Walter Haslinger

Small-Scale Pellet Boiler with Thermoelectric Generator

Pellet boilers need auxiliary electrical power to provide CO2 -balanced heat in a comfortable and environment-friendly way. The idea is to produce this and some extra electricity within the furnace in order to save resources and to gain operation reliability and independency. Thermoelectric generators (TEGs) allow direct conversion of heat to electrical power. They have the advantage of a long maintenance-free durability and noiseless operation without moving parts or any working fluid. The useful heat remains almost the same and still can be used for heating. The challenge is the system integration and optimisation of TEGs in pellet burners. The consumption of electricity by the complete heating system is analysed and optimised in order to fulfil the purpose of independency. Grid independent operation is difficult to realise and optimise. In order to be successful it needs a simplified system. We do experiments with different arrangements of burners, heat exchangers and TEGs. We identified the important parameters to maximise the electricity produced. The potential of this technology strongly correlates with the efficiency and costs of thermoelectric materials. Optimised integration will result in additional benefits and saved resources. A novel kind of decentralised small-scale and micro-scale biomass-based combined heat and power generation will be developed. The basic system allows grid-independent operation of automatically running biomass furnaces including fuel delivery from storage and circulating the cooling/heating water respectively. The advanced system also provides electricity for other electrical devices like radio, TV or light and is an additional benefit

Ventilation of Carbon Monoxide from a Biomass Pellet Storage Tank—A Study of the Effects of Variation of Temperature and Cross-ventilation on the Efficiency of Natural Ventilation

Wood pellets have been reported to emit toxic gaseous emissions during transport and storage. Carbon monoxide (CO) emission, due to the high toxicity of the gas and the possibility of it being present at high levels, is the most imminent threat to be considered before entering a pellet storage facility. For small-scale (<30 tons storage capacity) residential pellet storage facilities, ventilation, preferably natural ventilation utilizing already existing openings, has become the most favored solution to overcome the problem of high CO concentrations. However, there is little knowledge on the ventilation rates that can be reached and thus on the effectiveness of such measures. The aim of the study was to investigate ventilation rates for a specific small-scale pellet storage system depending on characteristic temperature differences. Furthermore, the influence of the implementation of a chimney and the influence of cross-ventilation on the ventilation rates were investigated. The air exchange rates observed in the experiments ranged between close to zero and up to 8 m(3) h(-1), depending largely on the existing temperature differences and the existence of cross-ventilation. The results demonstrate that implementing natural ventilation is a possible measure to enhance safety from CO emissions, but not one without limitations.

Development of a biomass heating device for low energy and passive houses

Purpose – Decreasing energy demand due to improved building standards requires the development of new biomass combustion technologies to be able to provide individual biomass heating solutions. The purpose of this paper is, therefore, the development of a pellet water heating stove with minimal emission at high thermal efficiency.Design/methodology/approach – The single components of a 10 kW water heating pellet stove are analysed and partly redesigned considering the latest scientific findings and experimental know‐how in combustion engineering. The outcome of this development is a 12 kW prototype which is subsequently down‐scaled to a 6 kW prototype. Finally, the results of the development are evaluated by testing of an accredited institute.Findings – Based on an existing pellet water heating stove, the total excess air ratio was reduced, a strict air staging was implemented and the fuel supply was homogenized. All three measures improved the operating performance regarding emissions and thermal efficie...

Optimizing the Control Strategy of a Low-Energy House’s Heating System

The objective of this work is to analyze the heat demand of a low-energy house and to optimize the heating system control strategy. Low-energy houses minimize their heat losses by means of a highly insulated envelope. The considered heating system is composed of a pellet boiler supplying hot water to a floor heating system. The annual heat demand has been calculated with a focus on the effect of internal heat gains. Different solutions have been investigated to optimize the control strategy.