the temperature from 313.15 K and 413.15

25


K. The total vapor pressure values at the same temperature, was found around 5% differ-

ence, which is in good agreement with the reported data [Gillespieet al., 1987] as shown

in figure 4.3.

4.5 VLE of Water - Salt Binary Mixture

In the present study, the VLE of water-salt binary mixture was also studied using six dif-

ferent salt. The effect of potassium acetate, copper acetate, ammonium sulphate, sodium

thiocyanate, sodium nitrate and potassium nitrate on the VLE of water was studied at 5,

10 and 15 mass%. It was found that the addition of salt reducesthe total vapor pressure

of system.

30 40 50 60 70 80 90 100 110 120 130 140

Temperature 0C

0

0.5

1

1.5

2

2.5

3

Tot

al V

apor

Pre

ssur

e (a

tm)

Antonie EquationPure Water5 Mass% CH

3COOK

10 Mass% CH3COOK

15 Mass% CH3COOK

Figure 4.4: VLE of Water - Potassium Acetate.

26


30 40 50 60 70 80 90 100 110 120 130 140

Temperature 0C

0

0.5

1

1.5

2

2.5

3

Tot

al V

apor

Pre

ssur

e (a

tm)

Antonie EquationPure Water5 Mass% (CH

3COO)

2Cu

10 Mass% (CH3COO)

2Cu

15 Mass% (CH3COO)

2Cu

Figure 4.5: VLE of Water - Copper Acetate.

It was observed that the addition of potassium acetate showed maximum reduction in

the total vapor pressure of system as compaired to copper acetate, due to high solubility

of potassium acetate in water. The total vapor pressure of water - potassium acetate and

water - copper acetate with salt concentration is shown in figure 4.4 and 4.5 respectively.

30 40 50 60 70 80 90 100 110 120 130 140

Temperature 0C

0

0.5

1

1.5

2

2.5

3

Tot

al V

apor

Pre

ssur

e (a

tm)

Antonie EquationPure water5 Mass% (NH

4)2SO

4

10 Mass% (NH4)2SO

4

15 Mass% (NH4)2SO

4

Figure 4.6: VLE of Water -Ammonium Sulphate.

27


30 40 50 60 70 80 90 100 110 120

Temperature 0C

0

0.25

0.5

0.75

1

1.25

1.5

Tot

al V

apor

Pre

ssur

e (a

tm)

Antonie EquationPure Water5 Mass% NaSCN10 Mass% NaSCN

Figure 4.7: VLE of Water - Sodium Thiocyanate.

30 40 50 60 70 80 90 100 110 120 130 140

Temperature 0C

0

0.5

1

1.5

2

2.5

3

Tot

al V

apor

Pre

ssur

e (a

tm)

Antonie EquationPure water5 Mass% NaNO

3

10 Mass% NaNO3

Figure 4.8: VLE of Water - Sodium Nitrate.

28


30 40 50 60 70 80 90 100 110 120 130 140

Temperaure 0C

0

0.5

1

1.5

2

2.5

3

Tot

al V

apor

Pre

ssur

e (a

tm)

Antonie EquationPure Water5 Mass% KNO

3

10 Mass% KNO3

Figure 4.9: VLE of Water - Potassium Nitrate.

Form figure 4.6 to 4.9, it was observed that, increase in the salt concentration in the

water showed negligible effect on the reduction in the totalvapor pressure of system.

Salting-in effect was due to the hydrophilic nature of sulphate, thiocyanate and nitrate

ion.

4.6 VLE of Ammonia - Water - Salt Systems

The different additives studied includes potassium acetate, copper acetate, ammonium

sulphate, sodium thiocynate, sodium nitrate and potassiumnitrate . All these additives

were tested at ammonia concentration of 10, 20 and 30 mass% {mass of ammonia / (mass

of ammonia + mass of water)} and at different concentrationsof additives.

4.6.1 Effect of Acetates(CH3COOK, (CH3COO)2Cu)

Following acetates were used to study the effect on the VLE ofammonia-water-salt sys-

tem.

29


1. Potassium Acetate

2. Copper Acetate

The effect of potassium acetate and copper acetate on the VLEof ammonia-water system

were studied at different conc. as shown in the figures from 4.10 to 4.15.

Potassium acetate was studied at 5, 10, 15 and 20 mass% of saltconcentration as

shown in figure form 4.10 to 4.12. Use of 5, 10, 15 and 20 mass% ofpotassium acetate

leads to salting-out at 10, 20 and 30 mass% of ammonia. It has been observed that, as the

concentration of salt increases, the total vapor pressure of the system increases for 10, 20

and 30 Mass% of ammonia, but salt effect is small on the total vapor pressure of system.

30 40 50 60 70 80 90 100 110 120 130 140

Temperature 0C

0

1

2

3

4

5

6

7

8

Tot

al V

apor

Pre

ssur

e (a

tm)

Gillespie et al.0 Mass% CH

3COOK

5 Mass% CH3COOK

10% CH3COOK

15% CH3COOK

20% CH3COOK

Figure 4.10: VLE of Ammonia - Water - Potassium Acetate in 10 Mass % AmmoniaSolution.

30


30 40 50 60 70 80 90 100 110 120 130 140

Temperature 0C

0

2

4

6

8

10

12

Tot

al V

apor

Pre

ssur

e (a

tm)


3COOK

5 Mass% CH3COOK

10 Mass% CH3COOK

15 Mass% CH3COOK


30 40 50 60 70 80 90 100 110 120 130 140

Temperature 0C

0

2

4

6

8

10

12

14

16

18

20

Tot

al V

apor

Pre

ssur

e (a

tm)


3COOK

5 Mass% CH3COOK

10 Mass% CH3COOK

15 Mass% CH3COOK

20 Mass% CH3COOK


Copper acetate was studied at 5, 10, 15 and 20 mass% of salt concentration as shown

in figure 4.13 to 4.15 at 10, 20 and 30 mass% of ammonia. Copper acetate shows a

salting-out effect, as we increase the salt conc. Also it wasobserved that, this effect

31


was increasing as the ammonia concentration was increased.Copper acetate showed

salting-out effect due to hydrophilic nature of acetate group. At high ammonia conc.

copper acetate showed salting-in effect, this may be due to interaction betweenCu++

and ammonia.

30 40 50 60 70 80 90 100 110 120 130 140Temperature

oC

0

1

2

3

4

5

6

7

Tot

al V

apor

Pre

ssur

e (a

tm)

Gillespie et al.Exp NH

3-H

2O

Exp 5 Mass% (CH3COO)

2Cu


2Cu


2Cu

Figure 4.13: VLE of Ammonia - Water - Copper Acetate in 10 Mass% Ammonia Solu-tion.

