Research On Structure And Application Of Self-support Heat Exchanger With Pin-finned Tubes

With the rapid development of economy, the consumption of energy increases swiftly and energy crisises erupt repeatedly. Saving energy and reducing consumption have become a common goal of the world. Shell and tube heat exchangers are widely used in the industry such as petroleum production, chemical industry, etc. Research on heat transfer enhancement of shell and tube heat exchangers can reduce the costs of manufacture and running, which brings great social and economic benefits.In this paper the self-support heat exchanger with pin-finned tubes is a new kind of heat exchanger that synthesizes the structures of Sunrod pin-finned tubes and supports in the shell side, the function of tube-bundle supporting and heat transfer enhancement of shell side are both realized. Considering the high consumption and hard realization of true working condition in experiment, Software Fluent is used to study the self-support heat exchanger with pin-finned tubes in this paper. After some simplification of the heat exchanger in laboratory, the reasonable numerical model is established. In order to study the applicable working conditions and heat transfer rules of self-support heat exchanger with pin-finned tubes, many working conditions and structures of tube bundle are designed in this paper. The accuracy of numerical simulation is verified by comparing with the experiment results and empirical formulary results. The main conclusions of this paper are as follows:(1) For the structure with mixed tube bundles ,the effect of heat transfer enhancement is different to different medias. Compared with plain tubes, it shows better performance of heat transfer enhancement to air, the heat transfer coefficient per Pascal is about 30% higher. Compared with the segmental baffles, it shows better performance of heat transfer enhancement.(2) Taking air-vapor as working condition, heat transfer coefficient of mixed tube bundles with 20mm spacing cylinder pins is bigger than the others. It's about 98.49% higher than plain tubes. Making the heat transfer coefficient per Pascal as evaluation factor, mixed tube bundles with 30mm spacing cylinder pins has the best performance.(3) Taking air-vapor as working condition, the mixed tube bundles has better effect of heat transfer enhancement than the finned tube bundles when the difference of heat transfer area isn't significant.(4) Taking air-vapor as working condition, the mixed tubes with drop-shaped pin has the best effect of heat transfer enhancement, compared with the mixed tube bundles with 35mm spacing cylinder pins, the heat transfer coefficient of mixed tube bundles with 35mm spacing elliptic cylinder pin pins is 2.88% higher, and mixed tube bundles with 35mm spacing drop-shaped is 9.60%, making the heat transfer coefficient per Pascal as evaluation factor, the heat transfer coefficient of mixed tube bundles with 35mm spacing drop-shaped pins is 5.23% higher, and mixed tube bundles with 35mm spacing elliptic cylinder pin 14.21%.(5) The results of numerical simulation fit the experiment results and empirical formulary results very well. According to the results of numerical simulation, the'correlation Nu and f of heat exchanger with mixed tube bundles are made.(6) Heat exchanger with mixed tube bundle shows better performance of heat transfer enhancement than heat exchanger with segmental baffles.