Question

Consider the following statements:
i. Heat can flow of itself from lower temperature body to a higher temperature body
ii. A heat pump maintains a body at a temperature higher than the temperature of the surroundings
iii. The COP of a heat pump is greater than the COP of a refrigerator by unity
iv. The COP of a refrigerator using heat addition(Q1) and heat rejection(Q2) is expressed as \( \frac{Q_1}{Q_1 - Q_2} \)

• A. i and ii are true
• B. i and iv are true
• C. ii and iii are true
• D. ii, iii and iv are true

Hint:

Understanding the principles of heat transfer and the operation of heat pumps and refrigerators is crucial for designing efficient thermal systems.

Answer 1

The Correct Option is C

Evaluating each statement. 
Statement i: False, as heat naturally flows from a higher to a lower temperature without work input, per the second law of thermodynamics. 
Statement ii: True, as this is the fundamental operation of a heat pump. 
Statement iii: True, since the COP of a heat pump is always one plus the COP of its counterpart working as a refrigerator under the same conditions. 
Statement iv: Incorrect, as the correct expression for the COP of a refrigerator is \( \frac{Q_L}{Q_H - Q_L} \) where \( Q_H \) and \( Q_L \) are the heat rejected and absorbed, respectively.