Heat transfer and pressure drop characterization of a tubular evaporator using manifold on the microgrooved surfaces

Abstract

Miniaturization of heat and mass exchanger is needed for increasing COP and energy efficiency. For small scale systems where ample of waste heat is available, huge initial cost for absorption chillers becomes a deterrent. The paper talks about development of a tubular evaporator based on manifold microchannel systems and the results associated with microgroove surface made of aluminum. Manifold guided flow has been utilized on micro-grooved structure of high aspect ratio channels. Aluminum surface channel width is 60 microns and channel height is close to 600 microns. Two different components -one based on force fed and other plain tube insert has been tested on water side for getting enhanced water side heat transfer coefficients. The results would be discussed for wide variation for refrigerant side and water side mass flow rates. Very high overall heat transfer coefficient more than 20,000 W/m2-k has been achieved using plain tube insert on water side of the evaporator with a modest pressure drop close to 100 mbars. Cooling capacity more than 4KW has been achieved too.