Refrigerator power vs. dissipation

In summary, refrigerators and air conditioners both work by moving heat, not producing it. The amount of power consumed to move heat from the refrigerator cabinet to the surroundings is not necessarily equal to the amount of heat removed from the cabinet. Refrigerator performance is typically measured by the co-efficient of performance, which can be around 2 or 3 for air conditioners and slightly higher for refrigerators. While refrigerator specs may not give cooling capacity, air conditioner specs often do, and can be used to calculate the CoP.
  • #1
Pengwuino
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OK someoone on a different forum said his refrigerator is an 80 watt refrigerator (small lil college fridge). As in it takes 80 watts from the wall. Isnt it true that this isn't the same amount of heat that can be taken out of the contents inside?

I remember someone talking about an airconditioner using 2000watts of power while dissipating like 2500 watts... any help would be ... helpful :D
 
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  • #2
Just as with the air conditioner thread a week or so back, think of a refrigerator as a device which moves heat, rather than producing it.

The amount of power consumed to 'move' the heat from the refrigerator cabinet to the surroundings isn't necessarily equal to the amount of heat removed from the cabinet.

Just think of carrying a block of metal at 50000 degrees across a room. If you're wearing gloves, it doesn't matter that the block is hot. You're just moving heat.
 
  • #3
Ok good.. thought so... didnt want to give these guys incorrect info.
 
  • #4
Pengwuino said:
OK someoone on a different forum said his refrigerator is an 80 watt refrigerator (small lil college fridge). As in it takes 80 watts from the wall. Isnt it true that this isn't the same amount of heat that can be taken out of the contents inside?
A refrigerator performance is measured by the co-efficient of performance: Heat removed from the cold reservoir (ie inside) divided by the Work input:

[tex]CP_{ref} = \frac{Q_c}{W}[/tex]

The CP depends on the temperature difference but is typically about 2 or 3 for air conditioners and a little higher for refrigerators - ie. 2 or 3 times as much heat transferred as energy input.

Refrigerators are also rated in terms of 'cooling power' or heat removed / time divided by power input (x BTU/hr cooling/y watts input) but since the units are odd you can't really tell how efficient it is in terms of heat out/input.

AM
 
  • #5
AFAIK, refrigerator specs don't give cooling capacity, but often times, air conditioner specs give both cooling capacity and electrical usage. http://www.sears.com/sr/javasr/prod...vertical=APPL&pid=04273055000&tab=spe#tablink is an example. It says it has a capacity of 5600 BTU/hr and consumes 510 watts of energy to provide it. There are 3.4 BTU per watt, so that's 1647 watts of cooling. The heat rejected out the back will be the sum of the two. Using A_M's forumla, that's a CoP of 3.2.
 
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1. How does refrigerator power affect its energy dissipation?

Refrigerator power refers to the amount of electrical energy required to run the refrigerator, while dissipation refers to the release of heat energy by the refrigerator. The higher the power, the more energy is consumed and dissipated by the refrigerator.

2. Is there a relationship between refrigerator power and its cooling capacity?

Yes, there is a direct relationship between refrigerator power and cooling capacity. The higher the power, the more energy is available for the refrigerator to use for cooling, resulting in a higher cooling capacity.

3. How does the size of a refrigerator affect its power and dissipation?

The size of a refrigerator does not directly affect its power or dissipation. However, larger refrigerators may have a higher power and dissipation due to their larger cooling capacity and the need for more energy to maintain a consistent temperature.

4. What is the difference between active and passive cooling in refrigerators?

Active cooling refers to the use of electricity to power a compressor or fan to cool the refrigerator, while passive cooling utilizes natural convection or thermoelectric cooling to dissipate heat. Active cooling typically has a higher power and dissipation compared to passive cooling.

5. How can I reduce the power and dissipation of my refrigerator?

To reduce the power and dissipation of your refrigerator, you can choose a model with a higher energy efficiency rating, keep the door closed as much as possible, and regularly clean the coils to ensure proper airflow. Additionally, avoid placing the refrigerator near a heat source or in direct sunlight.

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