8:32 AMTypes of evaporators for household refrigerators
Types of evaporators for household refrigerators
The evaporator (in other words, it is called a heat exchanger) is one of the main components of the refrigeration or freezer, whose task is to convert the refrigerant substance - freon from a liquid state into a gas. It removes heat from the working area, leaving cool air instead. In other words, this process is called evaporation. Moreover, up to two of them can be contained in the construct. If there is only one evaporator, then it is located in the partition between the refrigerator and the freezer compartment. If there are two evaporators, then one is located at the top of the refrigerator compartment, and the second at the top of the freezer compartment.
What is an evaporator?
In fact, we are talking about an aluminum tube. Naturally, it is bent in a certain way, so that it becomes possible to compactly install the part in a refrigeration unit.
At the same time, the evaporator is almost always located at the top of the refrigerator. The main task of the evaporator is to take heat onto itself and remove it outside the chambers of the refrigeration unit.
In household refrigerators, mainly aluminum rolled-welded evaporators with swollen channels are installed. They are made from two aluminum blanks 3 mm thick each, with a width corresponding to the width of the evaporator, and a length of about 4 times less than the evaporator. The surface of the workpieces is carefully cleaned and one of them is stenciled with a special paint with a pattern of channels reduced in length by 4 times. Printing ink consists of a substance that prevents aluminum from being welded. Both workpieces, superimposed on each other, are passed through the rolls of the rolling mill. As a result of high rolling pressure, both workpieces are welded over the entire surface, with the exception of the applied channel pattern. In this case, the welded sheet is thinned to 1.5 mm, respectively, lengthening by about 4 times. After welding, the channels are inflated with a liquid under pressure of 80 ... 100 atm.
Rolled-welded evaporators are distinguished by a variety of channel patterns and a large number of parallel streams. The modern level of production of aluminum evaporators ensures their anti-corrosion resistance and operational reliability, however, aluminum evaporators must be handled carefully so as not to damage the protective coating and thin walls of the channels.
Evaporators made from a sheet with a coil attached to it are intended for freezers of two-compartment refrigerators.
SHEET-TUBE are the most common, as they are more convenient for placing food products. Finned-tube type evaporators are installed in absorption refrigerators that do not have freezing compartments, in two-chamber refrigerators for cooling the high-temperature chamber and when forced air circulation in them is provided in the chambers using a fan.
"Crying" ─ closed;
Behind the rear wall of the refrigerator is a closed self-defrosting evaporator of the refrigerator compartment filled with foamed insulator. Drops of condensate freeze on the wall, but no icing occurs. By turning off the compressor, thawing occurs and condensing moisture flows down the refrigerator wall, which is the coldest in the refrigerator compartment. The design is protected from accidental mechanical damage, self-defrosting and easy to clean. The freezer is cooled by other evaporators: closed; partially closed or open;
The part is installed behind the camera panel and is forcibly blown by a fan. This node type is very vulnerable. Since the fan often becomes unusable and needs to be replaced. They are installed in chambers with the No Frost system (No frost).
The evaporative units of the closed tubular type, located inside the wall of the refrigerator, have proved to be the most reliable, constructively eliminating the possibility of accidental mechanical damage to the evaporator.
No Frost is not the only solution to the problem of excess moisture in the chamber. There is a very simple design - a crying evaporator. It is used even in inexpensive modern refrigerators. In terms of efficiency and energy savings in the cold store, this system is more advantageous than No Frost.
The crying evaporator is hidden behind the back wall of the chamber. While the compressor is running and cooling is taking place, the wall becomes very cold. Excess moisture condenses on it, and a thin layer of frost forms. When the temperature in the chamber drops to the desired value, the compressor turns off and the wall heats up, absorbing heat from the air. Frost melts on her.
Basic design requirements for evaporators:
intensive heat transfer (the higher the heat transfer coefficient, the better)
reliability and safety
simplicity and low price
The evaporators of different refrigerators differ in their capacity, shape, overall dimensions, as well as the location of the nozzles for connecting to the pipelines of the unit.
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