Hence, if a real refrigerator has the coefficient of performance of cop, then. Coefficient of performance of a refrigerator engineering. Coefficient of performance an overview sciencedirect topics. The coefficient of performance is used to quantify the performance of refrigeration cycles. Jan 30, 2018 for the love of physics walter lewin may 16, 2011 duration.
Improvement in the cop of thermoelectric cooler jatin patel, matik patel, jigar patel, himanshu modi. Cop carnot, cop aktual, dan efisiensi refrigerasi dari sistem, c. The coefficient of performance cop of vapor compression refrigeration is higher than other available techniques. Since a carnot refrigerator is a reversible refrigeration cycle the above expression for cop r,rev is valid for the reversed carnot cycle. Typically the thermodynamic system in a refrigerator analysis will be a working fluid, a refrigerant, that circulates around a loop, as shown in figure 3. Paper open access related content experimental investigation. Refrigeration cycles the vapor compression refrigeration cycle is a common method for transferring heat from a low temperature to a high temperature. You get that convenient combination and much more with this splendid dualdoor compact refrigerator by danby. For household applications, to obtain an adequate cooling effect, the temperature differential between the sides of tec is considered to be about.
This effect is commonly used in camping and portable coolers and for cooling electronic components and small instruments. Hermes 2 1 department of mechanical engineering, federal university of santa catarina, 88040970, florianopolis, sc, brazil 2 department of mechanical engineering, federal university of. A refrigerant doesnt have a cop, but a refrigeration cycle does. In addition to being more accurate than the constant conductance model, the variable conductance model is also more flexible. The cop is the ratio of the heat output of a heat pump to its electrical energy input, expressible as follows. The above figure shows the objectives of refrigerators and heat pumps. The cop usually exceeds 1, especially in heat pumps, because, instead of just converting work to heat which, if 100% efficient, would be a cop of 1, it pumps. How to calculate coefficient of performance sciencing. Cop r,rev or cop hp,rev is the highest cop a refrigerator or a heat pump which operates between a hightemperature reservoir at temperature t h and a lowtemperature reservoir at temperature t l can reach.
The coefficient of performance cop is a measure of efficiency of the refrigerator. The refrigerant, which is now in a liquid state, passes through the expansion valve and turns into a cool gas due to the sudden drop in pressure. The reversed carnot cycle 111c because the compression process involves the compression of a liquidvapor mixture which requires a compressor that will handle two phases, and the expansion process involves the expansion of highmoisture content. Every 15 minutes or so you hear the motor turn on, and it magically keeps things cold. Coefficient of performance refrigerator, air conditioner. Copbased performance evaluation of domestic refrigerators. This is the ratio of cooling out pu t kilowatt com pa. How refrigerators work introduction to how refrigerators work. Abuzar qureshi1, shikha 2bhatt 1 prestige institute of engineeringand science, scheme 74 vijay nager indore m. The coefficient of performance is also called the advantage and is defined as c.
And thus project work is shaped, replacement of domestic refrigerator provided with regular condenser by spiral and micro channel type condenser to study percentage of enhancement come occurred in cop as an outcome 26. The coefficient of performance cop is the most common measure of heat pump efficiency. This paper compares the cop of a thermoacoustic refrigerator to that of a vapour compression based system for a variety of heat loads and temperature spans to investigate under what conditions a thennoacoustic refrigerator might be competitive with current refrigeration systems. It is also known as theoretical coefficient of performance. The coefficient of performance or cop sometimes cp or cop of a heat pump, refrigerator or air conditioning system is a ratio of useful heating or cooling provided to work required. Thermoelectric refrigeration principles intechopen. The effectiveness of refrigerators or air conditioners represents one way of comparing coefficient of performance as q c w in for q c the heat the refrigerator gives off q c and the work input to the system w in. Coefficient of performance and relative coefficient of. Cops of the rest of the alternative refrigerants has been made. The symbol used for coefficient of performance is cop with a subscript r, for refrigeration. Just like the efficiency of power cycles, the cop is defined as the ratio of the desired output to the required input. Cop heat transfer of interest total work input the heat transfer of interest is will either be the total heat transfer from the condenser or the evaporator.
