Refrigerator - Revision history

Jmdonev: 1 revision imported

2021-09-27T00:03:15Z

1 revision imported

← Older revision	Revision as of 00:03, 27 September 2021
(No difference)

energy>Ethan.boechler at 16:32, 13 September 2021

2021-09-13T16:32:18Z

← Older revision		Revision as of 16:32, 13 September 2021
Line 1:		Line 1:
	[[category:371 topics]]		[[category:371 topics]]
	[[Category:Done 2018-06-01]]		[[Category:Done 2018-06-01]]
			[[Category:Translated to French]]
			[[fr:Réfrigérateur]]
	[[File:Refrigerator.png\|350px\|thumbnail\|Figure 1: A refrigerator expels heat from its interior by the input of work.<ref>''Created internally by a member of the Energy Education team.''</ref>]]		[[File:Refrigerator.png\|350px\|thumbnail\|Figure 1: A refrigerator expels heat from its interior by the input of work.<ref>''Created internally by a member of the Energy Education team.''</ref>]]
	<onlyinclude>A '''refrigerator''' is an open system that dispels [[heat]] from a closed space to a warmer area, usually a kitchen or another room. By dispelling the heat from this area, it decreases in [[temperature]], allowing food and other items to remain at a cool temperature.</onlyinclude> Refrigerators appear to violate the [[Second law of thermodynamics\|Second Law of Thermodynamics]], but the key reason they do not is because of the [[work]] needed as input to the system. They are essentially [[heat pump]]s, but work to cool a region instead of heat it.<ref name=Knight>R. "Ideal Gas Refrigerators" in ''Physics for Scientists and Engineers: A Strategic Approach,'' 3nd ed. San Francisco, U.S.A.: Pearson Addison-Wesley, 2008, ch.19, sec.4, pp. 532 and 538</ref>		<onlyinclude>A '''refrigerator''' is an open system that dispels [[heat]] from a closed space to a warmer area, usually a kitchen or another room. By dispelling the heat from this area, it decreases in [[temperature]], allowing food and other items to remain at a cool temperature.</onlyinclude> Refrigerators appear to violate the [[Second law of thermodynamics\|Second Law of Thermodynamics]], but the key reason they do not is because of the [[work]] needed as input to the system. They are essentially [[heat pump]]s, but work to cool a region instead of heat it.<ref name=Knight>R. "Ideal Gas Refrigerators" in ''Physics for Scientists and Engineers: A Strategic Approach,'' 3nd ed. San Francisco, U.S.A.: Pearson Addison-Wesley, 2008, ch.19, sec.4, pp. 532 and 538</ref>

Jmdonev: 1 revision imported: Doing upload, largely of old redirects.

2018-06-04T16:52:20Z

1 revision imported: Doing upload, largely of old redirects.

← Older revision	Revision as of 16:52, 4 June 2018
(No difference)

