Refrigerator Definition and 148 Threads

Hi! I wonder how a refridgerator work. I understand that the Ideal Gas Law pV=N_{mol}RT is used somehow. This is my blog description of my preliminary understanding: "Here both N and V is constant. A compressor on the outside of the refridgerator enables high pressure of the gas there. A...

I am half way through my Electrical Engineering program and have only just started to learn about AC circuits and inductive loads but I did a little reading and went off to try a simple project on my on. A company I work for wanted a switch to turn off their large refrigerator for certain...

Hello, i am working about pot in pot refrigerator (zeer) and i have problem with calculation, i have to calculate how many % energy will be lost during T time, i know theory about this effect but i don't know how to calculate it, i have some reference but my english and math skills aren't...

i don't know where to post this so mods or admins can repost to whatever section is best fit. in my thermo class we were learning about the refrigerator and as soon as the prof said the working substance was CFC i remembered back to my high school chemistry days when my high school chem...

The question is: Consider a thermal battery - a device for storing mechanical energy. Use two large containers as heat reservoirs where one contains ice and water in equilibrium and the other contains steam and water in equilibrium. Both are held at pressure=1atm. Energy is stored by using a...

Dear all, I am a bit stuck trying to find out how heat is transferred through an evaporator in a refrigerator. I was using Newton's law of cooling before I realized there are more complexities in the equation as the refrigerant is in a mixture of saturated liquid and saturated gas in the...

I'm well aware that the default answer to this textbook default question is "it doesn't work", but still, I believe it does. To cool the insides of the refrigerator, the compressor must do work, and since the efficiency isn't 100% you are constantly warming the whole room to cool it's...

Homework Statement Hello guys, I've attempted a problem but I get a result that I find too low to make sense. Plus, I have a doubt. So here it comes: I've put in red the part I'm unsure of. As far as I know the efficiency of a refrigerator could be any real number from 0 to infinity (1 is...

I'm endeavoring to prototype a challenging sorting mechanism inside a fridge and would appreciate any tips on how to get from the specs to a plausible design. #Problem The aim of the game is to identify and sort food items in the limited space of a fridge - such that a user would push...

Homework Statement How long would a 3.50 kW space heater have to run to put into a kitchen the same amount of heat as a refrigerator (coefficient of performance = 3.13) does when it freezes 1.46 kg of water at 21.4°C into ice at 0°C? m=1.46 kg c_water=4186 J/kg Delta T= 21.4°C...

Homework Statement An ideal refrigerator utilizes a carnot cycle operating between 0 and 25 degrees celsius. To turn 10 kg of water at 0 degrees celsius into 10 kg of ice at 0 degrees celsius, a) how much heat is exhausted into the room? b) how much energy must be supplied to the...

Homework Statement The COP for heat pumps and refrigerators achieved in the industry is almost 50% of the Carnot limit. Make estimates for the following case: For refrigerator to achieve -10°C in the freezer area with an external temperature of 25°C Homework Equations COP for...

My refrigerator stopped working. I found that the relay switch that activates the compressor is cripsy fried. I called a local appliance parts store and it looks like I can buy a replacement for the switch. However, I am wondering why it fried in the first place. I want to test the compressor...

When opening a refrigerator door, the cold air inside mix with the warmer air outside. Directly after closing the door, it is noticably harder to open it again. Does anyone know how these temperature changes affect the pressure difference and exactly why? Thank you.

Carnot engine efficiency is: \eta_{work} = 1 - \frac{T_c}{T_h} Carnot refrigeration efficiency is: \eta_{cool} = \frac{ T_c }{T_h-T_c} \eta_{cool} = \frac{ 1 }{\frac{T_h}{T_c} - 1} Simple multiplication should give me the efficiency where both the engine and the refrigeration share the...

Homework Statement http://img21.imageshack.us/img21/1197/questionof.jpg The Attempt at a Solution For the first part, if we assume that the cycle is reversible from the 2nd law we have \Delta S = \frac{\Delta Q}{T}+S_{gen} = 0 And here is the Clasius Inequality S_{gen} \geq 0 \implies...

Your dorm room has a temperature of 72 °F, and you have two six packs of beer that you want to get ready to a drinking temperature of 61 °F for dinner. Your fridge has a temperature of 44 °F, and experience has shown that a room-temperature six pack, placed in the fridge, will be at drinking...

