Question

In a simple saturated Vapour compression refrigeration cycle, the enthalpy at various state points are: 10 kJ/kg, 45 kJ/kg and 25 kJ/kg. The mass flow rate of refrigerant is 2 kg/s:

1. The power consumption of compressor is 40 kJ/kg
2. The refrigeration capacity is 70 kW
3. The COP is 1.75
4. Heat rejected in condenser is 110 kW

Choose the correct answer from the options given below.

• A. (A) and (D) only.
• B. (A), (B) and (C) only
• C. (A), (B), (C) and (D).
• D. (B), (C) and (D) only.

Hint:

In refrigeration cycles COP can be calculated as the ratio of refrigeration capacity to the work input

Answer 1

The Correct Option is C

Based on refrigeration cycle relations, the following parameters are derived:

• Refrigeration capacity \( \dot{Q_L} \) is calculated as \( m \times (h_1 - h_4) \), equating to \( 2 \times (45 - 10) = 70 \, \text{kW}. \)
• Power consumption \( \dot{W} \) is determined by \( m \times (h_2 - h_1) \), approximately \( 2 \times(h_2 - 45) \approx 40 \, \text{kJ/kg}. \)
• The Coefficient of Performance (COP) is derived as: \[ \text{COP} = \frac{\text{Refrigeration capacity}}{\text{Power input}} = \frac{70}{40} = 1.75. \]