An air conditioner removes heat steadily from a house at a rate of 700 kJ/min while drawing electric power at a rate of 5.10 kW. Determine:

a. the COP of this air conditioner
b. the rate of heat transfer to the outside air.

Respuesta :

Answer:

a) The Coefficient of Performance of this air conditioner is 2.288.

b) The rate of heat transfer to the outside air is 16.767 kilowatts (1006.02 kilojoules per minute).

Explanation:

a) Air conditioners are applications of refrigeration cycles, whose performance is analyzed by means of the Coefficient of Performance ([tex]COP_{R}[/tex]), dimensionless:

[tex]COP_{R} = \frac{\dot Q_{L}}{\dot W}[/tex] (Eq. 1)

Where:

[tex]\dot Q_{L}[/tex] - Heat removal rate from the house, measured in kilowatts.

[tex]\dot W[/tex]- Electric power, measured in kilowatts.

If we know that [tex]\dot W = 5.10\,kW[/tex] and [tex]\dot Q_{L} = 11.667\,kW[/tex], the Coefficient of Performance of this air conditioner is:

[tex]COP_{R} = \frac{11.667\,kW}{5.10\,kW}[/tex]

[tex]COP_{R} = 2.288[/tex]

The Coefficient of Performance of this air conditioner is 2.288.

b) We find the rate of heat transfer to the outside air ([tex]\dot Q_{H}[/tex]), measured in kilowatts, by applying the First Law of Thermodynamics:

[tex]\dot Q_{H} = \dot Q_{L}+\dot W[/tex] (Eq. 2)

If we get that [tex]\dot W = 5.10\,kW[/tex] and [tex]\dot Q_{L} = 11.667\,kW[/tex], then the rate of heat transfer to the outside air is:

[tex]\dot Q_{H} = 11.667\,kW+5.10\,kW[/tex]

[tex]\dot Q_{H} = 16.767\,kW[/tex]

The rate of heat transfer to the outside air is 16.767 kilowatts (1006.02 kilojoules per minute).

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