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1.45 L of 16°C water is placed in a refrigerator. The refrigerator's motor must supply an extra 10.7 W power to chill the water to 6°C in 0.7 hr. What is the refrigerator's coefficient of performance?

User Sanjay Kumar
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1 Answer

7 votes
7 votes

Answer:

The coefficient of performance of the refrigerator is 2.251.

Step-by-step explanation:

In this case, the coefficient of performance of the refrigerator (
image), no unit, is equal to the ratio of the heat rate received from the water to the power needed to work, that is:


image (1)


image (2)

Where:


image - Heat rate received from the water, in watts.


image - Power, in watts.


image - Density of water, in kilograms per cubic meter.


image - Volume of water, in cubic meters.


image - Specific heat of water, in joules per kilogram-degree Celsius.


image - Temperature change, in degrees Celsius.


image - Cooling time, in seconds.

If we know that
image,
image,
image,
image,
image and
image, then the coefficient of refrigeration of the refrigerator is:


image


image

The coefficient of performance of the refrigerator is 2.251.

User Jackarms
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3.2k points