The GATE Grind

GATE 2020 AG – Question 21

Dairy and Food Engineering · Heat and Mass Transfer · 1 mark · Multiple choice

A cold store cools 100 metric tons of potatoes from 35°C to 8°C in five hours. Potato heat capacity is 3.1 kJ/(kg °C), refrigeration COP 3.66, and R-22 evaporation latent heat 230 kJ/kg at −10°C. Neglect respiration and losses. Find refrigerant rate and compressor power.

  1. 121.3 kg/min;127.1 kW
  2. 124.7 kg/min;121.3 kW
  3. 127.1 kg/min;121.3 kW
  4. 124.7 kg/min;127.1 kW

Practise this question in The GATE Grind →

Show answer and explanation

Correct answer: (A) 121.3 kg/min;127.1 kW

Explanation

Cooling rate is $100000(3.1)(35-8)/(5\times3600)=465$ kW. Refrigerant flow is 465/230=2.0217 kg/s=121.3 kg/min. Compressor power is 465/3.66=127.1 kW. Thus A.

More Heat and Mass Transfer questions

All Heat and Mass Transfer questions →