| 1. |
- Persson, Tomas, et al.
(författare)
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Modelling of dynamics and stratification effects in pellet boilers
- 2019
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Ingår i: Renewable energy. - : Elsevier. - 0960-1481 .- 1879-0682. ; 134, s. 769-782
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Tidskriftsartikel (refereegranskat)abstract
- Optimizing solar and pellet heating systems can be performed by system simulations in TRNSYS. However; this requires detailed boiler models that can properly model the thermal behaviour of the boilers, such as stratification and thermal response. This study uses a combination of existing models for modelling of the pellet burner part (TRNSYS Type 210) and the water volume (TRNSYS Type 340). This approach addresses the thermal dynamics and internal stratification more accurately than other available models. The objectives of this work are to develop a method for parameter identification for the model and to validate this method and the model itself. Sets of parameters are identified for two pellet boilers and one pellet stove with a water jacket (extended room heater) and the model is validated with a realistic dynamic operation sequence. The results show that modelling of stratification is essential in order to model the true behaviour of residential boilers. The test sequences used were adequate to parameterise the models and to provide the desired accuracy, except regarding the heat losses to room air. The model shows good accuracy for a stove and one boiler, but slightly worse performance for the other boiler regarding dynamics and modelling of the stratification.
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| 2. |
- Win, Kaung Myat, 1976-, et al.
(författare)
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Particles and gaseous emissions from realistic operation of residential wood pellet heating systems
- 2012
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310 .- 1873-2844. ; 59, s. 320-327
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Tidskriftsartikel (refereegranskat)abstract
- Gaseous and particulate emissions from six residential wood pellet heating systems are determined at a realistic six day operation sequence. The study aims to investigate the total emissions from a realistic operation of the heating systems including start-up and stop phases. Five combined solar and pellet heating systems and one reference boiler without solar system with an integrated DHW preparation was tested in a laboratory at realistic operation conditions. The investigated emissions comprised carbon monoxide (CO), nitrogen oxide (NO), total organic carbon (TOC) and particulate matter (PM2.5). In this study, the emissions are presented as accumulated total emissions from the whole six days period and the emissions from start-up and stop phases are also presented separately to evaluate the influence of the emissions from these phases on the total emissions. Emission factors of the measured systems from the six day period are between 192 and 547 mg MJ−1 for the CO emissions, between 61 and 95 mg MJ−1 for the NO, between 6 and 45 mg MJ−1 for the TOC, between 31 and 116 mg MJ−1 for the particulate matter and between 2.1 × 1013 and 4 × 1013 for the number of particles. The emissions from the start-up and stop phases are significantly high for the CO (63–95 %) and the TOC (48–93 %). NO and particles emissions are shown to dominate during stationary operation. However, 30–40 % of the particle emissions arise from the start and stop periods. It is also shown that the average emissions of CO, TOC and particles under the realistic annual conditions were higher than the limit values of two eco labels.
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