Jmdonev at 22:52, 31 May 2018

2018-05-31T22:52:36Z

← Older revision		Revision as of 22:52, 31 May 2018
Line 1:		Line 1:
	[[category:371 topics]]		[[category:371 topics]]
	[[Category:Done ~~2015~~-04-01]]		[[Category:Done 2018-06-01]]
	[[File:Refrigerator.png\|350px\|thumbnail\|Figure 1: A refrigerator expels heat from its interior by the input of work.<ref>''Created internally by a member of the Energy Education team.''</ref>]]		[[File:Refrigerator.png\|350px\|thumbnail\|Figure 1: A refrigerator expels heat from its interior by the input of work.<ref>''Created internally by a member of the Energy Education team.''</ref>]]
	<onlyinclude>A '''refrigerator''' is an open system that dispels [[heat]] from a closed space to a warmer area, usually a kitchen or another room. By dispelling the heat from this area, it decreases in [[temperature]], allowing food and other items to remain at a cool temperature.</onlyinclude> Refrigerators appear to violate the [[Second law of thermodynamics\|Second Law of Thermodynamics]], but the key reason they do not is because of the ~~necessary~~ [[work]] needed ~~to be~~ input to the system. They are essentially [[heat pump]]s, but work to cool a region instead of heat it.<ref name=Knight>R. "Ideal Gas Refrigerators" in ''Physics for Scientists and Engineers: A Strategic Approach,'' 3nd ed. San Francisco, U.S.A.: Pearson Addison-Wesley, 2008, ch.19, sec.4, pp. 532 and 538</ref>		<onlyinclude>A '''refrigerator''' is an open system that dispels [[heat]] from a closed space to a warmer area, usually a kitchen or another room. By dispelling the heat from this area, it decreases in [[temperature]], allowing food and other items to remain at a cool temperature.</onlyinclude> Refrigerators appear to violate the [[Second law of thermodynamics\|Second Law of Thermodynamics]], but the key reason they do not is because of the [[work]] needed as input to the system. They are essentially [[heat pump]]s, but work to cool a region instead of heat it.<ref name=Knight>R. "Ideal Gas Refrigerators" in ''Physics for Scientists and Engineers: A Strategic Approach,'' 3nd ed. San Francisco, U.S.A.: Pearson Addison-Wesley, 2008, ch.19, sec.4, pp. 532 and 538</ref>

	== How they work ==		== How they work ==
Line 8:		Line 8:
	According to the Second Law of Thermodynamics, heat will always flow spontaneously from hot to cold, and never the other way around. A refrigerator causes heat to flow from cold to hot by inputting work, which cools the space inside the refrigerator. It does this by following the steps below, which can be somewhat visualized with help from Figure 1:<ref>Energy Quest (n.d.). ''How Does a Refrigerator Work?'' [Online] Available: http://www.energyquest.ca.gov/how_it_works/refrigerator.html</ref>		According to the Second Law of Thermodynamics, heat will always flow spontaneously from hot to cold, and never the other way around. A refrigerator causes heat to flow from cold to hot by inputting work, which cools the space inside the refrigerator. It does this by following the steps below, which can be somewhat visualized with help from Figure 1:<ref>Energy Quest (n.d.). ''How Does a Refrigerator Work?'' [Online] Available: http://www.energyquest.ca.gov/how_it_works/refrigerator.html</ref>

	*Work is ~~input~~ (<m>W_{in}</m>) which compresses a coolant, increasing its temperature above the room's temperature.		*Work is inputted (<math>W_{in}</math>) which compresses a coolant, increasing its temperature above the room's temperature.
	*Heat flows from this coolant to the air in the room (<m>Q_H</m>), reducing the temperature of the coolant.		*Heat flows from this coolant to the air in the room (<math>Q_H</math>), reducing the temperature of the coolant.
	*The coolant expands, and it cools down below the temperature inside the refrigerator.		*The coolant expands, and it cools down below the temperature inside the refrigerator.
	*Heat flows from the refrigerator to the coolant (<m>Q_C</m>), decreasing the temperature inside.		*Heat flows from the refrigerator to the coolant (<math>Q_C</math>), decreasing the temperature inside.

	This process is cyclical, and allows refrigerators to be run for as long as necessary. The work needed ~~to be~~ input to the system is given by the equation		This process is cyclical, and allows refrigerators to be run for as long as necessary. The work needed as input to the system is given by the equation

	<center><m>W_{in}=Q_H-Q_C</m></center>		<center><math>W_{in}=Q_H-Q_C</math></center>

	with the variables being shown in Figure 1. This equation shows that a refrigerator must exhaust ''more'' heat to the room than it removes from the inside. This has significant implications for whether or not you can cool a room by leaving the refrigerator door open.<ref name=Knight/>		with the variables being shown in Figure 1. This equation shows that a refrigerator must exhaust ''more'' heat to the room than it removes from the inside. This has significant implications for whether or not you can cool a room by leaving the refrigerator door open.<ref name=Knight/>

