A unified model for the simulation of oil, gas and biomass space heating boilers for energy estimating purposes. Part II: Parameterization and comparison with measurements

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.

Experimental validation of a thermodynamic boiler model under steady state and dynamic conditions

“…In this study the pellet boilers have been simulated by means of the TRNSYS Type 869 boiler model, which is described in detail in [14,30]. The model calculates the mass and energy balance of the boiler under time variable inputs, thus describing the boiler operation in dynamic conditions.…”

“…30% of the nominal load) but no dynamic tests have been standardised yet. Dynamic tests in cycling operation have been performed on various types of boilers and stoves, in order to characterise the start-up and stop sequences as well as the burner's cycling operation [12][13][14][15]. In a recent work of Glembin et al [16], gas and oil boilers were tested under cycling operation and load transitions.…”

Impact of Reference Years on the Outcome of Multi-Objective Optimization for Building Energy Refurbishment

“…Windows have been modeled with LBNL Window 6.3 [60] and the linear thermal transmittances of thermal bridges calculated with LBNL THERM 6.3 [61]. TRNSYS "Type 56" has been used for multizone building modeling and "Type 869" [62,63] for the heating systems, together with "Type 2" for the ON-OFF control, "Type 3" for the calculation of the pump power consumption and "Type 31" for the estimation of distribution heat losses of pipes. As regards the climatic solicitations, Reindl et al [64] and Perez et al [65] models have been implemented for the calculation of the solar irradiation on the external surfaces, the fictive sky vault temperature estimated with "Type 69" and the other weather variables read directly from the reference year input.…”

Modelling of dynamics and stratification effects in pellet boilers

“…Petzold et al [26] performs parameter identification for a modified version of the Type 210 where a temperature correction factor was implemented to compensate for the deviation between average and outlet boiler water temperature. Problems to model boiler cycling are also mentioned by Haller et al [27] using the TRNSYS boiler model Type 869 [28], where comparisons between measured and simulated boiler cycling shows an overestimation of number of burner starts by about 25 % for the model. Carlon et al [29] attempted to validate the Type 869 boiler model and showed that the deviation of energy transferred to the water circuit is up to 10 % for steady operation and up to 30 % for the model during a dynamic load cycle.…”

“…However realistic operation sequences with standby periods increase the fraction of heat losses to room air and chimney and the heat losses can be determined with a higher relative accuracy. Comparisons of the validity and accuracy of this model with stratification versus other available TRNSYS pellet boiler models [24,27,29] are not possible since the validation procedures differ. Being able to use the model for system simulations also requires a model of the burner controller that calculates the fuel and combustion air consumption.…”