In this study, a theoretical model is presented to investigate the performance of a thermoelectric (TE) radiant cooling system combined with photovoltaic (PV) modules as a power supply in a building with an ambient temperature reaching more than 45ºC. The combined system TE/PV performance is studied under different solar radiation by using the hourly analysis program and photovoltaic system software. The thermal and electric characteristics of TE are theoretically investigated under various supplied voltages using the multi-paradigm programming language and numerical computing environment. Also, a theoretical analysis of heat transfer between the TE radiant cooling system and an occupied zone from the side, and the other side between the TE radiant cooling system and duct zone is presented. The maximum power consumption by TE panels and building cooling load of 130 kW is predicted for May and June. The 145 units of PV panels could provide about 50% of the power required by TE panels. The thermal and electric characteristics of TE panels results show the minimum cold surface temperature of 15ºC at a supplied voltage between 6 V and 7 V, and the maximum hot surface temperature of 62ºC at a supplied voltage of 16 V. The surface temperature difference between supplied current and supplied power increases as supplied voltage increases. At a higher supplied voltage of 16 V, the maximum surface temperature difference between supplied current, and supplied power of 150ºC, 3.2 A, and 48 W, respectively. The cooling capacity increases as supplied voltage increases, at a surface temperature difference of –10ºC and supplied voltage of 16 V, the maximum cooling capacity is founded at about 60 W. As supplied voltage decreases the coefficient of performance increases. The maximum coefficient of performance is about 5 at the surface temperature difference of –10ºC and supplied voltage of 8 V.

In this paper, the logarithmic mean temperature difference method is used to determine the heat power of a tube-in-tube exchanger. Analytical solutions of the heat balance equations for the exchanger are presented. The considerations are illustrated by an example solution of the problem. In particular, the heat power of the tube-in-tube heat exchanger is determined taking into account the variants of work in the co-current and counter-current mode. Apart from the analytical solutions, appropriate numerical calculations in Matlab environment have been carried out.

The paper presents the results of experimental investigations into variations of the stress tensor components due to both the interaction between subsurface fatigue crack faces and rolling contact. The load assumed represents real interaction between the railway wheel and rail. The Grating Holographic Interferometry (GHI) method was employed. The results obtained were compared with those resulting from numerical simulations performed using FEM. The results reveal a strong influence exerted by shape, crack thickness distribution and roughness of the crack faces, respectively, on the distribution of displacement and stress tensor component fields. A new concept consisting in application of the effective crack thickness was proposed. The best agreement between experimental and numerical results was achieved in the case when the real crack shape, effective crack thickness and the friction coefficient of 0.3 were assumed.

On the basis of mathematical modeling of fluid flow in vortex devices verification of use of detached-eddy simulation method in the swirling flows in vortex chamber superchargers is made. Research of a flow with use of different turbulence models was made for vortex chamber supercharger in two working points of the characteristic: with the open exit channel and closed. Verification has been spent on integrated parameters, and also on kinematic, by comparison of static pressure value of on the top end cover of the device. It is received that the hybrid turbulence model DES does not allow, as well as model SST precisely to predict value of vacuum on an axis of the vortex chamber. The error makes an order of 20 %. However, DES predicts almost correct, on 20 % big, than model SST, values of vacuum on an axis in a throat axial diffuser on an input in the vortex chamber. Besides, by means of DES it is possible to describe more adequately unsteady structures near to an axis of the vortex chamber, and also vortex core precession that does not allow to make SST turbulence model. By optimization of vortex devices, and vortex chamber superchargers in particular, simulation time essentially is better to use SST turbulence model with rotation-curvature correction.

In this paper, the authors report strain-balanced M-structures InAs/GaSb/AlSb/GaSb superlattice growth on GaSb substrates using two kinds of interfaces (IFs): GaAs-like IFs and InSb-like IFs. The in-plane compressive strain of 60-period and 100-period InAs��/GaSb/AlSb��/GaSb with different InAs (��) and AlSb (��) monolayers are investigated. The M-structures InAs/GaSb/AlSb/GaSb represent type II superlattices (T2SL) and at present are under intensive investigation. Many authors show theoretical and experimental results that such structures can be used as a barrier material for a T2SL InAs/GaSb absorber tuned for long-wave infrared detectors (8 μm–14 μm). Beside that, M-structure can also be used as an active material for short-wave infrared detectors to replace InAs/GaSb which, for this region of infrared, are a big challenge from the point of view of balancing compression stress. The study of InAs/GaSb/AlSb/GaSb superlattice with the minimal strain for GaSb substrate can be obtained by a special procedure of molecular beam epitaxy growth through special shutters sequence to form both IFs. The authors were able to achieve smaller minimal mismatches of the lattice constants compared to literature. The high-resolution X-ray diffraction measurements prove that two types of IFs are proper for balancing the strain in such structures. Additionally, the results of Raman spectroscopy, surface analyses of atomic force microscopy, and differential interference contrast microscopy are also presented. The numerical calculations presented in this paper prove that the presence of IFs significantly changes the energy gap in the case of the investigated M-structures. The theoretical results obtained for one of the investigated structures, for a specially designed structure reveal an extra energy level inside the energy gap. Moreover, photoluminescence results obtained for this structure prove the good quality of the synthesized M-structures, as well as are in a good agreement with theoretical calculations.