New generalized flow boiling heat transfer and frictional pressure drop correlations for R32
Abstract The objective of this study is to establish generalized correlations for R32 flow boiling heat transfer and frictional pressure drop in horizontal channels with wide ranges of geometric and flow parameters. In the paper, two consolidated databases for heat transfer and frictional pressure drop were amassed from open literatures, which involved R32 as working fluid. The heat transfer database consisted of 1509 data points from 10 sources, with hydraulic diameters of 1−6.3mm, while the pressure drop database included 496 data points from 8 sources, which covered hydraulic diameters of 0.643−6mm. New heat transfer coefficient correlation and frictional pressure drop correlation were developed based on prediction technique of dimensionless parameter analysis considering the governing force effect. Moreover, five existing flow boiling heat transfer empirical correlations and four existing frictional pressure drop correlations were also introduced to perform assessment. The validation results showed that all of the selected heat transfer correlations had poor results of mean absolute errors (MAE) and significantly high maximum absolute errors (MAX). The new heat transfer coefficient correlation provided superior prediction accuracy with MAE of 14.59% and 90.85% of data within ±30% error bands. In addition, the new pressure drop correlation exhibited the best performance, which yielded MAE of 17.86%. The two new correlations had broad application range and satisfactory prediction accuracy, which were applicable to analyze the heat transfer and pressure drop performance of heat exchangers with refrigerant R32.