answersLogoWhite

0


Best Answer

The coefficient of performance (see Wikipedia article on "coefficient of performance") is a measure of merit for a refrigerator. To understand what it is telling us, we need to understand what a refrigerator does. Heat flows naturally from a hot region to a cold region. Even though your kitchen refrigerator is insulated to minimize the heat flow, without the machinery, the inside would gradually warm up to the temperature of the room. To keep the inside cold, the refrigerator must counter the natural flow by moving heat from the colder region inside the refrigerator to the outside. We have to put energy (usually electrical work) into the refrigerator to accomplish this.

If the inside were warmer than the outside, it would take no work to remove heat from the inside. The warmer inside would pass heat to the colder outside naturally. If the inside is just a little colder than the outside, it would take just a little work to move heat from inside to outside. As the temperature difference you wish to maintain increases, so does the work needed. But when we deal with thermodynamics, we must use absolute temperatures. If the temperature of the room is 68 degrees Fahrenheit, that is 20 degrees Celcius, or 293 degrees Kelvin. (The Kelvin temperature scale starts at absolute zero) If the temperature inside the freezer compartment is -5 degrees Celcius, that would be 268 Kelvin. The difference of 25 degrees is less than a tenth the lower absolute temperature. So in essence, this is the case of a small temperature difference.

The coefficient of performance is the ratio of the heat removed at the colder temperature to the work required to do it. Like many other figures of merit (the efficiency of an engine, the miles per gallon your car gets, ) the coefficient of performance measures the ratio of what you get (heat moved out of the box) to what you have to pay for (work from the electric company). But unlike the efficiency of an engine, the number can be greater than one. Because the temperature difference is small compared to the absolute temperature of the box, the energy expended to run the refrigerator is less than the energy moved from the inside to the outside.

User Avatar

Wiki User

16y ago
This answer is:
User Avatar

Add your answer:

Earn +20 pts
Q: Why coefficient of performance of a refrigerator is greater than 1?
Write your answer...
Submit
Still have questions?
magnify glass
imp
Related questions

Why is the coefficient of performance of heat pumps always greater than 1?

Hi: Who told you it was always greater than one and what was their reasoning ? If they are operating outside of their design parameters and there fore useless for the job at hand I would consider their coefficient of performance totally rubbish. Hope this helps : Jimiwane


Can a correlation coefficient be greater than 1?

No.


Why cop of making ice is greater than that of refrigerator?

It is not."A typical 40°F(4°C) cooler's condensing unit might have a COP (Coefficient of Performance) of 2.5""A 0°F (-14°C) freezer's COP is more likely to be about 1.67"Source: http://www.freeaire.com/freezers.html


What is coefficient of friction..?

A higher coefficient of friction indicates that two surfaces in contact have a greater resistence. A lower coefficient of friction indicates that the two surfaces in contact have less resistence. Soccer cleats on grass have a greater coefficient of friction than skates on ice.


What is friction coefficient?

A higher coefficient of friction indicates that two surfaces in contact have a greater resistence. A lower coefficient of friction indicates that the two surfaces in contact have less resistence. Soccer cleats on grass have a greater coefficient of friction than skates on ice.


What numbers will a correlation coefficient not ever be?

34.32245Correlation coefficient is less than -1 and greater than 1.Note: The Correlation coefficient is lies between -1 to 1 if it is 0 mean there is no correlation between them.


What does a coefficient of friction of 1.0 or greater mean?

It means that the maximum force of friction is greater than the weight of the object.


Is -012 a negative correlation?

No. A correlation coefficient cannot be less than -1 (or greater than +1)


Why balloon fall slower than a marble?

The balloon falls slower than a marble because its buoyancy is greater and because its drag coefficient is greater.


Why is a greater force needed to move a refrigerator than it's needed to move a book?

The formula for force is Force= Mass x Acceleration. Therefore, you have to use a greater force to move the refrigerator because it has a greater mass than the book.


If a demand for a product is elastic the value of the price elasticity coefficient is?

greater than one


Why can't the probability of an event occurring be greater than 1?

If probability becomes greater than one, then the uncertainty coefficient fluctuates and results in a terminal case.