Modeling the Thermal and Emissions Performance of Commercial Boilers

Abstract

The current models of boilers and furnaces which are used in HVAC system simulation programs are primarily concerned with calculating the heat output of the device and its fuel consumption. The formulation of the models relies heavily on empirical terms that are derived from manufacturers' data or testing programs. This paper describes a one-dimensional modeling approach that enables the emissions of NOx, CO, and SOx to be calculated together with the thermal performance of the boiler derived from basic heat transfer relationships. The model was developed for boilers with outputs in the range 100 kW to 3 MW. It provides good prediction of heat transfer performance and reproduces the values and trends of emissions throughout the operating range of the device. The use of the model in its intended mode is shown by its incorporation in a TRNSYS system simulation.