大型低温环境室竖向气压变化特点分析

Analysis on characteristics of vertical air pressure variation in large-scale cryogenic environmental chamber

为了找出大型低温环境室室内正压设计方法存在的问题,对低温环境室在不同室温下的竖向气压变化特点进行分析,提出室内竖向气压分布的计算方法,该算法的准确性得到了实测数据的验证,其平均相对误差为5.9%。分析结果表明:大型深冷低温环境室的竖向气压变化很大,且在降温过程中室内正压不断增大。对于高度为20 m、室温为-165℃的大型深冷低温环境室,其下部正压值可超过421 Pa,远高于低温环境室室内正压以往的设计值(5—10 Pa)和安全防护值(200 Pa),因此应大幅度提高其室内正压的设计值和安全防护值。为确保室内全部空间维持正压,低温环境室的室内正压控制点应设置在顶部。

In order to find out the problems existing in the positive pressure design method of large-scale cryogenic environmental chambers,the characteristics of vertical air pressure change in cryogenic environmental chambers at different indoor air temperatures were analyzed and a calculation method for vertical air pressure distribution in the chambers was proposed.The accuracy of the algorithm has been verified by measured data,and its average relative error is 5.9%.The analysis results show that the indoor air pressure of large-scale cryogenic environmental chamber changes greatly in the vertical,and the pressure difference between the indoor and outdoor increases continuously during the cooling process.The air pressure difference between indoor and outdoor may exceed 421 Pa in the lower part of a chamber with height of 20 m and air temperature of-165℃,which is much larger than the previous design value(5-10 Pa)and safety protection value(200 Pa).Therefore,the design value and safety protection value of the indoor positive pressure should be greatly increased.In order to ensure the pressure in the chamber maintain positive,the indoor positive pressure control point should be set at the top of cryogenic environmental chamber.