Problems 5-1 Stead flow of steam enters a condenser with an enthalpy of 2400 kJ/kg and a velocity of 366 m/sec. the condensate leaves the condenser with an enthalpy of 162kJ/sec and a velocity of 6 m/sec what is the heat transferred to the cooling water per kg steam condensed. (-69198 kJ/kg) 5-2 An air compressor delivers 4.5 kg of air per minute at a pressure of 7 bar and a specific volume of 0.17 m³ /kg. Ambient conditions are pressure 1bar and specific volume 0.86 m³/kg. The initial and final internal energy values for the air are 28 kJ/kg and 110 kJ/kg respectively. Heat rejected to the cooling jacket is 76kJ/kg of air pumped. Neglecting changes in kinetic and potential energies, what is the shaft power required driving the compressor? (14.3kW)

4-7 Nitrogen (molecular weight 28) expands reversibly in perfectly thermally insulated cylinder from 3.5bar, 200°C to a volume of 0.09m. If the initial volume occupied was 0.03m³, calculate the work done during the expansion. Assume nitrogen to be perfect gas and take Cv = 0.741kJ/kg.K (9.31kJ) 4-8 1kg of air at 1.02bar, 20°C is compressed reversibly according to a law p.V¹³ = const., to a pressure of 5.5bar. Calculate the work done on the air and the heat flow to or from the cylinder walls during the compression. (133.5kJ/kg; -33.38kJ/kg)

Compare the masses and volumes of water, concrete, sand, and wood needed to store 106 Btu of heat if the operating temperatures are Tc = 85F and Th = 180F. In each case, calculate the edge length of a square storage unit with a height of 8 ft.

You serve as the president of XYZ corporation, which is an energy intensive manufacturing operation. You have four boilers to produce steam and electricity for your operations. One is a semi-suspension fired boiler with a capacity of 100 tons of coal per hour. The boiler can also burn supplemental fuel such as coconut or macadamia nut shells. The other three boilers arc peaking units and burn fuel oil. The City of Podunk has approached you about the possibility of burning solid waste as a supplemental fuel. As the president of the XYZ Corporation, you need to develop answers to many political, social, and technical questions before you make a commitment to the city. a. What specific questions would you ask your own power plant engineer about the possibility of accepting Podunk’s MSW? b. What specific additional data would you need from the city before you discuss this further?