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The typical operating range of domestic heating devices includes only heat generation. However, the availability of combined heat and power generation in microscale devices is currently becoming a more and more interesting option. This paper shows the experimental and numerical analysis of the possibility of developing a micro-cogeneration system equipped with a wood-fired heating stove and a prototype of the thermoelectric generator equipped with low-price thermoelectric modules. In the first step, mathematical modeling made it possible to analyze different configurations of the hot side of the thermoelectric generator (computational fluid dynamics was used). Next, experiments have been conducted on the prototypical test rig. The maximum power obtained during the discussed combustion process was 15.9 We when the flue gas temperature was approximately 623 K. Assuming a case, when such value of generated power occurred during the whole main phase, the energy generated would be at a level of approximately 33.1 Whe, while the heat transferred to the water would be approximately 1 078.0 Whth. In addition to the technical aspects, the economic premises of the proposed solution were analyzed. As was shown, an installation of TEG to the existing stove is economically not viable: the Simply Payback Time will be approximately 28.9–66.1 years depending on the analyzed scenario. On the other hand, the SPBT would be significantly shorter, when the installation of the stove with an integrated thermoelectric generator was considered (approximately 5.4 years). However, it should be noted that the introduction of the power generating system to a heat source can provide fully or partially network-independent operation of the hot water and heating systems. [ABSTRACT FROM AUTHOR]

A significant part of the world’s population (about 40%) cooks their meals and provides heating for their homes using wood-burning heating devices. Due to the relatively low cost of fuel and their aesthetic design, solid fuel stoves capable of heat accumulation are convenient and common. The use of dedicated small-scale power generators provides also additional benefits. This paper presents the results of a study conducted to verify the possibility of generating power using stove-fireplaces with heat accumulation systems. In such units, the temperature of the flue gas should be kept at a certain level for the purposes of storing heat, which results from certain limitations of the thermoelectric generators. To verify the possibility of applying thermoelectric modules in such heating devices, a dedicated system with thermoelectric generators was selected from among various microcogeneration systems and implemented. Three types of heat exchangers were studied and the most efficient unit was selected for further testing. Two types of generators, with maximum operating temperatures of 320 and 175 °C, were compared. Subsequently, the characteristics of the latter were determined. The conducted tests allowed to determine the performance and the total efficiency of the generators that were used. It has been demonstrated that the maximum power of the generator would not exceed ca. 30 W e and that there is no economic justification for such a device. However, providing a self-powered and self-sufficient operation of stove-fireplaces with heat accumulation systems remains an important goal. [ABSTRACT FROM AUTHOR]

Thermoelectric generators are devices that harvest waste heat and convert it into useful power. They are considered as an additional power source in the domestic sector, but they can also be installed in off-grid objects. In addition, they are a promising solution for regions where there is a lack of electricity. Since biomass heating and cooking stoves are widely used, it is very appropriate to integrate thermoelectric generators with wood-fired stoves. This paper shows the experimental analysis of a micro-cogeneration system equipped with a wood-fired stove and two prototypical constructions of thermoelectric generators dedicated to mounting on the flue gas channel. The first version was equipped with one basic thermoelectric module and used to test various cooling methods, while the second construction integrated four basic thermoelectric modules and a water-cooling system. During the tests conducted, the electricity generated in the thermoelectric generators was measured by the electronic load, which allowed the simulation of various operating conditions. The results obtained confirm the possibility of using thermoelectric generators to generate power from waste heat resulting from the wood-fired stove. The maximum power obtained during the discussed combustion process was 15.4 W (if this value occurred during the entire main phase, the energy generated would be at a level of approximately 30 Wh), while the heat transferred to the water was ca. 750 Wh. Furthermore, two specially introduced factors (CPC and CPTC) allowed the comparison of developed generators, and the conclusion was drawn that both developed constructions were characterized by higher CPC values compared to available units in the market. By introducing thermoelectric modules characterized by higher performance, a higher amount of electricity generated may be provided, and sufficient levels of current and voltage may be achieved. [ABSTRACT FROM AUTHOR]

• The optimal temperature of the drying agent should be a maximum of 130 °C. • It is possible to obtain 120 MJ more energy burning dry straw compared to wet fuel. • An increase in boiler return temperature from 20 to 80 °C reduces PM emission by 50%. • The functionality of batch boilers may be increased with power generation. • The expected power generation in the system should be at a level of 10 kW el. This paper shows the results of experimental and numerical investigations related to the energy use of straw from the point of view of its preparation (drying), combustion, energy production and emissions. Experimental works on straw drying were conducted on a specially developed installation based on dedicated batch straw dryers, which use flue gas, coming from a 500 kW th boiler, as a drying medium. The further part of the work was conducted on a prototype of a micro-scale cogeneration system that operates according to a low temperature Rankine cycle and it is powered by a 100 kW th biomass-fired batch boiler. Conducted so far research allowed to analyse selected operation aspects of the developed system. An analysis of straw drying, proximate, ultimate, and heating value analysis, heat generation process in the boiler, steam generation process in the evaporator and superheater, steam engine operation as well as dust emissions during straw combustion related to the boiler return temperature were presented. Energy transferred from flue gases to straw with a high value of moisture content was 5.75 kW, which allowed to evaporate about 18.6 kg of water from 192 kg wheat straw bale. The moisture content was reduced from 36.9 to 27.2%. The power generated in the system was lower than the one expected, since only 1.15 kW el was achieved which was about 1% of the boiler's heat capacity. Such result was caused by construction restrictions of the installation. Experimental results were supported by dynamic simulations performed in TRNSYS software. The simulations were performed for both the current configuration of the system and suggested modifications. Simulation results showed, that the expected power generation in the final version of the system should be at a level of 10 kW el. Results obtained during the analysis of multi-cyclone operation showed, that the concentration of dust was reduced in a range from 55% to even 85% depending on the temperature of the boiler return and flue gas flowrate in multi-cyclone. [ABSTRACT FROM AUTHOR]