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DEPAF: A Computer Model for Design and Performance Analysis of Furnaces



J. Chi


The report covers the development of a computer simulation program DEPAF (Design and Performance Analysis of Furnaces) for residential fossil-fuel-fired furnaces. DEPAF is based upon an analytical model which accounts for cyclic (on-and-off) operation of furnace burner and blower. Transmission of heat at on-cycle uses the theory of radiative and convective heat transfer; transmission of heat at Off-cycle uses the theories of turbulent and free convective heat transfer. Confidence in DEPAF was established by the use of available experimental data on a gas-fired forced-war-air furnace. While the theory of transient heat transfer in combustion is complex in nature, theoretical results based upon quasi-steady-state analysis are in excellent agreement with experiments. If the building heat loss is known, DEPAF can be used to calculate the annual performance and operating cost residential heating systems with furnaces. Examples are given to illustrate applications of DEPAF to examine quantitatively the effect of design and operating variables on annual performance and operating costs of residential forced-warm-air furnaces. It was found that considerable savings in fuel and operating costs can often be achieved by performing certain modifications to existing furnaces.
Proceedings Title
American Society of Mechanical Engineers
Conference Dates
August 15-17, 1977
Conference Location
Salt Lake City, UT
Conference Title
Heat Transfer Conference


furnaces, computer models, transmission, computer simulation, heat transfer, combustion, experiments, heat loss, costs, heating, design applications, equations


Chi, J. (1977), DEPAF: A Computer Model for Design and Performance Analysis of Furnaces, American Society of Mechanical Engineers, Salt Lake City, UT, [online], (Accessed April 20, 2024)
Created August 15, 1977, Updated February 19, 2017