Irreversible refrigerators with isothermal heat exchanges: Réfrigérateurs irréversibles avecéchanges thermiques isotherms

A maximum for the coefficient of performance (COP_f) is verified for a temperature difference between reservoirs and the hot isotherm of a closed irreversible cyclical refrigerator working at steady-state conditions. A maximum also exists when the COP_f is considered as a function only of a parameter depending on the thermal characteristics of the heat exchangers. The influence of the parameter and entropy generation on the COP_f maxima is described.     

溴化锂吸收式制冷机制冷量衰减问题的可靠性工程分析

可靠性工程的理论和方法已经深入到科学研究以及产品、工程设计的各个专业领域。本文通过应用可靠性工程基本概念和故障树分析方法,就溴化锂吸收式制冷机的制冷量衰减问题进行分析讨论,提出了提高机组性能和可靠性的主要途径。     

Balloon-borne He cryostat for millimetre bolometric photometry

A cryostat including a ³He refrigerator has been designed, built, coupled to a multiband far infrared (FIR) photometer and successfully operated on a balloon flight. Here the cryostat, which is able to cool three bolometers to 0.3 K and one to 1.5 K, is described. The total holding time of the cryostat exceeds 5 days, being limited by exhaustion of the main ⁴He and N₂ baths. The autonomy of the ³He cryostat is more than 50 h, and the recycling time is ≈3 h. The performance of the system in the ARGO 1993 flight is also reported.     

Estimation on Magnetic Refrigeration Material （Gd1-xREx）5Si4 （RE=Dy, Ho）

A systematic (Gd1-xREx)5Si4 (RE=Dy, Ho) alloys are investigated to estimate their magnetocaloric effect.The Curie points of (Gd1-xREx)Si4 alloys can tunable from 266 K to 336 K when RE=Dy, Ho; x=0～0.35 and 0～0.15, respectively, and decrease nearly linearly with increasing x. These alloys keep orthorhombic structures Ge5Sm4 and exhibit second order transition when they experience in a change magnetic field at about Curie when magnetic field changes 0～2 T. The adiabatic temperatures changes (△Tad) of these alloys at Curie points are larger than 1 K in a field change 0～1.4 T, the curve of △Tad is wide as that of Gd. The relative cooling power is about 0.8～0.9 J/cm3 when field changes 0～2 T, 55% of that of Gd. Comparing with Gd5(Si1-xGex)4, these alloys do not contain expensive element Ge, so that their cost are lower than the former. Because they could work at temperature region 260～340 K due to their Curie points can be tuned, which is an advantage comparing with Gd, these alloys are potential magnetic refrigerants working in a magnetic refrigerator with a low magnetic field at room temperatures.     

Two-dimensional model for tapered pulse tubes: Part 3: unsteady components of second-order mass flux and temperature

Unsteady components of the second-order axial velocity and temperature within a tapered pulse tube were obtained by using a hybrid method of solution. In this method, the unsteady components of the second-order axial velocity and temperature consist of an analytical solution and a numerical solution. The effects of the operating frequency and the taper angle on the unsteady components of the second-order mass flux and temperature were shown. The unsteady second-order mass flux and the time-averaged enthalpy flow by the unsteady second-order mass flux increase as the second-order displacement volume at the cold end increases.     

Influence of absorber effectiveness on performance of vapour absorption heat transformers

The effects of mass transfer effectiveness of absorber on the performance of single stage vapour absorption heat transformers were studied by making a thermodynamic analysis. The refrigerant absorbent pairs considered were R21-DMF and R21-DMETEG. The variations in performance parameters such as coefficient of performance, exergetic efficiency, concentration difference and circulation ratio with mass transfer effectiveness of the absorber at various operating temperatures were computed. Increasing the effectiveness of absorber resulted in increases in coefficient of performance, exergetic efficiency and concentration differential across the absorber. The improvements in coefficient of performance and exergetic efficiency with mass transfer effectivensss of the absorber were more pronounced for the R21-DMF pair than for R21-DMETEG. Correlations are presented for quick estimation of performance under different operating conditions.     

基于微功率无线通信技术的电冰箱能效试验系统的设计（下）

传统的电冰箱能效试验采用的热电偶连接线必须跨越冰箱门才能连接到温度记录仪上,这样必定在冰箱门处产生细小的缝隙,从而影响了间室的密封性,使检测的结果出现误差。该文介绍了一种利用微功率无线通信技术开发的新型检测系统,避免了此类误差的产生,并阐述了该系统的工作原理和软硬件结构。实际应用证明,该系统各方面性能良好,测量数据准确...     

Closed door moisture transport in refrigerator/freezers

An experimental technique for determination of exterior and interior water mass transport in domestic refrigerator cabinets is presented. Water vapour mass transfer rates from the freshfood cabinet to the evaporator, and water vapour mass transfer rates from the surrounding ambient into the cabinet are presented. An estimate of the energy impact of water mass transfer into a typical domestic refrigerator cabinet is presented. Copyright © 2002 John Wiley & Sons, Ltd.     

半导体制冷器的应用研究

提出一种节能型的培养箱,用半导体制冷器来实现培养箱内的温湿度的平衡,通过手动控制实验、自动控制分系统实验和自动控制整机实验证明,将半导体制冷器用于培养箱是可行的。