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ACRC Contract Report 44PDF


Title:Exploratory Research on MEMS Technology for Air Conditioning and Heat Pumps
Author(s):Leicht, T.M.; Hrnjak, P.S.; Shannon, Mark A.
liquid mass fraction
plate evaporators
Abstract:This report presents an experimental investigation of refrigerant liquid mass fraction (LMF) in the exit flows of plate evaporators. The objective is to identify a sensor that is capable of measuring small amounts of refrigerant liquid in the superheated vapor at evaporator exits. This sensor should have the potential to be combined with an active control scheme that increases the fill factor of the evaporator while simultaneously reducing superheat temperature at the evaporator exit. Four methods were used to detect refrigerant droplets in the superheated vapor stream exiting a plate evaporator: (1) an energy balance calculation, (2) a microfabricated thin-film resistance sensor developed specifically for this project, (3) an exposed beaded thermocouple, and (4) photodiodes that detected laser light scattered by droplets. The design, fabrication, calibration procedures, and theory of operation of the MEMS thin-film resistance sensor are also presented in this report. Experimental results indicate that a MEMS thin-film resistance sensor is more sensitive than a beaded thermocouple to LMF of non-equilibrium evaporator exit flows. The MEMS sensor accurately detected refrigerant LMF as low as 1.5% in superheated evaporator exit flows.
Issue Date:2002-01
Publisher:Air Conditioning and Refrigeration Center. College of Engineering. University of Illinois at Urbana-Champaign.
Series/Report:Air Conditioning and Refrigeration Center CR-44
Genre:Technical Report
Date Available in IDEALS:2009-08-06

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