What is Refrigerator: Definition and 146 Discussions

A refrigerator (colloquially fridge) is a home appliance consisting of a thermally insulated compartment and a heat pump (mechanical, electronic or chemical) that transfers heat from its inside to its external environment so that its inside is cooled to a temperature below the room temperature. Refrigeration is an essential food storage technique in developed countries. The lower temperature lowers the reproduction rate of bacteria, so the refrigerator reduces the rate of spoilage. A refrigerator maintains a temperature a few degrees above the freezing point of water. Optimum temperature range for perishable food storage is 3 to 5 °C (37 to 41 °F). A similar device that maintains a temperature below the freezing point of water is called a freezer. The refrigerator replaced the icebox, which had been a common household appliance for almost a century and a half.
The first cooling systems for food involved ice. Artificial refrigeration began in the mid-1750s, and developed in the early 1800s. In 1834, the first working vapor-compression refrigeration system was built. The first commercial ice-making machine was invented in 1854. In 1913, refrigerators for home use were invented. In 1923 Frigidaire introduced the first self-contained unit. The introduction of Freon in the 1920s expanded the refrigerator market during the 1930s. Home freezers as separate compartments (larger than necessary just for ice cubes) were introduced in 1940. Frozen foods, previously a luxury item, became commonplace.
Freezer units are used in households as well as in industry and commerce. Commercial refrigerator and freezer units were in use for almost 40 years prior to the common home models. The freezer-over-refrigerator style had been the basic style since the 1940s, until modern, side-by-side refrigerators broke the trend. A vapor compression cycle is used in most household refrigerators, refrigerator–freezers and freezers. Newer refrigerators may include automatic defrosting, chilled water, and ice from a dispenser in the door.
Domestic refrigerators and freezers for food storage are made in a range of sizes. Among the smallest are Peltier-type refrigerators designed to chill beverages. A large domestic refrigerator stands as tall as a person and may be about 1 m wide with a capacity of 600 L. Refrigerators and freezers may be free-standing, or built into a kitchen. The refrigerator allows the modern household to keep food fresh for longer than before. Freezers allow people to buy food in bulk and eat it at leisure, and bulk purchases save money.

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  1. M

    Torque before slipping in a refrigerator

    The solution lists out mg(b/2)=ma(h/2) and then proceeds to solve for a. I am a bit stuck on how the initial equation is listed - why is the (b/2) swapped with the (h/2)? (namely, why isn't the equation mg(h/2)=ma(b/2)? My logic for this is y-direction and x-direction ) I feel that I am missing...
  2. H

    Refrigerator Too Cold: Wrapping Veggies in a Blanket?

    My refrigerator is on the minimal setting but still freezes the vegetables a little bit. It didn't do that a week ago. I'm renting and moving out in a few days so I'm not going to do anything drastic. How about wrapping my veggies in a blanket? I never understood the physics of those...
  3. guyvsdcsniper

    Work required to extract heat from a refrigerator

    The answer key says the work done should be +.043cal. I am getting a negative sign. I have posted my work in the attached image. My logic is that since this a reversible engine we can say the integral of dQ/T=0. Looking at the cycle, Qc isi being absorbed (Qc>0) and Qh is being rejected...
  4. L

    Can any type of refrigerator work without a chemical refrigerant?

    I was just wondering if a mini fridge could ever work on electricity alone with no toxic chemicals inside?
  5. F

    Calculate time to defrost Prime Rib roast from freezer to refrigerator

    I don't know where. to even begin inserting numbers here. I know the Temperature would be -5 for the first T and 36 for T sub zero but I do not know how to solve this. I never had Calculus.
  6. questionmonkey123

    Will this increase the Coefficient of performance of my refrigerator?

