螺旋管内超临界甲烷换热关联式的分析与拟合

Analysis and Fitting of Correlation Equations for Supercritical Methane Heat Transfer in Spiral Tubes

对超临界工质在螺旋管内流动换热关联式进行研究,基于实验数据和模拟数据,通过对比Nu计算值和Nu模拟值,对现有关联式进行分析。对未考虑工质物性关联式、考虑工质物性但未修正比定压热容关联式、考虑工质物性并修正比定压热容关联式、考虑曲率和工质物性但未修正比定压热容关联式共4种Nu准则关联式进行拟合。现有Nu准则关联式中,未考虑工质物性的关联式的预测效果较好,而考虑工质物性的关联式的预测结果明显偏大。未考虑工质物性的关联式中,通过对比拟合数据以及验证数据的Nu计算值与Nu模拟值,发现拟合后的未考虑工质物性的关联式与现有Nu准则关联式相比,具有更好的预测效果。考虑工质物性但未修正比定压热容关联式中,拟合后的考虑工质物性但未修正比定压热容关联式与现有Nu准则关联式、拟合后的未考虑工质物性的关联式相比,均具有更好的预测效果。考虑工质物性并修正比定压热容关联式中,拟合后的考虑工质物性并修正比定压热容关联式与现有Nu准则关联式对比具有更好的预测效果,但与拟合后的考虑工质物性但未修正比定压热容关联式相比,没有展现出更好的预测效果。拟合后的考虑曲率和工质物性但未修正比定压热容关联式,与其他3种拟合后的Nu准则关联式相比预测效果最好,更适用于螺旋管内超临界甲烷流动换热研究。

A study was conducted on the heat transfer correlation equation of supercritical working fluid flow in a spiral tube.Based on experimental and simulation data,the existing correlation equations were analyzed by comparing the calculated and simulated values of Nu.Four Nu criterion correlation equations were fitted,including the correlation equation that does not consider the physical properties of the working fluid,the correlation equation that does consider the physical properties of the working fluid but does not correct the specific pressure heat capacity,the correlation equation that considers the physical properties of the working fluid and corrects the specific pressure heat capacity,and the correlation equation that considers the curvature and the physical properties of the working fluid but does not correct the specific pressure heat capacity.Among the existing Nu criterion correlation equations,the correlation equation that does not consider the physical properties of the working fluid has better predictive results,while the correlation equations those consider the physical properties of the working fluid have significantly higher predictive results.In the correlation equation that does not consider the physical properties of the working fluid,by comparing the fitted data and verifying the calculated Nu values with the simulated Nu values,it is found that the fitted correlation equation that does not consider the physical properties of the working fluid has better predictive performance compared to the existing Nu criterion correlation equation.The fitted correlation equation that considers the physical properties of the working fluid but does not correct the specific pressure heat capacity has better predictive performance compared to the existing Nu criterion correlation equations and the fitted correlation equation that does not consider the physical properties of the working fluid.The fitted correlation equation that considers the physical properties of the working fluid and corrects the specific pressure heat capacity has better predictive performance compared to the existing Nu criterion correlation equations.However,compared with the fitted correlation equation that considers the physical properties of the working fluid but does not correct the specific pressure heat capacity,it does not show better predictive performance.Compared to the other three fitted Nu criterion correlation equations,the fitted Nu criterion correlation equation that considers the curvature and the physical properties of the working fluid but does not correct the specific pressure heat capacity has the best predictive performance and is more suitable for the study of supercritical methane flow and heat transfer in spiral tubes.