Experimental Characterization of Heat Transfer and Pressure Drop Inside a Tubular Evaporator Utilizing Advanced Microgrooved Surfaces

Performance enhancement of heat exchangers with a focus in optimum weight/volume and the amount of working fluid in circulation is of significance to a diverse range of industries. This paper presents heat transfer and pressure drop characteristics of a compact tubular evaporator which utilizes a manifold force-fed microchannel design. A microgrooved structure with an aspect ratio of 3:1 (channel width of 100 μm and channel height of 300 μm) forms the channels used on the refrigerant side and minichannels of 1 mm depth were used on the water side. The system was tested using R134a as the refrigerant with a refrigerant flow rate of 6 to 22 g/s and water flow rate of 150 to 640 ml/s. Overall heat transfer coefficients of more than 10,000 W/m² K were obtained with modest values of pressure drop. The present results indicate a significant enhancement in thermal performance when compared to the state-of-the-art technologies in the same application area.