What is the constellation principle of refrigerator _ What is the constellation principle of refrigerator?

What is the working principle of refrigerator?

Working principle of refrigerator

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First, the principle and types of refrigerator refrigeration

There are nine refrigeration principles, as follows.

(1) compression refrigerator:

Mechanical energy is provided by the motor, and work is done to the refrigeration system through the compressor.

The refrigeration system is made by using the principle that the low boiling point refrigerant (or refrigerant) absorbs the heat of vaporization when it evaporates.

Advantages: long service life and convenient use.

At present, 9 1 ~ 95% refrigerators in the world belong to this category.

Principles and types of refrigerator refrigeration

(2) absorption refrigerator:

This kind of refrigerator uses gas, kerosene, electricity and other heat sources as power.

Ammonia-water-hydrogen mixed solution realizes refrigeration in the process of continuous absorption-diffusion.

Its disadvantages are low efficiency and slow cooling.

Now it has been gradually eliminated.

(3) semiconductor refrigerator:

The refrigerator can be refrigerated by using the principle that PN semiconductor is electrified with direct current and produces Peltier effect at the junction.

Nowadays, many electronic circuits and miniature instruments often use this method to dissipate heat.

(4) Chemical refrigerator:

A refrigerator that uses some chemicals to absorb heat strongly when they are dissolved in water to obtain refrigeration effect.

(5) Electromagnetic vibration refrigerator:

The principle and structure of refrigerator driven by electromagnetic vibrator are basically the same as those of compression refrigerator.

(6) Solar refrigerator:

Using solar energy for refrigeration

Energy refrigerator.

(7) adiabatic demagnetization refrigeration refrigerator

(8) Radiant refrigeration refrigerator

(9) Solid refrigeration refrigerator

Second, the composition of the compression refrigerator

compressor

Condenser-heat exchange tube

Drying screening program

Capillary gas expansion valve

evaporator

The refrigeration system consists of five basic units.

Second, the composition of the compression refrigerator:

Functions of the compressor:

Used to supplement energy, the low-temperature and low-pressure refrigerant (Freon) in the evaporator is compressed by the steam compressor into superheated steam with high temperature and high pressure, and then sent to the condenser.

Functions of condenser:

It condenses high-temperature and high-pressure steam into high-pressure and normal-temperature liquid and releases a lot of heat.

Function of drying screen:

Absorb moisture in freon to prevent ice blocking, and filter impurities in refrigeration system to prevent dirty blocking.

Second, the composition of the compression refrigerator:

Function of capillary: It has two functions.

One is to control the Freon cycle of refrigeration system by throttling;

Second, depressurize to ensure that the pressure in the condenser meets the condensation pressure and the pressure in the evaporator meets the evaporation pressure.

Evaporator:

It is the place where the refrigeration system makes cold energy, where liquid Freon evaporates into gas and absorbs a lot of vaporization heat.

The five basic parts of any refrigerator

(or air conditioning system)

Five basic units necessary for all refrigerators

Compressor (compressor)

Heat exchange pipe or condenser-serpentine or coiled pipe group outside the device.

Expansion valve

Heat removal pipe or evaporator-serpentine or coiled pipe group inside the device.

Refrigerant-a liquid that evaporates in a refrigerant to produce a low temperature.

Refrigerant (refrigerant)

Many industrial plants use pure ammonia as refrigerant.

Many refrigerators often use pure Harmonia as refrigerant.

Pure ammonia evaporates at -32 degrees Celsius.

The evaporation temperature of pure ammonia refrigerant at atmospheric pressure is -32℃.

Basic mechanism of

The refrigerator can work

Basic mechanism of refrigerator operation

A. in the refrigerator

Heat exchange tube

Heat exchange tube in refrigerator;

1. Low pressure and low temperature refrigerant is in the pipeline.

2. The low-temperature refrigerant in the tube exchanges heat with the hot air in the refrigerator to reduce the temperature of the air in the refrigerator.

3. Isobaric heat transfer process.

Refrigerant flow direction

B. compressor:

1. Quasi-isothermal compression process

2. Pressurize the returned low-pressure refrigerant into high-pressure refrigerant or even liquefy it into liquid refrigerant.

C. capillary expansion valve:

1. The physical process of thermal change of adiabatic expansion is carried out here.

2. After passing through this valve, high-pressure refrigerant or liquefied refrigerant suddenly expands into low-temperature and low-pressure refrigerant, and even gasifies into gaseous low-temperature refrigerant.

Basic working mechanism of refrigerator

A compressor compresses refrigerant gas.

This increases the pressure and temperature (orange) of the refrigerant, so the heat exchange coil outside the refrigerator allows the refrigerant to dissipate the pressurized heat.

When it cools, the refrigerant condenses into liquid (purple) and flows through the expansion valve.

When it flows through the expansion valve, the liquid refrigerant is allowed to move from the high pressure area to the low pressure area, so it expands and evaporates (light blue). In the process of evaporation, it absorbs heat and makes it cool.

The coil inside the refrigerator allows the refrigerant to absorb heat, which makes the refrigerator cool. Then the cycle repeats.

life

Because refrigerators are high-grade durable goods, service life is an important indicator.

Therefore, in the design, from the structure, material selection, manufacturing technology and other items, life has been carefully considered.

According to the development situation, economic conditions and living standards, the current refrigerator design should be no less than 15 years.

Foreign refrigerators, because of their new styles and varieties, are often designed with shorter service life.

Common sense of commercial refrigerator

1. Difference between single-door refrigerator, double-door single-temperature refrigerator and double-door double-temperature refrigerator

Single-door refrigerator: a refrigerator with only one door and one evaporator, which can store a small amount of frozen food, is the earliest popular refrigerator and has gradually disappeared from the market.

