Thermo physical properties of acetone–zinc bromide for using in a low temperature driven absorption refrigeration machine

ORIGINAL

Thermo physical properties of acetone–zinc bromide for usingin a low temperature driven absorption refrigeration machine

Salman Ajib Æ Ali Karno

Received: 30 July 2007 / Accepted: 25 April 2008 / Published online: 14 May 2008

� Springer-Verlag 2008

Abstract Thermal physical properties (vapor pressure,

density, viscosity, specific heat capacity, specific electrical

resistance and specific enthalpy of mixing) of the solution

acetone–zinc bromide, which will be used as a working

solution in an absorption refrigeration machine, are mea-

sured and analyzed. The experimental data were correlated

with high accuracy. The required state diagrams (log p, T

and h, T) for this solution as well as the log P, h-diagram

for the pure acetone are calculated, represented, correlated

and discussed. The results indicate that the solution ace-

tone-zinc bromide might be suitable as a working solution

to operate an absorption refrigeration machine at low

temperature.

List of symbols

cp specific heat capacity (J/kg K)

H enthalpy (J)

DH enthalpy difference (J)

h specific enthalpy (J/kg)

Dh specific enthalpy difference (J/kg)

m mass (kg)

p pressure (N/m2)

ps vapor pressure(N/m2)

s specific entropy (J/kg K)

T temperature (�C, K)

v specific volume (m3/kg)

x absorbent mass fraction (kgZnBr2/kgsol) %

Greek symbols

n refrigerant concentration (kgAc/kgsol)

l dynamic viscosity (N s/m2)

q density (kg/m3)

qel specific electrical resistance (Ohm m)

Subscripts

A absorber

Ac acetone

C condenser

c critical

COP coefficient of performance

E evaporator

G generator

s saturated

sol solution

ZnBr2 zinc bromide

1 Introduction

A working solution for an absorption refrigeration machine

consists of a refrigerant and an absorbent. Both substances

must have the properties that the refrigerant shall be well

absorbed at cooling water temperatures of 20–40�C and

separable out of the solution again at desorption tempera-

tures higher than 50�C. Furthermore the working solution

shall fulfill the most or all the following requirements:

• Thermal and physical stability as well as chemical

compatibility

• Not explosive and no toxicity

• Low viscosity

• High heat of vaporization

• Low specific heat capacity and

• Low prices.

S. Ajib � A. Karno (&)

Department of Thermo and Magneto Fluid dynamics,

Ilmenau University of Technology, P.O. Box 100565,

98684 Ilmenau, Germany

e-mail: [email protected]

123

Heat Mass Transfer (2008) 45:61–70

DOI 10.1007/s00231-008-0409-1

In principle, the absorbent must have a high affinity for the

refrigerant and have a low freezing point as well as a higher

boiling point in comparison with the refrigerant so that the

absorbent absorbs the refrigerant well and can be desorbed

easily [1].

The two most common working solutions for absorption

refrigeration machines are: NH3–H2O with ammonia (NH3)

as refrigerant and water (H2O) as absorbent and H2O–LiBr

with water (H2O) as refrigerant and lithium bromide (LiBr)

as absorbent.

The NH3–H2O solution is well suitable for the cold

production under 0�C particularly. The use of flat plate

solar collectors is not sufficient to supply the generator

with a temperature of at least 120�C. Vacuum tube col-

lectors are rather suitable here. In addition, the generator

must be connected with a rectifier so that the water vapour

can be separated from the ammonia vapour. Sierra et al. [2]

have built a laboratory model for an ammonia water

absorption refrigerator. Their machine was driven by a

heating medium with a temperature about 80�C. The

results show that the machine has achieved an evaporation

temperature of less than -2�C at a desorption temperature

of 73�C without problems. However, the reached coeffi-

cient of performance (COP) of the machine, which is

defined as the refrigeration rate over the rate of heat sup-

plied to the generator, was only between 0.24 and 0.28.

