| The heat exchanger is one of key equipment in the thermodynamic energy process, and has been widely used in the fields of energy engineering, power industry, chemical industry, metallurgy, machinery, transportation, aviation, etc. The heat exchanger is not only a piece of equipment which satisfies the particular demand of technology, but also an effective device for energy recycling and saving. The energy crisis of 1970s accelerated the development of heat transfer enhancing technology dramatically. In order to reduce the energy consuming and yield good economic returns, developing high performance heat exchanger which is applicable for different industry process is required. Twisted tube heat exchanger is just the kind of equipment which is developed from conventional shell-tube heat exchanger and meets the requirements of modern industries. Study of twisted tube heat exchanger's performance was conducted by numerical simulation and experimental research in this thesis. The main work of the study is summarized as follows:(1) Field synergy principle and stream analysis method were applied in the research of heat transfer and flow friction properties in tube-side of twisted tube heat exchangers. The composition of those properties between twisted tube heat exchanger and vertical baffle heat exchanger was conducted. The results indicate that swirl flow is produced in tube-side of twisted tube heat exchangers, the swirl flow result in strong disturbance and improve heat transfer process. Because there isn't any baffle in the shell-side, twisted tube heat exchanger doesn't have stagnant zones, so it doesn't foul easily and the pressure drop is reduced too. Twisted tubes are firmly supported while allowing a well distributed longitudinal flow along the tubes, which makes the unit practically vibration free and promoted operational reliability of twisted heat exchanger.(2)Numerical simulation method was applied to investigate the effects of flow state, fluid property and geometric parameter to heat transfer and flow friction properties in tube-side of twisted tube heat exchangers, the heat transfer enhancement and characteristics of twisted tube were illustrated.(3)The effect of twisting direction on heat transfer enhancement of twisted tube was researched by numerical simulation. In order to illustrate the heat transfer enhancement dominance of twisted tube heat exchanger, Comparison of flow friction properties was conducted between twisted tube exchanger and other kinds of dry- evaporator.(4) Analysis of twisted tube heat exchanger in air conditioning, as the application of the evaporator has practical value and engineering significance, It can be used to guide the twisted tube dry- evaporator.
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