History and development
Plate heat exchangers appeared in the 1920s and mainly in the food industry. The heat exchanger made of plate instead of tube has compact structure and good heat transfer effect. Therefore, it has gradually developed into various forms.
In the early 1930s,
Sweden made the spiral plate heat exchanger for the first time. Then the British used brazing to produce a plate-fin heat exchanger made of copper and its alloy materials. And it usually appeared in the heat dissipation of aircraft engines.
the British Alston Chun used the indoor return air and outdoor fresh air which is positively intertwined. Due to the temperature difference and water vapor partial pressure difference between the airflows on both sides of the flat partition, simultaneous heat and mass transfer between the two air streams, causing a total heat exchange process. Through heat exchange to achieve indoor and outdoor air circulation, built-in blower and exhaust fan. The two-way equal amount takes place of the built-in blower and exhaust fan. Thus suppress the change of room temperature and keep enough fresh air indoors.
At the end of the 1930s,
Sweden produced the first plate and shell heat exchanger for pulp mills. During this period, in order to solve the heat exchange problem of strong corrosive media, people began to pay attention to heat exchangers made of new materials.
Around the 1960s,
due to the rapid development of space technology and cutting-edge science, there is an urgent need for various high-efficiency and compact heat exchangers. Coupled with the development of stamping, brazing and sealing technologies, the heat exchanger manufacturing process was further improved. This has promoted the vigorous development and wide application of compact plate heat exchangers.
Since the 1960s,
in order to meet the needs of heat exchange and energy saving under high temperature and high pressure conditions, typical shell and tube heat exchangers have also been further developed.
In the mid-1970s,
heat pipe heat exchangers appeared on the basis of research and development of heat pipes, so as to strengthen heat transfer.
Heat exchangers fall into three types according to different heat transfer methods.
1. Hybrid type
Hybrid heat exchanger is a heat exchanger that exchanges heat through direct contact and mixing of cold and hot fluids. Since the two fluids must separate in time after mixing and heat exchange. This type of heat exchanger is suitable for heat exchange between gas and liquid.
For example, in the cooling water towers in chemical plants and power plants. we usually spray hot water from top to bottom, while suck cold air from bottom to top. On the surface of the water film of the filling or the surface of droplets and water drop, hot water and cold air contact with each other for heat exchange. Then, the hot water is cooled, the cold air is heated, and then separated in time by the density difference between the two fluids.
2. Recuperative type
The cold and hot fluids of the recuperative heat exchanger are separated by solid partition walls and exchange heat through the partition wall. Therefore, it is also called surface heat exchanger. This type of heat exchanger is the most popular one.
3. Regenerative type
Regenerative heat exchanger is a heat exchanger that uses cold and hot fluid to alternately flow through the surface of the regenerator (filler) to exchange heat. For instance, the regenerator for preheating air under the coke oven. This type of heat exchanger is suitable for recovering and utilizing the heat of high-temperature exhaust gas.