    If I orient my refrigerator such that the condenser coils at the back are facing a glass door (least insulation in room, cold outdoors) will CP increase? CP=Qc/(Qh-Qc) so Qh-Qc will be smaller thus CP larger. Could this damage refrigerator?
  7. ib43

    Thermal physics problem -- Pressure and temperature of air in a refrigerator

    There is this one problem from past exam papers which I cannot seem to do: The air in a kitchen has pressure 1.0 x 10^5 Pa and temperature 22'C. A refrigerator of internal volume 0.36 m^3 is installed in the kitchen. (a) With the door open the air in the refrigerator is initially at the same...
  8. R

    Work done pushing a refrigerator up an Incline

    My teacher told me that answers are F=1200 N for lifting straight up and F= 360 N for using the ramp. I can get the force for lifting straight up by using 1800=F(1.5)cos(0) but I do not understand why for using the ramp the equation 1800 = F(1.5)cos(72.5) does not produce the correct answer.
  9. Spinnor

    B Phase change or not: oil in the refrigerator

    Cooked some french fries last night using oil saved in the refrigerator. The oil appears to have undergone a phase change, after some time in the refrigerator instead of being a yellowish transparent liquid it was a semi-solid soft whitish non-transparent stuff when I took it out of the...
  10. F

    Does a good heat engine make a bad refrigerator?

    Hi all, the efficiency ##\eta## of a generic heat engine working between two temperatures is bound from above by the efficiency ##\eta_{\rm C}## of a Carnot machine working between the same temperatures. That is, if the temperatures are the same, a (ideal) Carnot machine is better than any...
  11. M

    When the COP of refrigerator is greater or less than 1?

    I still confuse about COP of refrigerator. When i read some journal, it is said that COP of VCRS can be greater than 1 (usually 2 - 4). But, why the COP other than VCRS usally lower than 1? like vortex tube, vapour absorption refrigeration system, etc. Actually, now i am doing a research about...
  12. Foreverlearning

    I The role of capillaries in a dilution refrigerator

    I've been trying to understand how dilution refrigerators work and inbetween intermediate steps, between different temperature points, I see capillaries here and there under the name of impedances. After some googling, I somewhat convinced myself that it's to build up pressure before and after...
  13. D

    Refrigerator overload protector problem

    Hi, I want an expert opinion cause I've seached all web to no avail. I have an old fridge that can't start. Internet says this an overload protector problem because it tries to start then buzzes for exactly 10 seconds ( sounds like a locked rotor ) then a click is heard , it goes off for 2...
  14. patrickmoloney

    Optimizing Refrigerator Efficiency: Solving for Necessary Power Draw

    Homework Statement Suppose that heat leaks into your kitchen refrigerator at an average rate of 300W. Assuming ideal operation, how much power must it draw from the wall. Homework Equations \eta = \dfrac{T_C}{T_H - T_C} W= \dfrac{Q}{COP} The Attempt at a Solution A typical refrigerator...
  15. patrickmoloney

    Why can the efficiency of a refrigerator (heat pump) be greater than one?

    In a heat engine thermal energy is converted into mechanic energy. In a heat pump or refrigeration cycle - fluid is being circulated between hot and cold wells. But how can the efficiency be greater than 1? Is it because COP_{\text{heating}}>COP_{\text{cooling}}
  16. M

    A Few questions about how a refrigerator works

    I am trying to understand how refrigerator works from the thermodynamic perspective. I've read many articles and watched several youtube videos but still trying to figure out following stuff. 1. What exactly is the purpose of compressor? Ok it compresses vapor and thus increases it's pressure...
  17. E

    Coefficient of performance of refrigerator

    Homework Statement The pV-diagram in Fig. P20.51 (See attached file) shows the cycle for a refrigerator operating on 0.850 mol of H2. Assume that the gas can be treated as ideal. Process ab is isothermal. Find the coefficient of performance of this refrigerator. Homework Equations K = QC/|QH -...
  18. grandpa2390

    Find Coefficient of Performance of a refrigerator

    Homework Statement I need to find the coefficient of a refrigerator that uses a monatomic gas and only has two steps. I know the: initial pressure of the refrigerant initial temperature initial volume and final pressure Every formula I know requires 4 steps or a knowledge of the outside and...
  19. K

    Energy use, conductive-convective layers and air films

    Homework Statement The door of a refrigerator is 1.5 m high, 0.80 m wide and 6.0 cm thick. Its thermal conductivity is 0.21Wm-1 degrees Celsius-1. a) what is the heat loss per hour through the door neglecting convection effects? b) Air is usually still inside the refrigerator so there will be a...
  20. ervays

