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. Its main types are:
① Spiral plate heat exchanger Rolled from two parallel metal plates with a certain distance (Figure 1). 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 fluid can be completely countercurrent flow), small flow resistance, and is not easy to knot Dirt; but maintenance is difficult. Use pressure does not exceed 2MPa.
② Flat plate heat exchanger It consists of a certain shape of corrugated thin plates and sealing gaskets alternately stacked and clamped and assembled with a frame (Figure 2). 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 board is usually punched from stainless steel, aluminum, titanium, molybdenum and other thin plates with a thickness of 0.5 ~ 3mm. 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), it 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 usually does not exceed 2 MPa, and the operating temperature does not exceed 250 ° C.
③ Plate-fin heat exchanger consists of heat exchange plate bundles enclosed in a header with cold and hot fluid inlet and outlet. The plate bundle is formed by overlapping the flat plates and corrugated fins alternately and brazing them (Figure 3). Cold and hot fluids flow through both sides of the plate to exchange heat. The fins increase the heat transfer area, promote the turbulence of the fluid, and enhance the equipment. The plate-fin heat exchanger has a very compact structure (the heat exchange area reaches 4400m / m), the heat transfer effect is good, and the use pressure can reach 15MPa. However, its manufacturing process is complex, the flow channel is small, and the internal leakage is not easy to repair, so it is limited to clean non-corrosive fluids, such as heat exchangers for air separation.