I make human powered machines for offgrid living and have been getting ready to start on a human powered fridge. The idea is to use a deep freezer and replace the compressor with an automotive one, and connect the shaft to pedals (might require two riders). 1) Are the freon types compatible...

Power of an Ideal Refrigerator -- Carnot Engines Homework Statement The inside of an ideal refrigerator is at a temperature T_c, while the heating coils on the back of the refrigerator are at a temperature T_h. Owing to a malfunctioning switch, the light bulb within the refrigerator remains...

Homework Statement I just want to know when do I use the formula for COP refrigerator vs COP Heat pump. If the heat is absorbing something then what formula do I use Homework Equations [b]3. The Attempt at a Solution [/b} Uh I just trying 2 figure out the concept so Idk how 2...

As per II law of thermodynamics you it is NOT possible that a hotter body becomes hotter and colder body becomes colder when in contact. But in a Carnot refrigerator, the heat is taken from a cold reservoir and pushed to a hotter one. It sort of opposite the II law. Help me over this paradoxical...

Homework Statement The motor that drives a reversible refrigerator produced 142 W of useful power. The hot and cold temperatures of the heat reservoirs are 20°C and -6.1°C. What is the maximum amount of ice that can produce in 2.2 hours from water that is initially at 6.0°C? Homework...

Homework Statement A Carnot engine is operated as a refrigerator, taking in 18 J of heat every second and expelling 20 J into a 23oC room. What is the temperature inside the refrigerator? a. 15.4oC b. 3.33oC c. -6.62 oC d. -15.4 oC Homework Equations e=1-T(cold)/T(hot) U=Q-W...

Homework Statement A freezer has a coefficient of performance of 6.30. It is advertised as using electricity at a rate of 457kWh/yr. a)On average how much energy does it use in a single day? b) What maximum mass of water at 20.0 degree celsius could the freezer freeze in a single day...

Okay, this is a long post so buckle up (not sure if this counts as Homework Help or not - technically it WAS homework, but now it's basically exam revision). I was wondering if anyone would mind helping me with a few physics problems I have? It was originally for a mastering physics...

Homework Statement A refrigerator is operated by a 0.25 horsepower motor. If the interior of the box is to be maintained at –20ºC against a maximum exterior temperature of 35ºC, what is the maximum heat leak (in watts) into the box that can be tolerated if the motor runs continuously...

Einstein's Refrigerator - Cooling Agent & Size Matter?? I'm looking at Einstein's patent #1,781,541 for a closed non-mechanical refrigeration unit approved Nov. 11, 1930, filed Dec. 16, 1927. http://www.fourmilab.ch/etexts/einstein/uspat1781541/www/" I'd like to power it with the solar heat...

Homework Statement A reversible refrigerator has a coefficient of performance equal to 9.55 What is its efficiency? Homework Equations COP = Qh/W e = W/Qh The Attempt at a Solution I thought e would simply be 1/9.55 = 0.1047 =0.105 (Sig. fig) This answer was incorrect...

Q) A closed chamber containing working refrigerator is pefectly insulated and d door of refrigerator is opened, wat ll happen to temperature inside the chamber a)Decrease b) Remain same c) Increased d) Cant say coz it depends on quality of insulation

A refrigerator with an average COP of 2.8 is used to cool a well-insulated container whose contents are equivalent to 12 Kg of water from 40 degree C to 10 degree C. When running, the refrigerator consumes 400W of electric power. The length of time the refrigerator must run to accomplish this...

Urgent! Thermodynamic refrigerator Homework Statement One mole of a monatomic ideal gas is allowed to expand isothermally from an initial volume of 10 liters to a final volume of 15 liters, the temperature being maintained at 400K. The work delivered is used to drive a thermodynamic...

Homework Statement An air conditioner operates on 800W of power and has a performance coefficient of 2.80 with a room temperature of 21oC, and an outside temperature of 35oC. a) Calculate the rate of heat removal for this unit. b) calculate the rate at which heat is discharged to the...

Homework Statement An air conditioner operates on 800W of power and has a performance coefficient of 2.80 with a room temperature of 21oC, and an outside temperature of 35oC. a) Calculate the rate of heat removal for this unit. b) calculate the rate at which heat is discharged to the...

