Partition wall heat exchanger with plate as heat transfer surface. This type of heat exchanger has a compact structure and a large heat transfer area per unit volume. The main types of brazed plate heat exchange are:
1. Spiral plate heat exchanger is made by rolling two parallel metal plates with a space between them. Cold and hot fluids flow in spiral channels on both sides of the metal plate. This type of heat exchanger has a high heat transfer coefficient (about 1 to 4 times higher than that of the shell and tube heat exchanger), a large average temperature difference (because cold and hot fluids can flow countercurrently), small flow resistance, and difficult to scale; But maintenance is difficult. Use pressure is not greater than 2MPa.
2. The flat plate heat exchanger is composed of corrugated thin plates and sealing gaskets alternately superposed and clamped and assembled with a frame. Cold and hot fluids flow through the flow channels on both sides of the corrugated plate, respectively, and exchange heat through the plates. The corrugated plate is usually punched from stainless steel, aluminum, titanium, molybdenum and other thin plates with a thickness of 0.5 to 3 mm. The advantage of the flat plate heat exchanger is that the heat transfer coefficient is high (about 2 to 4 times higher than that of the shell and tube heat exchanger), which is easy to remove and wash, and the number of plates can be increased or decreased to adjust the heat transfer area. The operating pressure is usually not greater than 2 MPa, and the operating temperature is not greater than 250 ° C.
3. The plate-fin heat exchanger consists of heat exchange plate bundles enclosed in a header with cold and hot fluid inlets and outlets. The plate bundle is formed by overlapping the flat plate and the corrugated fins alternately and brazing and fixing. Cold and hot fluids flow through both sides of the flat plate to exchange heat, and the fins increase the heat transfer area, which in turn promotes the turbulence of the fluid and increases the equipment. The plate-fin heat exchanger has a compact structure (a heat exchange area of 4400m2 / m3), good heat transfer performance, and an operating pressure of up to 15MPa. However, its manufacturing process is complicated, the flow channel is small, and the internal leakage is not easy to be trimmed, so it is limited to clean non-corrosive fluids, such as heat exchangers for air separation.
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