Main factors affecting the heat exchange efficiency of heat exchangers and technologies to improve heat exchange efficiency

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Since the emergence of heat exchangers in the 20s of the last century, heat exchangers have a history of nearly 100 years of development. The forms of heat exchangers have become more and more abundant. Heat exchangers have been widely used in factories, hotels, restaurants, office buildings, entertainment venues and entertainment venues. Figure 1 Cooler heat exchanger is used in the industrial field. In the industrial water consumption, cooling water accounts for more than 60% of the total water. However, the cooling water is in the circulation system. Due to the increase in water temperature, changes in water flow velocity, water evaporation, concentration of various inorganic ions and organic substances, the cooling tower and pool are outdoors. Exposure to sunlight, wind and rain, the entry of dust and debris, as well as the combined effects of various factors such as equipment structure and materials, can easily cause a large number of microorganisms to breed, equipment corrosion and sedimentation, and the resulting slime and dirt to block pipes and other problems, and even cause equipment to stop production, causing economic losses. Figure 2 Pipe blockage Figure 3 Scaling on the inner wall of the pipe Figure 4 Scaling on the outer wall of the pipe According to observation and research, more than 90% of ordinary shell and tube heat exchangers have varying degrees of scaling problems. From the heat transfer rate equation Q=KS△tm, it can be seen that the main factors affecting the heat transfer effect of the heat exchanger are: Heat transfer coefficient K, heat transfer area S and average temperature difference Δt. The heat transfer area S decreases, causing the heat transfer performance to deteriorate and the heat transfer efficiency to decrease. The average decrease can reach more than 30%. In addition to directly causing energy loss, it will also reduce the operating load of production equipment and affect production capacity. In addition, equipment fouling will also cause an increase in fluid flow resistance, which will lead to an increase in equipment power consumption and periodic cleaning, which will also increase the operating costs of the equipment. Figure 5 Comparison of pipelines After the heat exchanger is scaled, its thermal resistance increases significantly. At this time, the flow rate of the refrigerant (or heating medium) remains unchanged, and the fluid cannot easily transfer the cooling capacity (or heat) to the exchanged working fluid side, and its heat exchange efficiency will significantly deteriorate. Under this situation, if the process still requires that the original exchange efficiency remains unchanged, the inlet water pressure must be increased while increasing the flow rate into the heat exchanger, which results in a doubled increase in energy consumption. Obviously, this has very high requirements on the descaling ability of the heat exchanger equipment itself. Take the new generation shell and tube heat exchanger developed by Hangzhou Shenshi Energy Saving Technology Co., Ltd. for example. The Shenshi 130KW shell and tube heat exchanger adopts 7mm heat transfer tube upgrade, spiral baffle optimization, spiral groove tube, inner tube surface strengthening treatment, and the combined use of a number of Shenshi patented distributors, which can effectively improve the descaling ability of the heat exchanger itself, thereby improving the heat exchanger efficiency. Figure 6 Shen's 130KW shell and tube heat exchanger Figure 7 The inner tube wall is 7mm heat exchange tube, the bottom wall thickness is 0.35mm, the number of teeth, tooth height and helix angle are all self-owned parameters, and the results are repeatedly optimized. Figure 7 Shen's patented design - distributor Figure 8 Embossed processing and spiral groove tube heat exchange tube adopts spiral groove tube design and enhanced surface treatment, which can enhance the turbulence of the fluid, improve the descaling ability of the heat exchanger, reduce the surface scaling thickness, and enhance the heat exchange capacity of the heat exchanger. Hangzhou Shen's new generation shell and tube heat exchanger has good performance, safe use, long service life, small size and high cost performance. It is widely used in hot and cold water units and modular machines.