30 40 50 60 70 80 90 100 110 120 130 140Temperature

oC

0

1

2

3

4

5

6

7

8

9

10

11

12

Tot

al V

apor

Pre

ssur

e (a

tm)


3-H

2O


2Cu


2Cu


2Cu


2Cu


32


30 40 50 60 70 80 90 100 110 120 130 140Temperature

oC

0

3

6

9

12

15

18

Tot

al V

apor

Pre

ssur

e (a

tm)


3-H

2O


2Cu


2Cu


2Cu


2Cu


Acetate group is hydrophilic in nature. Because of the interactions of potassium

acetate and copper acetate with water, salting out effect was noticed. Potassium acetate

salt showed more salting-out effect as compared to the effect shown by copper salt. This

is due to more solubility of potassium salt in water than copper salt.

4.6.2 Effect of Ammonium Sulphate((NH4)2SO4)

The effect of ammonium sulphate on the VLE of ammonia-water system was studied at

different conc. as shown in the figures from 4.16 to 4.18. 5, 10, 15 and 20 mass% conc.

of salt were studied at 10, 20 and 30 mass% of ammonia, the saltshows the salting-

out effect. It was observed that, salting-out effect increases with conc. of ammonium

sulphate.

NH3 (aq) + H2O (aq) ⇋ NH+

4 (aq) + OH− (aq)

33


H2O (l) ⇋ H+ (aq) + OH− (aq)

(NH4)2SO4 (s) → 2NH+

4 (aq) + SO2−

4 (aq)

SO−2

4 ion is hydrophilic in nature and shows interaction with water, because of

the complex formation with water, salting-out effect was seen. Due to this, less water

molecule is available for ammonia, therefor free ammonia from ammonia-water mixture,

increases the total vapor pressure of the system. The complex formation ofSO−2

4 with

water molecule is given below.

SO2−

4 (aq) + H+ (aq) ⇋ HSO−

4 (aq)

30 40 50 60 70 80 90 100 110 120 130 140Temperature

oC

0

1

2

3

4

5

6

7

8

Tot

al V

apor

Pre

ssur

e (a

tm)


3-H

2O

Exp 5 Mass% (NH4)2SO

4


4


4


4

Figure 4.16: VLE of Ammonia - Water - Ammonium Sulphate in 10 Mass % AmmoniaSolution.

34


30 40 50 60 70 80 90 100 110 120 130 140Temperature

oC

0

2

4

6

8

10

12

14

Tot

al V

apor

Pre

ssur

e (a

tm)


3-H

2O


4


4


4


4

Figure 4.17: VLE of Ammonia-Water-Ammonium Sulphate in 20 Mass % Ammoniasolution.

30 40 50 60 70 80 90 100 110 120 130 140Temperature

oC

0

2

4

6

8

10

12

14

16

18

20

Tot

al V

apor

Pre

ssur

e (a

tm)


3-H

2O


4


4


4


4

Figure 4.18: VLE of Ammonia - Water - Ammonium Sulphate in 30 Mass % AmmoniaSolution.

35


4.6.3 Sodium Thiocyanate(NaSCN)

The effect of sodium thiocyanate on VLE of ammonia-water system studied at 5, 10, 15

and 20 mass% of salt on on 10, 20 and 30 mass% of ammonia as shownin figure 4.19 to

4.21.

From figure 4.19 to 4.21, we can observe that, as we increase the concentration of

salt in ammonia-water mixture, the system showed salting-out effect. This is due to the

hydrophilic nature ofSCN−ion, it showed a strong interaction with water molecule due

to electrostatic force of attraction. We can observe that, after 10 mass% of salt , effect

on total vapor pressure remains constant even after we increase the salt concentration, it

means that saturation of salt occures in the ammonia - water solution at 10 mass% salt.

30 40 50 60 70 80 90 100 110 120

Temperature 0C

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

Tot

al V

apor

Pre

ssur

e (a

tm)

Gillespie et alExp NH

3-H

2O

Exp 5 Mass% NaSCNExp 10 mass% NaSCNExp 15 Mass% NaSCN

Figure 4.19: VLE of Ammonia - Water - Sodium Thiocyanate in 10Mass % AmmoniaSolution.

36


30 40 50 60 70 80 90 100 110 120

Temperature 0C

0

1

2

3

4

5

6

7

8

Tot

al V

apor

Pre

ssur

e (a

tm)

Gillespie et alExp NH

3-H

2O

Exp 5 Mass% NaSCNExp 10 Mass% NaSCN


30 40 50 60 70 80 90 100 110 120

Temperature 0C

0

2

4

6

8

10

12

14

Tot

al V

apor

Pre

ssur

e (a

tm)


3-H

2O

Exp 5 Mass% NaSCNExp 10 Mass% NaSCNExp 15 Mass% NaSCNExp 20 Mass% NaSCN


37


4.6.4 Effect of Nitrates(NaNO3, KNO3)

1. Sodium Nitrate

2. Potassium Nitrate

The effect of Sodium and Potassium Nitrate on the VLE of ammonia - water system

were studied at different conc. as shown in the figures from figure 4.22 to 4.27. 5 and

10 mass%, 5, 10 and 15 mass% and 5, 10, 15 and 20 mass% conc. of salt were studied

at 10, 20 and 30 mass% of ammonia respectively as shown in figure 4.22 to 4.27. As we

increase the concentration of salt in ammonia-water mixture, the system showed salting-

in effect. but, increase in this salt concentration shows very negligible effect on the total

vapor pressure of the system. Sodium nitrate is more solublein ammonia than in water,

where this salt get solvated with ammonia and shows the salting-in effect.

30 40 50 60 70 80 90 100 110 120 130 140Temperature

oC

0

1

2

3

4

5

6

7

Tot

al V

apor

Pre

ssur

e (a

tm)


3-H

2O

Exp 5 Mass% NaNO3

Exp 10 Mass% NaNO3

Figure 4.22: VLE of Ammonia - Water - Sodium Nitrate in 10 Mass% Ammonia solu-tion.

38


30 40 50 60 70 80 90 100 110 120 130 140Temperaure

oC

0

1

2

3

4

5

6

7

8

9

10

11

12

Tot

al V

apor

Pre

ssur

e (a

tm)


3-H

2O

Exp 5 Mass% NaNO3

Exp 10 Mass% NaNO3

Exp 15 Mass% NaNO3

Figure 4.23: VLE of Ammonia-Water-Sodium Nitrate in 20 Mass% Ammonia Solution.

30 40 50 60 70 80 90 100 110 120 130 140Temperature

oC

0

2

4

6

8

10

12

14

16

18

20

Tot

al V

apor

Pre

ssur

e (a

tm)

NH3-H

2O, Gillespie et al.

Exp NH3-H

2O

Exp 5 Mass% NaNO3

Exp 10 Mass% NaNO3

Exp 15 Mass% NaNO3

Exp 20 Mass% NaNO3

Figure 4.24: VLE of Ammonia-Water-Sodium Nitrate in 30 Mass% Ammonia Solution.

Potassium Nitrate was studied at 5 and 10 mass% of salt concentration on 10, 20 and

30 Mass% of ammonia as shown in figure 4.25 to 4.27. It was observed that, as the salt

concentration increases, it was showing less salting-in effect on system.

39


30 40 50 60 70 80 90 100 110 120 130 140Temperature

oC

0

1

2

3

4

5

6

7

Tot

al V

apor

Pre

ssur

e (a

tm)


3-H

2O

Exp 5 Mass% KNO3

Figure 4.25: VLE of Ammonia - Water - Potassium Nitrate in 10 Mass % AmmoniaSolution.

