Analysis of energy transfer in direct-fired furnaces

Kirby Scott Chapman, Purdue University

Abstract

This document describes the development of a mathematical model to predict the physical phenomena that occur in the combustion space of a direct-fired natural gas furnace. The combustion gas model was separated into individual models which represent the momentum, species concentration, and energy conservation equations. Several supplemental equations were included to predict the turbulent kinetic energy, the turbulent dissipation rate, and the radiative heat flux in the combustion gases. In addition, models were incorporated to predict soot formation and oxidation, and nitric oxide concentrations. The individual components of the combustion space model were either validated with experimental data, or verified by comparing the numerical predictions to the results from analytical calculations. The complete thermal system model was used to examine the performance of a prototypical natural gas furnace. The first part of the study involved an assessment of the sensitivity of the system model predictions to the details of individual submodels including the turbulent combustion model, the radiation model, and the soot formation model. The second part of the study examined the effect of several furnace operating and design parameters on the furnace performance.

Degree

Ph.D.

Advisors

Viskanta, Purdue University.

Subject Area

Mechanical engineering

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