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Thermodynamic Calculations of Two-Stage Vapor Compression Cycle with Flash Chamber/Regenerative

Author: Volodymyr Voloshchuk

[email protected]

Introduction In the event that a high COP of a refrigeration cycle is of greater importance compared to other factors, it is possible to significantly increase the COP of a basic cycle through the use of a multistage vapor compression cycle. This is especially true when the ratio between the rejection and heat absorption is large 5 or more. Multistaging involves one or more intermediate pressures between the heat rejection and heat absorption pressures, and a series of operating between successive pressure intervals. Creation functions on properties and processes of working fluids > >

Vapor pressure on the saturated line as a function of >

Liquid pressure on the saturated line as a function of temperature >

Liquid temperature on the saturated line as a function of pressure >

Vapor temperature on the saturated line as a function of pressure >

Liquid specific on the saturated line as a function of temperature >

Vapor specific enthalpy on the saturated line as a function of temperature > Liquid specific enthalpy on the saturated line as a function of pressure >

Vapor specific enthalpy on the saturated line as a function of pressure >

Liquid specific on the saturated line as a function of temperature >

Vapor specific entropy on the saturated line as a function of temperature >

Liquid specific entropy on the saturated line as a function of pressure >

Vapor specific entropy on the saturated line as a function of pressure >

Temperature as a function of pressure and specific entropy >

Temperature as a function of pressure and specific enthalpy >

Specific enthalpy as a function of pressure and temperature >

Specific entropy as a function of pressure and temperature >

>

Input Data Temperature of heat source > (3.1) Temperature of heat consumption > (3.2) Temperature difference in the > (3.3) Temperature difference in the condenser > (3.4) Isentropic efficiency of the > (3.5) Pressure increase in compressor 1 > (3.6) > (3.7)

Calculations Temperature of the working fluid at the evaporator outlet > (4.1) Pressure of the working fluid at the evaporator outlet > (4.2) Specific enthalpy of the working fluid at the evaporator outlet >

(4.3)

Specific entropy of the working fluid at the evaporator outlet >

(4.4)

Pressure of the working fluid at the flash intercooler outlet > (4.5) Pressure of the working fluid at the flash intercooler outlet > (4.6) Temperature of the working fluid at the flash intercooler outlet > (3.2)

> (4.7) Specific enthalpy of the working fluid at the flash intercooler outlet >

(4.8)

Specific enthalpy of the working fluid at the flash intercooler outlet >

(4.9)

Pressure of the working fluid at the evaporator intlet > (4.10) Specific enthalpy of the working fluid at the evaporator intlet >

(4.11)

Temperature of the working fluid at the evaporator intlet > (4.12) Specific enthalpy of saturated liquid of the working fluid at the evaporator inlet >

(4.13)

Quality of the working fluid at the evaporator intlet

> (4.14) Specific entropy of saturated liquid of the working fluid at the evaporator inlet >

(4.15)

Specific entropy of the working fluid at the evaporator inlet >

(4.16)

Specific entropy of the working fluid at the compressor 1 outlet after isentropic compression >

(4.17)

Temperature of the working fluid at the compressor 1 outlet after isentropic compression > (3.2)

> (4.7)

> (4.18) Specific enthalpy of the working fluid at the compressor 1 outlet after isentropic compression >

(4.19)

Enhtalpy change in the compressor after isentropic compression >

(4.20)

Enhtalpy change in the compressor 1 after actual compression

>

(4.21)

Specific enthalpy of the working fluid at the compressor 1 outlet after actual compression >

(4.22)

Specific enthalpy of the working fluid at the compressor 1 outlet after actual compression > (4.23) Specific entropy of the working fluid at the compressor 1 outlet after actual compression >

(4.24)

Pressure of the working fluid at the compressor 2 intlet > (4.25) Temperature of the working fluid at the compressor 2 intlet > (4.26) Specific enthalpy of the working fluid at the compressor 2 intlet >

(4.27)

Specific entropy of the working fluid at the compressor 2 intlet >

(4.28)

Temperature of the working fluid at the condenser outlet > (4.29) > (3.2)

> (4.7)

> (4.18)

(4.29) Pressure of the working fluid at the condenser outlet > (4.30) Specific enthalpy of the working fluid at the condenser outlet >

(4.31)

Specific entropy of the working fluid at the condenser outlet >

(4.32)

Pressure of the working fluid at the compressor 2 outlet > (4.33) Pressure increase in the compressor 2

> (4.34) Specific entropy of the working fluid at the compressor 2 outlet after isentropic compression >

(4.35)

Temperature of the working fluid at the compressor 2 outlet after isentropic compression > (4.36) Specific enthalpy of the working fluid at the compressor 2 outlet after isentropic compression >

(4.37)

Enhtalpy change in the compressor 2 after isentropic compression >

(4.38)

Enhtalpy change in the compressor 2 after actual compression

>

(4.39)

Specific enthalpy of the working fluid at the compressor 2 outlet after actual compression >

(4.40) > (3.2)

> (4.7)

> (4.18)

(4.29)

(4.40)

Specific enthalpy of the working fluid at the compressor 2 outlet after actual compression > (4.41) Specific entropy of the working fluid at the compressor 2 outlet after actual compression >

(4.42)

Specific enthalpy of the working fluid at the flash intercooler intlet >

(4.43)

Pressure of the working fluid at the flash intercooler intlet > (4.44) Temperature of the working fluid at the flash intercooler intlet > (4.45) Specific enthalpy of saturated liquid of the working fluid at the flash intercooler inlet >

(4.46)

Quality of the working fluid at the flash intercooler intlet

> (4.47) Specific entropy of saturated liquid of the working fluid at the flash intercooler inlet >

(4.48)

Specific entropy of the working fluid at the flash intercooler inlet >

(4.49)

Ratio of flow rates between the high pressure circuit and that of the low pressure circuit

> (4.50) Heat rejection in the condenser referred to 1 kg of in the low pressure circuit >

(4.51) > (3.2)

> (4.7)

> (4.18)

(4.29)

(4.40)

(4.51)

Heat addition in the evaporator referred to 1 kg of refrigerant in the low pressure circuit >

(4.52)

The total of compressors referred to 1 kg of the working fluid in the low pressure circuit >

(4.53)

Coefficent of performance of a

> (4.54) Coefficent of performance of a heat

> (4.55)

Plot the Refrigeration Cycle on a P-h-T Chart > > > > > > > (3.2)

> (4.7)

> (4.18)

(4.29)

(4.40)

(4.51)

>