夹杂物对粉末冶金高温合金力学性能的影响

综述了非金属夹杂物对粉末冶金镍基高温合金力学性能影响的研究现状,特别着重夹杂物尺寸、位置、形态、数量等对粉末冶金镍基高温合金低周疲劳寿命(LCF)的影响。文中提出粉末冶金高温合金存在的问题及今后的研究方向。     

EES在有机朗肯循环系统热力特性仿真研究中的应用

有机朗肯循环（OrganicRankineCycle,ORC）是在传统朗肯循环中采用有机工质（~IRl13,R123等）代替水推动膨胀机做功的循环,本文根据集总参数法和能量守恒定律建立有机朗肯循环系统的数学模型,运用软件工程方程求解器（EngineeringEquationSolver,EES）进行仿真研究,得到不同工况下有机朗肯循环系统热力特性的变化规律。研究结果表明,提高系统蒸发压力、降低系统冷凝压力以及选择效率尽可能高的膨胀机,可以提高有机朗肯系统循环热效率。仿真计算结果与实验数据二者吻合较好,表明所发展的数学模型可以满足有机朗肯循环热力系统仿真的要求。     

CO2 heat pump systems

After the CFCs and the HCFCs were deemed unfit as working fluids in refrigeration, air conditioning, and heat pump applications, there has been a renaissance for carbon dioxide technology. Heat pumps is one of the application areas where theoretical and experimental investigations are now performed by an increasing number of research institutions and manufacturers. This paper gives an overview of some of the current activities in the CO₂ heat pump field. Discussed are the important characteristics of the transcritical CO₂ process applied to heat pumps, and also discussed are theoretical and experimental results from several heat pump applications. Provided that calculations and system designs are performed on the premises of the working fluid, and that test plants are constructed and operated to fully exploit the specific characteristics of both the fluid and the transcritical process, the results show that CO₂ is an attractive alternative to the synthetic fluids. Competitive products may be launched in the near future.     

逆布雷顿循环微型低温制冷机

在目前广泛采用的低温制冷循环中,以透平机械为主的逆布雷顿循环制冷机有望能够满足卫星,宇宙飞船等航天器上低冷量,高性能,高效率的特殊要求,成为空间制冷的一种选择,总结了近几年空间用逆布雷顿循环制冷机的研究成果,表明由ＤＣ－ＡＣ转换器,微型离心式压缩机,微型透平膨胀机及高效紧凑式换热器组成的微型逆布雷顿循环制冷机是一种有前途的微低温制冷机。     

循环淬火工艺对连铸10CrNi3MoV钢组织与性能的影响

针对高温热成型及正常调质处理后结构件用连铸10CrNi3MoV钢性能恶化这一问题,采用循环淬火热处理工艺研究了力学性能、显微组织及晶粒度。结果表明,采用860℃三次循环淬火+高温回火(630℃×3 h)热处理工艺,能够有效细化连铸10CrNi3MoV钢的晶粒,改善其低温韧性,使其力学性能满足使用要求。     

Hybrid absorption heat pump with ammonia/water mixture – Some design guidelines and district heating application

An ammonia/water mixture can be used as an efficient working fluid in industrial-type heat recovery heat pumps and heat transformers. Several configurations of such systems are possible depending on the availability of the waste (thermal) and primary (thermal or electrical) energy sources. This article presents the configurations, the main thermodynamic and hydraulic parameters, and some design guidelines and operating experiences of a medium-temperature, ammonia/water-based compression/re-sorption heat recovery system for district domestic hot water production. In-field experiments have proven the advantages of the concept and its applicability limits in a particular economical environment, while hot water was produced at 55 °C with industrial cooling water at 36 °C as a waste heat source.     

电动汽车的发展及配套蓄电池

分析了发展电动汽车的必要性,介绍了国内外电动汽车的现有水平。对我国今后如何进一步开展电动汽车及配套蓄电池的研究与开发,发表了粗浅的议论。     

不同剂量 X射线全身照射对小鼠胸腺细胞周期进程的影响

本文采用细胞计量术研究了不同剂量Ｘ射线全身照射后小鼠胸腺细胞周期进程的变化。结果表明,７５ｍＧｙ Ｘ射线全身照射后２４～７２ｈ胸腺细胞周期各时相细胞数目发生明显变化,Ｇ０／Ｇ１期细胞数低于对照组,Ｓ期细胞数增多,说明其ＤＮＡ合成能力增强,至７ｄ时达到对照组水平;２．０Ｇｙ全身照射后４ｈ时胸腺细胞便开始出现明显的Ｇ２阻滞,１２ｈＧ２阻滞达最高点,７２ｈ其细胞周期进程明显加快,至７ｄ时达对照组水平。不     

A correlation-free on-line optimal control method of heat rejection pressures in CO2 transcritical systems

This paper proposes a novel correlation-free on-line optimal control method for CO₂ transcritical refrigeration systems. It uses the on-line correction formula to track the optimal pressure set point. As a critical advantage against the existing empirical correlations of the heat rejection pressure, it is independent of the cycle, the system specifications, and the operating conditions. Dynamic numerical simulation demonstrates how to apply the new method to a basic CO₂ transcritical refrigeration system. The results show that the proposed method can well track the optimal pressures and is robust to resist the sampling noise.     

Design of high efficiency mixed refrigerant Joule–Thomson refrigerator for cooling HTS cable

The substitution of high temperature superconducting (HTS) cables for existing subterranean electric transmission lines is arising as a solution to continuously increasing electricity demand in urban areas. A cryogenic refrigeration system having the characteristics of high reliability, high efficiency, large cooling capacity, and low capital cost is essential to enable such a substitution. These requirements can be satisfied with a mixed refrigerant Joule–Thomson (MR JT) refrigerator. Unfortunately, usual MR JT refrigerators exhibit good performance at refrigeration temperatures above 80 K. A precooled neon–nitrogen MR JT refrigerator is proposed in this paper that can cool HTS cables at 70 K. The coefficient of performance (COP) of the proposed MR JT refrigerator is predicted to be 0.058 at 70 K (19.2% for exergy efficiency) with the optimized design variables. The COP can be improved further to 0.064 by enhancing the efficiency of the precooling cycle. The maximum achievable COP demonstrates the feasibility of MR JT refrigerator for cooling HTS cable.