The Refrigerator?

Question

We are doing a class discussion at school and this question is the one to answer. we have many answers so i was wondering if anyone actually knew .... What method(s) is/are used to transfer the heat in each part (does each part use conduction/convection/radiation or a combination)?

Answer 1

The cooling coils in the freezer or refrigerator compartment chill the air in the compartment as it passes them, so there is a combination of convection and conduction involved. The cooling coils are chilled by the expansion of the refrigerant in them, which thereby absorbs the heat of vaporization from the surroundings.

The expanded refrigerant is then pumped to the compressor, where it is re-liquefied and heats up as it gives up the heat of condensation. This heat is conducted to the outside air, which convects it away.

Answer 2

its generally the combination of the three when the refrigerator is considered as a whole

Answer 3

The heat removed from inside the frig is dissipated, primarily by convection (air passing over the coils), but there is some radiation going on to.

The real removal of heat comes from utilizing the heat of vaporization and condensation though.

bye for now.

Answer 4

It's a combination of Convection and Conduction.

Let us start with the main air circulation system fan that is moving the air around the building or room being cooled.

*...Air from the fan is blown across the refrigerant coils in the A/C system Evaporator. This flow of air is 'Forced Convection'.

*...The heat of the circulated air passes into the evaporator  refigerant coils by 'Conduction' through the metal.

(NOTE: The cooling of the refrigerant occurs  by 'Expansion' from a High Pressure liquid into a low pressure system. This partially vaporises the liquid which cools down by a refrigeration process called the 'Joule's -Thompson Effect').

*...The refrigerant picks up heat from the air passing over the evaporator coils thereby cooling down the air. The cool air, by forced Convection, is circulated around the area being cooled.

*..The warmed refigerant, now fully vaporised, flows back to the refrigerant Compressor where it is compressed and picks up 'Heat of Compression'.

*...The hot gas is cooled in the Cooler/Condenser coils in the outside unit where by 'Conduction' through the metal coils, the refrigerant is cooled by the 'Convected' air from the cooling fan causing 'Condensation' of the refrigerant gas.

*...This refrigerant liquid is passed through an Expansion valve where its pressure decreases causing the 'Joule's-Thomson' cooling effect as mentioned above and, the 'Thermo-dynamic Cycle' is repeated until the thermostat temperature setting temporarily shuts down the system.

(Note that 'Radiated' heat isn't incorporated into the system. Heat exchange between the refigerant and air is by Conduction and Convection only).

For the thumbs down merchant, I've worked in Refrigeration Processes most of my working life including Cryogenics down to -165°C.  Do you have that kind of experience, Toddio ?

Answer 5

conduction