30 40 50 60 70 80 90 100 110 120 130 140Temperature

oC

0

3

6

9

12

15

Tot

al V

apor

Pre

ssur

e (a

tm)


3-H

2O

Exp 5 Mass% KNO3

Figure 4.26: VLE of Ammonia - Water - Potassium Nitrate in 20 Mass % AmmoniaSolution

40


30 40 50 60 70 80 90 100 110 120 130 140Temperature

oC

0

3

6

9

12

15

18

Tot

al V

apor

Pre

ssur

e (a

tm)

NH3-H

2O Gillespie et al.

Exp NH3-H

2O

Exp 5 Mass% KNO3

Exp 10 Mass% KNO3

Figure 4.27: VLE of Ammonia - Water - Potassium Nitrate in 30 Mass % AmmoniaSolution

Sodium nitrate and potassium nitrate are more soluble in ammonia than in water,

where these salt get solvated with ammonia and showed the salting-in effect. Also it was

observed that both nitrate showed more or less same effect, this is due to the comparable

size of both sodium and potassium ions.

4.7 Data Fitting

4.7.1 Modeling of Ammonia - Water - Salt System by Redlich - Kister

Equation

The variations of total vapor pressure of ammonia-water-salt system with temperature

at different salt concentrations are given in the previous section 4.6. Attempts to fit

this VLE data using NRTL, Wilson and Tan-Wilson activity coefficient models did not

give satisfactory results [Gillespieet al. , 1987]. Gillespie et al. have successfully used

Redlich-Kister activity coefficient model model for ammonia-water binary system and

hence, this model was chosen for data fitting. A modified form of the equations was

41


used for this purpose. The equations given by Gillespie et al. [Gillespieet al. , 1987] for

ammonia-water system are as given below:

P = x1Psat1 γ1 + x2P

sat2 γ2 (4.1)

lnγ1 = x2

2

{A + B(x2 − x1) + C(x2 − x1)

2}

+ 2x2

2x1 {B + 2C (x2 − x1)} (4.2)

lnγ2 = x2

1

{A + B(x2 − x1) + C(x2 − x1)

2}− 2x2x

2

1 {B + 2C (x2 − x1)} (4.3)

Where,

γ1 - Activity coefficient of ammonia

γ2 - Activity coefficient of water

x1 andx2 are mole fractions of ammonia and water in the liquid phase

A, B and C are functions of temperature and given as follows;

A = −18.676 + 22.9345(1000/T )− 8.8293(1000/T )2 + 1.0286(1000/T )3 (4.4)

B = −0.5 T ≤ 450K (4.5)

B = 3.485 − 1.79(1000/T ) T > 450K (4.6)

C = −0.445 + 0.098(1000/T )2 (4.7)

The modified Redlich-Kister activity coefficient model usedfor Ammonia-Water-Salt

data fitting is as follows;

P = (1 − xsalt)(x1P

sat1 γ1 + x2P

sat2 γ2

)(4.8)

42


lnγ1 = x2

2

{A + B(x2 − x1) + C(x2 − x1)

2}

+ 2x2

2x1 {B + 2C (x2 − x1)} + a

lnγ2 = x2

1

{A + B(x2 − x1) + C(x2 − x1)

2}− 2x2x

2

1 {B + 2C (x2 − x1)} + b

The modified equation contains additional parameters a and bwhich are functions of

salt concentration and temperature.

x1 andx2 are mole fractions of ammonia and water in the liquid phase onsalt free

basis and are given as,

x1 =moles of ammonia

moles of ammonia + moles of water(4.9)

x2 =moles of water

moles of ammonia + moles of water(4.10)

Correlation for calculating saturated vapor pressure at a given temperature for ammo-

nia and water are given in equation 3.2 and 3.3.

a - lnγ of ammonia in the presence of salt but in the absence of water.

b - lnγ of water in the presence of salt but in the absence of ammonia.

In the present study, the liquid phase mole fractions of ammonia and waterx1, x2 and

total pressure P are measured. Vapor phase compositionsy1 andy2 are not measured.

The data sets ofx1, x2 and P at a particular temperature and salt concentration areused

in equations 4.8, 4.2 and 4.3 and to find the optimised values of a and b using scilab

program. The variation of a and b with salt concentration is expressed in terms of equa-

tions 4.11 and 4.12 respectively. The variations of coefficients for these equations with

temperature is given by from equations 4.14 to 4.17.

a = R1 xsalt + R2 xsalt (4.11)

b = K1 xsalt + K2 x2

salt (4.12)

43


where xsalt is the mole fraction of salt considering total salt dissociation and it is given

by

xsalt =moles of salt × ν

moles of ammonia + moles of water + (moles of salt × ν)× 100 (4.13)

whereν is the number of ions produced on the dissociation of one molecule of salt

R1 = D0 + D1 × T (4.14)

R2 = D2 + D3 × T (4.15)

K1 = E0 + E1 × T (4.16)

K2 = E2 + E3 × T (4.17)

The values of ’a’ and ’b’ would be zero in the absence of salt and the modified

Redlich-Kister activity coefficient equation reduces to the original Redlich-Kister activ-

ity coefficient equation for the ammonia-water system, given by Gillespie et al [Gillespie

et al. , 1987]. Here ’b’, which is lnγ of water in the presence of salt but in the absence

of ammonia was fitted with total pressure equation 4.8. Same correlation method for

experimental data can used for other salts and constants areevaluated using VLE data of

water-salt as shown in table 4.1.

44


Table 4.1: Redlich-Kister constants for Water - Salt

Salt D0 D1 D2 D3

Potassium Acetate 1.487 -0.017 0.001 0.018Copper Acetate 2.247 -0.017 0.001 0.231

Ammonium Sulphate 5.0 -0.027 99.571 -0.015Sodium Thiocyanate -5.0 -0.023 -0.001 -0.001

Sodium Nitrate 5.0 -0.023 -0.001 -0.001Potassium Nitrate 4.853 -0.021 -0.001 -0.001

Parity plot for water-salts system using the proposed modified Redlich-Kister activity

coefficient equation is shown in Figure 4.28 and 4.29, we can observed that, most of the

points are close to fitted line and showed a±5% error with experimental points.

0.0 0.5 1.0 1.5 2.0 2.50.0

0.5

1.0

1.5

2.0

2.5

Calculated Pressure (atm)

Mea

sure

d P

ress

ure

(atm

)

Figure 4.28: Parity plot for Bubble Pressure of Water - Potassium Acetate Mixture.

45


0.0 0.5 1.0 1.5 2.0 2.5 3.00.0

0.5

1.0

1.5

2.0

2.5

3.0


Mea

sure

d P

ress

ure

(atm

)

Figure 4.29: Parity plot for Bubble Pressure of Water - Copper Acetate Mixture.

