To increase the thermal efficiency of a reversible power cycle operating between thermal reservoirs at TH and Tc, would you increase TH while keeping To constant, or decrease To while keeping TH constant? Are there any natural limits on the increase in thermal efficiency that might be achieved by such means? Consider how η responds to a change in temperature-if either temperature is changed by some r, which will have a greater effect? Hint: Check the derivative of η with regard to TH and Tc separately

Agas contained within a piston-cylinder assembly e end nation about same energy states, 1 and 2, where pi 10 bar, v undergoes two processes, a and b, between the sam 0.1 m3, ui-400 kj and p2 1 bar, v2 1.0 m2, u2 200 kj: process a: process from 1 to 2 during which the pressure- volume relation is pv constant process b: constant-volume process from state 1 to a pressure of 2 bar, followed by a linear pressure-volume process to +20 0 state 2 kinetic and potential energy effects can be ignored. for each of the processes a and b, (a) sketch the process on p-v coordinates, (b) evaluate the work, in kj, and (c) evaluate process the heat transfer, in kj