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Postby wrghcharl » Mon Mar 05, 2012 2:15 pm

1.the pump of a distribution system is powered by 6kw electric motor whose efficiency is 95%. The water flowrate through the pump is 18L/s. The diameter of the inlet and outlet are the same and the elevation difference acrossthe pump is neglible. if the pressure at the inlet and outlet of the pump are measured to be 100kpa and 300kpa (absolute), respectively, determine (a) the mechanical efficiency of the pump. B. the temp rise of the water as ti flows through the pump due to the mechanical efficiency.

2. A piston cylinder device initally contains 2kg of refrigerant-134a at 800kpa and 80 degree C. At this state, the piston is teachin on a pair of stops. The mass of the piston is such that a 500kpa pressure is require to move it. A valve at the bottom of the tank is open and r-134a is withdrewn from the cylinder. After a while, the piston is observed to moved and the valve is closed when half of the refrigetant is withdrewn from the tank and the temp in the tank drop to 20 degree C. determine A. the work done. B. the heat transfer.

3. In a large gas-turban powerplant, air is preheated by the exhaust gas in the heat exchanger called the regenerator before it enters the combustion chamber. Air enters the regenerator at 1mpa and 550k at a mass flow rate of 800kg/min. heat is transfer to the air at a rate of 3200kj/s. exhaust gas enters the regenerator at 140kpa and 800k and leaves at 130kpa and 600k. Treating exhaust gas as air, determine A. the exit temp of the air. B. the mass flow rate of exhaust gases.

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Re: thermodynamics

Postby midwestphysics » Mon Mar 05, 2012 3:21 pm


Now do your own homework

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