A fluid temperature interpolation method for wide temperature range distributed flow calorimeter

The distributed flow calorimeter is employed to measure reaction enthalpy, mixing enthalpy, and other thermodynamic parameters of hydrocarbon fuels. This information serves as a foundation for selecting and developing hydrocarbon fuels for hypersonic flight. The fluid temperature in the tube is a key factor in characterizing its thermodynamic behavior. Given the challenges of monitoring fluid temperature within a tube using current flow calorimetry, a distributed method for calculating fluid temperature in tubes under high-temperature conditions is proposed. This method realizes the interpolation of the enthalpy function of the experimental fluid through several sets of experiments with varying power levels. The fluid temperature in the tube is calculated by considering the microelement as the research object. First, the methodology for calculating fluid temperature in narrow pipes across a wide temperature range is presented. Second, the simulation model of the flow calorimeter is established, and the methodology is verified through numerical simulation. Finally, a flow calorimetric experimental device is setup. N-decane was used as the fluid in the experiment, and the temperature was calculated, and the calculated results were compared with the NIST data. In the temperature range of 295.50-609.38 K, the relative error range of the calculation of n-decane temperature is -0.61% to 1.24%. The experimental results show that the method can effectively estimate the fluid temperature of the distributed flow calorimeter.