0 0.02 0.04 0.06 0.08x

salt

0.9

0.95

1

1.05

1.1

P/(

P no s

alt (

1-x sa

lt))

Exp 40 0C

Exp 60 0C

Exp 80 0C

40 0C

60 0C

80 0C

Figure 4.30: P/(Pno salt(1 − xsalt)) for Water-Potassium Acetate Mixture.

Also, If we plot the graph of P/(Pno salt(1 − xsalt)) vs xsalt, it was observed that,

P/(Pno salt(1 − xsalt)) ratio increases with salt concentration. This ratio decreases with

46


temperature due to salting-in effect, as shown in above figure. Similar type of graph can

be drown for remaining salts.

on, ’a’ which is lnγ of ammonia in the presence of salt but in the absence of water,

was evaluated from the same equation using VLE data of ammonia-water-salt data and ’b’

constant. The constants for ’a’ are as shown in table 4.2. Parity plot for ammonia-water-

salts system using the proposed modified Redlich-Kister activity coefficient equation is

shown in Figure 4.31 and 4.32.

Table 4.2: Redlich-Kister constants for Ammonia - Water - Salt

Salt E0 E1 E2 E3

Potassium Acetate 5 -0.033 225.2 -0.251Copper Acetate 51.75 -0.166 183.6 0.931

Ammonium Sulphate 56.02 -0.161 -613.5 1.862Sodium Thiocyanate 5.0 -0.026 273.5 -0.639

Sodium Nitrate -5.0 -0.034 -500.0 2.032Potassium Nitrate -93.99 0.165 3907 -8.496

0 2 4 6 8 10 12 14 16 18 200

2

4

6

8

10

12

14

16

18

20


Mea

sure

d P

ress

ure

(atm

)

Figure 4.31: Parity plot for bubble pressure of Ammonia - Water - Potassium AcetateMixture.

47


0 2 4 6 8 10 12 14 160

2

4

6

8

10

12

14

16


Mea

sure

d P

ress

ure

(atm

)

Figure 4.32: Parity plot for Bubble Pressure of Ammonia - Water - Copper Acetate Mix-ture.

We can see that most of the data points lie close to the fitted line and showed maxi-

mum±5% error with experimental pressure. This shows that the results obtained by the

modified Redlich-Kister activity coefficient model are satisfactory. Similarly, parity plot

for remaining salt-water and ammonia-water-salt data can be drown.

After evaluating ’a’ and ’b’ constants for total pressure equation using ammonia-

water-salt and water-salt data respectively, the correlated value and experimental values

were compaired using total pressure equation. From figures it is observed that, the cor-

related pressure and experimental pressure are showed±5%, which is good agreement

with experimental data.

48


0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4x

1

0

0.5

1

1.5

2

2.5

3

3.5

4

Bub

ble

Pre

ssur

e (a

tm)

Exp NH3-H

2O

Exp 5 Mass% CH3COOK

Exp 10 Mass% CH3COOK



NH3-H

2O

5 Mass% CH3COOK

10 Mass% CH3COOK

15 Mass% CH3COOK

20 Mass% CH3COOK

Figure 4.33: Calculated Bubble Pressure of Ammonia - Water -Potassium Acetate at400C.

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1x

1

-2000

-1500

-1000

-500

0

500

GE J

/Mol

e

NH3-H

2O

5 Mass% CH3COOK

10 Mass% CH3COOK

15 Mass% CH3COOK

20 Mass% CH3COOK

Figure 4.34: Calculated Excess Gibbs free Energy of Ammonia- Water - PotassiumAcetate at 400C.

49


0 0.1 0.2 0.3x

1

0

1

2

3

4

5

6

Bub

ble

Pre

ssur

e (a

tm)

Exp NH3-H

2O

Exp 5 Mass% CH3COOK




NH3-H

2O

5 Mass% CH3COOK

10 Mass% CH3COOK

15 Mass% CH3COOK

20 Mass% CH3COOK


0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1x

1

-2000

-1500

-1000

-500

0

500

GE J

/Mol

e

NH3-H

2O

5 Mass% CH3COOK

10 Mass% CH3COOK

15 Mass% CH3COOK

20 Mass% CH3COOK

Figure 4.36: Calculated Excess Gibbs Free Energy of Ammonia- Water - PotassiumAcetate at 600C.

The graph of mole fraction of ammonia in vapor phase as shown in appendix showed

that, as we goes on increasing concentration of salt in ammonia-water mixture, the am-

50


monia mole fraction in vapor phase was increased. It means that, ammonia showed less

interaction with salt.

0 0.1 0.2 0.3 0.4x

1

0

1

2

3

4

5

6

7

8

9

10B

ubbl

e P

ress

ure

(atm

)Exp NH

3-H

2O

Exp 5 Mass% CH3COOK




NH3-H

2O

5 Mass% CH3COOK

10 Mass% CH3COOK

15 Mass% CH3COOK

20 Mass% CH3COOK


0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1x

1

-1500

-1250

-1000

-750

-500

-250

0

250

500

GE J

/Mol

e

NH3-H

2O

5 Mass% CH3COOK

10 Mass% CH3COOK

15 Mass% CH3COOK

20 Mass% CH3COOK


51


0 0.1 0.2 0.3 0.4x

1

0

3

6

9

12

15

Bub

ble

Pre

ssur

e (a

tm)

Exp NH3-H

2O

Exp 5 Mass% CH3COOK




NH3-H

2O

5 Mass% CH3COOK

10 Mass% CH3COOK

15 Mass% CH3COOK

20 Mass% CH3COOK


0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1x

1

-1000

-800

-600

-400

-200

0

200

GE J

/Mol

e

NH3-H

2O

5 Mass% CH3COOK

10 Mass% CH3COOK


20 Mass% CH3COOK


52


0 0.02 0.04 0.06x

salt

0.9

1

1.1

1.2

1.3

1.4

1.5

P/(

P no s

alt*(

1-x

salt))

Exp 10% NH3

Exp 20% NH3

Exp 30% NH3

10% NH3

20% NH3

30% NH3

Figure 4.41: P/(Pno salt(1 − xsalt)) for Ammonia - Water - Potassium Acetate mixture at400C.

0 0.02 0.04 0.06x

salt

0.8

1

1.2

1.4

1.6

1.8

P/(

P no s

alt*(

1-x

salt))

Exp 10% NH3

Exp 20% NH3

Exp 30% NH3

10% NH3

20% NH3

30% NH3

Figure 4.42: P/(Pno salt(1 − xsalt)) for Ammonia - Water - Potassium Acetate Mixture at600C.

53


0 0.02 0.04 0.06x

salt

1

1.1

1.2

1.3

P/(

P no s

alt(1

-xsa

lt))

Exp 10% NH3

Exp 20% NH3

Exp 30% NH3

10% NH3

20% NH3

30% NH3

Figure 4.43: P/(Pno salt(1 − xsalt)) for Ammonia - Water - Potassium Acetate Mixture at800C.

If we plot the graph of P/(Pno salt(1 − xsalt)) vs xsalt, it was observed that, as we

increases salt concentration, the P/(Pno salt(1−xsalt)) ratio also increases, due to salting-

out effect, as shown in figure from 4.41 to 4.43. Similar type of graph can be drown at

different temperature and for remaining salts too.

