Experimental Investigation On Condensation Heat Transfer And Its Enhancement Of HFC245fa Outside Horizontal Tube Bundles

Nowadays, the issues of energy resource and environment are the great social problems that all over the world especially our country faces. China has severe situations such as lacking energy resources, low energy efficiency, high energy consumption, exhaust of CO2 and SO2 whose quantity has been on the top of world. With the quickening of process of urbanization and speed of economy development, China will face great pressure of energy resource supply and environment protection for a long time. Heat pump has been an important technology using low quality waste heat, remaing waste and natural energy (water, terrestrial heat, soil, etc) to meet the requirement of low quality energy resources both in civil and industrial areas, to reduce energy consumption of fossil energy resource and environment pollution, to improve energy efficiency and resolve the issues of energy conservation and environmental protection be faced with China. .The performance of high temperature heat pump(HTHP) is depended on the heat transfer capability of shell-tube condenser, which is an important part of HTHP. The usage of three-dimensional (3D) enhanced tube can increases greatly the heat transfer ability of shell-tube heat transfer and improves the operational efficiency of heat pump, achieving better compactness effect which has a large contribution to improve the integrity performance index of heat pump. The self-development design of high efficiency shell-tube condenser needs shell side condensation heat transfer characteristic parameters of alternate refrigerant. Currently, the experimental data of condensation heat transfer coefficient of alternate refrigerant on horizontal tube in condenser design of heat pump system are rarely to found, especially that on tube-bundle. . Accordingly, the condensation heat transfer test-board for high-temperature refrigerant is retrofited; the condensation heat transfer performance of HFC245fa outside kinds of tubes is researched under high-temperature condition, providing a theoretical and basical data for optimization of shell-tube condenser and the development of HTHP. The detailed content is given as followed.1. The experimental theory and results in condensation heat transfer and heat transfer enhancement field are summarized and analyzed by predecessors. the development track is explored by analyzing the complementary relationship through several milestones. Indicate next development direction, points out the main problems in this area and brings forward the major research goals.2. The monitoring and controlling systems of the test-board is optimize.3. Condensation heat transfer characteristics of HFC245fa on horizontal smooth tube and enhanced Turbo-CSL tube is Analyzed. Introduce the tube material and define the experiment mode. Method to deal with the experiment data is introduced in detail. Direct and indirect influent factors of condensation heat transfer outside single-tube are analyzed.4. Analyze the enhance theory of condensation heat transfer, based on the analysis; the enhancing factor and it calculation expression are brought forward, the strengthening surface condensation heat transfer theory method is set up.5. Put forward a method to enhance condensation heat transfer coefficient outside the tube bundle and design relevant experiment tube which were validated by experiment.The last part is conclusion and expectation. The main conclusions are presented and the direction to further research on condensation heat transfer outside tubes is put forward.