	== Efficiency ==		== Efficiency ==
	Refrigerator [[efficiency]] has improved dramatically over the years. Today U.S. refrigerators consume less than 500 kWh/year, far less than the typical 1800 kWh in 1972. Improvements were made, and continue to be made, in the insulation, compressor efficiency, heat exchange in the evaporator and condenser, fans, and other components of the refrigerator.<ref>Appliance Standards Awareness Project, ''Refrigerators and Freezers'' [Online], Available: http://www.appliance-standards.org/product/refrigerators-and-freezers</ref>		Refrigerator [[efficiency]] has improved dramatically over the years. Today U.S. refrigerators consume less than 500 kWh/year, far less than the typical 1800 kWh in 1972. Improvements were made and continue to be made in the insulation, compressor efficiency, heat exchange in the evaporator and condenser, fans, and other components of the refrigerator.<ref>Appliance Standards Awareness Project, ''Refrigerators and Freezers'' [Online], Available: http://www.appliance-standards.org/product/refrigerators-and-freezers</ref>

	U.S. Energy Star certified refrigerators must use 20% less electricity than the U.S. minimum standard for refrigerators. There is a calculator that allows you to calculate yearly savings from ~~the model you are considering~~, compared to the model you own, based on what you pay for electricity.<ref>Energy Star (n.d.). ''Refrigerator Retirement Savings Calculator'' [Online] Available: http://www.energystar.gov/index.cfm?fuseaction=refrig.calculator</ref>		U.S. Energy Star certified refrigerators must use 20% less electricity than the U.S. minimum standard for refrigerators. There is a calculator (which can be found [https://www.energystar.gov/index.cfm?fuseaction=refrig.calculator here]) that allows you to calculate yearly savings from an Energy star certified fridge, compared to the model you own, based on what you pay for electricity.<ref>Energy Star (n.d.). ''Refrigerator Retirement Savings Calculator'' [Online] Available: http://www.energystar.gov/index.cfm?fuseaction=refrig.calculator</ref>

	== Coefficient of performance (Efficiency) ==		== Coefficient of performance (Efficiency) ==
	:''[[Coefficient of performance\|main article]]''		:''[[Coefficient of performance\|main article]]''

	For refrigerators, a manufacturer would want to make the area colder while doing as little work as possible. By doing little work to cool the appliance, the refrigerator can stay at the desired temperature while using less electricity, therefore saving the owner money. The number that describes this idea is the [[coefficient of performance]], <m>K</m>, which is essentially a measure of efficiency. The equation for it is<ref name=Knight/>		For refrigerators, a manufacturer would want to make the area colder while doing as little work as possible. By doing little work to cool the appliance, the refrigerator can stay at the desired temperature while using less electricity, therefore, saving the owner money. The number that describes this idea is the [[coefficient of performance]], <math>K</math>, which is essentially a measure of efficiency. The equation for it is<ref name=Knight/>

	<center><m>K=\frac{Q_C}{W_{in}}</m></center>		<center><math>K=\frac{Q_C}{W_{in}}</math></center>

	The higher this value the better, because it means that less work is being done to cool down the refrigerator.		The higher this value the better, because it means that less work is being done to cool down the refrigerator.

			==For Further Reading==
			*[[Work]]
			*[[Heat]]
			*[[Second law of thermodynamics]]
			*[[Coefficient of performance]]
			*Or explore a [[Special:Random\| random page]]

	==References==		==References==
	{{reflist}}		{{reflist}}
	[[Category:Uploaded]]		[[Category:Uploaded]]

J.williams: 1 revision imported

2015-08-26T21:31:35Z

1 revision imported

← Older revision	Revision as of 21:31, 26 August 2015
(No difference)

