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[en] The Carnot, Diesel, Otto, and Brayton power cycles are reconsidered endoreversibly in finite time thermodynamics (FTT). In particular, the thermal efficiency of these standard power cycles is compared to the well-known results in classical thermodynamics. The present analysis based on FTT modelling shows that a reduction in both the maximum and minimum temperatures of the cycle causes the thermal efficiency to increase. This is antithetical to the existing trend in the classical references. Under the assumption of endoreversibility, the relation between the efficiencies is also changed to , which is again very different from the corresponding classical results. The present results benefit a better understanding of the important role of irreversibility on heat engines in classical thermodynamics. (paper)
[en] Efficiency of a finned single-pass solar air collector was studied. This paper presents the experimental study to investigate the effect of solar radiation and mass flow rate on efficiency. The fins attached at the back of absorbing plate to improve the thermal efficiency of the system. The results show that the efficiency is increased proportional to solar radiation and mass flow rate. Efficiency of the collector archived steady state when reach to certain value or can be said the maximum performance
[en] Presented here is a review of two methods by which the thermal contact resistance occurring at the metal-to-metal interfaces that exist in heat exchanges can be reduced. The two methods discussed, inserting a thin metal foil into the interface or coating one of the surfaces with a thin metallic coating, have the potential to significantly reduce the thermal contact resistance and thereby improve the overall system thermal efficiency and performance
[en] In the presented work, the specific features of the crystal lattice of the TISe type and the principle of producing semiconducting thallium chalcoindianates and alloys based on them with rareearth elements are described in detail. Correlations between the physical properties and the content of rare-earth elements in the compositions of the studied materials are given. The results of experimental studies on the radiation effects arising under the influence of gamma radiation are presented.
[en] The results of numerical research on the determination of the temperature value of the internal surface of the heat-removing channel (HRC) walls of the light-absorbing heat-exchange panels (LAHPs) with the tubeon- sheet and thin-parallelepiped form of flat-plate solar water-heating collectors (FPSWHCs) are presented. The research method is based on compilation of the system of the balance equations for the light-absorbing plate (LAP) and HRCs of the LAHPs of the studied types and their designs with respect to the desired parameter. A practical example of calculation of the determination of the temperature value of the internal surface of the HRC wall of the tube-on-sheet LAHP, where the results of experimental research on the determination of the specific thermal efficiency of the mean-quality FPSWHC in full-scale terms, as well as laboratory and numerical research on determination of the optical and thermotechnical indicators of the copper tube-on-sheet LAHP.
[en] In this paper, a comparative analysis of single-gate dopant-segregated Schottky barrier (DSSB) SOI MOSFET and raised source/drain ultrathin-body SOI MOSFET (RSD UTB) has been carried out to explore the thermal efficiency, scalability and analog/RF performance of these devices. A novel p-type δ-doped partially insulated DSSB SOI MOSFET (DSSB Pi-OX-δ) has been proposed to reduce the self-heating effect and to improve the high-frequency performance of DSSB SOI MOSFET over RSD UTB. The improved analog/RF figures of merit such as transconductance, transconductance generation factor, unity-gain frequency, maximum oscillation frequency, short-circuit current gain and unilateral power gain in DSSB Pi-OX-δ MOSFET show the suitability of this device for analog/RF applications. The reduced drain-induced barrier lowering, subthreshold swing and parasitic capacitances also make this device highly scalable. By using mixed-mode simulation capability of MEDICI simulator a cascode amplifier has been implemented using all the structures (RSD UTB, DSSB SOI and DSSB Pi-OX-δ MOSFETs). The results of this implementation show that the gain-bandwidth product in the case of DSSB Pi-OX-δ MOSFET has improved by 50% as compared to RSD UTB and by 20% as compared to DSSB SOI MOSFET. The detailed fabrication flow of DSSB Pi-OX-δ MOSFET has been proposed which shows that with the bare minimum of steps the performance of DSSB SOI MOSFET can be improved significantly in comparison to RSD UTB
[en] The SP-100 reactor subsystem design has been developed in more detail since last reported. Several key requirements have influenced the design substantially as the more detailed nuclear, thermal/hydraulic, and structural analyses have been completed for the various mission phases including accident safety performance characteristics. This paper summarizes the status of the design evolution as a result of these evaluations and provides a summary of selected performance characteristics for the design as it stood just prior to the System Design Review in May 1988
[en] The thermal efficiency of a nuclear power station may be determined by measurement, particularly simply, from an energy balance incorporating the whole power station. Thereby, only two energy flows of equal order of magnitude, i.a. the electrical output and the waste heat flow, and two energy flows which are smaller by several orders of magnitude, i.a. the energy flow of exhaust air and the rate of outside radiation, have to be measured. The practical application of this method in connection with an acception test is described. (orig.)
[de]Der thermische Wirkungsgrad eines Kernkraftwerks kann messtechnisch besonders einfach aus einer Energiebilanz ueber das gesamte Kraftwerk ermittelt werden. Dabei sind nur zwei Energiestroeme gleicher Groessenordnung - elektrische Uebergabeleistung und Abwaermestrom - und zwei um Groessenordnungen kleinere Energiestroeme - Abluftenergiestrom und Abstrahlungsleistung - zu messen. Ueber die praktische Anwendung der Methode bei einem Abnahmeversuch wird berichtet. (orig.)