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Carnot engine diagram (modern) - where an amount of heat Q H flows from a high temperature T H furnace through the fluid of the "working body" (working substance) and the remaining heat Q C flows into the cold sink T C, thus forcing the working substance to do mechanical work W on the surroundings, via cycles of contractions and expansions.
The section substitutes W=Qh-Qc into the starting definition COP.heating=Q.h/W, to find COP.heating = Qh/(Qh-Qc). Then for the perfect engine (Carnot) the section says COP.heating = Th/(Th-Tc). If I have the concept right, the equation subscript should add .ideal to show COP.heating.ideal, to avoid confusing it with COP.heating in the previous ...
By conservation of energy, the maximum amount of work/energy that can be extracted from a heat engine = difference between heat/energy taken from the hotter reservoir (Qh) and heat/energy lost to the colder reservoir (Qc) = Qh - Qc. The efficiency of an engine is defined as: η = work out/ energy in = (Qh - Qc)/Qh = 1 - Qc/Qh So what is Qc/Qh?
The COP is used in thermodynamics. The COP usually exceeds 1, especially in heat pumps, because instead of just converting work to heat (which, if 100% efficient, would be a COP of 1), it pumps additional heat from a heat source to where the heat is required. Most air conditioners have a COP of 3.5 to 5. [3]
In thermodynamics, the thermal efficiency is a dimensionless performance measure of a device that uses thermal energy, such as an internal combustion engine, steam turbine, steam engine, boiler, furnace, refrigerator, ACs etc.
For quasi-static and reversible processes, the first law of thermodynamics is: d U = δ Q − δ W {\displaystyle dU=\delta Q-\delta W} where δQ is the heat supplied to the system and δW is the work done by the system.
Created Date: 8/30/2012 4:52:52 PM
Then if is more efficient than , the machine will violate the second law of thermodynamics. Since a Carnot heat engine is a reversible heat engine, and all reversible heat engines operate with the same efficiency between the same reservoirs, we have the first part of Carnot's theorem: