MS Thesis Defense by J. R. Aspinwall
Monday, April 26, 2004

( Dr. Said Abdel-Khalik, Co-Chair, Dr. Sheldon Jeter, Co-Chair)

"Design of an Improved Moisture Separator in a Turbocharger System for Fuel Cells"

Abstract

Moisture recovery is important in the operation of fuel cell systems, especially polymer electrolyte membrane (PEM) fuel cells. Water is needed to hydrate the membrane and to reform hydrocarbon fuels to generate hydrogen. An improved moisture separator could improve the overall performance of PEM fuel cell systems by recovering moisture from the humid exhaust stream to supply these needs.

An axial flow centrifugal separator design was chosen as the best candidate due to its high efficiency and low pressure drop and a prototype was designed and constructed. The improved separator was built to allow variable settling lengths to be investigated.

A well-instrumented test system that generates fuel cell exhaust conditions was available to simulate energy and moisture recovery using an automotive turbocharger. The test system included a conventional centrifugal separator for liquid water recovery from the turbocharger exhaust. This device had only marginal performance. The test system has been upgraded to include an axial flow separator that incorporates a streamlined swirl generator to minimize pressure drop. Experimental trials have been conducted to document moisture recovery from the simulated humid exhaust stream of a 25 kW fuel cell with the improved separator.

Results are presented for varying turbine inlet conditions at three separate separation lengths. The improved separator design was shown to have a moisture separation efficiency of 90% while the conventional separator only had 65% efficiency. The pressure drop across the improved design was found to be only 35% of that across the conventional separator.