Date on Master's Thesis/Doctoral Dissertation
Mechanical Engineering, MS
Committee Co-Chair (if applicable)
pressure drop; low flow; U-bend; evaporation; refrigerator; orientation
This study was conducted to evaluate three currently popular two-phase pressure drop models for extremely low velocity refrigerant flow through smooth circular evaporators in household refrigeration systems. Experimental data was taken at mass fluxes under 70 kg/m2s for two refrigerants, R134A and R600A, internal diameters of aluminum evaporators ranging from 0.186 to 0.317 inches, U-bend internal radii ranging from 0.342 to 0.750 inches in horizontal and vertical orientations of evaporators. The geometry of the samples closely resembled a commonly used serpentine shape with multiple U-bends experiencing both, up- and down-flow of the refrigerant. Two empirical models, Müller-Steinhagen & Heck (1986) and Grönnerud (1979), as well as one phenomenological model, Silva Lima & Thome (2012), were compared to experimental data and all performed very well for horizontally oriented samples. However, in vertical orientation only 60.6 %, 63.3 % and 75.8 % data fell within ± 30 % accuracy band for Grönnerud, Silva Lima & Thome and Müller-Steinhagen & Heck correlations, respectively. The predicted values showed what steps could be taken to improve the performance of all models, which could be accomplished with future work.
Fenko, Anna, "Evaluation of two-phase evaporation pressure drop correlations for low refrigerant mass flux." (2015). Electronic Theses and Dissertations. Paper 2292.