Research Of Heat Transfer Enhancement And Application Of Polymeric Hollow Fiber Heat Transfer Element

Heat exchanger device is vital equipment which is used to achieve heat exchange between materials in process of industrial production. However, the wide use of traditional metal heat exchange device is limited for the corruption and fouling especially in the high salt, acid, alkali and hardness situation. For their ability to resist the corrosion and fouling problem, the heat exchange devices which were made of polymeric heat transfer element have gained more attention.In this study, polymeric hollow fiber as heat transfer element was used to prepare the novel hollow fiber heat exchanger(HFHE) with segmental baffles. And the heat transfer performance of HFHE was analyzed by experiment and Fluent simulation. The results show that the results of simulation are in good agreement with the experimental results. The comparison between heat transfer performance of HFHE with and without baffles reveals that the overall heat transfer coefficient of HFHE is improved by 35% after adding baffles. The pressure drop of shell-side is improved by 14% after adding baffles. And the ratio of shell-side heat resistance to overall heat resistance of HFHE is decreased from 59%-70% to 34.5%-46.7% after adding baffles. The ratio of shell-side heat transfer coefficient to pressure drop of shell-side is boosted after adding baffles. All the results indicate that adding segmental baffles in shell-side strengthens the heat transfer performance of HFHE.In this study, polymeric hollow fiber heat exchange device as evaporator was used to build up the single effect and three effect evaporation system. The effects of operation status on the water yield and gained output ratio(GOR) of evaporation system were investigated in experiment when the feed was pure water and 3%wt Na Cl solution, respectively. The results show that for both single and three effect evaporation system, increasing feed temperature and temperature difference of heat exchange increases water yield and GOR of evaporation system. The water yield of evaporation system is increased when the feed flow rate is boosted, but GOR is relatively stable. When the feed is pure water, with the increase of feed flow rate the GOR of single and three effect evaporation system keeps approximately 0.85 and 1.65, respectively. When the feed is Na Cl solution, with the increase of feed flow rate the GOR of single and three effect evaporation system keeps approximately 0.76 and 1.48, respectively. When the feed flow rate is 90L/h, temperature of heating steam is 97°C, temperature of feed is 78°C and the heat exchange temperature difference is 12°C, the water yield of three effect evaporation system reaches 6.55kg/h when the feed is pure water; And the water yield of three effect evaporation system achieves 5.9kg/h when the feed is Na Cl solution. In addition, under the same conditions, when the feed is Na Cl solution the water yield and GOR of single and three effect evaporation system are both less than the water yield and GOR of single and three effect evaporation system when the feed is pure water.This project provides a method to strengthen the heat transfer performance of heat exchanger made of polymer hollow fiber heat transfer element. Moreover, it lays a foundation for designing evaporation system made of polymeric hollow fiber heat transfer element.