1. Introduction

Clean sources of enhanced energy recovery offer the best mitigating solution to the economic, environmental and climate effects from the continued high consumption/utilisation of fossil fuels. Biomass resource is an excessive source of carbon-neutral renewable energy (RE) available far and worldwide and is a good source of environment-friendly, clean energy resource. In the near future, the biomass energy is likely to be one of the most dominant REs, contributing to a substantial reduction in consumption of carbon-emitting fossil fuels and electricity for cooking as well as lighting. Many methods have been adopted to produce combined heat energy and power (CHP), in improved cookstoves with advanced features of the flat thermoelectric generator (FTEG). Easy availability, accessibility, low-cost per capita produced energy, reduced emissions and inbuilt driving force have led to greater attention to CHP cookstove systems. Subsequently, exploring an efficient biomass advanced cookstove technology is necessary. An accurate inbuilt electricity generation unit to drive forced draft combustion fan/blower, to optimise performance with high efficiencies, is proposed in this current study.

explored only the performance evaluation of energy efficiency and exergy efficiency of the cookstove with an FTEG. The advantage of using an ATEG instead of FTEG is that it enhances the heat transfer surface area on both hot side and cold side, due to cylindrical structure. It is proposed to study the behaviour of ATEG placed outside the cylindrical CC to convert waste heat (hot side) into electricity as well as dissipate heat (cold side) by passing and preheating air through annular fins. Hence, it is indeed essential to study the energy and exergy analysis of an advanced cookstove-based ATEG for clean combustion and self-sustained cooking options, particularly suited for developing countries. Here, the exergy analysis (second law of thermodynamics) is an advanced method to enumerate the real irreversibilities

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

The design and fabricated CC of the proposed biomass advanced micro-gasifier

cookstove [10–15] are clearly depicted in Figure 1. The CC is fabricated using carbon steel with an inner diameter of 110 mm and an inner height of 155 mm. By means of increase in the proportion percentage (%) of carbon content, the cylinder material becomes harder and stronger providing higher creep properties. Carbon steel with high carbon content has been used to ensure it can withstand high

The secondary air (combustion air) injection of the proposed cookstove is skewed to an angle of 45° towards bottom grate [11, 12, 16]. This is to confirm the better turbulence in the course of volatile combustion and for the period of char combustion. Exfoliated vermiculite mineral matter of 93% with glass wool of 2%

delivered in the thermodynamic process.

DOI: http://dx.doi.org/10.5772/intechopen.84237

2. Materials and methods

2.1 System description

temperatures.

Figure 1.

179

Model of the proposed cookstove.

For the previous two decades, the use of thermoelectric generators and its applications have been investigated and improved worldwide due to its significant advantages of straight conversion of thermal energy into electricity with minimum/ no moving parts and reduced noise. Hence, newly developed thermoelectric generators (TEGs) are accepted as green sustainable technology and are widely used as flexible generators for a diversified applications [1, 2]. A combined advanced micro-gasifier cookstove with the TEG for heat and power cogeneration from a single system is presented here.

Champier et al. [3] have developed a prototype of a biomass cookstove with a higher-efficient combustion chamber (CC), and TEG modules are attached to either side of the cookstove. It was found from the experimental investigations that 6 W of electrical power was generated from four numbers of TEG. Experimental analysis was performed by Nuwayhid et al. [4] on the biomass domestic wood stove coupled with natural convection-cooled thermoelectric generator. It was obtained from the results that about 4.2 W of power was produced from each component. Kraemer et al. [5] built an innovative solar flat thermal panel for electricity generation adopting Seebeck effect concept with higher thermal concentration. There was an interesting result obtained from the study that an electrical convention efficiency of 4.6% for 1000 W/m<sup>2</sup> solar conditions is about eight times much more powerful than the other systems. Omer and Infield [6] proposed a conceptual model of a TEG for the estimation of an optimal device in power production. By means of using their developed model, four different TEGs were compared. Besides, they have developed a two-stage solar concentrator for a cogeneration system (combined heat and power from the thermoelectric modules). It was proven from the studies conducted by Omer and Infield [7] that an improvement of thermal efficiency as well as overall characteristics of the solar thermal concentrator for combined heat and thermoelectric power generation can be achieved using second stage concentrator.

Atik [8] studies the thermoelectric performances of the concentrating collector, receiver and TEG modules. The electric power generation efficiency, system efficiency and surface area temperature of the receiver system were obtained from the different solar radiation (W/m<sup>2</sup> ) and from different concentration ratios. Chen [9] suggested a model to examine the conceptual efficiency of solar thermoelectric generators (STEGs), which includes thermal concentration as well as optical concentration. It was obtained from his study that the component efficiency increases with increase in hot side temperature, but thermal efficiency decreases with increasing hot side temperature. Furthermore, he stated that the STEG efficiency can be improved when it has been maintained under evacuated condition.

Manikandan and Kaushik [1] performed the energy and exergy study of the solar annular thermoelectric generator (SATEG) in view of the impact of Thomson effect in concurrence with Peltier effect, Joule effect and Fourier heat conduction. Their study proposed annular thermoelectric generator as an alternative for flat thermoelectric generator (FTEG) to increase the cross-sectional area along the radial direction. They have established that the power output (W) and whole exergy efficiency (%) of the SATEG were 1.92 W and 5.02%, respectively, which was established to be 0.52 and 0.40% greater than that of SFTEG. They suggested that this SATEG system could be effectively used as the thermal insulation material as it offered better heat transfer characteristics; it was simple to drive and maintain compared to the solar flat plate thermoelectric generator.

From an in-depth literature survey, it is established that there are certainly no research studies available on CHP system in cookstove and an ATEG. Studies have Energy and Exergy Analysis of an Advanced Cookstove-Based Annular Thermoelectric… DOI: http://dx.doi.org/10.5772/intechopen.84237

explored only the performance evaluation of energy efficiency and exergy efficiency of the cookstove with an FTEG. The advantage of using an ATEG instead of FTEG is that it enhances the heat transfer surface area on both hot side and cold side, due to cylindrical structure. It is proposed to study the behaviour of ATEG placed outside the cylindrical CC to convert waste heat (hot side) into electricity as well as dissipate heat (cold side) by passing and preheating air through annular fins. Hence, it is indeed essential to study the energy and exergy analysis of an advanced cookstove-based ATEG for clean combustion and self-sustained cooking options, particularly suited for developing countries. Here, the exergy analysis (second law of thermodynamics) is an advanced method to enumerate the real irreversibilities delivered in the thermodynamic process.
