This document summarizes a presentation on single and two-stage absorption cooling and power cycles. The presentation discusses how combined cycles use a Rankine cycle and absorption refrigeration cycle to produce power and cooling from a single heat source. It then analyzes the thermodynamics and performance of a single-stage and two-stage absorption cooling and power cycle that uses ammonia-water as the working fluid. Charts are presented showing how the cooling capacity, power output, coefficient of performance, and efficiency vary based on absorber, condenser, and evaporator temperatures for both cycles. The conclusion is that the two-stage cycle has higher coefficient of performance and efficiency than the single-stage cycle, though the single-stage cycle has

1. 4th INTERNATIONAL CONFERENCE ON
ADVANCES IN ENERGY RESEARCH
Indian Institute of Technology Bombay, Mumbai
10-12 December 2013
ENERGY ANALYSIS OF SINGLE AND
TWO STAGE ABSORPTION
COOLING AND POWER CYCLES
Dr.C.P.Jawahar
Associate Professor
Department of Mechanical Engineering
Karunya University
Coimbatore - 641 114, India
1

2. INTRODUCTION
Combined cycle
 Combination of Rankine cycle and absorption
refrigeration cycle which produces power and
cooling simultaneously with a single heat
source
 Employs binary
ammonia-water
working
fluid
such
Advantages of ammonia-water
• Good thermo-physical properties
• Environment friendly
as

3. SINGLE STAGE ABSORPTION
COOLING AND POWER CYCLE

4. TWO STAGE ABSORPTION
COOLING AND POWER CYCLE
QSH
SH
QR3
25
28
QR2
24
R3
27
T
R2
P
23
22
30
G2
QC
29
C
QR1
14
10
9
18
7
R1
G1
QA2
8
3
11
4
SHX1
2
EV
PRV1
SP1
1
12
13
E
26
6
A1
QE
15
19
SHX2
17
20
PRV2
SP2
5
QA1
QG2
16
21
A2

5. THERMODYNAMIC ANALYSIS ASSUMPTIONS
•
The system operates under steady state
conditions.
•
Pump work and the frictional pressure drop
in the cycle are neglected except through the
expansion valve.
•
The weak solution leaving the absorber(s),
strong solution leaving the generator(s) and
the refrigerant at the outlet of condenser and
evaporator are saturated.
•
The concentration of the refrigerant leaving
the rectifier(s) R1 and R3 is 0.999.

6. THERMODYNAMIC ANALYSIS ASSUMPTIONS
• The effectiveness of solution heat
exchanger(s) is 0.75 and the temperature of
super heater is 200°C.
• Split ratio (S) is assumed to be 0.75.
• The degassing width in the single stage cycle
is assumed as 0.10, while the degassing
width in the first and second stage of the
two stage cycle is assumed to be 0.04 and
0.06 respectively.

7. THERMODYNAMIC ANALYSIS ASSUMPTIONS
• Mass flow rate of the weak solution from the
absorber to the generator is 1 kg/s.
• Temperature of the weak solution leaving the
second stage absorber is 0.10°C higher than
the temperature of the strong solution
leaving the first stage generator.
• Mass flow rate of the refrigerant vapour
leaving the first stage rectifier is same as
that of the one entering the second stage
rectifier and first stage absorber.

8. PERFORMANCE ANALYSIS - EQUATIONS
Single stage combined cycle
QA = m6 h6 + m13 h13 + m16 h16 - m1 h1
QC = m10(h10 - h11)
QE = m13(h13 - h12)
QG = m4h4 + m7h7 - m3h3 - m8h8
QR = m7h7 - m8h8 - m9h9

9. PERFORMANCE ANALYSIS - EQUATIONS
QSHX = m3(h3 - h2)
QSH = m15(h15 - h14)
PT = m15 (h15 - h16)
CR = (Xr - Xss) / (Xws - Xss)
COP = QE/QG

10. PERFORMANCE ANALYSIS - EQUATIONS
Two stage combined cycle
QA1 = m6h6 + m26m26h26 - m1h1
QC = m10(h10 - h11)
QE = m13(h13 - h12)
QR1 = m7h7 - m8h8 - m9h9
QSHX1 = m3(h3 - h2)

11. PERFORMANCE ANALYSIS - EQUATIONS
PT = m28 (h28 - h29)
QA2 = m15h15 + m21h21 + m29h29 - m16h16
QR2 = m22h22 - m23h23 - m24h24
QR3 = m24h24 - m25h25 - m30h30
QSHX2 = m18(h18 - h17)

12. PERFORMANCE ANALYSIS - EQUATIONS
QSH = m28(h28- h27)
CR1 = (Xr1 - Xss1)/ (Xws1 - Xss1)
CR2 = (Xr3 - Xss2)/ (Xws2 - Xss2)
COP = QE/QG2

13. COOLING CAPACITY Vs
ABSORBER TEMPERATURE

14. POWER OUTPUT Vs
ABSORBER TEMPERATURE

15. COEFFICIENT OF PERFORMANCE Vs
ABSORBER TEMPERATURE

16. EFFECTIVE FIRST LAW EFFICIENCY Vs
ABSORBER TEMPERATURE

17. COOLING CAPACITY Vs
CONDENSER TEMPERATURE

18. POWER OUTPUT Vs
CONDENSER TEMPERATURE

19. COEFFICIENT OF PERFORMANCE Vs
CONDENSER TEMPERATURE

20. EFFECTIVE FIRST LAW EFFICIENCY Vs
CONDENSER TEMPERATURE

21. COOLING CAPACITY Vs
EVAPORATOR TEMPERATURE

22. POWER OUTPUT Vs
EVAPORATOR TEMPERATURE

23. COEFFICIENT OF PERFORMANCE Vs
EVAPORATOR TEMPERATURE

24. EFFECTIVE FIRST LAW EFFICIENCY Vs
EVAPORATOR TEMPERATURE

25. CONCLUSION
Cooling capacity and Power output of single
stage cycle is higher than that of a two stage
cycle.
Coefficient of performance and Effective first
law efficiency of the two stage cycle is found
to vary between 21 to 66% and 20 to 60%
respectively, more than the single stage cycle.
It is also observed that the two stage
combined cycle could effectively utilize a high
temperature heat source than the single stage
one.

26. THANK YOU