Rankine Cycle Report

IZMIR INSTITUTE OF TECHNOLOGY

DEPARTMENT OF MECHANICAL ENGINEERING

ME 307 THERMODYNAMICS II

Experiment Title: DEMONSTRATION OF RANKINE CYCLE

Student Name: YUNUS EMRE ALACA

Student Number: 130203001

Date: 09.12.2010

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Table of Contents

Abstract............................................................................................................................................3

1. Introduction..............................................................................................................................3

1.1. Process of Rankine Cycle...................................................................................................3

2. Methods and Equipments.........................................................................................................4

2.1. Boiler..................................................................................................................................4

2.2. Steam Turbine....................................................................................................................5

2.2. Condensing Tower.............................................................................................................5

2.2. Sight Glass.........................................................................................................................5

3. Experimental Procedure...........................................................................................................6

4. Results......................................................................................................................................6

5. Conclusion..............................................................................................................................12

References......................................................................................................................................12

List of Figure

Figure 1.1. Rankine Vapor Power Cycle………………………………………………………3

Figure 1.2. Rankine Cycle T-S Diagram……………………………………………………….4

Figure 2.1. Simple schematic for the Rankine Cycler………………………...……………….4

Figure 2.2. Photograph of Turbine Technologies Rankine Cycler ……………………...…….5

Figure 4.1. Fuel flow vs. time …………...…………………………………………………….6

Figure 4.2. Boiler pressure vs. time ……..…………………………………………………….7

Figure 4.3. Boiler temperature vs. time ……………………………………………………….7

Figure 4.4. Turbine inlet pressure vs. time …...……………………………………………….8

Figure 4.5. Turbine outlet pressure vs. time………………………………………..………….8

Figure 4.6. Turbine inlet temperature vs. time…………...…………………………………….9

Figure 4.7. Turbine outlet temperature vs. time ……………………………………………….9

Figure 4.8. Generator DC amperage vs. time …………...…………………………………...10

Figure 4.9. Generator DC voltage vs. time ………………………………...………………...10

Figure 4.10. Turbine RPM vs. time……………………………………...…………………...11

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Abstract

The aim of this experiment is to analyze the Rankine Cycle System with components of the

system and to do some calculations with acquired data.

1. Introduction

A Rankine cycle describes a model of the operation of steam heat engines most

commonly found in power generation plants. Common heat sources for power plants using

the Rankine cycle are the combustion of coal, natural gas and oil, and nuclear fission.

Figure 1.1. Rankine Vapor Power Cycle

Our system is open system. So our system has not got pump like Figure 1.1

1.1. Process of the Rankine Cycle

Process 1-2: The working fluid is pumped from low to high pressure, as the fluid is a

liquid at this stage the pump requires little input energy.

Process 2-3: The high pressure liquid enters a boiler where it is heated at constant

pressure by an external heat source to become dry saturated vapor.

Process 3-4: The dry saturated vapor expands through a turbine generating power.

This decreases the temperature and pressure of the vapor, and some condensation may occur.

Process 4-1: The wet vapor then enters a condenser where it is condensed at a constant

pressure and temperature to become a saturated liquid. The pressure and temperature of the

condenser is fixed by the temperature of the cooling coils as the fluid is undergoing a phase

change.

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Figure 1.2.Rankine Cycle T-S diagram

In rankine cycle available and unavailable energy on a T-S diagram, like a T-S of a

carnot cycle, is represented by the areas under the curves.

2. Methods and Equipments

Figure 2.1. Simple schematic for the Rankine Cycler [1]

The system components are listed and described below:

2.1. BoilerThe Rankine Cycler boiler is a dual-pass, flame through tube-type unit. A forced air

gas burner fires it. The burner fan speed is electronically adjustable to operate with a

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minimum of excess air. The system’s purpose-built burner fan results in extremely clean combustion while burning LP gas. [2]

2.2. Steam TurbineThe steam energy is converted mechanical work by expansion through the turbine.  

The expansion takes place through a series of fixed blades (nozzles) and moving blades each row of fixed blades and moving blades is called a stage.   The moving blades rotate on the central turbine rotor and the fixed blades are concentrically arranged within the circular turbine casing which is substantially designed to withstand the steam pressure. [3]

2.3. Condensing TowerThe condenser tower’s outer mantle is formed from a single piece of aluminum. The

tower’s large surface area affects heat transfer to ambient air and provides a realistic appearance. Turbine exhaust steam is piped into the bottom of the tower. The steam is kept in close contact with the outside mantle by means of 4 baffles. A drain hose and clamp are located at the left rear of the system. Following an experiment, the condensate can be drained into a beaker and measured. [2]

Figure 2.2. Photograph of Turbine Technologies’ Rankine Cycler [1]

2.4. Sight Glass

A sight glass is provided to indicate boiler water level. Two level indicators, set by

thumbscrew bezels, can be adjusted at the beginning and end of each experiment to determine

steam rate. [2]

