Vol 52, No 2 (2016)

The voltage-current characteristics and electroluminescence of a light-emitting-diode (LED) n/(3C-SiC)–p/ C_DIAMOND heterostructure with white glow without phosphor created on the basis of diamond film grown by the CVD method on n/(3C-SiC) substrates with a doped level of (5–8) × 10¹⁷ cm^–3 are considered It is shown the possibility to improve the characteristics of created LED structures by their irradiation with a flux of high-energy (5 MeV) electrons of a certain dose and heat treatment.

Properties of GaAs/Al_xGa_1–xAs heterophotoconverters fabricated on two sides of monocrystal plates from GaP and GaAs under lighting conditions by V-shaped concentrators are described. It it found that, owing to the increased transparency of the photoconverter structure with respect to thermal photons and comparatively low GaP thermal resistance, the temperature increment of the p–n junctions and relative losses of the electrical power are notably lower than for photoconverters of the same structure on the basis of GaAs.

A procedure for accelerated determination of main heat engineering parameters of flat-plate solar collectors (FSCs) for heating of a heat transfer fluid (HTF) according to the results of their short-term thermal testing in full-scale quasi-stationary conditions has been proposed and implemented.

A method for calculating a uniformly perforated constant cross-section water distributor of the stratified heat accumulator is developed.

Results are presented of calculation studies of the influence of inlet air flow humidity and temperature on thermal efficiency of an evaporation chamber of a solar desalination plant where the process of humidification of the air inlet to an evaporation chamber occurs due to the heat and mass exchange with the saltwater surface in it.

The thermoelectric effect, i.e., generation of current and voltage under uniform heating, is for the first time observed in a graded-gap Si_1–xGe_x (0 ≤ x ≤ 1) continuous solid solution and an n–Si–p–Si_1–xGe_x heterostructure made on its basis. Currents of 0.0025–0.0035 µA and voltages of 0.05–0.3 mV have occurred in the temperature range of 40–250°C.

In this work the program AMPS-1D was used to optimize the performance of the organic solar cells. The cells considered consist of poly(3-HexylThiophène) [P3HT] as electron donors, and (6,6)-phenyl- C61-butyric acid methyl ester [PCBM] as electron acceptor, (P3HT/PCBM) is used as photo-active material, sandwiched between a transparent indium tin oxide (ITO) and layer of poly(3,4 ethylenedioxythiophene)/ poly(styrenesulfonate) (PEDOT/PSS) on top of the ITO electrode and an AL backside contact. The results showed that the optimum thickness of the solar cell is about 400 nm, V_oc = 0.61 at T = 300 K. This is in the good agreement with the corresponding computer simulation value of 0.63 V. The maximum limit for the organic solar cell efficiency is about 8%, provided that the band-gap of the cell is about 1.5 eV.

In order to desalinate sea water by only solar energy using they were designed and built three distillers in which experimental measurements were taken to calculate production, performance and cost. Distillers by solar concentration are: a parabolic trough distiller (PTD) and a Fresnel linear distiller (FLD), and a stepped basin distiller (SBD). As a result, fresh water production under similar climatic conditions was 990 cm³/m²/day with an efficiency of 45.8% for the PTD, 855 cm³/m²/day with 38% of efficiency for the FLD and 5910 cm³/m²/day with an efficiency of 4.4% for the SBD. That is, although the SBD has 10 times lower efficiency than the PTD, it produces almost 6 times more fresh water per m² of distiller’s surface. Regarding the cost of production of each liter of desalinated water, it was calculated in € 0.086, € 0.103 and € 0.034 for the PTD, FLD and SBD, respectively.

Analytical approaches for calculation of the density distribution of radiant flux from the Sun for a parabolic–cylindrical mirror concentrating system are considered in this work.

This paper considers the spatial and temporal variability of the effect of solar radiation in local territories of different macroclimatic regions in Uzbekistan and analyzes the variability of solar radiation intensity in daily and annual time intervals depending on the variants of orientation of the beam-receiving surface.

Experimental studies on increasing the transmittance of a light–receiving element (LRE) by applying an antireflection coating were carried out. As an antireflection coating on the solar furnace, the fluoride composite material MgF₂–CaF₂ was synthesized. Transmission spectra of the LRE without the antireflection coating and with the antireflection coating were measured. The effect of translucence (increase of transmittance) of the LRE after applying the antireflection coating is observed in the spectral region of 0.4–1.1 μm.

This report provides information on the current state of work on the development of standards in the field of solar energy of the Republic of Uzbekistan.