Abstract

Vapor compression systems have dominated the HVAC area for close to 100 years. These systems require significant amounts of energy to complete the compression cycle and the refrigerants used are known contributors to global warming. As a result, new innovations are being sought and a membrane-based system, the subject of this thesis, is one such technology. Water selective membrane materials offer a promising alternative to vapor compression for dehumidification of building air. For HVAC systems, process air pressure drop constrains flow path design in a membrane-based approach. The transport resistance for water vapor from air flow channels is experimentally investigated for a plate-type membrane mass exchanger design. Convective and diffusive resistances are measured for polymer membranes with varying flow channel dimensions. A series of experiments and analyses is developed to separate diffusive and convective transport resistance to water vapor removal from supply air. Results are compared with empirical Sherwood number correlations to enable improved mass exchanger design. The validated mass transfer correlations were used to develop a mass transfer model and later implemented for the simulation of a 3 rTon (1 rTon = 3.516kW) membrane heat pump dedicated outdoor air systems. From the various analyses, maintaining process air pressure drop at less than 50 Pa while at a typical HVAC face velocity results in a convective resistance that is 6 times greater than the diffusive resistance to water vapor through an ionic membrane. Furthermore, the tradeoff between required membrane area, system size, pressure-drop and effective latent cooling is explored. Simulation results show that when conforming mass exchanger designs to meet ASHRAE standards, a system electrical COP of 7.5 or greater can be achieved.

Library of Congress Subject Headings

Heat exchangers; Water vapor transport; Air conditioning; Membrane filters--Testing

Publication Date

4-20-2020

Document Type

Thesis

Student Type

Graduate

Degree Name

Mechanical Engineering (MS)

Department, Program, or Center

Mechanical Engineering (KGCOE)

Advisor

Ali Ogut

Advisor/Committee Member

Jason Kolodziej

Advisor/Committee Member

Robert Stevens

Campus

RIT – Main Campus

Plan Codes

MECE-MS

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