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[en] Thermal energy storage system (TES) is developed to extend the operation of power generation. TES system is a key component in a solar energy power generation plant, but the main issue in designing the TES system is its thermal capacity of storage materials, e.g. insulator. This study is focusing on the potential waste material acts as an insulator for thermal energy storage applications. As the insulator is used to absorb heat, it is needed to find suitable material for energy conversion and at the same time reduce the waste generation. Thus, a small-scale experimental testing of natural cooling process of an insulated tank within a confined room is conducted. The experiment is repeated by changing the insulator from the potential waste material and also by changing the heat transfer fluid (HTF). The analysis presented the relationship between heat loss and the reserved period by the insulator. The results show the percentage of period of the insulated tank withstands compared to tank insulated by foam, e.g. newspaper reserved the period of 84.6% as much as foam insulated tank to withstand the heat transfer of cooking oil to the surrounding. The paper finally justifies the most potential waste material as an insulator for different temperature range of heat transfer fluid
[en] The applicability of the generalized BCS approximation in the presence of proton-neutron pairing is studied in the context of two algebraic models. The analysis suggests that approximations based solely on pair correlations cannot describe the ground states of these models. Full symmetry restoration or inclusion of four-body α-like correlations is required. (author)
[en] Highlights: ► Two types of solar thermally driven absorption refrigeration machines (ARMs) have been investigated. ► We investigated the influence of the operating conditions on the effectiveness of the ARMs. ► The influence of the flow rate of the work solution on the effectiveness of the ARMs has been tested. ► Two laboratory test plants have been built and tested under different operating conditions. - Abstract: A big increase in the number of solar thermal cooling installations and research efforts could be seen over the last years worldwide. Especially the producers of solar thermal collectors and systems have been looking for thermal chillers in the small capacity range to provide air conditioning for one or two family houses. Furthermore, many developments aim to increase the efficiency of the system and to decrease the specific costs of the produced refrigeration capacity. The growth in the use of solar thermal cooling systems amounted about 860% from 52 units in 2004 to 450 units in 2009 . This tendency is expected to be continuously in the next years. The practical examinations on solar thermally driven absorption machines with refrigeration capacity of 15, 10 and 5 kW have shown that this technology has a good chance to be standardized and to replace partly the conventional one. These systems can save more primary energy at high fraction of solar thermally driving by suitable control and regulation of the system. The investing costs still higher as the conventional one, however, the operating costs are less than the conventional one. The Coefficient of Performance (COP) depends on the kind of the system, work temperatures and conditions as well as the refrigeration capacity of the systems. It lies between 0.4 and 1.2. In the framework of the research on this field, we built, tested and measured two prototypes. After measuring the first prototype, the chillers were redesigned to reduce internal heat losses and make the heat and mass transfer over the surfaces of heat exchangers more effective. Thus, many investigations have been done on some types of heat exchangers for optimization of heat and mass transfer in the system. In this contribution we will show some investigation results on solar thermally driven system in small capacity range. Moreover, we will illustrate an experimental setup for investigation of heat transfer by shell tube heat exchanger consisting of two kinds of tubes. The first one has a smooth outer surface and the other one has a ribbed outer surface. The aim of these investigations is to optimize the whole system.
[en] Relevance is determined by necessity of utilizing of local low-grade fuels by energy equipment. Most widespread Tomsk oblast (Russian Federation region) low-grade fuels are described and listed. Capability of utilizing is analysed. Mass balances of heat-technology conversion materials and derived products are described. As a result, recycling capability of low-grade fuels in briquette fuel is appraised
[en] Highlights: ► Thermal interferences progress with borehole compaction, 7 × 6 and 21 × 2 grids analyzed. ► Two numerical models used for heat transfer; ASHRAE/Kavanaugh and Lund/Eskilson. ► A/K model uses simplistic borehole interaction to predict heat build up in the ground. ► L/E model more advanced borehole interaction which results in greater loop length. ► Detailed evolution of ground and borehole fluid temperatures given for 30 year period. - Abstract: Properly sized borehole heat exchanger in geothermal heat pump system (widely known also as ground source heat pump system) needs to minimize long-term ground and working fluid temperature changes. These changes occur due to imbalances of heat extracted from the ground during winter and heat rejected into the ground during summer months, as well as thermal interferences of adjacent boreholes in borehole array. Simple calculations and spreadsheet-based analogical solutions of required borehole length for heat transfer run into difficulties when dealing with such large, complex ground source heat pump heating and cooling systems which use compact borehole array. A number of analytical computer programs are available to simulate how ground loop fluid temperature varies in such complex systems, using so-called ‘g-function’ – a mathematical function dependent on the geometry and shape of the borehole array. The type of calculation involves a type of ‘step-function’, where 24 h ‘step’ of peak loading is superimposed on a top of a long-term base load. In analytical simulation models, the base load is typically specified as the heating and cooling load per month of a typical year, and is simulated as the combination of sequential monthly steps. This paper will show, by simulating long-term operation of complex geothermal heat pump system with multiple boreholes in various geometric arrays, how spacing of adjacent boreholes and thermal interferences influence required borehole length for heat transfer.
