Experimental Investigation of Two-Phase Refrigerant Distribution in a Microchannel Manifold

Abstract

The affects of microchannel protrusion, mass flux, quality and inlet distance on the distribution of two phase refrigerant R-134a was studied through a series of experiments conducted in two different horizontally oriented microchannel manifolds. One manifold was constructed in such a manner that the cross sectional area was rectangular in nature, with dimensions of 12.7 x 18.5 mm. The second manifold was constructed using a transparent PVC tube in order to achieve a circular cross-section; the inner diameter of this manifold was 20.4 mm. Both manifolds fed a linear array of 15 microchannels with hydraulic diameter of 1.54 mm. In the rectangular manifold, three different uniform microchannel protrusion schemes were studied; the microchannels protruded one-quarter, one-half, and three-quarters of the flow field depth. While in the circular manifold the same three uniform schemes were studied, two staggered schemes were studied as well. In each manifold the expansion device was put at two different lengths from the microchannel array. In the case of the rectangular manifold, these lengths were 50 mm and 250 mm, and in the case of the circular manifold 89 mm and 267 mm. Flow parameters were also varied in this study. The inlet quality of the refrigerant was varied from 0-0.35, and the mass flow rate from 15-35g/s. Liquid refrigerant distribution was measured through the use of a series of a collection tanks, in which a time averaged mass flow rate could be obtained.Air Conditioning and Refrigeration Project 15