Abstract
A semi-physical model for the simulation of oil, gas and biomass space heating boilers has been parameterized based on measurements on nine different boiler units and simulation results have been compared to results obtained from measurements in steady state and transient operation. Although the agreement between simulated and measured boiler efficiencies was within the range of measurement uncertainties in most cases, model improvements are expected to be possible concerning the heat capacitance modelling in cycling on/off operation as well as influences of start and stop behaviour on the overall efficiency. It is found that electricity consumption during cycling on/off operation of small pellets or oil space heating boilers may have a significant influence on the overall energy balance of these units. This influence increases strongly with decreasing heat load and increasing number of on/off cycles.
Acknowledgements
The work presented was financed by projects supported by the European Union 6th research framework programme, Marie-Curie early stage research training network, Advanced solar heating and cooling for buildings – SOLNET, as well as the Swiss Federal Office of Energy SFOE and the Austrian Climate and Energy Fund as part of the ‘Energy of Tomorrow’ programme in the project ‘PellSol Plus’.
Notes
1. This percentage is calculated as the ratio of the square of the product of the partial derivative and uncertainty of each measured variable to the square of the uncertainty in the calculated variable.
2. The value of 0.6 kJ/kg K is close to the specific heat of materials commonly used for the construction of heat exchangers and combustion chambers of boilers, e.g. cast iron (0.5), steel (0.5), aluminum (0.9) or fireclay (0.8).