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Condensing Heat Exchanger for Optimization of Energy Efficiency
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Historically, boiler efficiency has been limited due to the minimum temperature allowed at the stack. Heat lost up the stack was in exchange for keeping the flue gas temperature above the water vapor dew point. If water vapor was allowed to condense out, rapid deterioration, due to acid corrosion, of the outlet duct and stack would result. With the development of the condensing heat exchanger, boiler efficiency can now exceed 90%. Approximately 1% gain in boiler efficiency can be expected for every 40F (4.5C) reduction in flue gas stack temperature. In the CHX® condensing heat exchanger, all gas wetted surfaces are covered with DuPont Teflon®. The Teflon covered heat exchanger surfaces are impervious to all acids normally resulting from the combustion of fossil fuels. This allows the flue gas to be cooled to below the water vapor dew point with no subsequent corrosion of the heat exchanger surfaces.
Carrigan, J. F.; Johnson, D. W.; DiVitto, J. G.; Schulze, K. H. (1995). Condensing Heat Exchanger for Optimization of Energy Efficiency. Energy Systems Laboratory (http://esl.tamu.edu). Available electronically from