Other plants of small capacity with the working solution of

ammonia water were investigated experimentally also in

the works [3–6]. The two of the referenced systems are

diffusion absorption systems, which need a high generation

temperature and have a low COP. The system mentioned in

[3] is with aircooling for the condenser and absorber. The

temperature of cooling water of the system mentioned in

[6] is for absorber 30/35�C and the hot-water temperature

is 147�C. The measured COP amounted 0.2 till 0.3. The

operation of these plants depended upon the outside tem-

peratures and type of the solar collectors with the heating

temperature between 80 and 200�C. The obtained COPs

were between 0.12 and 0.50 at evaporation temperatures of

-18 to 10�C. As a heating source in these plants were

served either high efficient flat plate solar collectors or

vacuum tube collectors. Both collector types are more

expensive compared with the standard economical flat plate

solar collectors. It is known that the higher the needed

work temperature of the flat plate collectors the lower is the

efficiency of such collectors therefore it is prefer to use

work pairs, which can be driven at low generation tem-

perature in the absorption refrigeration machine.

The H2O–LiBr solution needs a desorption temperature

of 75–96�C to be able to operate the absorption refrigera-

tion machine at evaporation temperatures above 4�C

satisfactorily. A disadvantage of the H2O–LiBr solution

would be the possible crystallization of LiBr in the

absorber. To realize the cold production with low tem-

perature drive sources from flat plate solar collectors many

plants were built up and investigated with the working

solution water lithium bromide. These plants were tested

depending upon the cooling water temperatures with a hot

water temperature between 65 and 105�C [7–9]. The results

show that the produced cold is between 6 and 16�C and the

reached COPs are between 0.6 and 0.8.

As above mentioned, a disadvantage of the two common

working solutions is that they require temperature in the

generator of at least 65�C. Therefore we looked for new

working solutions, which may enable to drive the absorp-

tion refrigeration machine with a low drive temperature

(about 55�C).

Within the last 10 years numerous suggestions were

made to find new working solutions [10–13] whose

refrigerant is separable at low-drive temperatures (about

55�C) in the generator and therefore makes use of the flat

plate solar collectors to drive the absorption refrigeration

machine possible.

Pilatowsky et al. [12] have suggested the working solu-

tion monomethylamine–water to run the plant at low

temperatures of 60–80�C. The operating characteristic of

the plant with this new working solution were analyzed and

discussed theoretically, obtaining evaporation temperatures

from -5�C to 10�C and COP from 0.05 to 0.55 at desorp-

tion temperature of 60�C. However, the disadvantage of this

solution is that the COP is low and a rectification for the

vapor produced in the generator is required.

Lucas et al. [13] have suggested the absorbent (LiBr:

CHO2K = 2:1) instead of the pure lithium bromide for the

refrigerant (H2O) to lower the required drive temperature.

Using a simulation model of the system the authors have

calculated the thermal parameters of the machine with this

new working solution. The results have shown that the

machine can produce a cold temperature of 6�C with a

COP of 0.85 at a desorption temperature of 56�C. How-

ever, a disadvantage of the working solution is that the

absorption temperature must be 15�C and the condensation

temperature 46�C for the provided results. These two

temperatures are not practicable in the range of the outside

temperatures. That means one needs heat source for driving

the absorption refrigeration machine and cold source for

supply with cooling water.

We have made many investigations at the working

solution acetone/ZnBr2. Firstly we studied and analyzed

the thermo physical properties of the work pair in the

laboratory [10, 11]. After that we tested the ability to use of

the work pair as work solution in an absorption refrigera-

tion machine with a refrigeration capacity of 10 kW.

The results of investigation have shown that the

absorption refrigeration machine could be driven at tem-

perature up 55�C with a cold-water temperature of 13�C

62 Heat Mass Transfer (2008) 45:61–70

123

and cooling water of 27�C. The refrigeration capacity

amounted ca. 2–3 kW and the COP can be improved to be

in the range of 0.4 till 0.7 [1, 14]. That means there is an

important potential by using of this new working solution

in the low temperature driven absorption refrigeration

machine. The planed application of this working pair is for

air conditioning and for supply with cold water for indus-

trial processes, especially in Europe.