Two-door single-temperature refrigerator: a refrigerator with two doors but only one evaporator. Its internal structure is the same as that of a single-door refrigerator, so it is also called "fake double door".

Double-door double-temperature refrigerator: a refrigerator with two doors and two evaporators, one of which is installed in a four-star freezer and the other is installed in the freezer. This kind of refrigerator is very popular at present.

D. the meaning of the star symbol on the refrigerator

Indicates the storage temperature level of the frozen part of the refrigerator.

International uniform standard for marking freezing room temperature.

Each star indicates that the storage temperature in the freezer should be reduced by -6℃, and the storage time of frozen food should reach one week.

For example, a three-star refrigerator means that the storage temperature of the freezer should be below-18℃, and it has the ability to quickly freeze a certain amount of food.

Simply put, the freezing ability refers to a certain amount of lean beef at 25℃, which can be frozen below-18℃ after 24 hours.

E. direct cooling and indirect cooling of refrigerators

The cooling mode of refrigerator can be divided into "direct cooling" and "indirect cooling".

Direct cooling refrigerator:

Use the natural convection of air in the refrigerator to cool food.

Because that evaporator is usually instal in the upper part of the refrigerator,

The air around the evaporator will exchange heat with the evaporator, and the air will transfer heat to the evaporator, and the evaporator will transfer cold to the air.

After air absorbs cold energy, its temperature drops, its density increases and it moves downward.

The air in the lower part of the refrigerator exchanges heat with the cooled food, and the food transfers heat to the air; After the air is heated, the temperature increases, the density decreases, and it rises around the evaporator to transfer the heat to the evaporator.

Cold and hot air naturally circulates and convects to achieve the purpose of refrigeration.

Indirect cooling refrigerator

Indirect cooling refrigerator:

Evaporators usually adopt finned tube type,

Placed in the interlayer between the freezing chamber and the refrigerating chamber or at the rear upper part of the box.

Use a small fan to force air convection in the box to achieve the purpose of cooling.

The vast majority of refrigerators are directly cooled refrigerators, and the output of indirectly cooled refrigerators is relatively small.

Frost-free/frosted refrigerator

Why does frost-free refrigerator consume more electricity than frost-free refrigerator?

Frost type is artificial defrosting, without electric heating.

Frost-free type is equipped with 150W electric heater for defrosting, which is heated 2 ~ 3 times a day for 20 ~ 3o minutes each time.

Two refrigerators with the same volume, the frost-free type consumes more power than the frost-free type, so the frost-free type consumes more power.

Comparison of power consumption between strong cooling refrigerator and direct cooling refrigerator

Forced cooling type is equipped with a fan to force cold air convection and cool the box.

Direct cooling relies on the natural convection of cold air in the box.

After testing, strong cooling with the same volume consumes more power 10% than direct cooling.

Fluorine-free "double green" refrigerator

The refrigerant of refrigerator and the foam material of box insulation do not use chlorofluorocarbons (Freons) that will destroy the environment.

Use substitutes to avoid environmental pollution.

According to international practice, this kind of refrigerator can be called "double green", that is, it reduces the freon content of 100%.

It is a new type refrigerator that completely meets the international environmental protection requirements.

Why promote fluorine-free refrigerators?

The use effect of fluorine-containing refrigerator is good, why should we promote fluorine-free refrigerator?

In recent years, scientists have found that freon, which is widely used and leaked in the refrigeration industry, causes cavitation damage to the atmospheric ozone layer and produces excessive ultraviolet rays, which will endanger human health, such as decreased vision, increased cataract and skin cancer patients, and destroyed ecological balance.

Therefore, the Montreal Protocol signed by the United Nations in 1987 declared freon as a controlled substance, and initially stipulated that it should be stopped in 2000 at the latest. With the increasing harm of freon in the future, the international community decided to advance the time to stop using freon to 1996.

Take the "cold" on the road-car refrigerator

In go on road trip, an easy-to-use car refrigerator is undoubtedly a good tool. Introduce three typical car refrigerators:

Cold catalyst type

Cold storage type

Compressor type

The principle and technical quality of car refrigerator are different, so the price varies greatly, ranging from several hundred yuan to thousands of yuan. According to different needs, choosing the most suitable car refrigerator is the basis of the final choice.

Cold catalyst type

The "cold catalyst type" car refrigerator body is similar to an insulated travel bag.

Built-in heat insulation material, refrigerator is cooled by cold catalyst.

Before use, it is necessary to put the cold catalyst material in the household refrigerator for more than 10 hour, and then move the cold catalyst to the vehicle refrigerator.

Relying on the cold catalyst to absorb heat, the refrigeration function is realized.

Advantages: the refrigerator is light in weight, easy to carry, does not need to be connected to electricity, and is cheap.

Disadvantages: complex preparation and limited cold storage time.

Cold storage type

_ "Refrigerated" car refrigerator adopts plastic shell, metal liner, with heat insulation layer, similar to a thermos cup.

Can be connected to 12V vehicle power supply, with the lowest refrigeration temperature of 0℃.

Advantages: Good refrigeration effect and moderate price.

Disadvantages: limited refrigeration capacity.

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Compressor type

This kind of car refrigerator also adopts plastic shell and inner container, but it is equipped with a miniature refrigerator compressor, so it is a real refrigerator.

Can be connected to 12V vehicle power supply to realize refrigeration and freezing.

① Advantages: It has real refrigeration function and is convenient to use.

Disadvantages: heavy weight, difficult to carry and high price.

The principle and technical quality of car refrigerator are different, so the price difference is also great.

From a few hundred dollars at the low end to several thousand dollars at the high end, choosing the most suitable car refrigerator according to different needs is the basis of the final choice.