Sunil S. Mehendale

Bio: Sunil S. Mehendale is an academic researcher from Michigan Technological University. The author has contributed to research in topics: Micro heat exchanger & Heat exchanger. The author has an hindex of 13, co-authored 38 publications receiving 727 citations. Previous affiliations of Sunil S. Mehendale include University of Illinois at Urbana–Champaign & Delphi Automotive.

Vapor-liquid equilibrium for R-32 and R-410A mixed with a polyol ester: non-ideality and local composition modeling

Abstract: Vapor-liquid equilibrium (VLE) data were obtained over a wide range of mixture compositions and saturation conditions for difluoromethane (R-32) mixed with a polyol ester oil (POE). These data were correlated using the following local-composition models from the literature: Wilson, Heil, Wang and Chao, Tsuboka and Katayama, NRTL and UNIQUAC. The results were used to evaluate the suitability of these models in predicting the saturation behavior of the R-32/POE mixture. The Heil model had the best performance, with a 2− σ error of 4.81% in the predicted saturation pressure. UNIQUAC was the worst, with a 2− σ error of more than 12%. Using VLE results from the literature for pentaflouroethane (R-125) mixed with the same oil and model parameters for that mixture, an effort was made to make a priori predictions of the p-T-x behavior of a blend containing 50% R-32+50% R-125 (R-410A) and the POE. Data were obtained for this blend, and the results indicate that the Heil model can make such predictions with a 2− σ error of about 11% in pressure.

Flat tube evaporator with enhanced refrigerant flow passages

Abstract: A heat exchanger for a heating, ventilating and air conditioning system comprises a plurality of heat exchange tubes extending between a pair of spaced header tanks and arranged in groups of tubes with varying number of tubes in each group to cause a refrigerant to flow in multiple passes in the interior of the tubes across another fluid flowing on the exterior of the tubes. The heat exchange tubes comprise a plurality of flow passages having at least one corner formed by a pair of straight or arcuate sides with an included angle of less than or equal to ninety degrees, more preferably less than or equal to thirty degrees, to promote intense pool boiling within the flow passages. In addition to at least one corner region, the flow passage has a passage-specific optimal hydraulic diameter determined by the relationship between the optimal hydraulic diameter of the passage and the optimal hydraulic diameter of a baseline circular passage.

Fundamental issues related to flow boiling in minichannels and microchannels

Abstract: Flow boiling in small hydraulic diameter channels is becoming increasingly important in many diverse applications. The previous studies addressing the effects of the channel size on the flow patterns, and heat transfer and pressure drop performance are reviewed in the present paper. The fundamental questions related to the presence of nucleate boiling and characteristics of flow boiling in microchannels and minichannels in comparison to that in the conventional channel sizes (3 mm and above) are addressed. Also, the effect of heat exchanger configuration—single-channel and multichannel—on the heat transfer and pressure drop performance is reviewed. The areas for future research are identified.

Evolution of Microchannel Flow Passages-Thermohydraulic Performance and Fabrication Technology

Abstract: This paper provides a roadmap of development in the thermal and fabrication aspects of microchannels as applied in microelectronics and other high heat-flux cooling applications. Microchannels are defined as flow passages that have hydraulic diameters in the range of 10 to 200 micrometers. The impetus for microchannel research was provided by the pioneering work of Tuckerman and Pease [1] at Stanford University in the early eighties. Since that time, this technology has received considerable attention in microelectronics and other major application areas, such as fuel cell systems and advanced heat sink designs. After reviewing the advancement in heat transfer technology from a historical perspective, the advantages of using microchannels in high heat flux cooling applications is discussed, and research done on various aspects of microchannel heat exchanger performance is reviewed. Single-phase performance for liquids is still expected to be describable by conventional equations; however, the gas flow may...