Reducing the power consumption of household refrigerators through the integration of latent heat storage elements in wire-and-tube condensers

This study evaluates the influence of latent heat storage elements on the condenser temperature of a commercial household refrigerator. In order to determine the power consumption and the temperature distribution, a standard wire-and-tube condenser is equipped with different heat storage elements (containing water, paraffin or copolymer compound). The results indicate that particularly the application of phase change materials (PCM) lowers the condenser temperature, which leads to a significantly reduced power consumption.     

Effect of expander shape on cooling characteristics by using a model pulse tube refrigerator

Pulse tube refrigerators do not have moving parts in the cold section, and they have low vibration, high reliability, and long life. The expander in refrigerators typically has an inverted U or coaxial shape because this attains a wider absorber area, lower height, and compactness. However, the performance of a Stirling-type pulse tube refrigerator is inferior to that of a Stirling refrigerator. Cooling characteristics of the pulse tube refrigerator greatly depend on the shape of the expander. In this study, an inertance-type refrigerator, which uses ambient air for the working gas, was developed to examine the effect of expander shape. This refrigerator model with changeable expander operated with a Stirling cycle, and it was composed of a reciprocating compressor, after-cooler, regenerator, absorber, pulse tube, hot-end, and inertance tube with reservoir. The following expander shapes were tested: in-line, L shape, L-L shape, and coaxial shape. The effect of expander shape on cooling capacity was examined experimentally and numerically using the model pulse tube refrigerator. The results of experiments showed that the L shape expander had the highest performance and the coaxial expander had the lowest performance. In addition, the characteristics of the gas flow in each expander were confirmed by fluid dynamics analysis.     

对利用低温位热能来驱动的几种制冷装置性能的比较

对利用低温位热能来驱动的几种制冷装置性能进行了比较，以喷射式制冷为基础，以HCFC－123为工质的制冷装置是比较理想的新型空调用制冷装置．     

浅析一次泵系统变流量的可行性

分析了一次泵系统变频中变流量运行对制冷机和系统COP的影响。认为采取变频运行可行,并提出一些技术要求。     

提高浅冷装置轻烃产量技术研究

根据浅冷装置的运行现状,对制约轻烃产量的因素进行分析,对轻烃生产及输送工艺实施优化,使现有资源得到有效利用,实现提高装置轻烃产量及装置本质安全的目的。     

SAFARI engineering model 50 mK cooler

SAFARI is an infrared instrument developed by a European based consortium to be flown in SPICA, a Japanese led mission. The SAFARI detectors are transition edge sensors (TES) and require temperatures down to 50 mK for their operation. For that purpose we have developed a hybrid architecture based on the combination of a 300 mK sorption stage and a small adiabatic demagnetization stage. An engineering model has been designed to provide net heat lifts of 0.4 and 14 μW respectively at 50 and 300 mK, with an overall cycle duration of 48 h and a duty cycle objective of over 75%. The cooler is self-contained, fits in a volume of 156 × 312 × 182 mm and is expected to weigh 5.1 kg. It has been designed to withstand static loads of 120 g and a random vibration level of 21 g RMS.     

低温技术在太空监测领域的应用

随着低温技术的发展,制冷机的各方面工作性能显著改进,低温技术在航天领域得到了广泛应用。介绍了低温技术在国外太空监测卫星中的应用情况,分析其发展趋势。对太空监测所需要不同温度区间的制冷方法进行了总结,最后以国外执行监测任务卫星上的制冷系统为例说明制冷系统设计过程。     

Research and Development of Superconducting Magnet for Fusion Power

This paper describes mainly technological achievment of superconducting magnet for fusion power for the latest 10 years in Japan. The magnet development had been devoted to tokamak Fusion Experimental Reactor (FER). The major results obtained up to now are as follows.

In toroidal coil program, 12 T field generation, which is requested in a reactor toroidal coil, was realized with 6 kA multifilamentary Nb3Sn conductor in 1 m bore. For scaling-up of toroidal coil, half size coils of FER, LCT coils were tested up to 9 T.

In poloidal coil program, Demo Poloidal Coil project is now under way and coil testing will be started in spring of 1989. The stored energy of this coil is around 40 MJ.

In cryogenic technology program, fabrication and operation of large helium refrigerator technology were well established. A supercritical helium pump of 500 g/s was tested for forced flow coil.     

Experimental investigation of energy consumption and environmental impact of adaptive defrost in domestic refrigerators

With the development of human modern society at the turn of the new century, more and more people tend to use new technologies. To keep in tandem with modern technologies, food storage became easier with domestic refrigerators. In such systems, frost formation can be a fundamental problem especially in tropical countries with hot and humid ambient conditions. An adaptive method for defrosting the evaporator of a domestic refrigerator system is presented in this paper. In this method, parameters namely open door time, compressor ON time, previous defrost duration, mode of compressor, fans, and heater action before, during, and after defrost have been considered effective on defrost operation. Experiments have been carried out on two different case study top mounted freezers. Experimental results for case study 1 showed that the adaptive defrost in comparison to the fixed defrost cycles could reduce the energy consumption and Total Equivalent Warming Impact (TEWI) about 13% and 12.5%, respectively. The same parameters for case study 2 were decreased 5.5% and 5.2%, respectively. Furthermore, temperature variation of the compartments for both case studies decreased in comparison to that of their corresponding base case, which prevents quality loss of the stored food during defrost. Briefly, the results showed lower energy consumption, more environmentally friendly effects, and lower compartment temperature change.     

Numerical investigation of thermoacoustic refrigerator at weak and large amplitudes considering cooling effect

In this paper, OpenFOAM package is used for the first time to simulate the thermoacoustic refrigerator. For simulating oscillating inlet pressure, we implemented cosine boundary condition into the OpenFOAM. The governing equations are the unsteady compressible Navier–Stokes equations and the equation of state. The computational domain consists of one plate of the stack, heat exchangers, and resonator. The main result of this paper includes the analysis of the position of the cold heat exchanger versus the displacement of the pressure node at large amplitude for successful operation of the refrigerator. In addition, the effect of the input power on the successful operation of the apparatus has been investigated. It is observed that for higher temperature difference between heat exchangers, the time of steady state solution is longer. We show that to analyze and optimize the thermoacoustic devices, both heat exchangers should be considered, coefficient of performance (COP) should be checked, and the successful operation of the refrigerator should be evaluated.