In the following we are going to illustrate the thermo

physical properties of this investigated working solution

(acetone/ZnBr2).

2 Results of experimental investigation

Before using a new working solution in an absorption

refrigeration system, it is very important to know its ther-

modynamic properties and its chemical stability. These

properties have a great influence on the efficiency of the

refrigeration system and on the required operating tem-

peratures. Therefore many experimental investigations

have been realized to determine the thermodynamic prop-

erties of the suggested working solution (acetone–zinc

bromide). The thermo physical properties are measured at

liquid saturated state at the atmospherically pressure or

vapor pressure. The uncertainties for the experiments were

depending on the measured properties and on the measur-

ing devices. More details about that are given in [11].

The experiments of the solubility have shown that the

solubility of the absorbent zinc bromide is very high in the

refrigerant so that solutions can be used for investigation in

a broad range of absorbent mass fractions [30–70%, (kgzinc

bromide/kgsolution)] at the solution temperature of 20�C.

The experiments of dissolubility of acetone from the

solution have shown that at a concentration of 30% of zinc

bromide nearly all of the acetone has been evaporated at a

temperature of 50�C and a pressure of 750 mbar (mea-

suring value). That means that the acetone could be driven

out from the solution at the given conditions. Other

experiment conditions have been investigated (other tem-

perature and other concentrations). The investigation

results are shown in the appendix.

The system acetone–zinc bromide has been tested to

operate as a work solution in an absorption refrigerator at

low temperature and therefore many experiments have

been realized to determine its thermodynamic properties

(density, viscosity, specific heat capacity, specific electrical

resistance, vapor pressure and enthalpy) [10, 11].

2.1 Density

The density was measured at various concentrations in

the range of temperatures from 0 to 36�C [11]. The

experimental results are plotted in Fig. 1 and correlated as

follows:

q ¼ 1:051385 � 0:002577258 � T þ 4:75227e� 6ð Þ � x3

ðg=cm3Þ ð1Þ

The used units for temperature T is (�C) and for 9 (kgzinc

bromide/kgsolution)%. The given correlation equation was

adapted in the temperature and concentration ranges of

0–36�C and from 30 to 50 mass% of zinc bromide,

respectively. The calculated values are plotted in Fig. 1. At

the comparison with the experimental results, it is clear,

that the equation 1 provides a very good result with about

2% deviation.

2.2 Specific heat capacity

The specific heat capacity of the solution acetone-zinc

bromide has been measured with Differential Scanning

Calorimeter DSC 7 at the Jena University [11]. The

measurements have been accomplished at different tem-

peratures and different concentrations of zinc bromide at

the Ilmenau University of Technology. The results of the

investigations are shown in Fig. 2.

The proof of the results at the laboratory of the Ilmenau

University of Technology has confirmed the investigation

results with a deviation of ±2%. A new correlation has

been derived for the specific heat capacity of the liquid

solution of acetone-zinc bromide as a function of the

solution temperature in (�C) and the concentration 9 in

(kgzinc bromide/kgsolution)% as follows:

cp¼1= 0:60901191�0:000977949�Tþ 8:121438e�5ð Þ�x2� �

kJ=kgKð Þ ð2Þ

The given correlation equation was adapted in the tem-

perature and concentration ranges of 0–70�C and from 30

to 70 mass% of zinc bromide, respectively. The used units

0,901,001,101,201,301,401,501,601,701,801,902,002,102,202,302,402,502,602,70

10 15 20 25 30 35 40 45 50 55 60 65 70 75 80

Temperature [°C]

Den

sity

[g

/cm

³]

70%

65%

60%

55%

50%

45%

40%

35%

30%

Zinc bromidemass fraction

Fig. 1 The density of the solution acetone–zinc bromide depending

upon the temperature and concentration

Heat Mass Transfer (2008) 45:61–70 63

123

for temperature T is (�C) and for 9 (kgzinc bromide/

kgsolution)%.

