电冰箱最佳灌注量的实验研究和理论解释

提出了最佳灌注量原理。利用新研制的实验用电冰箱对其制冷剂的灌注量进行了观察研究，对最佳灌注量原理进行了理论解释。     

Thermal grounding of a transmission line in a dilution refrigerator

The paper describes the design and use of transmission lines for applications in the gigahertz range. The lines are required to have uniform electrical impedance and low loss and to provide thermal grounding.     

Cooling load density characteristics of an endoreversible variable‐temperature heat reservoir air refrigerator

The performance optimization of an endoreversible air refrigerator with variable‐temperature heat reservoirs is carried out by taking the cooling load density, i.e. the ratio of cooling load density to the maximum specific volume in the cycle, as the optimization objective in this paper. The analytical relations of cooling load, cooling load density and coefficient of performance are derived with the heat resistance losses in the hot‐ and cold‐side heat exchangers. The maximum cooling load density optimization is performed by searching the optimum pressure ratio of the compressor, the optimum distribution of heat conductance of the hot‐ and cold‐side heat exchangers for the fixed total heat exchanger inventory, and the heat capacity rate matching between the working fluid and the heat reservoirs. The influences of some design parameters, including the heat capacitance rate of the working fluid, the inlet temperature ratio of heat reservoirs and the total heat exchanger inventory on the maximum cooling load density, the optimum heat conductance distribution, the optimum pressure ratio and the heat capacity rate matching between the working fluid and the heat reservoirs are provided by numerical examples. The refrigeration plant design with optimization leads to a smaller size including the compressor, expander and the hot‐ and cold‐side heat exchangers. Copyright © 2002 John Wiley & Sons, Ltd.     

Refrigeration performance enhancement of pulse tube refrigerators with He-H2 mixtures and Er3NiHx regenerative material

The computation with heat transfer, fluid flow and thermodynamics indicates that higher pulse tube refrigeration performance can be achieved with He-H₂ mixtures as working fluids than that with pure He in the cooling temperature region of 30 K. In addition, it is found that Er₃Ni, a regenerative material, is able to absorb H₂ and forms Er₃NiH_x. The hydrogen absorption capacity of Er₃Ni is about 3.5 H/Er₃Ni in the H₂ pressure region of 0.1-2.0 MPa at 30 °C. The calculation shows that the regenerative performance of Er₃NiH_3.5 is better than that of Er₃Ni due to its higher volume specific heat. Experimental results show that the pulse tube refrigeration performance in 30 K cooling temperature region is obviously enhanced with He-H₂ mixtures and Er₃NiH_x regenerative material.     

冷柜箱体粉末涂装线的技术改造

根据某冷柜厂产品特点及生产实际情况,对其原有洗衣机粉末涂装线依据冷柜箱体涂装的技术特点进行改造,详细介绍了冷柜粉末涂装的工艺及设备设计参数,重点阐述了前处理设备、水分烘干、粉末固化并体炉、喷粉系统、悬挂输送机和电气控制系统的改造方案.改进、调试后的涂装线很好地满足了生产要求.     

Efficient helium recondensing using a 4 K pulse tube cryocooler

This paper introduces helium recondensing in a 4000 l dewar using a 4 K pulse tube cryocooler at Amundsen-Scott research station at the South Pole. The helium dewar has a normal boil-off rate of 14 l/day. Two features of cooling the dewar neck by helium vapor and precooling helium gas to be liquefied ensured high efficiency of the pulse tube recondenser in this application. The liquefier/recondenser has being successfully operating in the dewar at South Pole station since February 2005. It not only maintains zero boil-off of the dewar, but also liquefies helium gas supplied from outside of the dewar with a rate around 2.7 l/day.     

二级塑料斯特林制冷机的热力设计探讨

本文对二级塑料斯特林制冷机的传热和流体流动进行了分析,以第二级最低制冷温度为目标函数,进行了二级机的直径比和长度比的优化设计探讨,给出了直径比和长度比与各级制冷温度和理论功耗的三维函数图,指出了转速、冲程和缝隙尺寸对塑料制冷机制冷性能的影响。     

中国散裂中子源低温系统氦制冷系统的安装与调试

氦制冷系统是中国散裂中子源(CSNS)低温系统的重要组成部分,能够为氢循环系统提供2 200 W@20 K的冷源。介绍了CSNS氦制冷系统的组成及设备布局图及氦制冷系统的调试原理,完成了控制界面图及氦制冷系统的安装和调试准备工作,详细说明了调试的过程,获得了700 W/1 400 W/2 200 W 3种制冷功率下的状态参数。氦制冷系统调试顺利完成,结果满足了验收指标。     

Effect of ordered helium bubbles on deformation and fracture behavior of α-Zr

Radiation-induced helium bubbles are detrimental to the mechanical properties of metals, usually causing severe hardening and embrittlement. Hexagonal close-packed (HCP) α-Zr alloys are one of the primary structural materials for nuclear applications, however, the effect of helium bubbles on their deformation and fracture behaviors still remains unexplored. Here, we found that ordered helium bubbles prefer to align along the basal plane in HCP α-Zr. Micro-scale in situ tensile tests revealed that helium bubbles less than 8 nm in size can increase the critical resolved shear stress of the prismatic slip. However, once the helium bubbles are larger than 8 nm, a bubble-softening effect happens due to a decrease in number density of helium bubbles and an increase in porosity. Once the Schmid factor of basal slip is considerably higher than prismatic slip, bubble coalescence along the basal plane becomes the major failure mode in helium-irradiated α-Zr.     

Design of non-flammable mixed refrigerant Joule-Thomson refrigerator for precooling stage of high temperature superconducting power cable

A cryogenic Joule-Thomson (JT) refrigerator has many advantages for large industrial applications, including easy cooling power adjustability and high reliability because there are no moving parts at low temperature. In this paper, a single stage and a cascade type of non-flammable (NF) mixed refrigerant (MR) JT refrigerators have been proposed for the precooling process of a neon/nitrogen mixed refrigerant JT refrigerator. The neon/nitrogen MR JT refrigerator is used to maintain a subcooled state of liquid nitrogen coolant for an HTS (high temperature superconductor) cable.Both selected MRs for the 1st stage (low temperature cycle) of the cascade MR JT refrigerator and the single MR JT refrigerator are composed of Nitrogen (N₂), Argon (Ar), Tetrafluoromethane (CF₄, R14) and Octafluoropropane (C₃F₈, R218). R410A is selected as the refrigerant for the 2nd stage (high temperature cycle) of the cascade MR JT refrigerator, of which the cooling temperature is approximately 240 K. A commercial software with Peng-Robinson equation of state (EOS) is utilized to design the non-flammable MR JT refrigerator. The optimal design is discussed with consideration for various parameters such as the temperature staging, the operating pressure of the compressor and the mass flow rate of the working fluid. The maximum coefficient of performance (COP) and Carnot efficiency of the cascade MR JT refrigerator are obtained as 0.216 and 40%, respectively at 105 K. Exergy analysis is also carried out in this paper to reveal the irreversibility of the refrigeration cycle.