air-to-air heat exchanger - Industrial purification heat recovery

The utilization of air-to-air heat exchangers in ventilation and energy-saving engineering

The core function of an air-to-air heat exchanger is to transfer the residual heat carried in the exhaust air (indoor exhaust air) to the fresh air (outdoor intake air) through heat exchange, without directly mixing the two airflows. The entire process is based on the principles of heat conduction and energy conservation, as follows:

Exhaust waste heat capture:
The air expelled indoors (exhaust) usually contains a high amount of heat (warm air in winter and cold air in summer), which would otherwise dissipate directly to the outside.
The exhaust air flows through one side of the heat exchanger, transferring heat to the heat conducting material of the heat exchanger.
Heat transfer:
Air to air heat exchangers are usually composed of metal plates, tube bundles, or heat pipes, which have good thermal conductivity.
Fresh air (air introduced from outside) flows through the other side of the heat exchanger, indirectly contacting the heat on the exhaust side, and absorbing heat through the wall of the heat exchanger.
In winter, fresh air is preheated; In summer, the fresh air is pre cooled (if the exhaust air is air conditioning cold air).
Energy recovery and conservation:
By preheating or pre cooling fresh air, the energy consumption of subsequent heating or cooling equipment is reduced. For example, in winter, the outdoor temperature may be 0 ° C, with an exhaust temperature of 20 ° C. After passing through a heat exchanger, the fresh air temperature may rise to 15 ° C. This way, the heating system only needs to heat the fresh air from 15 ° C to the target temperature, rather than starting from 0 ° C.
Airflow isolation:
Exhaust and fresh air flow through different channels in the heat exchanger to avoid cross contamination and ensure indoor air quality.
technological process
Exhaust collection: indoor exhaust gas is guided to the air-to-air heat exchanger through a ventilation system (such as an exhaust fan).
Fresh air introduction: Outdoor fresh air enters the other side of the heat exchanger through the fresh air duct.
Heat exchange: Inside the heat exchanger, exhaust and fresh air exchange heat in isolated channels.
Fresh air treatment: Preheated (or pre cooled) fresh air enters the air conditioning system or is directly sent into the room, and the temperature or humidity is further adjusted as needed.
Exhaust emission: After completing heat exchange, the exhaust temperature decreases and is finally discharged outdoors.
Types of air-to-air heat exchangers
Plate heat exchanger: composed of multiple layers of thin plates, with exhaust and fresh air flowing in opposite or intersecting directions in adjacent channels, resulting in high efficiency.
Wheel heat exchanger: using rotating heat wheels to absorb exhaust heat and transfer it to fresh air, suitable for high air volume systems.
Heat pipe heat exchanger: It utilizes the evaporation and condensation of the working fluid inside the heat pipe to transfer heat, and is suitable for scenarios with large temperature differences.
advantage
Energy saving: Recovering 70% -90% of exhaust waste heat, significantly reducing heating or cooling energy consumption.
Environmental Protection: Reduce energy consumption and lower carbon emissions.
Enhance comfort: Avoid direct introduction of cold or hot fresh air and improve indoor environment.

Mine exhaust heat extraction box with built-in air-to-air heat exchanger

The built-in air-to-air heat exchanger in the mine exhaust heat extraction box is a device specifically designed to recover waste heat from mine exhaust air. Mine exhaust refers to the low-temperature, high humidity waste gas discharged from a mine, which usually contains a certain amount of heat but is traditionally discharged directly without being utilized. This device uses a built-in air-to-air heat exchanger (i.e. air-to-air heat exchanger) to transfer heat from the exhaust air to another stream of cold air, thereby achieving the goal of waste heat recovery.

