Air Conditioner and refrigerator

Air conditioner and refrigerator have same work principle, it is refrigeration cycle. Refrigeration is reverse of Power cycle (rankine cycle) which use heat for produce some work (Power), refrigeration use  work to move the heat. If we read some books, maybe we will find that refrigeration cycle is a system which allow heat transfer from cold area to warm area (figure a) whereas heat transfer is spontaneously from warm area to cold area. Actually, if we focus on each component of refrigeration cycle, heat transfer from cold area to warm area is not happen. But because of we assume the refrigeration cycle as one system, we can say like that.

Fugure (a). refrigeration system as one system

Figure (b). refrigeration system produce cold and hot part

In fact, refrigeration cycle produce the difference of temperature, there are cold part and hot part (figure b). We use cold part to cool the objects. Object in this content is defined as all things that we want to make it cold. In refrigerator, the objects are foods, water, etc. But, in air conditioner system the object is the room air.

Refrigeration system at least needs four components, there are compressor, condenser, expansion valve, and evaporator. Refrigeration system also need work fluid, it is called refrigerant. There are many types of refrigerant, some of them are forbidden because of the environment issue. Refrigerant  always goes around from one component to another component, and at each component refrigerant experiences the process based on the function of component.