4.7.2 Modeling of Ammonia - Water - Salt System by NRTL Equa-

tion

The Non-Random Two Liquid model (short NRTL equation) is an activity coefficient

model that correlates the activity coefficients of i of a compound with its mole fractions

xi in the concerning liquid phase. It is frequently applied in the field of chemical engi-

neering to calculate phase equilibrium. The NRTL equation for the molar excess Gibbs

energy of a binary mixture as a function of mole fractionx1 andx2. The Three-parameter

(α, τ12, τ21) NRTL equation is

GE

RT= x1 x2

[τ21 G21

x1 + x2 G21

+τ12G12

x2+x1G12

](4.18)

where,

54


G12 = exp {−α12 τ12}

G21 = exp {−α12 τ21}

hereα12 is the non-randomness parameter, which, to a good approximation, does not

depend on the temperature and can often be estimated with sufficient accuracy from the

nature of compound 1 and 2 [Renon and M, 1969].τ12 andτ21 are the dimensionless

interaction parameter, which are related to the interaction energy parameter by;

τ12 =g12 − g22

RT

τ21 =g12 − g11

RT

from equation 4.18, the activity coefficient,γ1 andγ2 are obtained by differentiation.

The activity coefficients of ammonia is

lnγ1 = x2

2

[τ21

(G21

x1 + x2 G21

)2

+τ12 G12

(x2 + x1 G21)2

]

and activity coefficients of water is given by;

lnγ2 = x2

1

[τ12

(G12

x1 + x2 G12

)2

+τ21 G21

(x2 + x1 G21)2

]

and

τ12 = D0 + D1 × x + D2 × x2 + D3 × x3

τ21 = E0 + E1 × x + E2 × x2 + E3 × x3

55


4.7.2.1 Modeling of Ammonia - Water - Salt System by Psudobinary Method

In this study, a different pseudo binary approach was adopted, solvent 1, which salting

out, was designated as component1∗while the mixture of solvent 2 and the salt in a

constant mole ratio was designated component2∗. Defining the system in this manner

means that it can be treated as a binary and the equilibrium relationships governing the

behavior of the system can then be written as [Booneet al. , 1976],

γi xi f0

i∗ = φi yi P

where,

x∗

1 =n1

n1 + n2 + n3

and

x∗

2 =n1 + n2

n1 + n2 + n3

since the salt is nonvolatile,

y∗

i = yi

since salt have negligible solubility in the salting out component [Rousseauet al. ,

1972] ,

f 0

1∗ = P sat1

one of the effect of salt is to lower the vapor pressure pressure of the liquid in which

it is soluble. For water the vapor pressure lowering is almost a linear function of salt

concentration. Since the salts are more soluble in the water, however reference fugacity

for the latter component may be redefined as,

f 0

2∗ = P sat2∗ = P sat

2 − ∆P

56


Here, The NRTL constants are evaluated using scilab program, whereα12 for ammonia-

water system is 0.4 which is constant for ammonia-water-salt too.

0 0.1 0.2 0.3 0.4x

1*

0

0.5

1

1.5

2

2.5

3

3.5

Bub

ble

Pre

ssur

e (a

tm)

Exp NH3-H

2O

Exp 5 Mass% CH3COOK




NH3-H

2O

5 Mass% CH3COOK

10 Mass% CH3COOK

15 Mass% CH3COOK

20 Mass% CH3COOK


0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1x

1*

-2000

-1750

-1500

-1250

-1000

-750

-500

-250

0

GE J

/Mol

e

NH3-H

2O

NH3-H

2O-CH

3COOK, M=0.5

NHNH

3-H

2O-CH

3COOK, M=1

NH3-H

2O-CH

3COOK, M=1.5

NH3-H

2O-CH

3COOK, M=2


57


0 0.1 0.2 0.3 0.4x

1*

0

1

2

3

4

5

6

7

Bub

ble

Pre

ssur

e (a

tm)

Exp NH3-H

2O

Exp 5 Mass% CH3COOK




NH3-H

2O

5 Mass% CH3COOK

10 Mass% CH3COOK

15 Mass% CH3COOK

20 Mass% CH3COOK


0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1x

1*

-2000

-1750

-1500

-1250

-1000

-750

-500

-250

0

GE J

/Mol

e

NH3-H

2O

NH3-H

2O-CH

3COOK, M=0.5

NH3-H

2O-CH

3COOK, M=1

NH3-H

2O-CH

3COOK, M=1.5

NH3-H

2O-CH

3COOK, M=2


58


0 0.1 0.2 0.3 0.4x

1*

0

3

6

9

12

Bub

ble

Pre

ssur

e (a

tm)

Exp NH3-H

2O

Exp 5 Mass% CH3COOK




NH3-H

2O

5 Mass% CH3COOK

10 Mass% CH3COOK

15 Mass% CH3COOK

20 Mass% CH3COOK

Figure 4.48: Calculated Bubble Pressure of Ammonia - Water-Potassium Acetate at800C.

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1x

1*

-1500

-1250

-1000

-750

-500

-250

0

GE J

/Mol

e

NH3-H

2O

NH3H

3-H

2O-CH

3COOK, M=0.5

NH3-H

2O-CH

3COOK, M=1

NH3-H

2O-CH

3COOK, M=1.5

NH3-H

2O-CH

3COOK, M=2


59


0 0.1 0.2 0.3 0.4x

1*

0

5

10

15

20

Bub

ble

Pre

ssur

e (a

tm)

Exp NH3-H

2O

Exp 5 Mass% CH3COOK




NH3-H

2O

5 Mass% CH3COOK

10 Mass% CH3COOK

15 Mass% CH3COOK

20 Mass% CH3COOK


0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1x

1*

-1500

-1250

-1000

-750

-500

-250

0

GE J

/Mol

e

NH3-H

2O

NH3-H

2O-CH

3COOK, M=0.5

NH3-H

2O-CH

3COOK, M=1

NH3-H

2O-CH

3COOK, M=1.5

NH3-H

2O-CH

3COOK, M=2


From the figures we observed that, experimental pressure andcorrelated pressure

were showed± 5%. error. Also mole fraction of ammonia in vapor phase is increasing

as salt concentration increases. Same correlation method for experimental data can used

for other salts. Constants for other salt is given in tables form 4.3 to 4.14.

60


Table 4.3: Table showing values ofD0, D1, D2, and D3 at different Temperature forAmmonia - Water - Potassium Acetate Mixture.

Temperature0C D0 D1 D2 D3

40 0.109 -3.124 3.032 -0.82950 -1.998 3.264 -2.039 0.41460 -1.031 0.237 -0.091 0.02770 -0.602 0.600 -0.763 0.22880 0.457 -2.466 1.835 -0.44790 -0.835 0.651 -0.213 -0.019100 -0.731 1.020 -0.627 0.129110 0.254 -1.443 1.516 -0.404120 -0.452 1.749 -1.759 0.593130 -1.218 2.496 -1.210 0.267

Table 4.4: Table showing values ofE0, E1, E2, and E3 at different Temperature for Am-monia - Water - Potassium Acetate Mixture.

