Chapter 5, Problem 33R

To determine

To identify the device which transfers thermal energy from a cooler region to a warmer region.

Explanation of Solution

Introduction:

According to a well-known fact, we know that thermal energy is transferred from a warmer to a colder region but if work is done continuously on the system, it is possible to obtain the reverse process too.

We know that the heat always flows from a body at a higher temperature to a body at a lower temperature in the absence of any external energy provided to the system. That is it is impossible to transfer heat spontaneously from a cooler body to a warmer body. If this is to be achieved, external work is to be done on the system continuously according to the second law of thermodynamics. The devices which work on this principle are refrigerators and air conditioners which transfer thermal energy from a cooler region towards a warmer region.

Conclusion:

Hence, out of the four solar panels, refrigerator, the internal combustion engine and thermal conductor, refrigerator transfers thermal energy from the cooler region to the warmer region.