Design And Construction Of Experimental For Steam Condensation Heat Transfer And Flow In Vacuum Horizontal Tubes

Tube condensation is widely used in life and industries,such as nuclear power,chemical industry,refrigeration and other industries.Therefore,the study of condensation heat transfers in tubes have had a profound impact on improving both the performance of heat exchangers and the quality of human life.Experiment and numerical simulation are widely used in research of gas-liquid two-phase flow,and experiment will be more credible especially when there is more gas-liquid two-phase flow in phase change process.Therefore,in this paper,with the background of low-temperature multi-effect evaporation desalination,the test tube of aluminum yellow copper tube(HALL-7)with external diameter of 19 mm,25.4mm and 38 mm is adopted,whose effective heat transfer length was 1800 mm.An experimental device was designed for the condensation of steam in a horizontal tube,and the reliability of the experiment table is verified by the construction and experiment of an experiment table for water vapor heat transfer in a horizontal tube.This study is mainly divided into three steps.First,according to the characteristics of high vacuum,low mass flow rate and small difference of heat transfer of the LT-MED evaporator,the design of saturated steam at 40-70 ? is carried out under the experimental condition of 1-5 degree heat transfer.The whole experiment table is divided into three sections,including the adjustment section with horizontal casing pipe,the test section with horizontal casing pipe and the test section with horizontal falling film.And the diameter of casing pipe,the cooling water temperature and the flow velocity are designed and calculated to meet the need of the adjustment section for working successfully between the mass air rate of 0~0.8.Also,test-bed and measuring instruments are also selected to meet requirements of experiment and data research.Second,the whole experimental system is built and the experimental device is installed and welded as a whole.Finally,experiments on the change of average heat transfer coefficient of saturated steam with different mass air rate are carried out on the experiment table,in order to make sure that the experiment table can meet the requirements of domestic researches such as heat transfer character and flow resistance.