Question

When the outside temperature is - ${10}^{o}C$, a residential heat pump must provide $3.5\times {10}^6$ kJ/day to a room to maintain its temperature to ${20}^{o}C$ . If electricity cost is Rs. 5/kWh. What is the minimum operating cost for each day of operation?

• A. Rs. 498
• B. Rs.600
• C. Rs.757
• D. Rs. 371

Answer 1

The correct option is A Rs. 498



$T_1=293K$

$T_2=263K$

$COP=\frac{T_1}{T_1-T_2}=\frac{293}{293-263}=9.77$

$W_{min}=\frac{Q}{COP}=\frac{3.5\times {10}^6}{9.77}\text{kJ/day}$

$\text{Operating cost}=W_{min}\times \frac{5}{3600}=₹497.5$