A Review on the Challenges of Using Zeolite 13X as Heat Storage Systems for the Residential Sector

In recent years, several attempts have been made to promote renewable energy in the residential sector to help reducing its CO2 emissions. Among existing approaches utilizing substances capable of directly storing and transporting thermal energy has recently become a point of interest. Zeolite 13X with exceptional capacity to safely store thermal energy for long periods and release heat due to its unique molecular structure is known to be one of the best options serving this purpose. However, the application of this ceramic as a heat storage material in the residential sector is associated with significant challenges dictated by the limitations of the sector, such as space restrictions and affordability. The current review attempts to explore the extent of these challenges, mainly related to design and efficiency from different perspectives. The main aim here is to provide a clear vision for a better understanding of the state of the art of this technology and to help to identify possible solutions fostering the adaptation of this technology to the residential sector.

Al-Si@Al(OH)3 Nanosheets Composite for Enhanced Efficient Strategy to Synthesize Al-Si@Al2O3 Core-shell Structure

Owing to the combined advantages of Al-Si alloy and Al2O3, Al-Si@Al2O3 is widely utilized as a heat storage material, catalyst carrier and what adsorption host. Hence, the preparation of Al-Si@Al2O3 and corresponding precursors is of utmost significance. Herein, Al-Si@Al(OH)3 precursor is investigated and Al(OH)3 nanosheets are in-situ formed on the surface of Al-xSi alloy (x = 10, 20 and 30) in the presence of water. The influence of Si content, diameter of Al-Si particles and heating parameters on morphology and thickness of Al(OH)3 nanosheets is systematically explored using X-ray diffraction, electron microscopy, Fourier transform infrared spectroscopy and N2 adsorption/desorption isotherms. The growth mechanism of Al(OH)3 nanosheets is revealed and a pathway to obtain Al-Si@Al2O3 nanosheets with desired structure and thickness is demonstrated.

CALCULATION OF CONSTRUCTION ELEMENTS OF HEAT ACCUMULATORS WITH LIQUID AND SOLID HEAT-ACCUMULATING MATERIAL

The depletion of traditional fuel resources and the deterioration of the ecology of the environment, an increase in emissions into the air make the research on renewable energy and the need to attract clean energy sources to the energy balance of Ukraine. A promising direction is the use of solar energy for municipal heat supply, which can provide large heat needs even in temperate climates. Basically, the methods of using thermal energy from the sun are generally economically effective, but the share of using thermal solar energy is quite small. It can also be solved by accumulating these surpluses and using them during the heating season. The experience of operating unorganized seasonal heat accumulators in the soil indicates the low efficiency of such heat storage due to significant heat losses into the surrounding soil mass. For such systems (solar collectors + seasonal heat accumulator), it is advisable to use organized seasonal heat accumulators, which are designed for a certain amount of heat. An organized seasonal heat accumulator is understood as a heat storage system, which consists of a heat insulated tank for storing heat storage material and a heat carrier, which is used to transport heat to the heat storage material during its accumulation during the warm period and heat supply in the cold season from the heat storage material to energy consuming systems (heating system, hot water supply, etc.). The design of a heat accumulator with solid and liquid heat accumulating material is considered, in which a more uniform distribution of temperatures in the volume of the heat accumulator is achieved. A method for calculating structural elements for a heat accumulator with liquid and solid heat accumulating material has been developed, taking into account the heat loss of the heat accumulator and the characteristics of the soils at the construction site.

Identification of Optimum Operational Parameter Levels for Plain Basin, Corrugated Basin and Compartmental Basin Solar Stills

This study aimed at optimizing or maximizing the distillate production in plain basin, corrugated basin and compartmental basin solar stills by integrating them with optimum level of the four operational parameters - Mass of Heat Storage Material, Basin Water Depth, Basin Cover Thickness and External Mirror Position. The efficiency of the parameters is not uniform and it differs from still to still due to variation in the structure of the basin. Further, the most efficient level in a parameter differs from still to still. A particular basin water depth which is highly productive in plain basin still may not suit well for corrugated or compartmental basin still. To find out the optimum parameter levels, the 4 operational parameters and the four levels of each parameter were combined as per L16 orthogonal array and the distillate production under different combination of operational parameter levels were analyzed using S/N ratio analysis, mean response method, analysis of variance and regression analysis. The analysis revealed that the optimum mass of heat storage material was 16 kg in plain basin, 12 kg in corrugated basin and 10 kg in compartmental basin still. The efficiency of corrugated basin and compartmental basin solar stills was maximum at a lower basin water depth of 15 mm and 10 mm respectively. But plain basin still efficiency was maximum at a higher basin water depth of 20 mm. The optimum basin cover thickness was 4 mm in all the solar stills, in spite of a difference in the structure of the basin. In the same way, the distillate production was maximum when the external mirrors were positioned on the two sloping sides of the solar still (east and west direction). The expected production from the solar stills integrated with the optimum parameter levels was estimated using regression analysis and mean response method. The average distillate production which was 3304, 3493 and 3629 ml/m2.day in the modified (not with optimum parameter levels) plain basin, corrugated basin and compartmental basin solar stills respectively, improved to 6414, 7153 and 7629 ml/m2.day respectively when they were modified with optimum parameter levels and the increase in production was 94 %, 105 % and 110 % respectively.

ONE OF THE APPROACHES TO SOLVE THE PROBLEM OF THE COST OF A PHASE TRANSITION HEAT ACCUMULATOR FOR A SOLAR HEAT SUPPLY SYSTEM

Based on the analysis of the Russian market of basic materials for phase-shifting heat accumulators (FPAT), including the issue of pricing policy, an attempt was made to reveal the dependence of the cost of a heat accumulator for a solar thermal supply system on operating and design parameters. In turn, to determine the latter, the method was used, which makes it possible to design FPAT with given design and technological parameters, at a given minimum temperature of the coolant at the outlet of the accumulator, the known thermophysical characteristics of the coolant and heat storage material (TAM), including the phase transition temperature