Air is compressed by a 15-kW compressor from P1 to P2. The air temperature is maintained constant at 258C during this process as a result of heat transfer to the surrounding medium at 208C.
Determine the rate of entropy change of the air. State the assumptions made in solving this problem.

Consider a large isothermal enclosure that is maintained at a uniform temperature of 2000 k. calculate the emissive power of the radiation that emerges from a small aperture on the enclosure surface. what is the wavelength ? , below which 10% of the emission is concentrated? what is the wavelength ? 2 above which 10% of the emission is concentrated? determine the wavelength at which maximum spectral emissive power occurs. what is the irradiation incident on a small object placed inside the enclosure?

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?

Steam at a pressure of 100 kpa and a quality of 50% initially fills a rigid vessel having a volume of 0.5 m^3. the steam is then heated, causing the pressure in the vessel to rise to 150 kpa. determine: i. the mass of the steam in the vessel. ii. the temperature and quality of the steam after the heating process. ii the mass of the vapour, mg and liquid, m in the vessel after the heating process. if the steam in the vessel is now further heated, what would the pressure and temperature in the vessel be when all steam has turned into saturated vapour? b. sketch the processes in part (a) and part (b) on p-v and t-v diagrams, indicating clearly the temperatures, pressures and the paths. c. (0.59kg, 111.4°c, 73%, 0.4307kg, 0.1 593kg, 2.11 bar, 121.84°c)