## Fundamentals of Engineering Thermodynamics 8th Edition

Published by Wiley

# Chapter 5 - Exercises: Things Engineers Think About: 7

#### Answer

In case of electric resistance heater, electric energy is converted into heat. Hence, we can say to supply 10 kW of heat energy electric resistance needs 10 kW of electric energy. In case of heat pump, COP is the ration of heat supplied to work done. Work done can be assumed equivalent to electric energy and COP of heat pump is always greater than one. Hence to supply 10 kW of heat energy heat pump requires less than 10 kW of electric energy. In conclusion, heat pump is better than electric resistance.

#### Work Step by Step

In case of electric resistance heater, electric energy is converted into heat. Hence, we can say to supply 10 kW of heat energy electric resistance needs 10 kW of electric energy. In case of heat pump, COP is the ration of heat supplied to work done. Work done can be assumed equivalent to electric energy and COP of heat pump is always greater than one. Hence to supply 10 kW of heat energy heat pump requires less than 10 kW of electric energy. In conclusion, heat pump is better than electric resistance.

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