It is impossible for heat to flow from a body at a lower temperature to a body at a higher temperature without the aid of external work. This statement is

Explanation:

Clausius statement:

“It is impossible to construct a device that operates on a cycle to produce no effect other than the transfer of heat from a lower-temperature body to a higher temperature body”

The conclusion of this statement is commonly known to us that heat does not, on its own, flow from a cold medium to a hot medium. On the surface, it looks that as per Clausius statement it is impossible to construct a device that transfers heat from a colder medium to warmer medium.

The Clausius statement implies that a refrigerator will not operate unless its compressor is driven by a power source, such as an electric motor.

Additional Information

Kelvin-Planck statement:

It is impossible to construct an engine, which while operating in a cycle produces no other effect except to extract heat from a single reservoir and do the equivalent amount of work.

Therefore if the engine has to work in a cycle then some amount of heat is rejected in the cycle, the Closed-cycle gas turbine, internal combustion engine and steam power plant rejects some heat to produce the work continuously in a cycle, therefore these devices imply with the Kelvin-Planck statement.