What is Refrigerators: Definition and 20 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. Refrigerators and Carnot Cycle (Sequence of 5 steps) #14

    Refrigerators and Carnot Cycle (Sequence of 5 steps) #14

    Refrigerators run on Carnot cycle. It is like a heat pump that operates on the reversed Carnot cycle. It utilizes the evaporation of the refrigerant to absor...
  2. E

    Engineering Efficiency of Heat Engines & Refrigerators: Is Impossible Possible?

    For the heat engine: First I converted all the temperatures to Kelvin, ηmax=1-(333)/(1000)=0.667 ηclaim=(1*10^3)/(1.75*10^3)=0.5714 So the heat engine seems to be less efficient than a Carnot heat engine which means it can exist. For the refrigerator: COPmax=(253)/(363-253)=2.3...
  3. K

    How does the capillary tube in refrigerators work?

    How does the capillary tube decrease the pressure on the liquid when its diameter is smaller? How small diameter of capillary tube is helpful in causing more pressure drop? And how, when pressure drops, the liquid instantly cools down?
  4. 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 ## -...
  5. Evangeline101

    Work, Power, energy: Appliances (refrigerators, freezer etc)

    Homework Statement Fill in the empty columns of the following table: Homework Equations y = ΔE x c P = ΔE/Δt ΔE = Y/ Δt The Attempt at a Solution [/B] Part d) Yearly energy cost: Use Y=ΔE x c Refrigerator, top freezer: Y = (448 kWh/yr) ($ 0.06) Y = $ 26. 88/yr Refrigerator, bottom...
  6. 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...
  7. M

    Calculating the Cost of Heating with a Less Efficient Heat Pump

    Homework Statement Assume that you heat your home with a heat pump whose heat exchanger is at Tc=2∘C, and which maintains the baseboard radiators at Th=47∘C. If it would cost $1000 to heat the house for one winter with ideal electric heaters (which have a coefficient of performance of 1), how...
  8. 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...
  9. C

    Entropy and Carnot refrigerators

    Homework Statement a)A stone at 400K with heat capacity ##c_p## is placed in a very large lake at 300K. The stone cools rapidly to 300K. Calculate the entropy change, due to this process, of the stone and lake. b)An insulated cool-box of a Carnot refrigerator at temperature T loses heat...
  10. B

    How did/do natural gas powered refrigerators work?

    My father told me that when he was a child in the 1950s, his parents owned a natural gas powered refrigerator. He said that the refrigerator made no noise when it was running. I can't fathom how a natural gas powered refrigerator would work. I mean, it would make no sense for natural gas to...
  11. R

    Conservation of Mass Principle applied to Refrigerators

    Dear all, Can the conservation of mass principle be applied to the mass flow rate of a refrigerant in an ideal refrigerator system? And what about for an actual refrigeration system? I'm reading the principle here but can't work it out. Says that it applies for steady flow, but I assume...
  12. C

    Archived Second Law of Thermodynamics - Refrigerators

    Homework Statement Suppose 10000 J is transferred between a large thermal reservoir at a temperature of 300 K to another large thermal reservoir at 500 K. What is the net change in entropy of the system? Write an expression for the factor by which the multiplicity of the system changes...
  13. A

    How Heat Pumps & Refrigerators Work

    could you explain me the working of a heat pump or a refrigerator
  14. P

    How refrigerators and air conditioners work

    Hi, I was looking at how refrigerators and air conditioners work as part of thermodynamics and I came across the expansion valve. I am a bit confused. From what I understand, there is this expansion valve. When the liquid freon, or ammonia as used as an example in this website, goes...
  15. D

    Refrigerators are like rockets, right?

    A refrigerator has coils in back that get hot, and heat is molecular motion. These moving molecules have both energy and momentum. Why doesn't the refrigerator need to be tied to the wall to keep it from recoiling from the momentum it loses out the back?
  16. R

    2 refrigerators maintaining temperature

    I can't go to sleep until I find an answer and I'm no student of physics so I was hoping for a little help. If two refrigerators are at the same thermostat setting. One empty (assumed regular Earth air inside) and one full of food. Both have already reached the temperature on the thermostat...
  17. J

    A question about refrigerators and energy

    Homework Statement The coefficient of performance of a refrigerator is 5.40. The compressor uses 30.0 J of energy per cycle. a) How much heat energy is exhausted per cycle? b) If the hot-reservoir temperature is 27.0C, what is the lowest possible temperature in C of the cold reservoir...
  18. E

    Carnot engines and refrigerators

    Homework Statement I am not necessarily having a problem with a particular homework problem. It is more of a conceptual issue. I have been reading about Carnot engines and refrigerators. In trying to understand the topic better, I did a little more digging and looked up how a refrigerator...
  19. M

    Kitty's Guide to Heat Engines, Refrigerators, & Air Conditioners

    Could someone explain to me how heat engines and refrigerators and air conditioners work. I'm very confused about the process and if they are isothermic, isovolumetric, or adiabatic. ~Kitty
  20. N

    Is a highly efficient Carnot engine suitable for use as a refrigerator and why?

    Show that the relationship betwee efficiency (n) of a Carnot engine and the coefficient of performance (w) of the same engine when operated as a refrigerator is given by nw= Tc/Th Is a Carnot engine whose efficiency is very high particularly suited as a refrigerator? Why? Well we know that...