    -40 to 70C Degrees Special Refrigerator

    Hi all, I'm trying to find a special refrigeration device that can goes from -40 Degrees to 70 degrees. I need this machine for a laboratory to test sensors in differente temperatures. Does anyone knows where can I find something like that? Kind Regards Vicente
  21. T

    Ideas for refrigerator door design

    Hi all, I just want to throw some ideas and get feedback from the community on refrigerator door design. If anybody notices in supermarkets, etc, the frozen food are kept in glass-doored refrigerators. the prupose of the glass door is so the customers can see if the stuff they're looking is...
  22. A

    Using Isothermally Compressed Air to Cool a Refrigerator

    If I have a steady supply of isothermally compressed air at 7 psi (approximately 148 kPa) at a temperature of 4 degrees C, how would I calculate the amount needed of that air per unit time to maintain the temperature of a 14 cf refrigerator at 3 degrees C? A 18 cf freezer at -18 degrees C?
  23. O

    Derive the energy required for an ideal refrigerator

    Homework Statement Show that the energy, E, that needs to be supplied to an ideal refrigerator to cool a mass M with specific heat C by \DeltaT from an initial temperature T_i is: E\sim \frac{MC\Delta T^2}{2T_i} Homework Equations Carnot efficiency where T_i is the starting higher temperature...
  24. Mohammed Alqadhi

    Carnot Refrigerator Work Input: 230 J Extracts 346 J Heat

    If a Carnot refrigerator requires a work input of only 230 J to extract 346 J of heat from the cold reservoir. Doesn’t this discrepancy imply a violation of the law of conservation of energy?
  25. TheAnt

    Classical The Refrigerator and the Universe

    Anybody knows this book : The refrigerator and the Universe ? Is it any good ? And what is the level required to read it? Thanks
  26. S

    Problem with refrigerator and radiator

    Homework Statement The following data refer to an electrically operated refrigerator: - Efficiency : ## \xi = 2.4## - Temperature inside: ##T_i = -9 ° C ## - Temperature of the radiator ## T_r = 40 °C ## - Room temperature: ## T_s = 35 °C## - Total surface of walls: ## A = 3.2 m ^ 2 ## -...
  27. duran9987

    Compute work in Carnot Refrigerator

    Homework Statement The temperature inside the room ##T_I= 25 C ## and the temperature outside the house is ##T_O = 32C##. The temperature difference causes energy to flow into the room (by conduction through the walls and window glass) at the rate 3,000 J/s. To return this energy to the...
  28. H

    Refrigerator magnets with four poles apiece

    I bought a couple of bar magnets at the local hardware store. They were acting so strangely. I couldn't figure out where the poles were. Finally I realized each magnet had four poles! They weren't quadropolar, rather half of each bar was magnetized one way and the other half the other way...
  29. V

    Microwave's vent close to refrigerator

    < Mentor Note -- Post edited > 1. Homework Statement So do you know how a microwave has air vents on the side? How much of a distance must be allowed between the vent and the side of refrigerator in order for the Microwave not to overheat? Is 10 cm enough? Would putting an aluminum foil on...
  30. physics411

    Finding the acceleration of a refrigerator

    Homework Statement The coefficient of kinetic friction between a refrigerator and the floor is 0.20. The mass of the refrigerator is 100.0 kg, and the coefficient of static friction is 0.25. Determine the acceleration when you apply the minimum force needed to get the refrigerator to move...
  31. H

    A refrigerator in a hospital removes 40 kW of heat from a sp

    A refrigerator in a hospital removes 40 kW of heat from a space used for blood storage. The coefficient of performance of the refrigerator is 8. What is the work (kJ) required to operate the refrigerator continuously for one day? What I attempted to do: W in = Qin/COP therefore, Win =...
  32. KingDaniel

    Refrigerator and Heat Pump question (Very Important)

    Homework Statement Hi, How come, for a refrigerator and a heat pump, we don't consider the changes in energy for the refrigerant for when the pressure drops (at expansion valve) and when it rises (at the compression valve)? We only consider the changes in energy when it evaporates and...
  33. KingDaniel

    Refrigerator and Heat Pump question

    Homework Statement Hi. I know that a refrigerator and heat pump do the exact same thing, which is transferring heat from a cooler area to a warmer area. This is what I've gathered from my university notes. My question is: is it necessary for the area it's transferring FROM to be COOLER than the...
  34. M