2.3 Dynamic viscosity

The knowledge of the viscosity of the solution is important

for heat and mass transfer performance. The measuring of

the solution viscosity was achieved with the Universal

Dynamic Spectrometer UDS at different Temperatures and

different concentrations of the salt zinc bromide [11]. The

investigation results are shown in Fig. 3.

It is clear from Fig. 3 that, the viscosity of the solution

increases to a large extent with an increase in the zinc

bromide concentration and slowly decreases with increas-

ing temperature. A new correlation equation was also

derived for the calculation of the dynamic viscosity of the

liquid solution of acetone–zinc bromide as a function of the

solution temperature in (�C) and the concentration 9 in

(kgzinc bromide/kgsolution)% as follows:

l ¼ aþ b � T þ c � T2 þ d � xþ e � x2 þ f � x3

1þ g � T þ h � xþ i � x2 þ j � x3mPa sð Þ

ð3Þ


perature and concentration ranges of 20–80�C and from 30

to 70 mass% of zinc bromide, respectively. The coeffi-

cients for this equation are listed in the Table 1. The used

units for temperature T is (�C) and for 9 (kgzinc bromide/

kgsolution)%.

2.4 Specific electrical resistance

The specific electrical resistance of the working solution

has been measured with the CMD 210 Conductivity Meter.

The measured values have been obtained at different

temperatures and concentrations of the solution. These

values are illustrated in Fig. 4.

The specific electrical resistance of the working solu-

tion is an important property of the solution and can be

used for determination of the concentration of the solution

(till the concentration of 55% acetone) and according to

that for the control of the capacity of the absorption

refrigeration machine [15]. The experimental values are

correlated with the following equation, which expresses

specific electrical resistance as a function of temperature

and concentration:

qel ¼ aþ bT�1 þ cn�1 þ dT�2 þ en�2 þ fT�1n�1

þ gT�3 þ hn�3 þ iT�1n�2 þ jT�2n�1 Ohm cmð Þð4Þ

The used units for Temperature T is (�C) and for n(kgacetone/kgsolution)%. The given correlation was adapted in

the temperature and concentration ranges of 25–50�C and

from 30 to 70 mass% of the refrigerant acetone, respec-

tively. The coefficients for this equation are listed in the

Table 2.

3 Generation of state diagrams

3.1 Log P, T diagram

The plotting of (log P, T) diagram is needed to determine

the solution concentration range of the operating process of

the absorption refrigeration machine. According to this

range one can determine the necessary heat source tem-

perature to operate the machine depending upon the

boundary conditions. For the preparation of this diagram

0,8

1

1,2

1,4

1,6

1,8

2

25 35 45 55 65 75 85

Temperature [°C]

Correlation equation

Measurement

Sp

ecif

ic h

eat

cap

acit

y [k

J/kg

.K]


31%

70%

50%

Fig. 2 The specific heat capacity of the solution acetone–zinc

bromide depending upon the temperature and concentration

0,1

1

10

100

1000

10000

15 20 25 30 35 40 45 50 55 60 65

Temperature [°C]

Dyn

amic

vis

cosi

ty [

mP

a.s] Correlation equation

Measurement


70%

60%

50%40%30%

Fig. 3 The dynamic viscosity of the solution acetone–zinc bromide

depending upon the temperature and concentration

Table 1 Coefficients for the calculation of the dynamic viscosity of

the liquid solution of acetone–zinc bromide with the Eq. 3

a 0.051106738 f 2.0606201 E-6

b -0.001617253 g 5.6658661 E-6

c 1.0151165 E-5 h -0.044457163

d 0.0094957964 i 0.0006597168

e -0.0002753312 j -3.2670638 E-6


123

for the solution acetone–zinc bromide, the vapor pressure

must be measured for pure acetone as well as for the

solution acetone–zinc bromide.

