Simulation of a recuperative heat exchanger integrated in a thermal incinerator with the Epsilon-NTU model

Abstract

Thermal recuperative incinerators are devices commonly used in the industry to control the emissions of organic compounds from the exhaust air of certain industrial process. This is achieved by using these compounds as a comburent in the incinerator and thus both controlling emissions and generating process heat. Thermal recuperative incinerators are designed to efficiently recuperate waste heat from the hot outbound combustion products and preheat the inbound process air. They are usually large and geometrically complex equipment, so modeling an entire thermal recuperative incinerator in detail is difficult. Along with the simulation of the combustion process, another of the challenging aspects is the detailed simulation of the combustion products-to-process gas heat exchanger that encloses the combustion chamber and that promotes heat recovery and thermal insulation of the chamber. One strategy to deal with this challenge is to decouple the simulation of the combustion products-to-process air heat exchanger from the simulation of the combustion chamber. By doing so, the amount of heat transfer from the combustion products to the inbound process air can be determined and imposed as a boundary condition for the simulation of the combustion chamber. This work presents a simple mathematical model for describing the combustion products-to-process air heat exchanger integrated in a TRI used in a paint shop of an automotive assembly plant. The model relies on the well-established effectiveness method for modeling heat exchangers, the ε-NTU method. The results obtained in this work are validated using experimental data obtained in an industrial environment