2300_hw_10

2300_hw_10 - Two air conditioners are considered for the...

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ME/CH EN 2300 Homework #10 Due March 28,2007 #1 (6-37) A refrigerator has a COP of 1.5. That is, the refrigerator removes 1.5 kWh of energy from a refrigerated space for each 1 kWh of electricity it consumes. Is this a violation of the 1 st law of thermodynamics? Explain. #2 (6-42) The coefficient of performance of a residential heat pump is 1.6. Calculate the heating, in KL/sec, this heat pump will produce when it consumes 2 kW of electrical power. #3 (6-43) A refrigerator used for cooling food in a grocery store is to produce 10,000 kJ/h cooling effect, and it has a coefficient of performance of 1.35. How many kilowatts of power will the refrigerator require to operate? #4 (6-56) Consider a building whose annual air conditioning load is estimated to be 120,000 kWh in an area where the unit cost of electricity is $0.10/kWh.
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Unformatted text preview: Two air conditioners are considered for the building. Air conditioner A has a seasonal average COP of 3.2 and costs %5,500 to purchase and install. Air conditioner B has a seasonal average COP of 5.0 and costs $7000 to purchase and install. All else being equal, determine which air conditioner is a better buy. #5 (6-78) You are an engineer in an electric generation station. You know that the flames in the boiler reach a temperature of 1200 K and that cooling water at 300 K is available from a nearby river. What is the maximum efficiency your plant will ever achieve? #6 (6-86) An inventor claimes to have developed a heat engine that receives 700 kJ of heat from a source at 500 K and produces 300 kJ of net work while rejecting the waste heat to a sink at 290 K. Is this a reasonable claim? Why?...
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