Modification of thermophysical model by friction theory and comparative analysis of regenerative cooling performance with hydrocarbon fuels

The prediction accuracy of thermophysical properties for hydrocarbon fuels plays a critical role in designing regenerative cooling structures. In this work, a novel thermophysical model based on PC-SAFT and modified friction theory for hydrocarbon fuels was developed, and then the influence of thermophysical properties on the convective heat transfer characteristics was investigated for RP-3. Firstly, to address the limitations of the applicable scope and potential constituent database for FT + PR model, a modified predictive FT + PR (mFT + PR) viscosity model and a subsequent pseudo-pure-based FT + PR (pFT + PR) model were proposed. The average prediction deviation of viscosity for seven hydrocarbon fuels dropped from 5.01 % to 2.58 %. Subsequently, the developed PC-SAFT EoS and pFT + PR model for RP-3, achieved prediction deviations of 3.66 % for density, 6.69 % for isobaric heat capacity, 2.95 % for viscosity, and 0.22 % for thermal conductivity, outperforming six literature surrogates. Furthermore, numerical studies for the convective heat transfer characteristics with different thermophysical models reveal that, Reynolds number deviations (15.1 %∼15.6 %) are strongly correlated with viscosity predictions, and a greater disparity is observed in wall temperature (21.1 K) compared to bulk temperature (7.4 K). Besides, owing to the endothermic nature of pyrolysis, the bulk and near-wall temperatures decrease substantially by 87.1∼92.0 K, and it reduces the maximum temperature differences for different models from around 29 K to 9.9 K for both bulk and near-wall regions. This study demonstrates that the accurate prediction of thermophysical properties, particularly the isobaric heat capacity and viscosity, is critical for reliable bulk and wall temperature predictions through numerical calculations.