Brief history of plate heat exchanger

In twentieth Century, the plate heat exchanger was used in the food industry in the year of 20s. The heat exchanger made of the board is a compact structure with good heat transfer effect. In the early 30s, Sweden made the first spiral plate heat exchanger. Then, the United Kingdom produced a plate fin heat exchanger made of copper and its alloy material by brazing. In the late 30s, Sweden produced the first plate and shell heat exchanger. In the meantime, in order to solve the problem of heat transfer of the strong corrosive medium, the new type of heat exchanger made of new material has been paid attention to.

Around 60s, due to the rapid development of space technology and cutting-edge science, the urgent need for a variety of efficient heat exchanger compact, coupled with the development of stamping, brazing and sealing technology, the manufacturing process of heat exchanger has been further improved, so as to promote the compact plate type heat exchanger of the rapid development and wide application. In addition, since the beginning of 60s, in order to meet the needs of heat and energy saving under the condition of high temperature and high pressure, the typical shell and tube heat exchanger has been further developed. In the middle of the 70s, in order to strengthen heat transfer, heat pipe heat exchanger was developed on the basis of research and development of heat pipe.

The heat exchanger can be divided into three types according to the different heat transfer modes, that is, mixed type, regenerative type and wall type.

The hybrid heat exchanger is a kind of heat exchanger, which is a kind of heat exchanger, which is directly connected with the hot and cold fluid. Due to the two fluid mixing heat transfer must be timely separation, this type of heat exchanger is suitable for gas, liquid heat transfer between the two fluids. For example, a cold water tower for chemical plant and power plant, hot water from the top down and bottom spray, cold air inhalation, filling water in the membrane surface or droplets and the surface of the water, hot water and cold air contact heat exchanger, hot water is cooled, the cold air is heated, and then rely on the two fluid itself the density difference and separation.

The utility model relates to a regenerative heat exchanger, which is a heat exchanger which uses cold and hot fluid to flow alternately through the surface of the heat storage body (filler) in the heat storage chamber to heat exchange. This type of heat exchanger is mainly used for the recovery and utilization of high temperature exhaust heat. The same kind of equipment, which is used for the purpose of recovering the cooling capacity, is called a cooler.

Recuperative heat exchanger of the cold and hot fluid separated by a solid partition wall, and the wall of the heat exchanger heat exchange, also known as the surface type heat exchanger, the heat exchanger is the most widely used.

According to the structure of heat transfer surface, the wall heat exchanger can be divided into tube type, plate type and other types. Tube type heat exchanger to the surface of the tube as the heat transfer surface, including the snake tube heat exchanger, tube heat exchanger and a shell and tube type heat exchanger; plate type heat exchanger with plate as heat transfer surface, including heat exchanger, spiral plate heat exchanger, plate fin heat exchanger, plate type the heat exchanger and the umbrella plate heat exchanger; other type heat exchanger is to meet some special requirements and the design of the heat exchanger, such as scraped surface heat exchanger, rotary heat exchanger and air cooler etc..

There are two kinds of relative flow in the heat exchanger. At the same time, the temperature difference between the two fluids at the entrance is the largest, and it decreases gradually along the heat transfer surface. The temperature distribution of the two fluid along the surface of the heat transfer surface is more uniform. When the temperature of the inlet and outlet of the cold and hot fluid is constant, when the two fluids have no phase change, the average temperature difference is the lowest. Under the condition of the same heat transfer, the average temperature can be increased and the heat transfer area of the heat exchanger can be reduced by using the counter current. If the heat transfer area is constant, the consumption of the heating or cooling fluid can be reduced by using the countercurrent flow. The former can save equipment costs, the latter can save operating costs, so in the design or production should be used as far as possible reverse heat transfer.

When the cold and hot fluid two or one phase change (boiling or condensation), because phase only emit or absorb the latent heat of vaporization temperature, there is no change in the fluid itself, so that the fluid inlet and outlet temperature are equal, then the temperature difference of two fluid and fluid flow selection. In addition to the two kinds of parallel flow and countercurrent flow outside, there is the flow and flow, such as flow.

In the process of heat transfer, it is an important problem to reduce the thermal resistance of the heat exchanger. Fluid film resistance mainly comes from the wall on both sides of the viscous in on the heat transfer surfaces (called boundary layer), the dirt layer is formed on both sides of the wall and the heat exchanger used in the thermal resistance of metal wall is relatively small.

Increasing the flow velocity and the disturbance of the fluid can reduce the boundary layer, reduce the thermal resistance and increase the heat transfer coefficient. However, increasing the flow velocity will increase the energy consumption, so it should be designed to reduce the thermal resistance and reduce energy consumption. In order to reduce the fouling thermal resistance, we can try to delay the formation of fouling, and regular cleaning heat transfer surface.

Are made of metal material heat exchanger in general, including carbon and low alloy steels are mostly used in manufacturing, low in heat exchanger; in addition to stainless steel is mainly used for corrosion resistance under different conditions, austenitic stainless steel can be used as high and low temperature resistant materials; copper, aluminum and its alloy used for the manufacture of low temperature heat exchanger; nickel alloy for high temperature conditions; non metallic materials in addition to the production of gasket parts, some have begun for the production of corrosion-resistant non-metallic materials such as graphite heat exchanger, heat exchanger, fluorine plastic heat exchanger and glass heat exchanger etc..