# Performance evaluation of ejector expansion combined cooling and power cycles

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## Abstract

This paper studies performance characteristics of a basic ejector expansion combined cooling and power cycle (EECCPC) as well as three modified ones. These modified cycles are EECCPC incorporating turbine bleeding, regenerative EECCP cycle, and EECCP cycle incorporating with both turbine bleeding and regeneration. The expansion valve has been replaced by a two-phase ejector-expander in the traditional CCP cycle to improve the first and second-law efficiencies. Furthermore, the exergy destruction for components of the systems as well as the whole systems has been calculated, leading to determination of the main source of irreversibility in different cycles. The results of the exergy analysis reveals that the generator has the major contribution role in the overall losses of the systems. The results also show that the EECCP cycle surpasses the TCCP cycle in terms of thermal and exergy efficiencies. As a matter of fact, the thermal and exergy efficiencies are improved by 6.02, and 5.44%, respectively, throughout this successive modification. At last, sensitivity analysis of different key parameters on performance of the cycles has been investigated. It is shown that one can obtain higher thermal efficiency by increasing of the generator and evaporator temperatures or decreasing of the condenser temperature.

## List of symbols

## Symbols

- CCPC
Combined cooling and power cycle

- \(\dot{E}\)
Exergy rate \(\left( {\text{kW}} \right)\)

- EECCPC
Ejector expander CCPC

- h
Specific enthalpy \(\left( {{\text{kJ}}\,{\text{kg}}^{ - 1} } \right)\)

- \(\dot{m}\)
Mass flow rate \(\left( {{\text{kg}}\,{\text{s}}^{ - 1} } \right)\)

*P*Pressure \(\left( {\text{MPa}} \right)\)

- \(\dot{Q}\)
Heat transfer rate \(\left( {\text{kW}} \right)\)

- REECCPC
Regenerative EECCPC

- RTBEECCPC
Both turbine bleeding and regeneration EECCPC

- s
Specific entropy \(\left( {{\text{kJ}}\,{\text{kg}}^{ - 1} \,{\text{K}}^{ - 1} } \right)\)

- T
Temperature \(\left( {\text{K}} \right)\)

- TBEECCPC
Turbine bleeding EECCPC

- TCCPC
Traditional CCPC

- U
Mass entrainment ratio

- v
Specific volume \(\left( {{\text{m}}^{3} \,{\text{kg}}^{ - 1} } \right)\)

- \(\dot{W}\)
Power \(\left( {\text{kW}} \right)\)

## Greek symbols

*η*Efficiency (%)

## Subscripts and superscripts

- c
Condenser

- CH
Chemical

- com
Compressor

- D
Destruction

- d
Diffuser

- e
Evaporator

- ej
Ejector

- EV
Expansion valve

- Ex
Exergetic

- F
Fuel

- FFH
Feed fluid heater

- g
Generator

- IHE
Internal heat exchanger

- i
Component of

*i*- in
Inlet

- int
Intermediate

- is
Isentropic

- KN
Kinetical

- m
Mixer

- n
Nozzle

- net
Net value

- out
Outlet

- P
Product

- p
Pump

- pf
Primary flow

- PH
Physical

- PT
Potential

- s
Constant entropy

- sep
Separator

- sf
Secondary flow

- t
Turbine

- suc
Suction

- th
Thermal

- total
Total value

- v
Vapor

- w
Water

- 1, 2, …
Cycle locations

- 0
Dead state

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