Vapor pressures PS of many pure substances are known

from the literature and are described by correlation equa-

tions, e.g., the Antoine equations [16] as follows:

lnPs

Pc

� �¼ 1� yð Þ�1 ayþ by1;5 þ cy3 þ dy6

� �ð5Þ

With y ¼ 1� T

Tcð6Þ

The parameters of these equations for acetone can be

obtained from [17] as follows:

a = -7.45514, b = +1.202, c = -2.43926, d =

-3.3559

The vapor pressures for the solution acetone-zinc bro-

mide were measured at various concentrations (from a

minimal concentration of 30–66% in steps of 5%) in the

range of temperature (from 0 to 70�C). The maximum

deviation of measurements and calculations for the vapor

pressure amounts 15.85% at temperature of 58.1�C and

concentration of 30% (kgzinc bromide/kgsolution). The mini-

mum is 0.04% at temperature of 19.3�C and concentration

of 30% (kgzinc bromide/kgsolution). The experimental values

are correlated with the following equation, which expresses

vapor pressure as a function of temperature and concen-

tration [11]:

Psacetone�zinc bromide¼ exp

X2

i¼0

X2

j¼0

aij � Ti � xj barð Þ ð7Þ

The used units for temperature T is (�C) and for 9 (kgzinc

bromide/kgsolution)%. The coefficients for this equation are

listed in the Table 3.

The calculated results from Eqs. (5, 6 and 7) are plotted

in Fig. 5. Also the high viscosity line (crystallization line)

is clear in the diagram. Under this line the absorption

refrigeration machine cannot be operated. By using the

solution as work solution in the absorption refrigeration

machine one has to take in account this limitation.

3.2 Temperature–enthalpy diagram

The enthalpy change DH due to the mixing of components

‘‘a’’ and ‘‘b’’ to form solution ‘‘c’’, at the same pressure and

temperature, are given by [18]:

DH ¼ Hc � Ha þ Hbð Þ ð8Þ

If ‘‘a’’ represents the acetone (Ac), ‘‘b’’ the zinc bromide

(ZnBr2), and ‘‘c’’ the acetone-zinc bromide solution (sol),

Eq. 8 may be written:

DH ¼ Hsol � HAc þ HZnBr2ð Þ ð9Þ

The enthalpy H can be replaced with the specific enthalpy h

and the mass m as follows:

DH ¼ mAc þ mZnBr2ð Þ � hsol � mAc � hAc � mZnBr2

� hZnBr2

ð10Þ

The reference state for zero enthalpy was chosen as 40�C

for the absorbent zinc bromide. The Eq. 10 becomes:

DHj40�

C¼ mAc þ mZnBr2ð Þ � hsolj40

�C�mAc � hAcj40

�C ð11Þ

Rearranging:

hsolj40�

C¼mAc � hAcj40

�CþDHj40

�C

mAc þ mZnBr2

ð12Þ

Using the following relationship (concentration of the

refrigerant in the solution) into the Eq. 12,

n ¼ mAc

mAc þ mZnBr2

kgAc=kgsolð Þ ð13Þ

Then the Eq. 12 becomes:

hsolj40�

C¼ n � hAcj40�

CþDhj40�

C ð14Þ

0

200

400

600

800

1000

1200

1400

1600

1800

2000

30 35 40 45 50 55 60 65 70

Acetone mass fraction [%]

Sp

ecif

ic r

esis

tan

ce [

Oh

m.c

m]