Temperature0C E0 E1 E2 E3

40 -1.660 1.878 -1.860 0.53350 0.026 -2.632 1.718 -0.34460 -0.636 -0.130 0.135 -0.03470 -0.915 -0.520 0.796 -0.23280 -1.963 2.871 -2.103 0.51990 -0.594 -0.245 -0.051 0.086100 -0.602 -0.788 0.501 -0.091110 -0.581 -1.062 0.728 -0.165120 -0.794 -0.977 1.008 -0.337130 0.060 -2.338 1.322 -0.277

Table 4.5: Table showing values ofD0, D1, D2, and D3 at different Temperature forAmmonia - Water - Copper Acetate Mixture.

Temperature0C D0 D1 D2 D3

40 6.804 -37.21 48.87 -18.8750 -0.030 3.317 -10.39 6.51260 -0.192 -1.345 0.961 -0.62170 -0.168 -1.688 0.547 0.32880 -1.692 7.276 -14.84 8.02990 0.001 -0.042 -2.903 1.920100 -1.455 5.596 -11.72 6.393110 0.202 -0.941 -1.393 1.033120 0.064 -1.363 0.725 0.087130 1.074 -8.324 16.39 -8.641

61


Table 4.6: Table showing values ofE0, E1, E2, and E3 at different Temperature for Am-monia - Water - Copper Acetate Mixture.

Temperature0C E0 E1 E2 E3

40 -10.10 49.13 -70.57 30.5350 -1.350 -3.556 10.520 -6.44860 -1.409 1.636 -1.090 0.62970 -1.255 1.254 0.831 -1.11580 0.683 -9.359 19.36 -10.4490 -1.150 -0.944 4.584 -2.609100 0.479 -7.290 15.44 -0.840110 -1.041 -0.573 3.938 -2.218120 -1.103 1.103 -0.434 -0.227130 -1.695 4.549 -9.062 4.788

Table 4.7: Table showing values ofD0, D1 and D2 at different Temperature for Am-monia - Water - Ammonium Sulphate Mixture.

Temperature0C D0 D1 D2

40 -0.834 -0.542 0.74350 -1.998 2.991 -1.13260 -1.508 1.188 -0.39270 -1.307 1.450 -0.56980 -0.987 0.150 0.01990 -0.824 0.739 -0.106100 -0.824 0.739 -0.106110 -2.940 6.849 -2.785120 1.203 0.016 -0.032130 1.227 0.144 -0.107

Table 4.8: Table showing values ofE0, E1 and E2 at different Temperature for Ammo-nia - Water - Ammonium Sulphate Mixture.

Temperature0C E0 E1 E2

40 -0.640 0.101 -0.39850 0.054 -1.977 0.74660 0.212 -1.215 0.47070 -0.129 -1.168 0.50380 -0.137 -0.076 -0.00790 -0.379 -0.654 0.177100 -0.174 0.019 -0.406110 0.679 -3.889 1.639120 -1.799 -0.038 0.082130 -1.843 -0.393 0.288

62


Table 4.9: Table showing values ofD0, D1 and D2 at different Temperature for Ammo-nia - Water - Sodium Thiocyanate Mixture.


40 0.641 1.889 -1.28250 -1.838 4.481 -1.77760 1.097 0.863 -0.57770 -0.995 3.514 -1.15480 -1.635 4.799 -1.94890 1.271 -0.055 0.019100 -0.875 0.552 -0.207110 -0.165 1.152 -0.478

Table 4.10: Table showing values ofE0, E1 and E2 at different Temperature for Am-monia - Water - Sodium Thiocyanate Mixture.


40 -2.181 -0.429 0.36250 -0.934 -1.845 0.74360 -2.136 -0.192 0.18170 -1.286 -1.184 0.39380 -0.843 -1.922 0.78790 -1.883 0.146 -0.049100 -0.769 -0.311 0.128110 -1.178 -0.505 0.024

Table 4.11: Table showing values ofD0, D1 and D2 at different Temperature for Am-monia - Water - Sodium Nitrate Mixture.


40 -0.657 -0.370 0.01550 -1.027 0.190 -0.04960 -0.762 0.072 -0.01370 -8.205 4.759 -0.67880 4.931 -3.957 0.65190 -0.239 -0.081 0.010100 -0.239 -0.095 0.010110 -0.161 1.236 -0.255120 1.261 0.016 -0.002130 1.270 0.013 -0.002

63


Table 4.12: Table showing values ofE0, E1 and E2 at different Temperature for Am-monia - Water - Sodium Nitrate Mixture.


40 -1.222 0.049 0.03950 -1.020 -0.248 0.05860 -1.109 -0.083 0.01170 -1.089 -0.248 0.03080 0.191 -1.128 0.19590 -1.307 0.079 -0.012100 -0.763 0.104 -0.005110 -2.066 0.037 0.011120 -1.194 -0.053 0.008130 -1.918 -0.058 0.008

Table 4.13: Table showing values ofD0 and D1 at different Temperature for Ammonia- Water - Potassium Nitrate Mixture.

Temperature0C D0 D1

40 -0.813 -0.25750 -0.819 -0.21160 -2.057 0.59170 -0.490 -0.12380 -0.639 -0.14490 -1.113 0.296100 -0.193 -0.258110 -0.256 -0.182120 -0791 1.029130 -0.020 0.649

Table 4.14: Table showing values ofE0 and E1 at different Temperature for Ammonia -Water - Potassium Nitrate Mixture.

Temperature0C E0 E1

40 -1.243 0.22450 -1.161 0.23560 0.590 -0.78370 -1.238 0.08380 -0.962 0.12690 -0.263 -0.388100 -1.197 0.224110 -0.993 0.132120 -0.863 -0.540130 -1.247 -0.401

64

Chapter 5

Conclusions

65


The addition of salt to binary Ammonia-water system changesthe VLE of system of

the solvents because of the interactions between the salt ions and solvent components.

VLE studies were necessary for ammonia-water-salt ternarysystem to suggest necessary

changes in AAR working fluid. The different additives studied includes Potassium Ac-

etate, Copper acetate, Ammonium Sulphate, Sodium Thiocyanate, Sodium Nitrate and

Potassium Nitrate using rocked static VLE cell at differentconcentrations of salt and

various temperature on 10, 20 and 30 mass% ammonia concentration.

Amongest the tested additives, potassium acetate showed maximum salting-out ef-

fect. The salting-out effect showed by the potassium acetate was mainly because of more

solubility and non reactive nature of salt as compaired to remaining salting-out salts.

Sodium nitrate showed a maximum salting-in effect as compared to potassium nitrate.

This is due to more salt get solvated with ammonia and showed the salting-in effect as

compaired to potassium nitrate. PTx data was generated for ammonia-water-salt ternary

system up to liquid phase ammonia concentration of 30 mass%.Redlich-Kister activity

coefficient model was modified to correlate the experimentalVLE data for ammonia -

water - salt system. The modified Redlich-Kister model showed maximum±5% error

with measured data. Also experimental VLE data was correlated using NRTL equation

by pseudo binary concept, showed maximum±5% error with measured data.