Working principle
Lack of air input: The mine's lack of air is introduced into the heat extraction box through the ventilation system. The temperature of the exhaust air is generally around 20 ℃ (the specific temperature varies depending on the depth of the mine and the environment), and the humidity is relatively high.
Function of Air to Air Heat Exchanger: The built-in air to air heat exchanger usually adopts a plate or tube structure, and the exhaust air and cold air exchange heat through a partition type in the heat exchanger. The heat from the lack of wind is transferred to the cold air, while the two airflows do not mix directly.
Heat output: After being heated by heat exchange, the cold air can be used for anti freezing of mine air inlet, heating of mining area buildings, or domestic hot water, while the exhaust air is discharged at a lower temperature after releasing heat.
Characteristics and advantages
Efficient and energy-saving: Air to air heat exchangers do not require additional working fluids and directly utilize the heat transfer from air to air. They have a simple structure and low operating costs.
Environmental friendliness: By recycling exhaust heat and reducing energy waste, it meets the requirements of green and low-carbon development.
Strong adaptability: The equipment can be customized and designed according to the flow rate and temperature of the mine exhaust, suitable for mines of different scales.
Easy maintenance: Compared to heat pipe or heat pump systems, air-to-air heat exchangers have a relatively simple structure and require less maintenance.
Application scenarios
Anti freezing at the wellhead: Use the recovered heat to heat the mine air intake and avoid freezing in winter.
Building heating: providing heating for office buildings, dormitories, etc. in the mining area.
Hot water supply: Combined with the subsequent system, provide a heat source for domestic hot water in the mining area.
precautions
Moisture treatment: Due to the high humidity of the exhaust air, the heat exchanger may face the problem of condensation water accumulation, and a drainage system or anti-corrosion materials need to be designed.
Heat transfer efficiency: The efficiency of an air-to-air heat exchanger is limited by the specific heat capacity and temperature difference of the air, and the recovered heat may not be as high as that of a heat pump system, but its advantage lies in its simple structure.

Plate type air-to-air heat exchanger made of polymer PP material

The plate type air-to-air heat exchanger made of polymer PP (polypropylene) material is a heat exchange device based on polypropylene material, mainly used for heat exchange between gases. Here are its main features and application areas:

Main features:
Corrosion resistance: PP material has strong chemical corrosion resistance and is suitable for acidic or alkaline gas environments, especially performing well in industrial environments with strong corrosiveness.

Lightweight: Compared to metal heat exchangers, PP material heat exchangers are lighter in weight, making them easier to install and maintain.

Good thermal stability: Polypropylene has good thermal stability and can typically operate within a temperature range of -10 ° C to+95 ° C.

High cost-effectiveness: Due to the low cost of PP material and relatively easy processing, the overall cost is relatively economical.

Environmental friendliness: Polypropylene is a recyclable polymer material with minimal impact on the environment after disposal.

Main application areas:
Chemical and pharmaceutical industries: used for heat recovery or temperature regulation of corrosive gases.
Exhaust gas treatment system: During the air purification process, heat is recovered from harmful gases through a heat exchanger.
Food processing: In some food production processes, it is used for gas exchange to maintain the stability of environmental temperature.
HVAC system: Used in the ventilation and air conditioning systems of buildings for air preheating or pre cooling, improving energy efficiency.
The plate type air-to-air heat exchanger made of polypropylene material has become an ideal choice for many specific industrial fields due to its unique corrosion resistance and good cost-effectiveness.

Working principle of plate air-to-air heat exchanger

Plate air-to-air heat exchanger is a commonly used heat exchange equipment, and its working principle is as follows:

The plate air-to-air heat exchanger is composed of a series of parallel metal plates, and a series of channels are formed between the plates. The heat medium flows in these channels. When the heat medium flows in the plate air-to-air heat exchanger, the heat medium transfers heat to the plate, and then the plate transfers heat to the other side of the heat medium, thereby achieving heat transfer and heat exchange.

The working principle of the plate air-to-air heat exchanger can be divided into two ways: direct heat transfer and indirect heat transfer.

Direct heat transfer: Direct heat transfer refers to the heat medium flowing directly through the plate, transferring heat to the other side of the heat medium. This method is suitable for situations where the temperature difference between the two sides of the heat medium is small.

Indirect heat transfer: Indirect heat transfer refers to the heat medium transferring heat to the other side of the heat medium through the plate. This method is suitable for situations where the temperature difference between the two sides of the heat medium is large.

In the plate air-to-air heat exchanger, the flow of the heat medium has two ways: one-way flow and two-way flow. One-way flow means that the heat medium flows in only one direction, while two-way flow means that the heat medium can flow in two directions. Plate air-to-air heat exchangers with two-way flow have higher heat exchange efficiency, but they are also more complex and expensive.

In summary, the plate air-to-air heat exchanger achieves heat transfer and heat exchange between heat media through the channels between plates. Its working principle can be divided into direct heat transfer and indirect heat transfer, and the flow of the heat medium has one-way flow and two-way flow.

Industrial purification heat recovery

Tag Archive air-to-air heat exchanger

The utilization of air-to-air heat exchangers in ventilation and energy-saving engineering

Mine exhaust heat extraction box with built-in air-to-air heat exchanger

Plate type air-to-air heat exchanger made of polymer PP material

The plate type air-to-air heat exchanger made of polymer PP (polypropylene) material is a heat exchange device based on polypropylene material, mainly used for heat exchange between gases. Here are its main features and application areas:

Working principle of plate air-to-air heat exchanger

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