Waste Heat Recovery Heat Exchanger for Supplemental Heaters

Grant # 00-02
Principal Investigator: Theodore F. Smith
Student: Emad Y. Tanbour
Organization: The University of Iowa and
HON Industries
Technical Area: Energy Efficiency

Background
The problem addressed by the project is to develop technology to assist in the design of a waste-heat-recovery heat exchanger that provides efficient recovery of waste heat from the exhaust gases of a natural gas-fired supplemental heating unit (fire place, stove), is cost effective, and meets all appropriate safety regulations and codes. Realizing that numerous supplemental heating units are being installed to provide a pleasant environment in residential and commercial structures, the significance of the problem is to make these supplemental units as energy efficient as possible without sacrificing the intent for which they are installed.

HON Industries has installed a test waste-heat-recovery heat exchanger in the exhaust duct of a natural gas-fired supplemental heating unit. Preliminary tests indicate that the heat exchanger lowered the exhaust gas temperature from about 800 to 190°F and increased the temperature of the room air passing through the heat exchanger by about 50°F. The heat exchanger worked for the considered design. However, further testing is required and the heat exchanger design must be optimized for maximum performance.

Project Objective
The objective of the project is to provide engineering analyses for development of a waste-heat-recovery heat exchanger for a natural gas-fired supplemental heating unit. The project involves a partnership between The University of Iowa (UI), HON Industries (HI), and the Iowa Energy Center . The partnership allows the development of technology that will aide in the design of products to recover waste heat from supplemental heating units. Investigators from UI and HI collaborated on the engineering aspects of the project by performing tests on, developing a simulation model for, and designing the waste-heat-recovery heat exchanger. For convenience, four tasks for the project have been defined, namely, model development, design considerations, testing, and economics.