25°C30°C35°C40°C45°C50°C

Fig. 4 The specific electrical resistance for the solution acetone–zinc

bromide depending upon the temperature and concentration

Table 2 Coefficients for the calculation of the specific electrical

resistance of the solution acetone–zinc bromide with the Eq. 4

a 1,605 f -384,661

b 26,741 g 2,454,940

c -158,568 h -1,234 E+8

d 237,886 i 1,936 E+8

e 6,183,595 j -33,760,052

Table 3 Coefficients for the calculation of the vapor pressure of the

solution acetone–zinc bromide with the Eq. 7

a00 -2.41 E+0 a10 5.35 E-2 a20 -2.13 E-4

a01 1.72 E-2 a11 -1.16 E-4 a21 3.66 E-6

a02 -5.58 E-4 a12 2.38 E-6 a22 -4.61 E-8


123

where Dh is the specific enthalpy of mixing:

Dh ¼ DH

mAc þ mZnBr2

kJ=kgsolð Þ ð15Þ

Experiments for the determination of the specific enthalpy

of mixing were carried out by acetone–zinc bromide at the

temperature 40�C [11]. The experimental results can be

correlated as follows:

Dhj40�

C¼ 80:275 � n� 92:927 kJ=kgsolð Þ ð16Þ

The validity range of this equation is 4.4 till 31.2% (kgzinc

bromide/kgsolution).

The specific enthalpy for pure acetone at the tempera-

ture 40�C is:

hAcj40�

C¼ 265:6 kJ=kgð Þ ð17Þ

Substituting equations (16, 17) into (14):

hsolj40�

C¼ 345:875 � n� 92:927 kJ=kgsolð Þ ð18Þ

Equation 18 was used in obtaining the enthalpy–

concentration curve at 40�C. The change in enthalpy with

temperature from the 40�C curve, at a given concentration,

was obtained from reference [18]:

Dhsol ¼ZT2

T1

cp � dT ffi �cp T2 � T1ð Þ ð19Þ

where �cp is the mean value of specific heat capacity of the

solution between T1 and T2, which can be calculated from

equation 2. The temperature–enthalpy diagram for the

solution acetone–zinc bromide is shown in Fig. 6.

The calculated results are correlated with the following

equation, which expresses the specific enthalpy of the

solution as a function of temperature and concentration:

hAc�ZiBr2¼X1

i¼0

X4

j¼0

aij � xi � Tj kJ=kgsolð Þ ð20Þ


perature and concentration ranges of 0–70�C and from 0 to

70 mass% of zinc bromide, respectively. The used units for

temperature T is (�C) and for 9 (kgzinc bromide/kgsolution)%.

The coefficients for this equation are listed in the Table 4.

3.3 Mollier log P, h-diagram of the pure acetone

As a comparison process, the Mollier log P, h-diagram is

preferred in the refrigeration technology. In this diagram,

the difference of enthalpy can be read as lines so that a

simple calculation of the specific energies, the amounts of

energy, the evaporation enthalpy and the thermal perfor-

mance is possible. With the thermal properties for pure

acetone, which are documented sufficiently in the literature

a simple Mollier log P, h-diagram was generated (Fig. 7).

10

100

1000

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90

Temperature [°C]

Vap

or

pre

ssu

re [

mb

ar]

ξ=0,34ξ=0,50 ξ=0,40ξ=0,60ξ=1,00

800

200

300

400

500600

80

20

30

40

5060

ξ=0,30

ξ=0,20

High viscosity line

Fig. 5 Log P, T-diagram for

the solution acetone-zinc

bromide

-50

0

50

100

150

200

250

300

0 10 20 30 40 50

Temperature [°C]

En

thal

py

[KJ/

Kg

]

60

0,3

0,4

0,5

0,6

0,7

0,8

0,9

1

Concentration of acetone[Kg Ac/ Kg sol]

Fig. 6 The temperature–enthalpy diagram for the solution acetone–

zinc bromide depending upon the concentration


123

New correlations for the values of the enthalpy as well

as of the evaporation enthalpy were derived from this

diagram in the boiling temperatures range of -70 to 230�C

as follows:

The enthalpy of the saturated liquid:

h0 ¼ 177:185þ 2:154 � Ts þ 1:06 e� 5ð Þ � T3s kJ=kgð Þ

ð21Þ

The enthalpy of the saturated vapor:

h00 ¼ 1�

0:001336� 2:172e� 6ð Þ � Ts þ 2 e� 11ð Þ � T3s

� �

kJ=kgð Þ ð22Þ

The evaporation enthalpy:

Dh ¼ 575:5� 1:048 � Ts � 7:833 e� 5ð Þ � T2:5s kJ=kgð Þ

ð23Þ

These are also correlation equations for all parameters (h,

v, cp, s) in the area of the saturated superheated vapor,

which were adapted in the temperature and pressure range

of -80 to 280�C and from 0.0001 bar to 100 bar,

respectively.

h ¼ e6:62þ0:0017�T�0:003�p kJ=kgð Þ ð24Þ

v ¼ e�0:917þ0:0026�T�ln p m3=kg� �

ð25Þ

cp ¼ 1225:49þ 2:73 � T þ 17:62 � p J=kg Kð Þ ð26Þ

s ¼ 2:793þ 0:00391 � T � 0:1432 ln p kJ=kg Kð Þ ð27Þ

4 Conclusion

As an alternative working solution for the absorption

refrigeration machines, the acetone-zinc bromide was

selected, and all thermo physical properties (vapor pres-

sure, density, viscosity, specific heat capacity, specific

electrical resistance and specific enthalpy of mixing) of this

solution were measured at various concentrations and

temperatures. The state diagrams (log p, T and h, T) for the

solution as well as the log P, h diagram for pure acetone

(necessary for the design of new absorption refrigeration

machines) are calculated, represented and discussed. The

data for all properties were correlated with new equations,

and the calculated results shows good agreement with the

measured results. The correlation results can be used to

give the required thermo physical data for the design and

optimization of the considered system. The investigation

Table 4 Coefficients for the calculation of the specific enthalpy of

the liquid solution of acetone-zinc bromide with the Eq. 20

a00 176.64 E+0 a10 -2.95 E+0

a01 1,892 E+0 a11 -1.31 E-2

a02 -1,616 E-4 a12 2.8735 E-5

a03 1,486 E-5 a13 -5.02 E-7

a04 -2,439 E-8 a14 1,755 E-9

Fig. 7 The Mollier log P, h-diagram for the pure acetone


123

results of an absorption refrigeration machine working with

this new working pair showed the possibility of using of it,

especially by drive the absorption refrigeration machine

with a low temperature heat sources (over 50�C). The

investigations on an absorption refrigeration machine with

refrigeration capacity of 10 kW have confirmed the pos-

sibility of using the working pair as working solution and

acetone as coolant. The advantages of using of this working

solution are based on the needed low drive temperature of

the heat source. The disadvantages are based on the bad

heat conductivity of acetone and on the low COP. Never-

theless we will continue the investigations on this new

working solution to improve its heat transfer properties

[19, 20].

Appendix

Calculated data of the thermo physical properties for the

solution acetone-zinc bromide (Tables 5, 6, 7, 8, 9 and 10).

Table 5 Specific heat capacity

(kJ/kg K)Temperature (�C) 25 30 35 40 45 50 55 60

Acetone %

30 1.018 1.023 1.028 1.033 1.038 1.044 1.049 1.055

35 1.078 1.084 1.089 1.095 1.101 1.107 1.113 1.119

40 1.140 1.147 1.153 1.160 1.166 1.173 1.180 1.187

45 1.204 1.212 1.219 1.226 1.234 1.241 1.249 1.256

50 1.270 1.278 1.286 1.294 1.302 1.310 1.319 1.327

55 1.335 1.344 1.353 1.362 1.371 1.380 1.389 1.399

60 1.400 1.409 1.419 1.429 1.439 1.449 1.459 1.470

65 1.462 1.472 1.483 1.494 1.505 1.516 1.527 1.539

70 1.521 1.532 1.544 1.555 1.567 1.579 1.592 1.604

Table 6 Vapor pressure (bar)Temperature (�C) 25 30 35 40 45 50 55 60

Acetone %

30 0.065 0.080 0.098 0.121 0.148 0.180 0.215 0.255

35 0.086 0.107 0.134 0.167 0.206 0.251 0.302 0.357

40 0.117 0.147 0.186 0.234 0.290 0.353 0.424 0.503

45 0.158 0.200 0.254 0.320 0.397 0.483 0.579 0.684

50 0.200 0.255 0.324 0.407 0.503 0.611 0.729 0.857

55 0.230 0.291 0.369 0.463 0.570 0.689 0.820 0.961

60 0.243 0.305 0.385 0.479 0.588 0.710 0.842 0.986

65 0.254 0.314 0.392 0.485 0.592 0.712 0.843 0.984

70 0.285 0.347 0.426 0.520 0.629 0.750 0.883 1.027

Table 7 Density (g/cm3)Temperature (�C) 25 30 35 40 45 50 55 60

Acetone %

30 2.617 2.604 2.591 2.578 2.565 2.553 2.540 2.527

35 2.292 2.279 2.266 2.253 2.241 2.228 2.215 2.202

40 2.013 2.001 1.988 1.975 1.962 1.949 1.936 1.923

45 1.778 1.765 1.752 1.739 1.726 1.713 1.700 1.687

50 1.581 1.568 1.555 1.542 1.529 1.517 1.504 1.491

55 1.420 1.407 1.394 1.381 1.368 1.356 1.343 1.330

60 1.291 1.278 1.265 1.252 1.240 1.227 1.214 1.201

65 1.191 1.178 1.165 1.152 1.139 1.126 1.113 1.101

70 1.115 1.102 1.089 1.077 1.064 1.051 1.038 1.025


123

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Table 8 Dynamic viscosity

(mPa s)Temperature (�C) 25 30 35 40 45 50 55 60

Acetone %

30 263.295 191.626 142.103 106.703 80.862 61.789 47.686 37.338

35 71.999 58.427 47.100 37.698 29.959 23.667 18.642 14.732

40 20.268 17.384 14.825 12.578 10.631 8.971 7.588 6.470

45 6.953 6.180 5.485 4.867 4.323 3.855 3.460 3.137

50 3.356 3.060 2.793 2.555 2.345 2.163 2.010 1.884

55 1.973 1.832 1.704 1.590 1.489 1.402 1.328 1.268

60 1.291 1.213 1.143 1.080 1.024 0.976 0.935 0.902

65 0.895 0.848 0.805 0.766 0.733 0.703 0.679 0.659

70 0.638 0.607 0.579 0.554 0.532 0.513 0.497 0.484

Table 9 Specific enthalpy (kJ/

kg)Temperature (�C) 25 30 35 40 45 50 55 60

Acetone %

30 -4.805 0.3824 5.598 10.84 16.09 21.36 26.65 31.95

40 27.89 33.7 39.55 45.42 51.32 57.24 63.19 69.17

50 60.58 67.03 73.5 80.01 86.55 93.13 99.74 106.4

60 93.28 100.3 107.5 114.6 121.8 129 136.3 143.6

70 126 133.7 141.4 149.2 157 164.9 172.8 180.8

80 158.7 167 175.4 183.8 192.2 200.8 209.4 218

90 191.4 200.3 209.3 218.4 227.5 236.7 245.9 255.3

100 224.1 233.6 243.3 252.9 262.7 272.5 282.5 292.5

Table 10 Specific electrical resistance (Ohm cm)

Temperature (�C) 25 30 35 40 45 50

Acetone %

30 1,900 1,507 1,263 925 702 571

35 1,241 972 838 691 583 461

40 822 736 617 533 461 402

45 599 533 478 422 371 346

50 498 444 412 371 338 315

55 402 380 361 334 318 302

60 392 375 364 344 333 321

65 421 408 395 372 362 349

70 459 446 434 424 413 396


123

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Thermo physical properties of acetone–zinc bromide for using in a low temperature driven absorption refrigeration machine

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