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为了准确测量高温高压条件下燃油的定压比热,基于定压比热与焓值的关系,提出一种适用于测量高温高压流体定压比热的方法并设计相应的实验装置,该方法可以显著地减小热损失测量误差对测量结果的影响,提高比热测量精度。经过误差分析,在常温至800K范围内,该方法具有最大3.7%的相对不确定度。利用该方法对正癸烷的定压比热(3MPa和5MPa,312~797K)进行了标定实验,实验结果表明,定压比热测量的平均偏差小于1.8%,拟临界点附近最大偏差7.6%,其它温度范围最大偏差不超过4.3%。对3MPa和5MPa下675~797K的正癸烷定压比热数据进行了补充。该方法同样适用于其它流体在该温度范围内的定压比热测量。
In order to accurately measure the specific heat of constant pressure of fuel under high temperature and high pressure, a method suitable for measuring the specific heat of constant pressure of high temperature and high pressure fluid is proposed based on the relationship between the specific heat at constant pressure and the enthalpy, and the corresponding experimental device is designed. Significantly reduce the heat loss measurement error on the measurement results, improve the measurement accuracy of specific heat. After error analysis, the method has a relative uncertainty of 3.7% maximum at room temperature to 800K. The calibration experiment of n-decane with constant pressure specific heat (3MPa and 5MPa, 312 ~ 797K) was carried out by this method. The experimental results show that the average deviation of constant pressure specific heat measurement is less than 1.8% and the maximum deviation near quasi-critical point is 7.6% , Other temperature range does not exceed the maximum deviation of 4.3%. The pressure-specific heat data of 675-797K n-decane at 3MPa and 5MPa were supplemented. This method is equally applicable to constant pressure specific heat measurements of other fluids within this temperature range.