Energy and Exergy Analysis of an Advanced Cookstove-Based Annular Thermoelectric Cogeneration System

This chapter deals with the energy and exergy analysis of the cookstove-based gasifier annular thermoelectric generator (GATEG). The vented waste heat is made available at the outer surface of the combustion chamber of an advanced micro-gasifier cookstove for added energy feed to the GATEG. This combined device has a competence to satisfy both cooking needs and micro-electrification of rural villages by a simultaneous recovery of heat energy and power (CHP) as cogeneration system. The power output (W), electrical energy efficiency (%) and exergy efficiency (%) of the proposed advanced micro-gasifier cookstove-based ATEG are 10 W, 6.78 and 15%, respectively. The maximum hot side wasted temperature without annulus gain is 275°C, which translates equivalent loss values as 7.64 W, 5.45 and 10.49%; this loss is higher than achievable minimum hot side temperature of 150°C on which this analytical chapter is drafted. This detailed study will be extremely useful to the designers of commercial biomass advanced micro-gasifier cookstove integrated ATEG systems

Practical design considerations for secondary air injection in wood-burning cookstoves: An experimental study

Billions of households worldwide cook using biomass fires and suffer from the toxic smoke emitted into their homes. Laboratory studies of wood-burning cookstoves demonstrate that secondary air injection can greatly reduce the emission of harmful air pollution, but these experimental advancements are not easily translated into practical cookstove designs that can be widely adopted. In this study, we use a modular cookstove platform to experimentally quantify the practical secondary air injection design requirements (e.g., flow rate, pressure, and temperature) to reduce mass emissions of particulate matter (PM), carbon monoxide (CO), and black carbon (BC) by at least 90% relative to a traditional cooking fire. Over the course of 111 experimental trials, we illuminate the physical mechanisms that drive emission reductions, and outline fundamental design principles to optimize cookstove performance. Using the experimental data, we demonstrate that low-cost (<$10) fans and blowers are available to drive the secondary flow, and can be independently powered using an inexpensive thermoelectric generator mounted nearby. Furthermore, size-resolved PM measurements show that secondary air injection inhibits particle growth, but the total number of particles generated remains relatively unaffected. We discuss the potential impacts for human health and investigate methods to mitigate the PM formation mechanisms that persist

Techno-economic analysis of different plant configuration for thermoelectric cogeneration from biomass boiler

Thermoelectric modules integration within biomass boiler for the direct conversion of heat into electricity is a possibility to increase efficiency and to realize a stand-alone biomass boiler. Due to the low conversion efficiency (up to 5%) of commercial thermoelectric modules, the aim of the integration shall not be the electricity production for external power supply, but the energy self-consumption of biomass boiler electric auxiliaries. The paper describes and analyses four different options for the integration of thermoelectric modules within a biomass boiler: in the combustion chamber, in the convective tubes, in the chimney and with a condensing fluid circuit to be realized outside the biomass boiler. Five quantitative and qualitative key performance indicators have been defined to assess how the integration strategy can influence the electric yield of thermoelectric modules, the ease of maintenance, the operation continuity, the need of auxiliaries systems to be added as well as the impact on biomass boiler redesign or retrofit. The analysis shows that the realization of a circuit with a condensing fluid allows reaching the best combination of key performance indicators. On the basis of this result, the paper also shows the preliminary design of a new test facility to test Glycerol Triacetate as condensing fluid to produce electricity by thermoelectric modules

Thermo-electric generation (TEG) enabled cookstoves in a rural Indian community: a longitudinal study of user behaviours and perceptions

Background: Traditional cookstoves that burn solid biomass are associated with inefficient burning, a high degree of household air pollution and high morbidity rates. A key barrier to the adoption of clean cookstoves has been the cost of fuels. Hence, a Thermo-Electric Generating (TEG) cookstove that used solid biomass fuels more efficiently and released less smoke was developed. The TEG cookstove also generates electricity to power small electric devices. Fifteen TEG cookstoves were distributed to villagers in the Indian state of Uttarakhand in 2019. / Objective: We wanted to understand whether, after two years of distribution, TEG cookstoves were still used, what and where they were used for, their perceived impacts on health, and the barriers to their use. / Methods used: We surveyed 10 of the 15 recipient households. We applied the Capability, Opportunity, Motivation-Behaviour and Behaviour Change Wheel frameworks to understand what the barriers to adoption were, and what could be done to surmount these. / Results: All respondents reported lower smoke levels and most respondents reported that the TEG cookstoves required less fuelwood than their traditional cookstoves, but none had used them in the month prior to the survey. / Discussion: For those whose TEG cookstoves were still usable and had not been made redundant by clean cookstoves, we found there to be physical opportunity barriers and psychological capability barriers. Physical opportunity barriers included a small inlet for fuel, limited versatility beyond cooking at low temperatures, and the availability of only one hob. To surmount these barriers, we recommend co-design to suit user needs and education emphasising visible benefits of avoided soot on kitchen walls, in addition to the health benefits

