Ways to increase efficiency of carnot refrigerator and a four stroke engine? What are ways to increase the efficiency of a Carnot refrigerator. I remember something about decreasing the temperature but also about something about the flow rate, and fins?
Also, for four stroke engines?
 A: The best-case, ideal thermodynamic thermodynamic efficiency of a refrigerator as calculated by considering a Carnot cycle is given by efficiency=Tc/(Th-Tc), where Th is the ambient temperature and Tc is the temperature inside the refrigerator. This efficiency describes how much work is required to move one unit of heat from the inside of the refrigerator to its outside. Note that if Th and Tc are close to each other, this efficiency can actually be greater than 100% (i.e., it can be greater than 1), meaning that, for example, 2 Joules of heat can be moved for the cost of only 1 Joule of input energy to the refrigerator.
So if you want your refrigerator to have a high efficiency, put it in a cool room rather than outside in the hot sun. Sort of makes sense, right?
As for "flow rate", "fins", etc., you are now starting to get into engineering details on a physics site. All we physicists can say is that, based on the laws of thermodynamics, that the maximum possible efficiency of a refrigerator is given by efficiency=Tc/(Th-Tc). It's up to engineers with their "flow rates", "fins", and other engineering design features to see how close they can get a real refrigerator to this maximum theoretical efficiency.
