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[en] In the design and operation of energy intensive systems, the possibility of improving the system's efficiency is very important to explore. The main way of improving efficiency is through thermodynamic analysis and optimization. Methods are universal and make it possible to estimate the fluxes and balances of all energy flows for every element of the system using a common criterion of efficiency. The thermoeconomical approach allows to retain all advantages of exergy method and simultaneously estimate the investment and other monetary costs of a system. In this paper is developed the method of thermoeconomical optimization of a heating system for cottage complex. Example of real optimization is given. (author)
[en] The article considers experimental studies of the hydrodynamic characteristics of the active section of the self-draining solar loop of a heating system. This element is designed as a flow constrictor referred to as Ventury tube, with a high degree of flow constriction of 2–5 in the region with strong viscous resistance. The experimental data are processed in a criteria form, the general type of which is obtained by dimensional technique and compared with data from other authors. The obtained criteria dependences can be used to calculate the hydrodynamic characteristics of the active section of the self-draining solar loop of a heating system.
[en] The author takes stock on the renewable energies available for a house, their advantages and efficiency. A special part is devoted to the heating (solar, wood and geothermal energy) and another to the electric power production and consumption. (A.L.B.)
[en] Glass micropipettes are versatile probing tools for performing micro- and nano-manipulation tasks. This paper presents the design and development of an automated pipette puller system for fabrication of glass micropipettes. The pipette puller employs a new strategy for fabrication of micropipettes that enables achieving independent control of their taper, tip diameter, and bend-angle, and also facilitates theoretical derivation of simple, approximate relationships between the pipette shape and the pulling parameters. Subsequently, the design and fabrication of the pipette puller is described, which include that of the pipette heating system, the mechanical motion stages, and the control electronics of the pipette puller. The fabricated pipette puller is experimentally evaluated to demonstrate control of the taper, tip diameter, and the bend-angle of the micropipette. Further, the dependence of the taper and tip diameter on the pulling parameters is evaluated and is shown to be in alignment with the proposed theoretical relationships
[en] The stability of α-, (β+γ)- and δ-tocopherols present in rice bran oil at different heating temperatures has been evaluated. For this purpose, samples of rice bran oil from chemical and physical refining processes in Brazilian industries were studied. The oils were submitted to cabinet drying without air circulation in the absence of light at 100 ºC, 140 ºC and 180 ºC. The samples were taken before heating and after 48, 144, 240, 336, 432, 576, 768, 1008 and 1368h of heating. The analyses of tocopherols were made by high performance liquid chromatography, with a fluorescence detector. It was determined that α-tocopherol was the compound with the fastest degradation rate at the three heating temperatures. The highest degradation rate of tocopherols in both oils occurred at 180 ºC. Among the tocopherols studied, α tocopherol presented the lowest stability, followed by (β+γ)- and δ-tocopherols.
[es]La estabilidad de los tocoferoles α-, (β + γ) - y δ presentes en los aceites de salvado de arroz a diferentes temperaturas de calentamiento fueron evaluadas. Para ello, se utilizaron muestras de aceite de salvado de arroz proveniente de los procesos de refinación química y física de industrias brasileñas. Los aceites fueron sometidos a 100 ºC, 140 ºC y 180 ºC, en cabinas de secado sin circulación de aire, bajo ausencia de luz. Las muestras fueron tomadas antes de la calefacción y después de 48, 144, 240, 336, 432, 576, 768, 1008 y 1368 h de calentamiento. El análisis de tocoferoles fue realizado por cromatografía líquida de alta eficacia, con detector de fluorescencia. Se observó que el α-tocoferol fue el compuesto con degradación más rápida en las tres temperaturas de calentamiento. La mayor tasa de degradación de los tocoferoles, en ambos aceites, ocurrió a la temperatura de 180 ºC. Entre los tocoferoles analizados, α-tocoferol presentó menor estabilidad, seguido por los (β + γ) - y δ-tocoferoles
[en] Radio frequency (RF) heating in the ion cyclotron range of frequencies (ICRF) is one of the primary auxiliary heating methods for EAST. The ICRF system provides 6 MW power in primary phase and will be capable of 10 MW later. Three 1.5 MW ICRF systems in a frequency range of 25 MHz to 70 MHz have already been in operation. The ICRF heating launchers are designed to have two current straps with each driven by a RF power source of 1.5 MW. In this paper a brief introduction of the ICRF heating system capability in EAST and the preliminary results in EAST are presented. (magnetically confined plasma)
[en] In this paper, experimental investigation of the molten metal jet's colliding and spreading behaviors on the flat steel surface covered with water layer was carried out. High-frequency induction heating system was utilized to produce the molten metal sample and it was released to the wet surface from a fixed elevation. As the molten metal collides against the surface, it rapidly goes through solidification while spreading on the wet surface. High-speed thermo-camera was utilized to measure the molten metal's surface temperature during the spreading transient. Once the molten metal completely solidifies, molten metal's spread area and thickness were measured. From the obtained database, a dimensional analysis was conducted to investigate the key parameters responsible for the molten metal spreading on the wet surface. Based on the key non-dimensional parameters identified in the current analysis, the new empirical correlation was proposed. Its predictive capability was found to be 18.9% in mean absolute relative deviation.
[en] Highlights: ► Which is better, to operate a heating system continuously under low boiler temperature or intermittently otherwise. ► Previous investigations were based on different building and operating conditions, such as those of Europe. ► Optimum boiler operation for different levels of insulations was obtained for Jordan. - Abstract: In this work, a comparative study of continuous versus intermittent heating in homes was performed. The thermal response factor and intermittent heating factor was found for a typical apartment building in Amman, Jordan. A comparison between several wall, roof, and floor constructions and several levels of insulation thickness was made and the heating load calculations for those constructions (steady state analysis and dynamic behavior) were performed. It was found that more comfort and more fuel saving and less initial and running costs were achieved when continuous heating at low temperature was adopted. Also, the optimization of continuous and intermittent heating was studied in order to minimize fuel economy and maximize thermal comfort. It was found that for high insulated apartment buildings, the continuous operation of the boiler at low water temperature is more economical than when it is operated intermittently at high temperature for more than 14 h per day.
[en] Highlights: • A new methodology to determine the pre-setting of a control valve was presented. • Exemplary calculations were performed for control valves for heating installations. • The results were compared with results obtained from alternative methodologies. • The proposed methodology returns results consistent with experimental data. • Proposed methodology in some cases is more accurate and versatile than compared ones. - Abstract: This paper presents and discusses a new methodology to determine the pre-setting of the radiator and balancing control valve, as one of the basic parameters in the process of the heating installation hydraulic balancing. Example calculations are also made for selected control valves using the proposed and alternative methodologies, including the methodology generally accepted and used in practice. A comparison of the results is presented. It is shown that the proposed methodology gives results consistent with experimental data. It is also more accurate and versatile than the other methodologies discussed in the paper
[en] Geothermal energy is generated from the radioactive decay of naturally occurring isotopes and about 20% is generated from primordial heat associated with the formation of the earth. Geothermal project reduce energy and water cost and reduces greenhouse gas emissions