How air heat exchangers work

- Aug 15, 2018-

The body of the air heat exchanger is composed of three main parts: a heat exchange core body, an indoor side fan, and an outdoor side fan, and also includes a metal protective casing and an air supply pipe and the like.

The inside of the heat exchanger is made of 100 flat aluminum plates. The area of the single aluminum plate is 495×495, and the total heat exchange area is 495×495×98.

The outer part of the heat exchanger is covered with a metal casing. The interface and seams are sealed with a sealant. Static pressure boxes are respectively arranged in the air inlet sections on both sides of the heat exchanger.

 

Air heat exchanger working diagram

Working principle: The indoor and outdoor temperature difference is used to exchange heat between the indoor and outdoor gases, thereby reducing the indoor temperature.

The working diagram is shown in Figure 1. From the perspective of the outdoor side, the outdoor air enters the device body from the outdoor side air supply port under the action of the outdoor side fan, and then exchanges heat through the heat exchange core body, and is discharged from the outdoor side air outlet port. To the outside;

From the perspective of the indoor side, the indoor air enters the device body by the indoor side air supply pipe under the action of the indoor side fan, and then exchanges heat through the heat exchange core body, and then returns to the machine room from the indoor side return air pipe.


Classification of air heat exchangers


As we all know, China is a big country in the production of heating air heat exchangers and a large country, and there are many types of radiators.

There are five kinds of steel, cast iron, aluminum, copper and plastic.

Formally divided into column type, plate type, airfoil type, column wing type, plate wing type, flat tube type, string type, fin tube type, convection type, composite type, combined type and the like.

Energy conservation and environmental protection are major issues that are of great concern to the world at present. In order to continue the rapid development of China's economy, the state has proposed a target of 50% energy saving in buildings in the near future. Some large cities such as Beijing even need to build energy savings of 65%.

China's current heating energy consumption is very large, about three times that of developed countries. The energy conservation of the new word air heat exchanger should be highly valued. From the perspective of energy conservation and environmental protection, the characteristics of various air heat exchangers in China are now available for scientific selection.


1. From the perspective of production conditions, the process is simple, mechanized, high degree of automation, and energy-saving products with less energy consumption.

Cast iron heat pipe production process is complex, the total energy consumption is high, the steel air heat exchanger production process is simple, mechanized, high degree of automation, low total energy consumption and low cost.


2, from the material point of view, good thermal conductivity, fast heat dissipation, high thermal efficiency, relatively energy-saving.

The thermal conductivity of various materials is ranked as follows: copper, aluminum alloy, cast aluminum, steel, cast iron, stainless steel, plastic. From the perspective of thermal efficiency, copper, aluminum, steel, and plastic are poor.


3. From the metal thermal strength index, the number is high. The metal heat intensity is the heat dissipation per unit mass of metal heat exchanger under standard test conditions. The unit is W/KG °C, which is a technical and economic indicator, reflecting the material and energy saving.

Different materials and forms of air heat exchangers have different metal heat strength values, cast iron 0.3-0.4. steel 0.8-1.0 or more, aluminum 1-3 or more, obviously, aluminum, steel, and cast iron.


4. From the water capacity of the air heat exchanger, the air heat exchanger with a small ratio of water capacity to heat dissipation is energy-saving.

The water capacity is small, the heating and conveying cycle energy consumption is small, the heating is fast, the efficiency is high, and the energy is saved. Steel string, steel finned tube convection air heat exchanger, copper tube convection air heat exchanger have small water capacity and energy saving.

At present, some air heat exchangers that introduce large waterways are misleading, and it does not save energy.

 

5, install thermostatic control valve, can regulate room temperature, save energy more than 20%, install thermostatic valve, should choose heat dissipation, high heat efficiency of the air heat exchanger, otherwise the regulation is not working, difficult to achieve the purpose of constant temperature.


6, the air heat exchanger cover is not energy-saving, will reduce heat dissipation 15% -25%.

7. From the height of the air heat exchanger and the number of assembled pieces, the air heat exchanger with the film is not too high and the number of assembled pieces is small, which is advantageous for better heat dissipation and energy saving.

The number of columns of the column type air heat exchanger should not be too much, and the two columns and the three columns are better on one side, and the number of columns is too large to save energy. The number of columns is too large, and the columns cannot be fully dissipated.


8, from the way of taking over, it is good to go in and out. Sometimes the heat dissipation in and out of the lower two sides will be reduced by 20%. It is now popular to concentrate in and out, in order to conceal the pipeline, the water flow inside the air heat exchanger is up and down, which has little effect on the heat dissipation (about 5%).

9, the building maintenance structure is well insulated, the door and window seals have good heat insulation and can use less air heat exchangers to save energy.


10. Install a heat insulation board on the wall of the air heat exchanger to reduce the heat loss of the wall and save energy.

11. The composite air heat exchanger has different thermal expansion coefficients of the two metals, and the thermal resistance of the composite surface increases, which reduces the heat dissipation and is unfavorable for energy saving.

12. From the appearance of the outer surface coating of the air heat exchanger, the traditional silver paint can reduce the heat dissipation by about 10%, and the paint can increase the heat dissipation and save energy.

13. The internal anti-corrosion coating has poor thermal conductivity, which affects heat dissipation and is not conducive to energy saving. The internal anti-corrosion coating process is complicated and the production environment is poor; in use, the paint may peel off and affect the quality of the heat medium.