Experimental Study On Passive Residual Heat Removal System Of Deep Pool Reactor

In the design of nuclear reactors,safety is the first consideration.Passive safety technology is widely used in advanced reactors because of its unique advantages.The Deep Pool Reactor(DPR)is completely submerged in the pool,and its operating parameters are low.The passive residual heat removal system suitable for pool reactors has the following characteristics: 1.The temperature difference between the cold and heat sources is small,and the driving force of the natural circulation is small.2.The final heat sink is the atmosphere,and the temperature changes with time.There are many deficiencies in the research on the passive residual heat removal system of the pool reactor.This paper introduces the passive residual heat removal system of the pool reactor,and conducts an experimental study on its flow and heat transfer characteristics.On the basis of theoretical calculation,an experimental device of passive waste heat removal system is built.The system includes two heat exchangers,namely,the pool water heat exchanger submerged in the pool and the air heat exchanger placed in the atmospheric environment,with a center height difference of 9m.The experimental parameter range of the system is: pool water temperature of 50 ～ 90℃,air temperature of 15 ～ 30℃,air flow of 15000～ 35000 m3/h,and circuit pressure of about 0.3 MPa.Then the calculated value of heat transfer coefficient in the tube is compared with the experimental value,and it is found that the traditional correlation is not suitable for the calculation under this condition.Finally,the transient change of heat exchange power of pool water heat exchanger after system startup is given.The system reaches steady state after about 1500 s.Secondly,the flow and heat transfer characteristics of air heat exchanger are analyzed.The pressure drop of air heat exchanger under different working conditions is analyzed.The results show that the calculated values are less than the experimental values.Then the transient change of pressure drop is analyzed.Finally,the whole heat transfer process of air heat exchanger is analyzed,and the detailed calculation method of heat transfer inside and outside the tube is given and verified.The results show that it is reliable to calculate the convection inside the tube by using Gnielinski correlation and the convection outside the finned tube by using Briggsyoung correlation.Finally,the distribution of water temperature in the pool and the development of thermal stratification are analyzed.The number of thermal stratification in the pool continues to increase with the operation of the system.After the thermal stratification develops to a certain extent,Ra number can predict the development speed of thermal stratification.At the same time,the influence of boundary conditions on the system power is analyzed.The system power has an exponential relationship with the flow.Through experiments,this paper studies the flow and heat transfer characteristics of heat exchanger in pool reactor passive residual heat removal system,and studies the influence of boundary on the system,which has important reference significance for practical engineering application.