Research On Heat Transfer Characteristics Of R22Condensation In Rotating State

Vapor-cycle cooling system for aerospace vehicles may operate in some dynamic environment,This thesis focuses on the problem that the rotation state of aerospace vehicles would affect the heattransfer characteristics of refrigeration condensation. Design the vapor-cycle cooling system usingR22as the working fluid by applying the basic principles of the ideal refrigeration cycle. By usingCatia to three-dimensional visual layout of the test bench, build a reasonable R22condensation heattransfer experiment platform. The rotation of the plate heat exchanger is used to simulate the rotationstate of the aerospace vehicles. Experiment by adjusting the motor speed、R22inlet temperature、R22inlet flows and other main parameters, then obtain part of the R22condensation heat transfercharacteristics in rotating state. These provide some guidance for theoretical design of airbornevapor-cycle cooling system，the main conclusions of experimental study are as follows：(1)In stationary condition of the plate heat exchanger vertically disposed, when the cooling waterflow rate increases from7m3/h to15m3/h, condensation heat transfer coefficient of both the coolingwater side and R22side increases, logarithmic mean temperature difference is on the decline; Theheat absorption capacity of cooling water side increased by a big margin, total heat loss decreaseswith the cooling water flow increases.(2)In rotating state, cooling water flow rate on the influence of R22condensation is similar tostatic conditions, but the influence extent is different. When the cooling water flow rate increases from7m3/h to9m3/h and rotational speed varies from12rpm to48rpm, total heat transfer coefficient andheat transfer coefficients of R22condensation increase with cooling water flow rate and rotationalspeed increase, the cooling water side is strongly influenced by rotating, heat transfer coefficientsincrease by20.3%compared to static state; R22steam flow and heat transfer affected by rotation isrelatively small, heat transfer coefficient of R22condensation increases up to4.1%.(3)In rotating state, condensation heat transfer coefficient of R22side is strongly influenced byspeed. For the same import superheat degree of R22, condensation heat transfer coefficient of R22side increases with the increase of rotational speed, it increases up to4.3%at speed of48rpm; For thesame rotational speed, condensation heat transfer coefficient of R22side fluctuates with the importsuperheat degree of R22increases, and the greater speed the greater volatility, but volatility does notexceed1%.(4)In rotating state, R22import flow rate increase makes the total heat transfer capacity increase. When speed rises from12rpm to48rpm, heat transfer coefficient of cooling water side respectivelyincreases by6%,9.1%,10.8%and11.9%; R22side is greatly influenced by the flow rate and rotatingspeed, condensation heat transfer coefficient of R22side at48rpm speed condition increased37.9%compared to the static conditions.(5)Rotation has no effect on inlet pressure of R22, outlet pressure of R22remains constant in lowspeed, while it increases in high speed, and the import and export pressure differential is reduced withspeed increases, outlet pressure of R22remains constant with time changes; Inlet flow of coolingwater decreases with the increase of rotational speed, and it fluctuating changes with time, but overallit remains the same.(6)Simulate the experimental correlation of condensation heat transfer of R22in the stationarycondition of the plate heat exchanger vertically disposed and rotating condition. The relationship ofthe condensation Nusselt number, Reynolds number of outlet condensate, Prandtl number of outletcondensate and Revolution number is obtained. Then compare the relational return values withexperimental measure values, it’s found that they have good fitting precision, the errors are within±15%in the stationary condition, and within±20%in rotating state.