An ideal vapor-compression refrigeration cycle using refrigerant-134a as the working fluid is used to cool a brine solution to −5°C. This solution is pumped to various buildings for the purpose of air-conditioning. The refrigerant evaporates at −10°C with a total mass flow rate of 7 kg/s, and condenses at 600 kPa. Determine the COP of the cycle and the total cooling lo

1141

7.2

Explanation:

The evaporator Temperature T1 = -10°C

h1 = 244.55kj/kg

S1 = 0.93782kj/kg

The enthalpy at second state from given condenser pressure from super heated refrigerant table

P2 = 600

S2 = S1

h2 = 267.19kj/kg

Enthalpy at 3 and 4 from condenser pressure

h3 = h4 = 81.5kj/kg

To get cooling load

QL = m(h1-h4)

M= 7

= 7(244.55-81.5)

= 7(163.05)

= 1141.35kw = 1141KW

COP

= h1-h4/h2 -h1

= 244.55-81.5/267.19-244.55

= 163.05/22.64

= 7.2