Thermoelectric (TE) technology is regarded as alternative and environmentally friendly technology for harvesting and recovering heat which is directly converted into electrical energy using thermoelectric generators (TEG). Conversely, Peltier coolers and heaters are utilized to convert electrical energy into heat energy for cooling and heating purposes The main challenge lying behind the TE technology is the low efficiency of these devices mainly due to low figure of merit (ZT) of the materials used in making them as well as improper setting of the TE systems. The objective of this work is to carry out a comprehensive review of TE technology encompassing the materials, applications, modelling techniques and performance improvement. The paper has covered a wide range of topics related to TE technology subject area including the output power conditioning techniques. The review reveals some important critical aspects regarding TE device application and performance improvement. It is observed that the intensified research into TE technology has led to an outstanding increase in ZT, rendering the use TE devices in diversified application a reality. Not only does the TE material research and TE device geometrical adjustment contributed to TE device performance improvement, but also the use of advanced TE mathematical models which have facilitated appropriate segmentation TE modules using different materials and design of integrated TE devices. TE devices are observed to have booming applications in cooling, heating, electric power generation as well as hybrid applications. With the generation of electric energy using TEG, not only does the waste heat provide heat source but also other energy sources like solar, geothermal, biomass, infra-red radiation have gained increased utilization in TE based systems. However, the main challenge remains in striking the balance between the conflicting parameters; ZT and power factor, when designing and optimizing advanced TE materials. Hence more research is necessary to overcome this and other challenge so that the performance TE device can be improved further.

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A comprehensive review of thermoelectric technology: materials, applications, modelling and performance improvement

Nowadays humans are facing difficult issues, such as increasing power costs, environmental pollution and global warming. In order to reduce their consequences, scientists are concentrating on improving power generators focused on energy harvesting. Thermoelectric generators (TEGs) have demonstrated their capacity to transform thermal energy directly into electric power through the Seebeck effect. Due to the unique advantages they present, thermoelectric systems have emerged during the last decade as a promising alternative among other technologies for green power production. In this regard, thermoelectric device output prediction is important both for determining the future use of this new technology and for specifying the key design parameters of thermoelectric generators and systems. Moreover, TEGs are environmentally safe, work quietly as they do not include mechanical mechanisms or rotating elements and can be manufactured on a broad variety of substrates such as silicon, polymers and ceramics. In addition, TEGs are position-independent, have a long working life and are ideal for bulk and compact applications. Furthermore, Thermoelectric generators have been found as a viable solution for direct generation of electricity from waste heat in industrial processes. This paper presents in-depth analysis of TEGs, beginning with a comprehensive overview of their working principles such as the Seebeck effect, the Peltier effect, the Thomson effect and Joule heating with their applications, materials used, Figure of Merit, improvement techniques including different thermoelectric material arrangements and technologies used and substrate types. Moreover, performance simulation examples such as COMSOL Multiphysics and ANSYS-Computational Fluid Dynamics are investigated.

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Thermoelectric generator (TEG) technologies and applications

A dynamic model for thermoelectric generator applied in waste heat recovery

Experimental investigation of the applicability of a thermoelectric generator to recover waste heat from a combustion chamber

Analysis and modeling of effective temperature differences and electrical parameters of thermoelectric generators

Development and validation of a new TRNSYS type for the simulation of thermoelectric generators

Magnus wind turbine uses rotating cylinders instead of conventional horizontal axis blades. These cylinders rotate around their own axes and create a rotational force according to Magnus effect. Although this kind of wind turbines have many benefits over conventional axis blades and can exhibit different blade characteristics, it is not clearly demonstrated which the most efficient blade geometry is. This paper focuses on assess the influence of the blade shape on the Mangus force, using particle image velocimetry.

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Blade shape influence on aerodynamic efficiency of a Magnus wind turbine using particle image velocimetry

An earth-air heat exchanger (EAHX), also known as Provençal well or Canadian well, is a system for cooling and heating buildings using the ground as a heat sink/source. This study is dealing with earth-air heat exchanger (EAHX) implementation for Spanish dwellings. The objective is to assess the potential of this solution for HVAC energy savings and greenhouse gas emissions reductions. A numerical study is conducted to assess the thermal behavior of EAHX using the transient simulation tool TRNSYS. The simulations are carried out for typical Spanish single family detached home, taken into account three different climate regions. Detailed results are presented concerning EAHX thermal behavior and its benefits in terms of energy savings and anti pollution effects for fresh air pre-heating and pre-cooling within mechanical ventilation system of the house.

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The potential of Earth-to-Air Heat Exchangers for reducing energy demand in Spanish dwellings

This study is focused on assessing the real performance of a solar thermal system under current Spanish regulation compliance using TRNSYS. The effects on consumption pattern and occupancy rate based on the relationship between the seasonal profiles and the asynchronism between production and demand of a solar thermal system is investigated. Besides, the effect of various parameters such as mass flow rate through collector and initial water temperature is analyzed. The results of the simulation show that the system performance is affected strongly by the change of demand profile, primary mass flow rate and initial water temperature. Furthermore, the research shows that current Spanish regulations do not guarantee the safety of use in such systems because overheating problems, caused by applying some combinations of the above parameters, appear during summer period.

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A. Massaguer

Papers

Development and validation of a new TRNSYS type for the simulation of thermoelectric generators

Blade shape influence on aerodynamic efficiency of a Magnus wind turbine using particle image velocimetry

The potential of Earth-to-Air Heat Exchangers for reducing energy demand in Spanish dwellings

Study of the influence of hot water consumption pattern on SHW systems under solar Spanish regulation compliance using TRNSYS