Firstly, Carnot cycle is an ideal reversible cycle, with its efficiency k= 1-(T 1/T2) and its refrigeration coefficient η =1-q1/q2 =1-t1/t2. In essence, the positive cycle is that the working medium absorbs heat from a high-temperature heat source, does external work and releases heat to a low-temperature heat source.

Then, if the cycle time is reversed (that is, reversed), the working mode will show that the outside world does work on the working medium, absorbs heat from the low-temperature heat source and releases heat to the high-temperature heat source. The work-heat ratio is still equal to K, and the definition of refrigeration efficiency is Q/W, which brings the available answer.

Carnot heat engine consists of four quasi-static processes, two of which are isothermal and two are adiabatic. The principle is that the first law and the second law of thermodynamics (the most basic principle) are derived from here.

Schematic diagram of refrigeration system:

Extended data:

Inverse Carnot cycle lays the foundation of refrigeration theory and reveals the limit of refrigeration coefficient of air conditioning (commonly known as EER or COP). All evaporative refrigeration can't break through the inverse Carnot cycle. Inverse Carnot cycle consists of four cycles: adiabatic compression, isothermal compression, adiabatic expansion and isothermal expansion.

Assuming that the temperature of the low-temperature heat source (i.e. the cooled object) is T0 and the temperature of the high-temperature heat source (i.e. the environmental medium) is Tk, the temperature of the working substance in the heat absorption process is T0 and the temperature of the working substance in the heat release process is Tk, that is, there is no temperature difference between the working substance and the cold source and the high-temperature heat source in the heat absorption and release process, that is, the heat transfer is carried out at an isothermal temperature, and there is no loss in the compression and expansion process.

The cycle process is as follows: firstly, the working medium absorbs heat q0 from the cold source at time T0 and performs isothermal expansion of 4- 1; Then, through adiabatic compression of 1-2, its temperature rises from T0 to the temperature of environmental medium; Secondly, isothermal compression of 2-3 is carried out at Tk to release heat QK to the environmental medium; Finally, it undergoes adiabatic expansion of 3-4, so that its temperature changes from Tk? When it drops to T0, the working medium returns to the initial state 4, thus completing a cycle.

References:

Baidu encyclopedia-Kanuo refrigerator