Study The Heat Transfer Characteristics And Verify The Heat Exchanger Model Of Passive Residual Heat Removal Heat Exchanger

The next generation of reactors CAP1400will use passive residual heat removal systemwhich is similar to the AP1000. To ensure the reliability of the passive residual heat removalsystem， using internationally recognized reactor safety analysis program RELAP5/MOD3.2analyzes and evaluates projects. In view of RELAP5/MOD3.2boiling heat transfer andcondensation heat transfer model can only be applied within a certain range, the ability toaccurately predict the passive residual heat removal heat transfer characteristics of the heatexchanger is not yet very clear.In order to master the passive residual heat removal system heat exchanger model of heattransfer characteristics and verify RELAP5/MOD3.2correctness. In this paper, study the tubeinside condensation heat transfer characteristics and tube outside boiling heat transfercharacteristics of the passive residual heat removal heat exchanger through experiments. Onthis basis, create the model of the experimental loop system using RELAP5/MOD3.2program.Contrast RELAP5/MOD3.2calculated results with the experimental results and verify theapplicability of the heat exchanger model which is called in RELAP5/MOD3.2program.The test results show that:(1) Experimental results show that the center tube of the condensing heat exchangercapacity is higher than the side pipes, center tube condensate flow, heat flux and condensationheat transfer coefficient is greater than the side pipes.(2) The center tube boiling heat transfer temperature difference is higher than next to thepipe, but the boiling heat transfer coefficient is lower than the side pipes. Compare thethermal resistance of the entire heat transfer process, it is found that the condensation heattransfer process thermal resistance is much higher than the other heat exchanger thermalresistance, the thermal resistance of the condensing heat exchanger to a large extent hinderedthe export of heat. the heat transfer coefficient the spiral microfin intensifier tubes is greaterthan3~4times more condensation heat transfer coefficient of Fluorescent tubes.(3) Contrast procedures calculated results of the single-tube condensation heat transfercoefficient with the experimental results, found the RELAP5/MOD3.2mainly call is Shahmodel in the entire experimental range. At Re>500, Shah model applicability of the RELAP5/MOD3.2program is very good, the relative error is about3%. However, at Re <500,the deviation is high up to20%.(4)The Chen relationship calculation result of the RELAP5/MOD3.2program is muchless than the experimental results, which may be a relationship with the low flow rate of theexternal fluid of the bundle in large volume boiling conditions.