Coefficients of performance for the refrigeration systems cops the concept of the performance index for a refrigeration cycle is expressed in terms of the coefficient of performance cop, which in the studied case consists of the ratio between intended energy q l and consumed energy w, according to stoecker and jones. Domestic refrigerator using conventional and nonconventional energy sources. Based on the results, usage of r600a in domestic refrigerators will reduce the odp and also gwp problems which fulfills the nominal requirements of human beings without any effects. Cop of reversible refrigeration cycles physics forums. Pdf solar energy is proved to be an ideal source for low temperature heating applications. Cop to run such refrigerator is estimated after numerical simulation of major components namely.
Oct 27, 2009 coefficient of performance of a refrigerator the coefficient of performance briefly written as c. All irreversible refrigerators or heat pumps working between the. Effectiveness of singlestage thermoelectric refrigerator may decrease with increase in the temperature ratio of heat source and heat sink. Improve the cop of vapor compression cycle with change in.
The effects of the condenser, freezerevaporator and refrigeratorevaporator temperatures on the exergetic performance coefficient, cop, exergy efficiency and exergy destruction ratios have been. The refrigeration capacity and coefficient of performance. The objective of a refrigerator is to remove heat ql from the refrigerated space. This is the ratio of cooling out pu t kilowatt com pa red with ener gy input ki lowatt, thus the higher the cop. The cop usually exceeds 1, especially in heat pumps, because, instead of just converting work to heat which, if 100%.
Coefficient of performance of refrigeration the refrigerator is a device that extracts heat from colder part reservoir of the system and delivered it to the hotter sink environment. Cop of alternative refrigerants must also be established. Without refrigeration, wed be throwing out our leftovers instead of saving them for another meal. Cop r black in the topfreezer refrigerators section of. Cop can be calculated by dividing the amount of heat absorbed at the cold side to the input power. A comparison between refrigerants used in air conditioning. Volume 29, issues 1112, august 2009, pages 23582364. The reality of a small household thermoacoustic refrigerator. The coefficient of performance cop is the standard measure of the efficiency of refrigeration systems. Air refrigerator working on bellcoleman cycle with pv and.
Compressor of the refrigerator system consumes work 80 to 100% of the total energy used. How does the cop of refrigerator is greater than 1. Enhancement of cop by using spiral and microchannel. Coefficient of performance an overview sciencedirect. Rating of a domestic refrigerator is of the order of a 0. It comes to attract an attention about condenser performance which leading to increase cop of overall refrigerator system. Bila kapasitas pendinginannya adalah 25 kw, tentukanlah. The cop of a domestic refrigerator is the ratio of the refrigeration capacity to the energy supplied to the compressor. May 15, 2017 cop of a carnot cycle depends upon the minimum and maximum temperature in the cycle. The coefficient of performance can take many forms that are unique to or inherently based on the principles of specific disciplines. As said above, an important property of every refrigerator is the cold surface for adsorption of the heat from the cooling object. Todays refrigeration and air conditioning systems have become necessary for the human. To accomplish this objective, it requires a work input of wnet,in. Pdf analysis of refrigeratorfreezer appliances having dual.
