Energy and Entropy Balances for Process Equipment

 Compressor

Entropy: 0 = -DSm + Sgen

Enthalpy: Wsnet = (H2 - H1)

Condenser:
Entropy: 0 = -
DSm + Sgen + (Qs/Tfluid)

Enthalpy: Qs = m (H3 - H4)

Throttle:
Entropy: 0 = -
DSm + Sgen

Enthalpy: H7 = H8

Evaporator:
Entropy: 0 =
DSm + Sgen + (Qe/Tfluid)

Enthalpy: Qe = m (H9 - H8)

H1 = enthalpy of refrigerant flowing into compressor
H2 = enthalpy of refrigerant flowing out of compressor
H3 = enthalpy of refrigerant flowing into condenser
H4 = enthalpy of refrigerant flowing out of condenser
H7 = enthalpy of refrigerant flowing into expansion valve
H8 = enthalpy of refrigerant flowing out of expansion valve and into evaporator
H9 = enthalpy of refrigerant flowing out of evaporator
DS = change in entropy for given process equipment
Sgen = entropy generator in given process equipment
m = mass flow rate of refrigerant
Qs = heat transfer from the condenser to the surroundings (positive)
Qe=heat transfer from the evaporator to the refrigerator (negative)
Tfluid = temperature of refrigerant

 

 

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