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991.
M. P. Annaorazov S. A. Nikitin A. L. Tyurin S. A. Akopyan R. W. Myndyev 《International Journal of Refrigeration》2002,25(8):1034-1042
The heat-pumping scheme based on the 1st order antiferromagnetism–ferromagnetism transition induced in FeRh alloy by one-dimensional tensile stress is proposed. Using the model S–T diagram for this alloy, the heat-pump cycles are drawn up based both on the transition latent heat absorption and emission when the transition is induced isothermally and on the change in alloy's temperature when the transition is induced adiabatically by applying tensile stress. The calculated values of heat coefficient φ for the cycles are 30 at ΔT=5 К and 20 at ΔT=10 К, where ΔT is the difference between the temperature surrounding and that of the heat receiver. These values are achieved using the tensile stress of 1·109 Pa. The high values of φ make it possible to consider Fe–Rh alloys near the equiatomic composition as an effective refrigerant for elastocaloric heat-pumping near the room temperature. 相似文献
992.
MELCOR has become the preferred code of the Swiss nuclear industry and of PSI for severe accident analysis, on account of its integrated systems-level approach and validation against experiments and more detailed codes, while MACCS is commonly used by safety authorities for independent assessment of off-site consequences, in particular health effects. The present work arises out of a programme to assess MELCOR independently using empirical data consistent with the recommendations of the OECD/CSNI validation matrix for core degradation codes. The MELCOR 1.8.5RD calculations are based on a model for phases 1 and 2 provided by the code developers but with a simplified thermal hydraulic noding in certain regions and the inclusion of a simple representation of the fission product release and transport pathways. The model has also been extended to simulate phases 3, 4, and the continuing initial period of core recovery and stabilisation. These calculations are a first attempt to demonstrate a MELCOR–MACCS capability to simulate the whole plant accident sequence beyond phase 4, including the containment response and off-site consequences arising from fission product release from the containment. Emphasis is placed on the overall accident evolution and whole plant response, rather than the detailed behaviour. Results are compared with observed and deduced data for the major accident signatures and rough estimates for exposure based on off-site monitoring. The results provide a good basis for the NPP analysis foreseen. 相似文献
993.
In recent years, multiphase steels have become a material of choice for use in the car manufacturing industry owing to their excellent mechanical properties. It is anticipated that in the years to come these steels will show the highest increase in usage. A particular aspect of their potential is that multiphase steels often show good bake hardening (BH) properties. The main factors that govern the microstructures and the properties of these steels are the chemical composition and the production process parameters. In this work two commercial cold rolled sheet steels with different carbon content were investigated. In order to produce dual phase (DP) steels with a ferrite‐martensite microstructure, the as‐received material was subjected to heat treatment simulating continuous galvanising line (CGL) cycles with an overageing zone before the zinc pot. After a first CGL cycle predominantly ferritic microstructures with small amounts of martensite, pearlite and retained austenite were obtained, which resulted in deviations from typical DP properties, e.g. in the occurrence of discontinuous yielding. A higher line speed led to improved mechanical properties. BH prestrain was varied between 0 and 10%. While only very little bake hardening was observed without prestrain, with increasing prestrain the amount of BH was evolving quickly towards larger values of more than 60 MPa. Generally, the BH values were somewhat larger for higher carbon content. Finally, an optimised CGL cycle was simulated at laboratory scale with changes in the process parameters. Thus, characteristic DP microstructures resulting in desired mechanical properties were obtained. For these optimised conditions, BH2 values in excess of 60 MPa were achieved for both steels investigated. 相似文献
994.
直流开关电源的研究 总被引:1,自引:6,他引:1
本文以Dickson电荷泵的基本原理为出发点,研冤了一种输出是负电压的开关电容电源电路参考功率MOSFET的电容模型通过增大驱动电路的电流减小了开关管的上升延时.提高了开关动作的速度,使转换效率得到明显提高。同时,针对开关电容的充放电特点,采用非交叠(nonoverlap-ping)时钟控制信号避免了由于时钟交叠而造成的两级开关同时导通的现象,提高了电路的稳定性和可测试性采用压控震荡器频率的变化来控制功率开关管的开关时间,有效地控制了由于负载变化而造成的输出电压不稳定等现象。此电路结构简单,性能优良,易于集成,可广泛应用于输出负电压的电源产品中。 相似文献
995.
996.
介绍一种新型的可以单独或同时利用多种能源的溴化锂吸收式冷温水机,并对其实际应用进行系统的说明。 相似文献
997.
应用于热泵热水器的工质性能对比研究 总被引:4,自引:0,他引:4
从热泵热水器的原理和基本理论循环出发,分别对R22、R134a、R407C和R417a四种工质进行理论计算和对比分析,以便对热泵热水器的设计提供一定的参考。结果表明,四种工质中R134a和R417a最具推广价值,其结果还有待实验进行进一步论证。 相似文献
998.
刘涛 《制冷与空调(四川)》2006,20(3):98-100
随着能源价格的上涨,太阳能的利用问题越来越引起人们的重视。本文主要介绍太阳能热泵装置的工作原理及技术特点,对太阳能热泵中央热水系统的效率进行分析,提出应大力推广太阳能热泵技术在我国的应用。 相似文献
999.
混合式土壤源热泵应用分析 总被引:7,自引:0,他引:7
土壤源热泵在冷热负荷有较大差异地区的应用会使土壤温度场恢复缓慢,导致热泵效率逐年降低,为此提出混合式土壤源热泵,对其组成结构、应用方式及控制策略进行分析与探讨。 相似文献
1000.
在地源热泵运行过程中,利用间歇过程,弥补土壤传热慢的缺陷。土壤源热泵间歇运行时间可以改变土壤温度的变化规律,增强传热并实现更佳的热泵运行工况。实验是在冬季运行工况下进行的,着重对间歇运行条件下地温变化趋势进行研究。 相似文献