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(a) What is the best coefficient of for a heat pump that has a hot 5.05 of 40.0°

ID: 1793560 • Letter: #

Question

(a) What is the best coefficient of for a heat pump that has a hot 5.05 of 40.0°c and a cold reservolr (b) How much heat transfer (In kcal) occurs nto the warm environment it 3,60-103 of work (10.0 kw-h) s 43451 put into it? kcal (c) If the cost of this work input is 10/kw h, how does Its cost compare with the direct heat transfer achieved by burning natural gas at a cost of 89.o cents per therm. (A therm is a common unit of energy for nstural gas and equals 1.055 -10.) cost of heat pump 0.854 cost of natural gas Reading of 6.75. What is the hot Suppose you want to operate an ideal refrigerator with a cold temperature of -17°C, and you would like it to have a coefficient of reservoir temperature (in °C) for such a refrigerator? 20.92 26

Explanation / Answer

C)

Cost of doing work by heat pump is

=10*0.1=$1

1 kcal =4184 J

Cost of direct heat transfer acheived by burning natural gas

=(43451*4184/1.055*108)*0.89=$1.534

therefore

Cost of heat pump/cost of natural gas =1/1.534=0.652