    Refrigerant for AC and refrigerator

    Can we use same refrigerant for both air conditioner and refrigerator?
  35. S

    Statics Problem Tipping Refrigerator

    Homework Statement A refrigerator with a mass of 100kg measures 150cm high by 75 cm wide by 75 cm deep. How much force applied horizontally at the top edge of the front will make it start tipping backward? Assume that the center of mass is at the center of the refrigerator. Homework Equations...
  36. W

    Refrigerator- thermodynamics: how do i start?

    Homework Statement Newton’s Law of Cooling. A building is maintained at temperature TH with a reversible heat pump operating between the building and a colder environment at temperature TC < TH. The heat pump consumes electrical power at a constant rate W. The building also loses heat...
  37. D

    Large heatsinks in refrigerator?

    I'm trying to keep my refrigerator cold when I have the door open and have read about putting water jugs in the back to help stabilize the temperature when the door is left ajar. Instead of water, would large aluminum heatsinks (with fins) work just as well? Thanks Don
  38. P

    Refrigerator Compressors Already have Refrigerant?

    I am a little confused, because I know how refrigerators work with a refrigerant and a compressor and heat exchanges, and I am looking to build one myself, just wondering because I was looking for refrigerator compressors online to buy. Do they have an inlet for refrigerant or is the...
  39. Avatrin

    Impossible refrigerator (thermodynamics and PV diagrams)

    Homework Statement I have a rectangular PV diagram of a heat engine. Like this one: I have to show why this cannot work in reverse as a refrigerator. Homework Equations U = 0.5fnRT (U = internal energy, f = degrees of freedom, n = number of moles of gas, R = ideal gas constant, T =...
  40. L

    Find Force to Tilt a Refrigerator

    Homework Statement You are trying to tilt a very tall refrigerator (2.0 m high, 1.0 m deep, 1.4 m wide, and 100 kg) so that your friend can put a blanket underneath to slide it out of the kitchen. Determine the force that you need to exert on the front of the refrigerator at the start of its...
  41. M

    Physics help -- pushing a refrigerator across a wooden floor

    I did attempt the problem, but I' now more confused than ever. Please help me. Joe is moving his refrigerator to take to college and he begins by pushing it across the wooden kitchen floor. On a flat surface like the floor, how do you calculate how hard he needs to push? Draw a free body...
  42. K

    Solving Heat Engine & Refrigerator Problems

    Homework Statement A Carnot heat engine operates between temperatures T1= 400K and T2= 300K. In each cycle the engine receives Qin=1200 J from the high temperature reservoir. a) Calculate the heat Qout delivered to the low temperature reservoir. b) Suppose the engine is operated in reverse as a...
  43. Chacabucogod

    Refrigerator Cycle Compressor Function

    I understand that you need certain work for the refrigerator to work, and that it comes from the compressor. Why isn't a pump used instead? Why do you have to compress and heat the air so much? Thank you
  44. G

    Reversing the Role of a Great Engine: Refrigerator or Heat Pump?

    Reverse of a great engine is refrigerator or heat pump?
  45. B

    Exploring the Boiling Point of Refrigerants in Freezers and Refrigerators

    Why is the boiling point of a refrigerant in a freezer lower than that of a refrigerator. I would think that a freezer needs more heat removed so the the refrigerant needs a higher heat of vaporization thus a higher boiling point. Thank you
  46. O

    Problem temperature refrigerator

    Why temperature of refrigerator show higher than standard ? Which is the temperature standard should be below 5 degree of Celsius but it show 9 degrees
  47. J

    Where Does Entropy Go in Inertial Frame During Relativistic Refrigeration?

    Let's say we have a long cylinder and two pistons inside the cylinder, and some vapour between the pistons. Now we make the pistons accelerate with some coordinate acceleration, along the cylinder axis, same coordinate acceleration for both pistons. Cylinder is static. Going to the frame of...
  48. rogerk8

    How is pressure related to the rate of momentum change in a gas?

    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...
  49. N

    What I thought was a simple AC circuit with a Refrigerator & SSR

    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...
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