66

Chapter 6

Future Scope

67


Ionic liquids have been used by many researcheres for changing the VLE of binary

systems. These ionic liquids may have potential to alter theVLE of ammonia-water

system and hence, the studies using ionic liquids as an additives needs to be carried out.

There are lesser number of studies on ammonia-water system.VLE data for ammonia-

water-salt system is scarce and studies on the system shouldbe carried out using different

additives at different temperature and throughout the liquid phase ammonia concentra-

tion.

68

Nomenclature

69


Abbreviations

AAR Ammonia Absorption Refrigeration

f fugacity

G Gibb’s free energy

R Universal gas Constant

T Temperature, K

x Liquid phase mole fraction

y Vapor phase mole fraction

Z Compressibility factor

Subscripts

1 Ammonia

2 Water

c Critical

P Constant pressure

T Constant temperature

Superscripts

E Excess

sat Saturated

Greek Letters

γ Activity Coefficient

φ Fugacity Coefficient

70

Appendix

71


0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1x

1

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

y 1

NH3-H

2O

5 Mass% CH3COOK

10 Mass% CH3COOK

15 Mass% CH3COOK

20 Mass% CH3COOK

Figure 6.1: Calculated mole fraction of Ammonia in vapor phase for Ammonia - Water -Potassium Acetate at 400C using Redlich - Kister equation.

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1x

1

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

y 1

NH3-H

2O

5 Mass% CH3COOK

10 Mass% CH3COOK

15 Mass% CH3COOK

20 Mass% CH3COOK

Figure 6.2: Calculated mole fraction of Ammonia in vapor phase for Ammonia - Water -Potassium Acetate at 600C using Redlich - Kister Equation.

72


0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1x

1

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

y 1


0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1x

1

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

y 1

NH3-H

2O

5 Mass% CH3COOK

10 Mass% CH3COOK

15 Mass% CH3COOK

20 Mass% CH3COOK


73


0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1x

1*

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

y 1*

NH3-H

2O

NH3-H

2O-CH

3COOK, M=0.5

NH3-H

2O-CH

3COOK, M=1

NH3-H

2O-CH

3COOK, M=1.5

NH3-H

2O-CH

3COOK, M=2

Figure 6.5: Calculated mole fraction of Ammonia in vapor phase for Ammonia - Water -Potassium Acetate at 400C using NRTL Equation.

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1x

1*

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

y 1*

NH3-H

2O

NH3-H

2O-CH

3COOK, M=0.5

NH3-H

2O-CH

3COOK, M=1

NH3-H

2O-CH

3COOK, M=1.5

NH3-H

2O-CH

3COOK, M=2


74


0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1x

1*

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

y 1*

NH3-H

2O

NH3-H

2O-CH

3COOK, M=1.5

NH3-H

2O-CH

3COOK, M=1

NH3-H

2O-CH

3COOK, M=1.5

NH3-H

2O-CH

3COOK, M=2


0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1x

1*

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

y 1*

NH3-H

2O

NH3-H

2O-CH

3COOK, M=0.5

NH3-H

2O-CH

3COOK, M=1

NH3-H

2O-CH

3COOK, M=1.5

NH3-H

2O-CH

3COOK, M=2


75


Table 6.1: P/(Pno salt(1 − xsalt)) for Water - Potassium Acetate Mixture.

Temperature0C 5 Mass % 10 Mass % 15 Mass %

40 0.98 0.972 0.9450 0.99 0.81 0.9560 0.9 0.81 0.9170 0.97 0.90 0.9680 1.05 1.00 1.0590 0.95 0.95 0.97100 1.02 1.04 1.06110 0.98 0.99 1.02120 1 0.92 1.05130 0.98 0.99 1.02

Table 6.2: P/(Pno salt(1 − xsalt)) for Water- Copper Acetate Mixture.


40 0.96 0.97 0.950 0.95 0.96 0.8760 0.9 0.91 0.8570 0.98 0.99 0.9180 1.1 1.11 1.0290 1.01 1.02 0.94100 0.9 0.91 0.86110 1.05 1.07 0.95120 1.09 1.11 1130 1.06 1.07 1

Table 6.3:P /( P no salt (1 − xsalt ) ) for Water - Ammonium Sulphate Mixture.


40 1.01 1 1.0450 0.97 0.93 0.9360 0.85 0.86 0.8970 0.93 0.94 0.9580 0.9 0.86 0.8990 0.76 0.8 0.81100 0.67 0.68 0.7110 0.98 1 1.02120 1 1.03 1.05130 0.92 0.94 0.96

76


Table 6.4: P/(Pno salt(1 − xsalt)) for Water - Sodium Thiocyanate Mixture.

Temperature0C 5 Mass % 10 Mass %

40 0.98 0.9850 0.92 0.8260 0.89 0.8370 1 0.9280 0.98 1.0190 0.94 0.97100 1.02 1.05110 1.03 1.06

Table 6.5: P/(Pno salt(1 − xsalt)) for Water - Sodium Nitrate Mixture.


40 0.97 1.0150 0.93 0.9460 0.89 0.970 0.97 0.9680 1.00 1.0190 1.02 1.04100 1.02 1.05110 0.98 1120 1.05 1.07130 1.02 1.04

Table 6.6: P/(Pno salt(1 − xsalt)) for Water - Potassium Nitrate mixture.

Temp0C 5 Mass % 10 Mass %

40 0.98 150 0.92 0.9360 0.89 0.8570 0.97 0.9380 0.98 190 1.02 1.02100 1.02 1.04110 1.02 1.01120 1.04 1.07130 1.02 1.04

77


Table 6.7: P/(Pno salt(1−xsalt)) for Ammonia - Water - Potassium Acetate Mixture in 30Mass % Ammonia Solution.

Temperature0C 5 Mass % 10 Mass % 15 Mass % 20 Mass %

40 1.02 1.09 1.24 1.2850 1.08 1.17 1.32 1.3660 1.09 1.2 1.31 1.3870 1.09 1.2 1.3 1.3780 1.07 1.17 1.26 1.3390 1.08 1.12 1.2 1.28100 1.04 1.09 1.18 1.26110 1.03 1.08 1.12 1.2120 1.03 1.08 1.11 1.14130 1.02 1.05 1.07 1.11

Table 6.8: P/(Pno salt(1− xsalt)) for Ammonia - Water - Potassium Acetate mixture in 20Mass % Ammonia solution.

Temp0C 5 Mass % 10 Mass % 15 Mass % 20 Mass %

40 1.02 1.15 1.17 1.4750 1.2 1.33 1.42 1.5960 1.02 1.16 1.32 1.6170 1.05 1.13 1.25 1.4680 1.08 1.15 1.24 1.490 1.05 1.12 1.18 1.3100 1.04 1.09 1.19 1.29110 1.03 1.09 1.14 1.22120 1.03 1.08 1.11 1.18130 1.03 1.06 1.11 1.14

Table 6.9: P/(Pno salt(1−xsalt)) for Ammonia - Water - Potassium Acetate Mixture in 10Mass % Ammonia Solution.