[en] A solar-assisted ejector cooling/heating system (SACH) was developed in this study. The SACH combines a pump-less ejector cooling system (ECS) with an inverter-type heat pump (R22) and is able to provide a stable capacity for space cooling. The ECS is driven by solar heat and is used to cool the condenser of the R22 heat pump to increase its COP and reduce the energy consumption of the compressor by regulating the rotational speed of the compressor through a control system. In a complete SACH system test run at outdoor temperature 35 deg. C, indoor temperature 25 deg. C and compressor speed 20-80 Hz, and the ECS operating at generator temperature 90 deg. C and condensing temperature 37 deg. C, the corresponding condensing temperature of the heat pump in the SACH is 24.5-42 deg. C, cooling capacity 1.02-2.44 kW, input power 0.20-0.98 kW, and cooling COPc 5.11-2.50. This indicates that the use of ECS in SACH can effectively reduce the condensing temperature of the heat pump by 12.6-7.3 deg. C and reduce the power consumption by 81.2-34.5%. The SACH can also supply heat from the heat pump. At ambient temperature from 5 deg. C to 35 deg. C, the heating COPh is in the range 2.0-3.3.
[en] The market development in the past 20 years for photo-thermal systems will be reviewed. The reasons for the collapse of the solar market in the early 1980's will be discussed. The Solar Energy market in recent years due to adverse environmental effects of burning fossil fuels and its consequences will be discussed. Various types of solar systems and their evaluation and definition as well as a study of the components used in the systems will be briefed. The latest development in solar collectors and systems will be reviewed. Projection of future developments in solar energy in Europe will be made and Governmental support to the solar industry in different EC countries will be presented. (author)
[en] This study emphasis the requirement of integrated approach for regulate the global temperature rises to protect the planet form climate changes and other system changes. It is clear that effect of global temperature increases, have already affected many physical and biological and human systems, This unbalances of global systems is more rapid after 1950' s increases of using environmental polluting energy sources with releasing the pollutants to global systems together with extra solar energy accumulation. How ever as a solution it is require to reduce pollutants and balance the energy level to optimum within the caring capacity. To protect the planet as a sustainable system with controlling temperature rises and other unbalances it is important to keep and protect the interrelationship of each and every system with protecting mechanisms. Therefore it is require integrated approach to establish protective mechanisms for each and every sectors of badly effecting with considering regional, national. international and global level.
[en] This paper presented a symmetric prismatic daylight collector to collect daylight for the natural light illumination system. We analyzed the characteristics of the emerging light when the parallel light beam illuminate on the horizontally placed symmetric prismatic daylight collector. The ratio of the relative intensities of collected daylight that emerging from each surface of the daylight collector shown that the ratio is varied with the incident angle during a day. The simulation of the emerging light of the daylight collector shown that the ratio of emerging light is varied with the tilted angle when sunshine illuminated on a symmetric prismatic daylight collector which was not placed horizontally. The integration of normalized intensity is also varied with the tilted angle. The symmetric prismatic daylight collector with the benefits of reducing glare and dividing intensity of incident daylight, it is applicable to using in the natural light illumination system and hybrid system for improving the efficiency of utilizing of solar energy. (paper)
[en] The reasons for the increasing popularity of using solar energy as one way of meeting the global energy demand are outlined. However, the solar energy industry needs to approach marketing its products rationally and carefully to assure future growth of its market share of power production. The need for clear marketing strategies alongside a good understanding of solar technology are emphasised. (UK)