20102HW9 - Determine; a) The rate of heat removed from the...

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MIDDLE EAST TECHNICAL UNIVERSITY DEPARTMENT OF CHEMICAL ENGINEERING Ch.E. 204- Thermodynamics I (Section 04) Dr. N. Sezgi, Ö . Mercan PROBLEM SET IX Question 1. Consider a steam power plant that operates on a simple ideal Rankine cycle and has a net power output of 45MW. Steam enters the turbine at 7 MPa and 500°C and is cooled in the condenser at a pressure of 10 kPa by running cooling water from a lake through the tubes of the condenser at a rate of 2000 kg/s. Show the cycle on a T-S diagram with respect to saturation lines, and determine; a) Thermal efficiency of the cycle, b) Mass flow rate of the steam, c) Temperature rise of the cooling water. Question 2. A refrigerator uses refrigerant-134a as the working fluid and operates on an ideal vapor-compression refrigeration cycle between 0.12 and 0.7 MPa. The mass flow rate of the refrigerant is 0.05 kg/s. Show the cycle on a T-S diagram with respect to saturation lines.
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Unformatted text preview: Determine; a) The rate of heat removed from the refrigerated space and the power input to the compressor, b) The rate of heat rejection to the environment, c) The coefficient of performance. Question 3. A heat pump is used to heat a house and maintain it at 24°C. On a winter day when the outdoor temperature is -5°C, the house is estimated to lose heat at a rate of 80,000 kJ/h. Determine the power required to operate this heat pump if it is Carnot cycle heat pump? If instead of Carnot cycle, a vapor-compression cycle was used for the heat pump with HFC-134a, what will be the coefficient of performance? Assume that the only pressure changes occur across the compressor and expansion valve and they are adiabatic such that the only heat transfer to or from the refrigerant occurs in evaporator and condenser....
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