Research On Condensation Heat Transfer Characteristics Of Plate Heat Exchanger In Rotating State

Vapor-cycle cooling system, as an important part of the airborne environment control system, has very important significance on the condensation heat transfer mechanism in airborne system research. This thesis chooses the plate-type condenser in vertical rotating state as the study object. Use experimental and numerical simulation methods to study on the heat transfer characteristics of plate type condenser in rotating state. Design single compression refrigeration cycle system by using R22 as refrigerant. Build the plate-type condenser heat transfer experimental platform in vertical rotating state. Install the data measurement and collection system in the experimental platform, to ensure the validity of experimental data. By changing the placement angle of the plate-type condenser, refrigerant inlet flow rate, cooling water inlet flow rate, the speed of rotating and other conditions, to study different experimental conditions of R22 condensation heat transfer process. Establish numerical model and then analyze R22 condensation heat transfer process in the flow channel.When the plate-type condenser in vertical rotating state, R22 inlet flow rate increases from 18 m3/h to 28 m3/h, heat transfer coefficient of R22 side, heat transfer coefficient of cooling water side and total heat transfer coefficient increases. In order to study the effect of gravity on the plate condenser, study on the plate-type condenser fluid flow and heat transfer characteristics by changing the placement angle from 0 degrees to 180 degrees. Gravity influence on the variation of the pressure, outlet temperature and heat transfer coefficient of the R22 side is within 4%, and the influence of cooling water side heat transfer characteristics can be neglected.The rotation will change the heat loss performance of the plate-type condenser. When the plate-type condenser in rotating state, the heat transfer form with surrounding environment is enhanced convection heat transfer. Heat loss caused by rotation can not be ignored. Use two different heat loss calculation methods to calculate heat loss: The change of heat loss ranges from 0.20 k W to 2.29 k W, the difference between the two calculation methods is range from-0.57 k W to 2.75 k W, the deviation is within 5%.When the plate-type condenser in vertical rotating state, R22 and cooling water heat transfer performance will be affected by the R22 inlet flow, cooling water inlet flow and the speed of rotating etc.. The speed of rotating varies from 0rpm to 60 rpm, the change of the pressure drop of the R22 Inlet and outlet is range from 0.2 Mpa to 0.6 Mpa. Cooling water inlet flow effect by the speed is not obvious, when the speed is increased to 60 rpm, cooling water inlet flow changes from 13 m3/h to 12.97 m3/h.When the R22 inlet parameters and cooling water inlet parameters are not changing, but the peed of rotating varies from 0 rpm to 60 rpm, heat transfer coefficient of R22 side increased by 83.98 W/(m2?K) to 129.49 W/(m2?K), growth rate is range from 4.42 to 8.26%. Heat transfer coefficient of cooling water side increased by 433.17 W/(m2?K) to 435.73 W/(m2?K), growth rate is range from 5.00% to 6.99%.According to the relationship between Reynolds number, R22 outlet condensate Prandtl number and Nusselt number, to simulate the experimental correlation of condensation heat transfer of R22 that is suitable for the experimental conditions of this paper. On the basis of the experimental correlation of the static state, introduce the influence of dimensionless parameters Ro, to simulate the experimental correlation of condensation heat transfer of R22 in vertical rotating state. The fitting accuracy is higher and the maximum deviation is less than ±5%.Using CFD numerical simulation method, select a section of unit flow passage as the calculating area. The speed of rotating varies from 0 rpm to 350 rpm. Under low speed(0~60 rpm), the numerical simulation results trend were consistent with the experimental results trend. The reliability of the numerical model is verified. Based on the numerical model, the high speed(120~350 rpm) had a greater effect on R22 condensation in the heat exchanger heat transfer process, especially the significant influence on the pressure drop along the path of the R22.