Cop outpuinput desired effect work input for a refrigerator working between two temperature limits, t1higher and t2lower refrigerator will. The coefficient of performance, cop, of a refrigerator is defined as the heat removed from the cold reservoir q cold, i. This initiates development of various ways to improve coefficient of performance cop of the thermoelectric refrigeration system. For the love of physics walter lewin may 16, 2011 duration. Pdf analysis of refrigeratorfreezer appliances having. The effects of the condenser, freezerevaporator and refrigerator evaporator temperatures on the exergetic performance coefficient, cop, exergy efficiency and exergy destruction ratios have been. It was seen that the performance of r 152 a is better than r 22, while the others are worse. To improve the coefficient of performance, its requires that the compressor. Heat transfer in refrigerator condensers and evaporators. Reversing the carnot cycle does reverse the directions of heat and work interactions. This heat flow corresponds to the cooling power or cooling capacity of the given refrigerator. Airsource heat pumps generally have cops ranging from 2 to 4, implying that they deliver two to four.
This implies that cop hp will be greater than one because cop r. The cop of the thermoacoustic and vapour compression refrigeration systems shown in figure 4 are respectively cop w 1 where, for the thermoacoustic system, qc is the heat load into the cold end of the stack and w is the acoustic power. Copbased performance evaluation of domestic refrigerators using accelerated flow evaporators paulo j. Cop, domestic refrigerator, eco friendly refrigerant, solar refrigerator. A textbook of refrigeration and air conditioning simple. Cop r,rev t l t ht l this is the basically the maximum cop a refrigeration cycle can achieve operating between two thermal energy reservoirs at t h and t l. Refrigerator is one of the home appliances utilizing vapour. As the cool refrigerant gas flows through the chiller cabinet, it absorbs the heat from the food items inside the fridge. As mentioned above, the reversed carnot cycle is a reversible process. Calculating cooling loads calculating chiller and cooling tower refrigeration in tons. Refrigerator cop with thermal storage sciencedirect. The internal energy and temperature of the refrigerant is alternately raised and lowered by the devices in the loop.
Th movement cooling by the removal of heat the movement of heat from a place where it is notot a ted to a wanted to a place where it is unobjectionable. Both coefficients of performance cop have a relationship. A i t f 200 250 212 100 sensible steam heat measurable temperature temperature above 212 f. The efficiencyof a refrigerator is expressed in terms of the coefficient of performance cop, denoted by copr. What is the formula of finding cop of a carnot refrigerator. Cascading improves the cop of a refrigeration cycle. According to the second law of thermodynamics, the heat flow from a cold body to a hot body occur only by doing some outside work. Ch4, lesson f, page 9 coefficient of performance for a. A refrigerator is a heat engine operated in reverse, more or less. The cop of a domestic refrigerator a is less than 1 b is more than 1 c is equal to 1 d depends upon the make e depends upon the weather conditions. Mainly, the cop rises with the reduction of the temperature difference. Air refrigerator working on bellcoleman cycle with pv and ts. Then the cop of a refrigerator can be expressed as.
Cop is the ratio of the thermal output power and the electrical input power of the tec. Heat absorbed by air per kg during this process is equal to q 41 cpt 1t 4 cop of air refrigerator working on reversed carnot cycle with pv and ts diagram. Cop is nothing but the efficiency in different words. Cop, refrigerant flow, and compressor works hermawans. The purpose of a refrigerator is the removal of heat, called the cooling load, from a lowtemperature medium. An introduction thermoelectric cooling uses the peltier effect to create a heat flux between the junctions of two different types of materials.
Compressor basic refrigeration cycle evaporator condenser receiver expansion device. The coefficient of performance cop of a thermoelectric module which is the thermal efficiency must be considered for a te system. Cooling load convert kwton to cop or eer convert cooling load units kwton, cop and eer. Coefficient of performance of a refrigerator the coefficient of performance briefly written as c. Introduction to how refrigerators work in the kitchen of nearly every home in america there is a refrigerator. Cascade cycle is used where a very wide range of temperature between tl and th is required. Coefficient of performance enhancement of refrigeration. Contoh kalkulasi bila diketahui refrigeran r22 digunakan pada suatu sistem refrigerasi kompresi uap yang bekerja dengan tekanan evaporasi 3 bar gauge dan rasio kompresi 4,5. The vapor compression refrigeration cycle is a common method for transferring.
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