Consider a circular furnace that is 0.3 m long and 0.3 m in diameter. the two ends have diffuse, gray surfaces that are maintained at 400 and 500 k with emissivities of 0.4 and 0.5, respectively. the lateral surface is also diffuse and gray with an emissivity of 0.8 and a temperature of 800 k. determine the net radiative heat transfer from each of the surfaces. consider two very large metal parallel plates.

Air inially occupying a volume of 1 m2 at 100 kpa, 27 c undergoes three internally reversible processes in series. process 1-2 compression to 500 kpa during which pv constant process 2-3 adiabatic expanslon to 100 kpa process 3-1: constant-pressure expansion to 100 kpa (a) calculate the change of entropy for each of the three processes. (b) calculate the heat and work involved in each process. (c) is this cycle a power cycle or refrigeration cycle?