Search

Neglecting the friction between the indenter and the thermoelectric layer (TEL), the discontinuous contact problem between the TEL and the rigid base is studied by using elastic theory and integral transformation technology. The external load is applied to the TEL through the rigid base. When the value of the external load λ exceeds the critical load (CL) λ c r , separation occurs along the interface between the TEL and the rigid base. The discontinuous contact problem is transformed into a system of singular integral equations (SIES) by boundary conditions. Numerical results of the contact stress and the separation distance between the TEL and the rigid base are considered by the external load, the specific weight of the TEL and the width of the indenter. The results show that the larger external load and the specific weight of the TEL will cause the separation distance between the TEL and the rigid base to increase. However, the increase in the width of the rigid indenter has the opposite effect on the contact stress between the TEL and the rigid base. The model developed in this article provides guidance for the design and safety and reliability judgment of thermoelectric components in practical applications. [ABSTRACT FROM AUTHOR]

• A model of the continuous contact problem between the thermoelectric layer and the rigid layer is established. • The body force of the thermoelectric layer is considered. • The continuous contact problem of finite thermoelectric layer is considered. • The influence of punch width and thermoelectric layer body force on critical load factor is discussed. In this study, the continuous contact problem of thermoelectric layer resting on a rigid substrate and loaded by a rigid punch is examined. Considering the body force of the thermoelectric layer, the model of stress distribution between thermoelectric layer and rigid layer is established. The general expressions for the stress between the thermoelectric layer and the substrate are given. Using the boundary conditions, the singular integral equation of the stress distribution is obtained and solved by Gauss-Chebyshev integral formula. The numerical results of the stress distribution between the rigid punch and the thermoelectric layer are obtained. It is found that the stress between the rigid punch and the thermoelectric layer exhibits singularity at the edge of the rigid punch. The influence of the parameters of the rigid punch and the thermoelectric layer on the critical load factor between the thermoelectric layer and the substrate is analyzed. The results show that the larger rigid punch width and the body force of the thermoelectric layer make it difficult to separate the thermoelectric layer from the rigid substrate. The results of this paper will provide a reference for studying the contact behavior of thermoelectric materials. [ABSTRACT FROM AUTHOR]

By using numerical simulation, the operating temperatures of a thin-film solar cell based on CuInSe2 have been determined and the solar radiation density values, at which stabilization of the temperature operating conditions of the thin-film solar cell is not required, have been optimized. The maximum possible efficiency value of ~14.8 % is achieved under actual operating conditions, and is maintained by the incoming thermal energy as both emitted in this cell and infrared radiation of the sun and the environment. A model of the proposed thin-film solar cell was implemented in the COMSOL Multiphysics program environment with the use of the Heat Transfer Module. The operating temperatures of the solar cell without thermal stabilization under conditions of the diurnal and seasonal variations of both the ambient temperature and the power density of the AM1.5 solar spectrum have been determined. The maximum value of this power density was varied from 1.0 to 500 kW/m2 when using concentrators. The obtained values of operating temperatures of the thin-film solar cell were used to determine its main parameters in the SCAPS-1D program. The graphs of the operating temperature, efficiency and fill factor of the thin-film solar cell versus the solar radiation density are provided. It is shown that in order to obtain the highest possible efficiency of a solar cell, it is necessary to use concentrated solar radiation with a power density, the maximum value of which should be 8 kW/m2 in July and 10 kW/m2 in January. In the case of lower and higher values of power density, an appropriate thermal stabilization of the cell under consideration is necessary. The dependencies of efficiency, fill factor and open-circuit voltage versus the stabilization temperature of the solar cell, temperature gradients at the interfaces of the thermoelectric layer were also calculated. It is shown that by choosing optimal values of the thermal stabilization, the efficiency of the proposed solar cell may be about 15 % or more.

CuInSe2 thin-film solar cells are promising materials for photovoltaic devices. One of the main tasks of researchers is to find ways to increase the solar cells efficiency. In this paper we propose an original structure of a thin-film solar cell based on a tandem connection of a photoelectric converter and a thermoelectric layer based on CuInSe2. The photoelectric converter consists of CuInSe2 and CdS layers. A 3D model of the proposed thin-film solar cell was implemented in the COMSOL Multiphysics environment with using the Heat Transfer module. The simulation was carried out taking into account the diurnal and seasonal variations of both the ambient temperature and the power density of the AM1.5 solar spectrum for the geographical coordinates of Minsk. The solar radiation power density of about 500 kW/m2 can be achieved by using concentrators. The temperature pattern and temperature gradients are calculated in each layer of the solar cell without and with the temperature stabilization of the substrate back side as well as without and with the thermal insulation of the substrate ends. Graphs of the temperature gradients of the thermoelectric layer and the temperature variations of the photoelectric converter of the solar cell are given. As a result of the simulation, it is shown how the uneven heating of both the surface of a thin-film solar cell and its layers occur under conditions of diurnal and seasonal variations of both the ambient temperature and the solar radiation power density. Under concentrated solar radiation exposure, the photoelectric converter surface can be heated up to 700 °C without temperature stabilization of the solar cell substrate. The operating temperature of the photoelectric converter was maintained at no more than 2.35 °C in January and at no more than 14.23 °C in July due to the temperature stabilization of the substrate back side of the proposed device. This made it possible to achieve an increase in the output power of the solar cell both by summing the photoand thermoelectric output voltages and by the concentration of solar radiation.

We present the development and results of a new simple method for thermal conductivity characterization of thin films and thermoelectric structures using a scanning thermal microscope in pulsed current mode. The presented method does not allow measurement of absolute thermal conductivity of the studied system, but only relative to the Si substrate. We present the results of the method on the Si substrate/layer step boundary. The nano-layers of different thickness and different materials were prepared for the experiments by the pulsed laser deposition from hot-pressed targets. [ABSTRACT FROM AUTHOR]

We report on the preparation of thermoelectric layers of FeSbTe and CeFeCoSb on silicon (100) and fused silica substrates via a combination of pulsed laser deposition (PLD) and rapid thermal annealing methods. A wide range of deposition conditions were tested including on- and off-axis approaches and variation of the annealing temperature profile. Wavelength dispersive x-ray spectroscopy was used to determine stoichiometry. An optical microscope, mechanical profilometer, and atomic force microscopy served to map layer topology. For the FeSbTe layers, S was between 1.4 nm and 6 nm, with S ranging from 2.1 nm to 7.8 nm. For CeFeCoSb layers, S was from 1.3 nm to 4.2 nm and S between 1.7 nm and 6.2 nm. Crystalline structure was determined by x-ray diffraction. The best layers (in terms of smooth surface and crystalline structure) prepared using a modified off-axis PLD arrangement were then characterized for thermoelectric properties. The smooth, stoichiometric and crystalline layers of both types were prepared at an annealing temperature of 423 K for 10 min. All experiments were conducted with the aim of finding the deposition condition providing smooth and crystalline layers. These conditions should be used for the deposition of multilayered systems composed of the FeSbTe and CeFeCoSb layers with a period of about 1 nm, where there could be layer roughness comparable to the period. [ABSTRACT FROM AUTHOR]