Heat Gain in a Fridge Experiment

In summary, the conversation discusses an experiment to determine the rate of heat gain in a refrigerator. The steps involve measuring the temperature of the main and freezer compartments, conducting a timed experiment when the refrigerator is not running, and using the power consumption and COP to calculate the average rate of heat gain. The use of a thermometer is not necessary for this experiment.
  • #1
Jacob87411
171
1
The following is an experiment I have to do:

Using a thermometer, measure the temperature of the main food compartment of your refrigerator, and check if it is between 1 and 4°C. Also, measure the temperature of the freezer compartment, and check if it is at the recommended value of -18°C. Using a timer (or watch) and a thermometer, conduct the following experiment to determine the rate of heat gain of your refrigerator. First make sure that the door of the refrigerator is not opened for at least a few hours so that steady operating conditions are established. Start the timer when the refrigerator stops running and measure the time Dt1 it stays off before it kicks in. Then measure the time Dt2 it stays on. Noting that the heat removed during Dt2 is equal to the heat gain of the refrigerator during Dt1 + Dt2 and using the power consumed by the refrigerator when it is running, determine the average rate of heat gain for your refrigerator, in W. Take the COP (coefficient of performance) of your refrigerator to be 1.3 if it is not available.
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I'm a little confused...So is the temperature change over t1+t2 equal to the heat gain? and then to find the average do I divide it by the time?
 
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  • #2
No, the heat gain Pg is related to the temperature difference from outside to inside, across the insulating walls. If Ta is room temperature,
Q = (Ta - Tm) * A1 / R1 + (Ta + T2) * A2 / R2
where A1,A2 are the surface areas of the main,freezer compartments and R1,R2 are the mean surface resistivities or "R-values" of the corresponding insulating walls.

You don't need to use any of that, however, nor do you really need to know the temperatures of the compartments. You know (or will look up) the power consumption when the motor is running. The fraction of electrical power converted to heat power is found by dividing by COP, then multiply that by the duty cycle Dt2/(Dt1 + Dt2) to find the average heat power gain. Does that make sense?
 
  • #3
Where does a thermometer come into place in this experiment then?
 

Related to Heat Gain in a Fridge Experiment

1. What is heat gain in a fridge experiment?

Heat gain in a fridge experiment refers to the increase in temperature inside a refrigerator due to external factors such as opening the door or placing warm items inside. It can also occur due to inefficiencies in the refrigerator's cooling system.

2. How is heat gain measured in a fridge experiment?

Heat gain in a fridge experiment can be measured using a thermometer placed inside the fridge. The temperature should be monitored before and after the experiment to determine the amount of heat gain.

3. What are the factors that contribute to heat gain in a fridge experiment?

The amount of heat gain in a fridge experiment can be affected by various factors such as the temperature of the room where the fridge is located, the frequency of door openings, the volume and temperature of items placed inside the fridge, and the efficiency of the fridge's insulation and cooling system.

4. How can heat gain in a fridge experiment be reduced?

To reduce heat gain in a fridge experiment, it is important to limit the frequency of door openings and avoid placing warm items inside the fridge. Additionally, ensuring that the fridge is properly insulated and maintaining its cooling system can also help reduce heat gain.

5. Why is it important to measure heat gain in a fridge experiment?

Measuring heat gain in a fridge experiment is important as it can give insight into the efficiency of the refrigerator's cooling system and help identify any potential issues. It can also help in determining the energy consumption of the fridge and finding ways to reduce it.

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