Converters of the Thermal Component of Concentrated Solar Radiation Based on Granular Silicon
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R ENERGY CONCENTRATORS
Dedicated to the memory of Academician Mukhtar Saidov
Converters of the Thermal Component of Concentrated Solar Radiation Based on Granular Silicon B. M. Abdurakhmanova, M. M. Adilova, *, Kh. B. Ashurova, and M. Sh. Kurbanova aInstitute
of Ion–Plasma and Laser Technologies, Academy of Sciences of the Republic of Uzbekistan, Tashkent, 100125 Uzbekistan *e-mail: [email protected] Received January 30, 2020; revised February 19, 2020; accepted April 6, 2020
Abstract—This study provides the results of researching electrophysical properties of granular silicon powder without any agglomeration of a powder placed in a dielectric, formative housing with metal contacts. The particles of silicon powder of the working body, made on this basis as a thermal energy converter, are mechanically pressed against each other with a certain force. The heating of this body results in abnormally high opencircuit voltage (Uoc) and short-circuit current (Isc). The Seebeck coefficient of this material at temperatures from 300 to 350 K is 10 times greater than that of single-crystal silicon and equal to ~500 μV/K and the thermal conductivity is ~16 W/(m K), which is, respectively, 9 times lower than that of single-crystal silicon. Short-circuit current Isc depends on the magnitude of the external pressure and the temperature gradient along the length of the specimen’s working body. Granular silicon thermal energy converters can be used in several extreme conditions, including exposure to high radiation levels, unlike single- or polycrystal silicon semiconductor devices. Various designs and characteristics of heat and pressure converters are presented, which use medium-intensity concentrated solar radiation as a source of thermal energy. Keywords: thermoelectricity, thermal energy, silicon, granular silicon, Seebeck coefficient, thermal conductivity, electrical conductivity, temperature, pressure, concentrated solar radiation DOI: 10.3103/S0003701X20040039
INTRODUCTION One possible solution for improving the thermoelectric quality factor (Z) of thermal energy converters (TECs) of technogenic or natural origin, for example, the non-photoactive component of concentrated solar radiation (CSR) is based on creating an electron crystal–photon glass (EC–PG) system [1–3], which is implemented by using expensive nanotechnologies. Another issue in this field is the search for more affordable materials for TECs instead of expensive existing materials synthesized from rare-earth elements; however, it remains far from being solved. In our opinion, the sought-after integral engineering solution is possible to implement to a certain extent by adding to the range of thermoelectric materials various modifications of non-single-crystal silicon, the single crystals of which are unfit as such due to their low Seebeck coefficient (α) and, on the contrary, high thermal conductivity levels (γ) [4, 5]. It was shown that the alloying of silicon with deep-level impurities to high concentrations with the help of ion implantation or fine-grain
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