摘 要：为提高吸热型碳氢燃料高温高压条件下比热容的测量精度，基于能量守恒的量热计理论，设计一套适用于高温高压的碳氢燃料定压比热在线测量系统。系统温度测量范围为450~900 K，测量压力可达10 MPa。选取环己烷和质量比1∶1正己烷-正庚烷二元混合物对测量系统进行标定，实验结果与文献的相对误差在±1%以内，相对误差绝对平均值小于0.32%。在此基础上对两种不同成分的吸热型碳氢燃料的定压比热进行了测量，温度为450~900 K，压力为2.0~5.0 MPa。实验结果表明：在低温区域范围内，碳氢燃料的比定压热容随温度的升高呈现近线性增长；在拟临界、临界温度时达到一个峰值，且峰值随压力的增加逐渐减小，且所对应温度点不断后移；大比热区后，燃料的比热容值随温度的升高急速增大。该测量系统的应用可为进一步提高碳氢燃料比热的测量温度范围创造条件。

Abstract:In order to improve the measurement accuracy of specific heat capacity under the condition of high temperature and high pressure of the heatabsorbing hydrocarbon fuel,this paper proposed an on-line measurement system for the isobaric specific heat capacity,based on the energy conservation theory of calorimeter.The system temperature measurement range is 450-900 K,and the measurement pressure can be up to 10 MPa. The calibration system was calibrated with cyclohexane and a binary mixture of n-hexane and n-heptane with mass ratio of 1∶1. The relative error between the experimental results and the literature was within ±1%,and the absolute average relative error was less than 0.32%. With this system calibrated,the isobaric specific heat of two endothermic hydrocarbon fuels with different compositions was measured at a temperature of 450-900 K and a pressure of 2.0-5.0 MPa. The experimental results showed that in the low-temperature range,the constant-pressure heat capacity of hydrocarbon fuel exhibits a nearly linear increase with temperature,reaching a peak at the pseudo-critical and critical temperature. The peak gradually decreases with the increase of pressure,and the corresponding temperature point is continuously moved backward. After the large specific heat zone,the specific heat capacity of the fuel increases rapidly with the increase of temperature. 

TK311

青年科学基金（21306147）；国家博士后科学基金（2013M532044）