“It is impossible to construct a device which, operating in a cycle, will transfer heat from lower temperature body to a higher temperature body at its sole effect.
Heat cannot flow of itself from a lower temperature body to a body at a higher temperature. Some work is to be done.
Fig. 6.7 shows that W is to be done on the system R to transfer Q1 amount of heat to a body at T1.
Here Q1 – Q2 = W.