Homework Statement 433J of heat is extracted from a massive object at 0\circC while rejecting heat to a hot reservoir at 19\circC. What minimum amount of work will accomplish this? Answer in units of J. Homework Equations COP= Qc/(Qh-Qc) = Tc/(Th-Tc) The Attempt at a Solution...

Homework Statement Three kilograms of liquid water at 0° C is put into the freezer compartment of a Carnot refrigerator. The temperature of the compartment is -13.5° C, and the temperature of the kitchen is 24.5° C. If the cost of electrical energy is ten cents per kilowatt · hour, how much...

Hi All, My textbook mentions that the coefficient of refrigeration for a Carnot refrigerator acting between a hot reservoir T_{H} and a cold reservoir T_{C} is K_{Carnot} = \frac{T_C}{T_H - T_C} This got me wondering - Suppose you had 1 kg of ice at it's melting point, and 1 kg of water...

Homework Statement can you please help me solve this problem? A carnot refrigerator takes heat from water @ 0 degrees celsius and rejects heat to a room at 27 degrees celsius. If 50 kg of water @ 0 degrees celsius is converted to ice @ 0 degrees celsius, how much energy must be supplied...

Homework Statement The question is simply: A reversible refrigerator has a coefficient of performance equal to 13.8. What is its efficiency? Homework Equations COPrefrigerator = Tc/(Th - Tc) Efficiency = (Th - Tc) / Th The Attempt at a Solution I'm assuming I need to use these equations to...

Homework Statement A Carnot refrigerator operating between -30.0 ^ C and + 20.0 ^ C extracts heat from the cold reservoir at the rate 300 J/s. What are (a) the coefficient of performance of this refrigerator, (b) the rate at which work is done on the refrigerator and (c) the rate at which heat...

I think this belongs here because its about magnets, except for the adhesive part which may be materials. Im improving my refrigerator door magnets that constantly get knocked off or shift around all the time. 1. What thickness of neodymium magnet will saturate a refrigerator door?? For...

I am interested in pursuing the modernized redesign of the eistein refrgeration system. It is a refrigeration system using anhydrous ammonia, liquid butane, and water. It is contained in a closed pressurized system, has no moving parts or compressor, and requires no maintenance. Sounds like a...

Ok is this article as silly as it seems to me? http://www.physorg.com/news202539967.html

Hi, I have a refrigerator (model No FRT18SJGW1) which consists of a freezer compartment on the top and a bigger frige compartment below. It is operating 24 hours a day and 365 days a year. There is a label in its fridge compartment saying: Electrial ratings: Amps 4.75, Volts 115, Hertz...

Homework Statement In an isolated room there is a refrigerator. The refrigerator consumes electric power P=50W. Mass of the air in a room m=500 kg, and it's specific heat capacity c=714 J/kg. Calculate the stream of heat (dQ/dT) from the refrigerator assuming it's stationary way of work and...

Homework Statement 600Kg of water at 25C has to be frozen into ice in an ideal refrigerator. The room temperature is 20C. What is the minimum amount of work input to the refrigerator to achieve this? ( specific heat capacity of water = 4170 J/Kg/K, latent heat of melting ice = 3.33 x10^5 J/Kg...

Hi everyone, I'm a computer scientist by training (BS in Computer Science, University of South Florida) and also have a strong interest in physics. One thing I've always wondered about is whether it is possible to convert heat energy into another form of energy. It is my understanding...

I read somewhere that a special fluid, called hydrofluorocarbon, is used in refrigerator. It carries hot temperature from the refrigerator and put it out. They says that it has a low specific heat capacity and low liquid/gas transition point (room temperature). Now my question is why ideal gas...

Homework Statement a carnot refrigerator takes heat from water at 0 degree celsius and rejects heat to a room at 27 degree celsius. if 50kg of water at 0 degree celsius is converted to ice at 0 degree celsius. how much energy must be supplied to the refrigerator? Homework Equations Sorry, i...

Has anyone heard of any home refrigerator that uses say some sort of duct to flow cold air from the bottom of the compartment back to the top that would otherwise become wasted outside? I'm aware that commercial refrigerators like those in supermarkets already do this, but are there any...

Homework Statement PROBLEM: Refrigeration units can be rated in "tons". A 1-ton air conditioning system can remove sufficient energy to freeze 1 British ton (2000pounds) = 909 kg) of 0 degree C water into 0 degree C ice in one 24-h day. QUESTION: If, on a 40 degree C day, the interior...