In situ membrane-based oxygen enrichment for direct energy conversion methods

Abstract

A method for combusting a diesel or JP-8 fuel at high temperatures enabling efficiency and power density improvements for portable direct energy conversion systems such as thermophotovoltaics and thermionics is provided. Oxygen enriched air is processed in situ using membrane separation methods. A blower or pump downstream from the membrane provides oxygen enriched air to a fuel burner where high temperature oxidation of a diesel or JP-8 fuel is then enabled in a burner assembly. The hot combustion gases in the burner heat an emitter specifically designed for a thermophotovoltaic or thermionic device. A second blower or pump provides nitrogen enriched air for auxiliary cooling purposes.

Description

GOVERNMENT INTEREST [0001] The invention described herein may be manufactured, used, sold, imported, and / or licensed by or for the Government of the United States of America.FIELD OF INTEREST [0002] The invention relates to oxygen enriched combustion of diesel and JP-8 fuels. In particular, the oxygen enrichment of the fuel raises combustion temperatures beyond that which is possible with ambient air, thereby enabling various improvements and design flexibility for soldier-portable direct energy conversion devices such as Thermionic and Thermophotovoltaic power systems. BACKGROUND OF THE INVENTION [0003] The U.S. Army has invested considerable research in the area of direct energy conversion. The appeal of these technologies is that they are characterized by solid-state designs and they utilize burner systems that can be readily adapted to logistics fuels, diesel or JP-8. Further, these technologies offer lower noise and vibration than conventional reciprocating internal combustion ...

AI Technical Summary

Benefits of technology

[0011] Accordingly, one object of the present invention is to provide an improved fuel-to-electric efficiency by increasing combustion efficiency. Combustion efficiency generally increases with higher combustion temperatures (see U.S. Pat. No. 4,931,013). Oxygen enrichment provides the means to directly achieve higher flame and exhaust gas temperatures (FIG. 2). In addition, power density can be increased through oxygen enriched combustion. Oxygen enrichment reduces the overall mass flow necessary for oxidation of a given mass flow of fuel (reduction in nitrogen), thereby enabling burner volume reductions. Alternatively, for a given burner volume and total mass flow, oxygen enrichment allows increased fuel flow, leading to a higher Heat of Combustion and higher power density. See the description of FIGS. 3-5 for detailed analysis.

Problems solved by technology

These temperatures are sometimes difficult to attain without oxygen enrichment, with or without a recuperator, due to losses from heat transfer and incomplete combustion.

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