A fuel of Qh = 6888 kcal/kg steam was bund in the furnace of a 223 m^2 water tube boiler which was generating 5443 kg steam per hour at 14.06 kg/cm^2 ab, d and s, fiom 109 °C feed, at a time when the fuel consumption was 612 kg per hour. (a) Find kcal rating and percent rating. (b) Calculate over-all thermal efficiency.

In a steady-state operating power plant, saturated liquid H2O at 122 deg C is fed to a boiler at 3.756 m/s through a pipe (0.03 m diameter). It leaves the boiler at 9 bar and 88.7 m/s. Then, it enters the turbine through a constant 0.13 m diameter pipe. The exit pipe of the turbine is 0.3 m in diameter and T = 310ºC while P = 1.37 bar. If 2.5 kg/s water is fed and there is change in KE, prove that the fluid enters the turbine at 637.06 deg C.

(2) Describe briefly why the following statements are wrong. (a) "Hot cup of coffee becoming cold spontaneously is an entropy-decreasing process. So the law of entropy increase can be violated." (b) “Air conditioners require bulky external unit, exhausting heat to outside. With the technology constantly advancing, external unit will be eliminated in the future."

It is planned to build a geothermal power plant for electricity generation purposes. The subsoil water reaches temperatures close to 170 ° C while the ambient temperature is 20 ° C. Find the maximum efficiency that a geothermal plant could aspire to if installed in that location.   Ans: η=33.85%