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详细讨论了微型金属杜瓦瓶热负载的测量原理和方法,提出了一种新的流量法测量微型金属杜瓦瓶热负载的数据处理方法。流量法通过流量计检测单位时间内的液氮蒸发量,利用相变在相同温度和压力下两相间的比焓差计算热负载,标准工况和测量工况下的计算因子分别为4.151和5.212。这种新方法通过检测微型金属杜瓦瓶内管冷端最低温度下的质量流量或者此时刻前1 min内汽化液氮的质量来计算热负载,可以统一称量法和流量法测量热负载的检测时刻和测量区间,有利于减少称量法中结霜的影响。
The principle and method of measuring the thermal load of the micrometallic dewar are discussed in detail. A new data processing method for measuring the thermal load of the micrometal dewar is proposed. The flow method measures the evaporation of liquid nitrogen per unit time through the flowmeter and calculates the thermal load by the specific enthalpy difference between the two phases under the same temperature and pressure using the phase change. The calculation factors under standard conditions and measurement conditions are 4.151 and 5.212 . The new method calculates the thermal load by detecting the mass flow rate at the lowest temperature of the cold end of the tube in the metal Dura or the mass of vaporized liquid nitrogen in the first 1 min at this point in time. Detection time and measurement interval, help to reduce the impact of frosting weighing method.