Improved thermoelectric biomass cookstove

Capstone Project submitted to the Department of Engineering, Ashesi University in partial fulfillment of the requirements for the award of Bachelor of Science degree in Electrical and Electronic Engineering, May 2020This paper documents the development of an improved, thermoelectric biomass cookstove, a product aimed at making the cooking process among off-grid communities more environment-friendly and safer for use. A biomass cookstove is embedded with a thermoelectric generator that uses the Seebeck effect to convert waste heat into electricity. Produced electricity is in return, used to blow air into the combustion chamber hence, increasing the air-to-fuel ration. In addition, this paper reports the building and testing of additional functionalities aimed at increasing efficiency of the stove. These are; automatic fuel-level indicator and fan-speed control. Results are recorded and analyzed, providing possible measures for optimization for the future.Ashesi Universit

Energy harvesting from household heat sources using a thermoelectric generator module

Inefficiency in energy usage has led to the subject of energy harvesting which simply means recycling dissipated waste energy into another useful form of energy. This paper presents the harvesting of waste thermal energy from household heat sources (kerosene stove and generator exhaust pipe) as an electrical energy. Thermoelectric generator (TEG) modules (TGM-161-1.2-2.0) and aluminium heat sinks were constructed and placed close to the heat sources for waste heat harvesting. The hot and cold side temperatures of the TEG modules were measured along with the corresponding output voltages and currents, while the power and energy harvested were estimated. The harvesting of energy from the stove yielded means of 1.532 ± 0.091 V, 0.388 ± 0.003 A, 0.597 ± 0.039 W and 536.87 ± 34.98 J, subject to an average temperature difference of 84.59 ± 3.64 °C. For the generator exhaust pipe, average values of 1.28 ± 0.074 V, 0.285 ± 0.007 A, 0.367 ± 0.029 W and 330.62 ± 26.15 J with an average temperature difference of 62.31 ± 4.88 °C were achieved. The obtained results agreed with previous studies on energy harvesting using TEG modules. This work revealed the potential of waste heat energy harvesting using TEG technology.Keywords: Waste heat; temperature; thermoelectric generators; heat source; energy harvestin

Evaluation of the power output characteristics of the small-scale thermoelectric generator

Tato bakalářská práce se zabývá termoelektrickými generátory a jejich aplikacemi. V úvodu je výčet nejpoužívanějších termoelektrických modulů u jednotlivých aplikací generátorů. Dále jsou popsány jednotlivé aplikace termoelektrický generátorů, rozdělené podle rozdílného způsobu získávání tepla a jejich následné porovnání. V závěru práce se nachází popis měření a vyhodnocení výkonových parametrů vybraných termoelektrických modulů a termoelektrického generátoru testovaného na Energetickém ústavu VUT v Brně.This bachelor thesis deals with thermoelectric generators and their applications. The introduction is a list of the most used thermoelectric modules in each applications of generators. A description of individual applications thermoelectric generators, divided by different methods of obtaining the heat, followed by their comparison. In conclusion there is a description of the measurement and evaluation of power parameters of thermoelectric modules and thermoelectric generator tested at the Energy Institute BUT.

Biomass for Bioenergy

Lignocellulosic wastes has been widely discussed as a promising natural chemical source and alternative feedstock for second-generation biofuels. However, there are still many technical and economic challenges facing its utilization. Lignin is one of the components of lignocellulosic biomass, and is the most rigid constituent and can be considered as a glue providing the cell wall with stiffness and the plant tissue with compressive strength. In addition, it provides resistance to chemical and physical damage. Resistance of lignocelluloses to hydrolysis is mainly from the protection of cellulose by lignin and cellulose binding to hemicellulose. The present book provides basic knowledge and recent research on different applications of biomass, focusing on the bioenergy and different pretreatment methods that overcome the aforementioned hurdles