The discussion centers on the efficiency of irreversible engines compared to reversible engines, particularly under varying source and sink temperatures. Participants explore theoretical implications and definitions of efficiency in thermodynamic systems.
Participants express disagreement regarding the conditions under which irreversible engines might be considered more efficient than reversible engines. There is no consensus on the implications of different temperature conditions on engine efficiency.
Participants reference definitions of efficiency that may depend on specific assumptions about the engines' operating conditions and the nature of the heat reservoirs involved.
This is at odds with what jbriggs444 said in his post. Also, according to the definition that you gave, it is well known that the efficiency of a reversible engine operating in a cycle is less than 1.Gopal Mailpalli said:If you consider efficiency(η) in terms of ratio of heat energy converted to work per heat energy derived from source. Then efficiency of reversible engine will always be 1, whereas in irreversible engine, the total heat energy will not be able to convert to work, since there may be many chances where heat derived may be dissipated. So the efficiency of irreversible engine(η) will between 0< η <1. Whatever be the temperatures.
It means, η(r) > η(I)
Based on the jbriggs444 definition, a reversible engine uses maximum amount of heat energy to work per unit of heat transferred, whereas in irreversible engine it uses less heat energy per unit heat energy transferred. In general efficiency of reversible engines is always greater than irreversible engine.Chestermiller said:This is at odds with what jbriggs444 said in his post. Also, according to the definition that you gave, it is well known that the efficiency of a reversible engine operating in a cycle is less than 1.
I therefore agree with jbriggs444.
That is correct if the comparison is fair. But the original post here contemplated a comparison where the irreversible engine can be given an unfair advantage -- working from a pair of reservoirs with a different temperature difference.Gopal Mailpalli said:Based on the jbriggs444 definition, a reversible engine uses maximum amount of heat energy to work per unit of heat transferred, whereas in irreversible engine it uses less heat energy per unit heat energy transferred. In general efficiency of reversible engines is always greater than irreversible engine.