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3. Experimental ProcedureWe followed these steps to operate Rankine Cycle System Firstly; we filled the boiler

with 6 liters of water and opened the fuel source. And then, we opened the gas valve, turned to master and the burner switch on. After lilting the burner the computer started to record data. When the pressure reached 100 psi we opened the valve slowly until the pressure decreased 40 psi. Then we closed it again. We did this process 3 times in order to reach a steady state condition. When pressure reaches 110 psi again, open the valve slowly without decreasing pressure too much. After that we opened the load switch. At this time amp meter showed 0.2 amps while volt meter shows 10 volts. Adjust steam admission valve and load rheostat to achieve steady state condition for: 110 psi pressure, 0.2 amp and 10 volts. After getting the data needed for a while the experiment finished by closing gas valve and burner, opening steam admission valve till turbine stops and closing the master switch. Finally the condensation amount from condensation water and the remaining water amount in the boiler are noted. [2]

4. ResultsFirstly, 10 different graphs were plotted using the data to determine a steady state

interval.

Figure 4.1. Fuel flow vs. time

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Figure 4.2. Boiler pressure vs. time

Figure 4.3. Boiler temperature vs. time

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Figure 4.4. Turbine inlet pressure vs. time

Figure 4.5. Turbine outlet pressure vs. time

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Figure 4.6. Turbine inlet temperature vs. time

Figure 4.7. Turbine outlet temperature vs. time

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Figure 4.8. Generator DC amperage vs. time

Figure 4.9. Generator DC voltage vs. time

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Figure 4.10. Turbine RPM vs. time

In excel data, steady state time interval was determined as 16:01:38 - 16:06:04 which has 266 seconds.

Boiler Pressure, P2 = 97,9044 psig = 675,0273 kPaTurbine Inlet Pressure, P3 = 7,9522 psig = 54,8288 kPaTurbine Outlet Pressure, P4 = P1 = 2,4515 psig = 16,9023 kPaBoiler Temperature, T2 = 179,6670 °CTurbine Inlet Temperature, T3 = 123,8571 °CTurbine Outlet Temperature, T4 = T1 = 103,4928 °CGenerator Amperage, I = 0,2140 AGenerator Voltage, V = 10,5563 V

Fuel Flow = 5,0335 L/min

Finding the enthalpy;

P1 = 16,9023 kPa h1 = hf = 235,6340 kJ/kg

P2 = 675,0273 kPa, T2 = 179,6670 °C h2 = 2761,2009 kJ/kg

P3 = 54,8288 kPa, T3 = 123,8571 °C h3 = 2729,0645 kJ/kg

P4 = 16,9023 kPa, T4 = 103,4928 °C h4 = 2686,7386 kJ/kg

After determining the enthalpy values for each stage of the process we can, now, calculate Qin, Qout, Wturbine and Qin,loss.

Qin = h2 - h1 = 2525,57 kJ/kgQout = h4 – h1 = 2451,10 kJ/kgWturbine = h4 – h3 = 42,33 kJ/kgQin, loss = h3– h2 = 32,14 kJ/kg

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We find the mass flow rate as 0,003064 kg/s. We multiply the mass flow rate value and 266 seconds.

Qin = 2058,40 kJQout = 1997,71 kJWturbine = 34,50 kJQin, loss = 26,19 kJ

The higher heating value of propane is 50,35 MJ/kg and the density of this gas is 0,001882 kg/L. The fuel flow was averagely 5,0335 L/min during 266 seconds. Qin,propane = (Fuel flow) × HHVpropane × ρpropane × 266 s × 1 min/60 s = 2114,55 kJ

Heat flow out of the boiler,

Qboiler, loss = Qin, propane - Qin = 56,16 kJ

Pturbine = Wturbine/266 s = 0,13 kW

Wgenerator = V × I × 266 s = 601,4768 J

ηgenerator = Wgenerator/Wturbine = 0,02 2 %

We found the heat out of the system at the condenser. It will be found with condensate amount which is 0,25 L of water. At 1 atm latent heat of condensation of water, hfg = 2257 kJ/kg and density of water, ρwater = 1 kg/L.

Qcondensation = Vcondensate × hfg × ρwater = 564,25 kJ

ηcondenser = Qcondensation/Qout = 0,28 28 %

ηtotal = Wturbine/Qin, propane = 0,0163 1,63 %

5. ConclusionIn conclusion, we learned rankine cycle system and observed all components of these.

In our experiment system is not so efficient. This low efficiency may be the system’s being an open cycle. While experiment was going on there was some leakage of steam in some parts. Because of that the efficiency was lower than it should be. Also there was heat loss between turbine inlet and boiler outlet.

6. References[1] University of Victoria Department of Mechanical Engineering - Steam Engine, Retrieved December 9, http://www.turbinetechnologies.com/steamlab/techpapers/Univ.%20of%20Victoria%20Lab.pdf

[2] Lab manuel for this experiment

[3] Thermodynamics-Steam Turbine, Retrieved December 9, http://www.roymech.co.uk/Related/Thermos/Thermos_Steam_Turbine.html

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