Temperature0C 5 Mass % 10 Mass % 15 Mass% 20 Mass %

40 1.06 1.15 1.3 1.6650 1.14 1.59 1.64 1.9160 1.15 1.17 1.21 1.4470 1.14 1.23 1.25 1.3680 1.2 1.25 1.26 1.2990 1.11 1.2 1.22 1.24100 1.09 1.19 1.21 1.29110 1.12 1.17 1.24 1.29120 1.15 1.18 1.28 1.36130 1.05 1.17 1.24 1.38

78


Table 6.10: P/(Pno salt(1 − xsalt)) for Ammonia - Water - Copper Acetate Mixture in 30Mass % Ammonia Solution.


40 1.04 1.23 1.44 1.4650 1.21 1.35 1.46 1.5860 1.14 1.22 1.27 1.3270 1.12 1.22 1.27 1.3480 1.09 1.21 1.26 1.3190 1.05 1.15 1.23 1.32100 1.1 1.17 1.21 1.17110 1.03 1.11 1.15 1.1120 1.03 1.03 1.04 1.04130 0.93 0.94 0.94 0.94



40 0.93 0.94 1.37 1.3950 1.11 1.33 1.41 1.5760 1.01 1.1 1.25 1.3470 1.01 1.05 1.12 1.2480 1.03 1.06 1.12 1.1790 1.04 1.08 1.12 1.16100 1.01 1.03 1.06 1.1110 1.07 1.04 1.02 1120 1.06 1.05 1.05 1.03130 0.93 0.94 0.92 0.93



40 2.14 1 1

50 1.88 1.7 1.5360 1.45 1.33 1.3470 1.19 1.14 1.1580 1.17 1.18 1.190 1.11 1.03 1100 1.06 1.06 1.06110 1.07 1.04 1.03120 1.08 1.03 1.04130 0.98 1 1.01

79


Table 6.13:P/ (Pno salt (1−xsalt )) for Ammonia - Water - Ammonium Sulphate Mixturein 30 Mass % Ammonia Solution.


40 1.26 1.29 1.31 1.3450 1.3 1.32 1.35 1.4160 1.31 1.34 1.43 1.5370 1.2 1.28 1.33 1.3980 1.26 1.31 1.4 1.4490 1.2 1.25 1.31 1.37100 1.18 1.22 1.27 1.32110 1.02 1.06 1.09 1.11120 0.84 0.88 0.9 0.92130 0.72 0.76 0.78 0.8

Table 6.14:P/ (Pno salt(1−xsalt) ) for Ammonia - Water - Ammonium Sulphate Mixturein 20 Mass % Ammonia Solution.


40 1.17 1.29 1.52 2.1550 1.32 1.75 1.89 2.1160 1.28 1.48 1.62 1.970 1.17 1.35 1.39 1.6880 1.3 1.4 1.45 1.690 1.19 1.32 1.44 1.62100 1.14 1.3 1.45 1.5110 1.06 1.22 1.43 1.47120 1.01 1.07 1.19 1.31130 1.02 1.07 1.14 1.23

Table 6.15:P/( Pno salt (1−xsalt)) for Ammonia - Water - Ammonium Sulphate Mixturein 10 Mass % Ammonia Solution.


40 1.43 1.48 1.85 1.8850 1.26 1.28 1.31 1.3360 1.16 1.3 1.35 1.4570 1.12 1.23 1.26 1.2880 1.1 1.19 1.28 1.4590 1.04 1.11 1.2 1.33100 1.03 1.08 1.27 1.38110 1.06 1.13 1.28 1.37120 1.09 1.17 1.27 1.34130 1 1.11 1.13 1.33

80


Table 6.16:P/ (Pno salt (1−xsalt )) for Ammonia - Water - Sodium Thiocyanate Mixturein 30 Mass % of Ammonia Solution.


40 1.01 1.18 1.29 1.3150 1.06 1.16 1.21 1.2760 1.03 1.13 1.17 1.2470 1.04 1.1 1.12 1.1780 1.03 1.06 1.1 1.1690 1.04 1.08 1.11 1.16100 1.06 1.11 1.13 1.15110 1.05 1.1 1.11 1.14

Table 6.17:P/ (P no salt (1−xsalt )) for Ammonia - Water - Sodium Thiocyanate Mixturein 20 Mass % Ammonia Solution.


40 1.19 1.2250 1.44 1.54

60 1.36 1.3970 1.27 1.2980 1.21 1.23

90 1.21 1.23100 1.19 1.21110 1.13 1.16

Table 6.18:P/ ( P no salt (1 − xsalt ) ) for Ammonia - Water - Sodium Thiocyanate Mix-ture in 10 Mass % Ammonia Solution.


40 2.04 1.85 1.8950 1.59 1.62 1.65

60 1.46 1.34 1.3670 1.24 1.26 1.2980 1.34 1.28 1.2990 1.3 1.29 1.32100 1.26 1.24 1.25110 1.17 1.17 1.19

81


Table 6.19: P/(Pno salt(1 − xsalt)) for Ammonia - water - Sodium Nitrate Mixture in 30Mass % Ammonia Solution.


40 1.01 1.03 1.05 1.1350 1.01 1.03 1.05 1.0660 0.98 1 1.03 1.0470 1 1 1 1.0280 0.97 0.99 1.03 1.0690 1.01 1.05 1.1 1.12100 0.97 1 1.05 1.1110 0.91 0.94 1 1.04120 0.81 0.85 0.88 0.89130 0.72 0.74 0.78 0.79

Table 6.20: P/(Pno salt(1 − xsalt)) for Ammonia - Water - Sodium Nitrate Mixture in 20Mass % Ammonia Solution.


40 0.66 0.55 0.5550 0.94 0.93 0.87

60 0.97 0.9 0.970 0.99 0.91 0.8880 1 1 0.9790 1.01 0.99 0.98100 1.02 1 1110 1 0.95 0.97120 0.96 0.96 0.98130 0.97 0.96 0.98

Table 6.21: P/(Pno salt(1 − xsalt)) for Ammonia - Water - Sodium Nitrate Mixture in 10Mass % Ammonia Solution.


40 0.75 0.7750 0.85 0.77

60 1.02 1.0470 1.02 0.9580 1.03 0.9890 0.93 0.95100 0.95 0.94110 1.04 0.99120 1 1.02130 1 1.01

82


Table 6.22: P/(Pno salt(1 − xsalt)) for Ammonia - Water - Potassium Nitrate Mixture in30 Mass % Ammonia Solution.


40 1.01 1.0250 1.02 1.0460 1.01 1.0370 1.02 1.0380 1.01 1.0290 1.01 1.03100 1.02 1.04110 1.01 1120 0.87 0.84130 0.79 0.72


Temperature0C 5 Mass %

40 0.8150 0.97

60 0.8370 0.8780 0.990 0.92100 0.89110 0.89120 0.89130 0.76


Temperature0C 5 Mass %

40 0.6750 0.84

60 170 0.9580 0.9990 0.97100 0.94110 0.98120 1130 1.02

83

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