Question

In the Carnot cycle to increase efficiency, which of the following parameters need to be changed?
A) Decrease source temperature
B) Decrease the sink temperature
C) No effect
D) None of these

Answer 1

Hint- A Carnot heat engine is an imaginary engine. It is useful for understanding the limitations of heat engines. When a thermodynamic system is taken through a series of different states, the thermodynamic cycle occurs. This cycle is called the Carnot cycle. It provides the maximum efficiency of any thermodynamic system while converting the heat into work.

Complete step by step answer:
(i) When a thermodynamic system is taken through a series of different states, Carnot cycles occur. This Carnot cycle provides the maximum efficiency of the thermodynamic system when converting the heat into work.
(ii) The efficiency of the Carnot engine is given by $1 - \dfrac{{{T_1}}}{{{T_2}}}$, where ${T_1}$ is the sink temperature and ${T_2}$ is the reservoir temperature.
(iii)From the relation for the efficiency, we can say that the efficiency can be increased either by increasing the reservoir temperature and decreasing the sink temperature.

(iv)So from the given options, option B is correct.

Additional information:
(i) According to Carnot’s theorem, the heat engine which operates under two extreme temperatures ${T_1}$(cold temperature) and ${T_2}$(hot temperature) can never attain efficiency more than the Carnot engine working under those two temperatures.
(ii) From this theorem, we can understand that the Carnot engine has the maximum efficiency. And it has the ideal efficiency as it is only a theoretical engine.

Note: The Carnot’s cycle is the result of a four cyclic processes called isothermal expansion, adiabatic expansion, isothermal compression, adiabatic compression. The Carnot cycle is the relation between the volume and the pressure attained by the heat engine which is operated under two extreme temperatures.