Heat Pump | Working, Coefficient of Performance [Briefly Explained]

By | February 12, 2019

What is a Heat Pump?

Heat pump is a device working in a cyclic process such that it transfers heat from low temperature to high temperature and absorbs work from the surrounding.

Below diagram shows working of a heat pump

Heat Pump


Th: Temperature of source

Tc: Temperature of sink

Qh: Heat rejected by the heat pump

Qc: Heat extracted by the heat pump

W: Work input to the heat pump

Given: Th > Tc

Coefficient of performance (COP)

Coefficient of performance (COP) is the ratio of desired effect (either heating or cooling) to the work input.

Since a heat pump is used for both cooling and cooling purpose hence it has two COPs.

COPHeating = (Qc+ W)/ W

COPCooling = Qc/ W

Clausius statement of second law

It is impossible to construct a device which, operating in a cycle, will produce no effect other than the transfer of heat from a cooler to a hotter body.

If we analyze heat engine and heat pump together then we will find two very important results regarding the inter-conversion of heat and work.

  1. Even in the ideal case all the heat can never be converted fully into the work
  2. Work can be fully converted to heat

Also read:

What is second law of thermodynamics?

What is first law of thermodynamics?

What is thermodynamic equilibrium?

Definition of a thermodynamic state

What are extensive properties?

What is availability of a thermodynamic system?

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