Thermodynamic Principles behind Refrigerators


Figure 1 shows the Clausius statement of the 2nd law of thermodynamics: heat cannot move from cold to hot unless work is done to the system. Figure 2 is a basic schematic of a typical refrigerator. 

Refrigerators work according to the Clausius statement of the second law of thermodynamic (Figure 1) that states that it is impossible for heat to move from a cold reservoir to a hot reservoir without work being done to the system.  A basic schematic of a typical refrigerator (Figure 2) illustrates this.From Valve 1 to Valve 2 (red; heat reservoir), the refrigerant is in a liquid form and releases the heat from the inside of the refrigerator to the outside (ie the kitchen). At valve 2, the expansion valve, the refrigerant is changed from a liquid to a vapor and pushed back inside the refrigerator. From valve 2 to the Compressor (blue, cold reservoir) the refrigerant, in vapor form, absorbs energy (ie. heat inside the refrigerator). At the compressor, work is done to the refrigerant to change it from a vapor to a liquid. The refrigerant is then pushed out of the refrigerator towards valve 1 and the process starts over.


Hello all! I’m Sarah Larson, a senior Chemistry Major with minors in Human Biology and Dance. I currently work on campus as a Student Ambassador and as a Lab Assistant. When I’m not busy with work and school (which is very rare) I spend most of my time dancing either at Ballroom Club or in the studio.