need help finding C FR#3 After enjoying a crockpot meal, you put the leftovers (
ID: 1882608 • Letter: N
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need help finding C
FR#3 After enjoying a crockpot meal, you put the leftovers (still in the pot) into your refrigerator while it is at a temperature of 30°C. Your refrigerator keeps its environment at 7°C and your A/C keeps your kitchen at 22°C. a) Assuming the pot and the leftovers have a combined mass of 2.5 kg and have a combined b) c) specific heat of 2500 J/kgoC, how much energy must the refrigerator remove? (5) If the refrigerator operates with a COP of 9.5 and draws 30 W of power to do this, how long would this take? (10) After the refrigerator comes to equilibrium, someone opens the door to grab some soda from the fridge. This causes all the air in the fridge to vent and be replaced by air from the kitchen at 22°C. If the air space in your refrigerator amounts to 1.60 m2, how much work is required to cool the air to the desired temperature of 7°C? (our air is primarily nitrogen and oxygen) (10) a) O to remove mcAT 2.5 kg*2500 J/(kg*oC) 23°C 143750 b) COP Q/W 9.5- 143750/w 143750/9.5 15130 15130 J/Power time15130 J/30 W 504 sExplanation / Answer
(C) We know that heat removed from the air will be done at constant volume.
Therefore
Q = mCV*(Tinit - TFinal)
Where m is mass of air = Density*Volume
= 1.2*(1.6) = 1.92 kg
CV is the specific heat of air at constant volume = 0.718 kJ/Kg-K
Q = 1.92*0.718*(22-7)
Q = 20.678 kJ
Hence the workdone by the refrigerator to cool down the air 20.678 kJ
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