THE OPTIMAL FLAT PANEL SOLAR THERMOELECTRIC GEOMETRIES FOR HEAT AND ELECTRIC POWER PRODUCTION

A calculation technique provides direct calculation of the heat and electric power of flat panel solar thermoelectric system is established, this was in order to determine the optimum system size optimization for combined water heating and electricity generation. The system size optimization is trade-off between the thermoelement length, cross-section area and the solar absorber size. The technique is developed under the conditions of given solar irradiation, the thermoelectric (TEG) cold side temperature, cross-section area and number of thermoelements. The calculation technique is verified by experimental setup, which comprises of uncovered flat black painted solar absorber, a heat sink partly submerged on water system and TEG device which was sandwiched in between, 5 commercial TEG devices of different sizes were examined, the steady state TEG open circle voltage and temperatures were measured to evaluate the electric and thermal power experimentally. The data obtained through the calculation technique was validated against the experimental data. The results show that there is an optimum size of the system, decreasing or increasing the size further wouldn’t achieve the optimum performance. The established calculation technique provide the designer (manufacturer) and users with good indication of what TEG size they should use, thus saving the user’s time of examining different TEGs with different aspect ratios (sizes ) and saving manufacturing cost by using less material

THE OPTIMAL FLAT PANEL SOLAR THERMOELECTRIC GEOMETRIES FOR HEAT AND ELECTRIC POWER PRODUCTION

A calculation technique provides direct calculation of the heat and electric power of flat panel solar thermoelectric system is established, this was in order to determine the optimum system size optimization for combined water heating and electricity generation. The system size optimization is trade-off between the thermoelement length, cross-section area and the solar absorber size. The technique is developed under the conditions of given solar irradiation, the thermoelectric (TEG) cold side temperature, cross-section area and number of thermoelements. The calculation technique is verified by experimental setup, which comprises of uncovered flat black painted solar absorber, a heat sink partly submerged on water system and TEG device which was sandwiched in between, 5 commercial TEG devices of different sizes were examined, the steady state TEG open circle voltage and temperatures were measured to evaluate the electric and thermal power experimentally. The data obtained through the calculation technique was validated against the experimental data. The results show that there is an optimum size of the system, decreasing or increasing the size further wouldn’t achieve the optimum performance. The established calculation technique provide the designer (manufacturer) and users with good indication of what TEG size they should use, thus saving the user’s time of examining different TEGs with different aspect ratios (sizes ) and saving manufacturing cost by using less material

Hybrid solar thermo-electric systems for combined heat and power

Solar energy has been extensively used in the renewable technology field, especially for domestic applications, either for heating, electrical generation or for a combination of heat and power (CHP) in one system. For CHP system solar photoelectric/thermal (PV/T) is the most commonly used technology for roof top applications. However, combination between solar hot water and thermoelectric generators has become an attractive for CHP system, this is due to its simplicity of construction and its high reliability. Moreover, this technology does not rely simply on sunlight and it can work with any other heat source, such as waste heat. However, its main drawback is its low efficiency. Recent publications by Kraemer et al (2011) and Arturo (2013) have shown that the efficiency of solar thermoelectric systems has improved dramatically, especially when combined with a solar concentrator system, as well as within a vacuum environment. The project recorded in this thesis focused on the design, construction and investigation of an experimental solar thermoelectric system based on a flat plate solar absorber. The aim was to study the technical feasibility and economical viability of generating heat and electric power using a solar thermoelectric hot water system. The design procedure involved on determining the heat absorbed and emitted, as well as the electrical power that was generated by the system. It began by obtaining the efficiency of the solar absorber, including selecting its paint, this was done through an experimental technique to determine the heat absorbed by the absorber, and the results obtained were verified by direct measurements of the light intensity. xvi An intensity meter was used, and results from both the experimental and theoretical models showed good agreement. The process also included calculating the heat from the system that was gained, lost and generated, as well as the electrical power provided. This was done to provide the system optimal size optimization to obtain the best and most economical system. Further improvement was made to the system by assembling a vacuum cavity, to improve the system’s efficiency. Although the maximum electrical efficiency obtained was relatively low (0.9%), compared to results recorded in the literature (Kraemer et al ,2011 and Arturo, 2013). However, the results of the electrical power output, under a vacuum level of 5 x 10-2mbar, increased approximately three times compared to the results obtained under normal (atmospheric) conditions. Additionally, the thermal power increased by 37% at this level of vacuum. The process involved determining the best thermoelectric geometries to achieve the optimum power outcome under different environmental conditions. The results showed that the system, which included the Thermoelectric device (TEG) with a larger geometric size, produced the best thermal power among other sizes. It was concluded that the system with the smallest TEG geometric size provided the best electrical power output