Dynamic model of a hot water boiler

Most of the dynamic models of hot water boilers are either "reference" models or too simplified ones. The formers require sophisticated computation facilities (they are CPU - time consumers) and very detailed data on boiler geometry which are usually not available. The latters are generally identified models based on experimental tests, thus their range of validity is limited to the domain covered by the experimental data. This paper presents a simplified second order dynamic model which uses available manufacturer data. The model's parameters are adjusted using physical assumptions which take into account real influences as water and flue gas circulation through the boiler. All the parameters defined are physically meaningful. A special attention is payed to the fast transient short periods (start-up and cut-down) due to their importance for pollutants emission (especially CO). The scope is to provide a flexible model according to the manufacturer data available : the boiler thermal efficiency or the pollutants emission can be predicted. The results of the model thus built compare well with data obtained on a fuel-oil boiler whose useful power goes up to about 400 kW.