Design And Analysis Of Air-cooler Used In The Containment Filtration And Exhaust System

When the coolant leakage accident occurred on the reactor’s primary loop,high temperature liquid containing radioactive material will flash. With the accumulation of steam,pressure in the containment will rise. To avoid damage to the containment’s integrity, we can use containment filtration and exhaust system to wash and filter the mixed gas, remove iodine and aerosols with radioactivity, and then discharge the mixed gas into the environment when reached the safety standards, thus can reduce the temperature and pressure of the containment.Due to the decay heat absorption,water in the water scrubber is evaporated,to make the water scrubber work for a long time without human’s intervention, the design of an efficient and durable heat exchanger is needed, allowing part of the "clean" steam condensate and return to the water scrubber, and ensuring continuous operation of the entire system loop.In this paper, the structure of the air-cooler under a natural circulation condition has been designed. After selected the basic structure of tube (or beam) and head, calculated the heat balance of the water scrubber by Matlab program, determined heat exchanger’s design heat capacity 195 kW. On this basis, for several different specifications of high frequency welding stainless steel finned tubes on the common market, edited program to make an analysis of coupling calculation of flow and heat transfer. Adjusted the parameters of tube and bundle arrangement to compare the effect of these parameters on heat exchanger’s performance.Determined reasonable structure parameters, so that the height of the heat exchanger’s additional wind channel within an acceptable range, and the volume of the main body as small as possible at the same time.Upon the completion of heat exchanger’s design, selected 1/10 number of the heat transfer tubes consisting a small heat exchanger as prototype, and also designed the main body of the experimental prototype and its condensate tank, preparing for the experimental analysis. In addition, this part mainly used a software named Star-ccm+ to design the details of the prototype heads through a numerical simulation method. Added diversion baffle plate and uniform flow orifice in the inlet head to make a uniform flow distribution, compared the effect of flow distribution under different options, finally the standard deviation of the velocity distribution redused from 5.19 to 1.9, the pressure drop was only 0.925% of the working pressure; Outlet head added gas-water separation orifice for condensate recovery,compared the effect of condensate recovery under different orifice plate options, and gave design and installation recommendations.