J.williams at 16:58, 12 August 2015

2015-08-12T16:58:50Z

New page

[[category:371 topics]]
[[Category:Done 2015-04-01]]
[[File:Refrigerator.png|350px|thumbnail|Figure 1: A refrigerator expels heat from its interior by the input of work.<ref>''Created internally by a member of the Energy Education team.''</ref>]]
<onlyinclude>A '''refrigerator''' is an open system that dispels [[heat]] from a closed space to a warmer area, usually a kitchen or another room. By dispelling the heat from this area, it decreases in [[temperature]], allowing food and other items to remain at a cool temperature.</onlyinclude> Refrigerators appear to violate the [[Second law of thermodynamics|Second Law of Thermodynamics]], but the key reason they do not is because of the necessary [[work]] needed to be input to the system. They are essentially [[heat pump]]s, but work to cool a region instead of heat it.<ref name=Knight>R. "Ideal Gas Refrigerators" in ''Physics for Scientists and Engineers: A Strategic Approach,'' 3nd ed. San Francisco, U.S.A.: Pearson Addison-Wesley, 2008, ch.19, sec.4, pp. 532 and 538</ref>

== How they work ==

According to the Second Law of Thermodynamics, heat will always flow spontaneously from hot to cold, and never the other way around. A refrigerator causes heat to flow from cold to hot by inputting work, which cools the space inside the refrigerator. It does this by following the steps below, which can be somewhat visualized with help from Figure 1:<ref>Energy Quest (n.d.). ''How Does a Refrigerator Work?'' [Online] Available: http://www.energyquest.ca.gov/how_it_works/refrigerator.html</ref>

*Work is input (<m>W_{in}</m>) which compresses a coolant, increasing its temperature above the room's temperature.
*Heat flows from this coolant to the air in the room (<m>Q_H</m>), reducing the temperature of the coolant.
*The coolant expands, and it cools down below the temperature inside the refrigerator.
*Heat flows from the refrigerator to the coolant (<m>Q_C</m>), decreasing the temperature inside.

This process is cyclical, and allows refrigerators to be run for as long as necessary. The work needed to be input to the system is given by the equation

<center><m>W_{in}=Q_H-Q_C</m></center>

with the variables being shown in Figure 1. This equation shows that a refrigerator must exhaust ''more'' heat to the room than it removes from the inside. This has significant implications for whether or not you can cool a room by leaving the refrigerator door open.<ref name=Knight/>

== Efficiency ==
Refrigerator [[efficiency]] has improved dramatically over the years. Today U.S. refrigerators consume less than 500 kWh/year, far less than the typical 1800 kWh in 1972. Improvements were made, and continue to be made, in the insulation, compressor efficiency, heat exchange in the evaporator and condenser, fans, and other components of the refrigerator.<ref>Appliance Standards Awareness Project, ''Refrigerators and Freezers'' [Online], Available: http://www.appliance-standards.org/product/refrigerators-and-freezers</ref>

U.S. Energy Star certified refrigerators must use 20% less electricity than the U.S. minimum standard for refrigerators. There is a calculator that allows you to calculate yearly savings from the model you are considering, compared to the model you own, based on what you pay for electricity.<ref>Energy Star (n.d.). ''Refrigerator Retirement Savings Calculator'' [Online] Available: http://www.energystar.gov/index.cfm?fuseaction=refrig.calculator</ref>

== Coefficient of performance (Efficiency) ==
:''[[Coefficient of performance|main article]]''

For refrigerators, a manufacturer would want to make the area colder while doing as little work as possible. By doing little work to cool the appliance, the refrigerator can stay at the desired temperature while using less electricity, therefore saving the owner money. The number that describes this idea is the [[coefficient of performance]], <m>K</m>, which is essentially a measure of efficiency. The equation for it is<ref name=Knight/>

<center><m>K=\frac{Q_C}{W_{in}}</m></center>

The higher this value the better, because it means that less work is being done to cool down the refrigerator.

==References==
{{reflist}}
[[Category:Uploaded]]