From the viewpoint of environmental preservation, considerable interest is being advanced by the recycling of industrial goods such as home appliances. In terms of waste home appliances, there is an urgent need for an improvement in recycling rates for waste, because four items (refrigerators, airconditioners, washing machines and televisions) were designated as primary specified goods under those laws that encourage the use of recycled materials.
Under this situation, new merits are being discovered in low temperature crushing technology as an appropriate disposal technology for recycling activities. Here, crushing and separating technology for metal composites, and crushing and sorting technology for plastics will be introduced as examples of low temperature crushing technology developed for waste home appliances that achieves recycling rates of over 90% through recycle system for waste home appliances.

抄録全体を表示

It is necessary to have rectifier in NH₃-H₂0 absorption cycle in order to remove steam from ammonia and steam mixed vapor that is regenerated in generator. Although many studies have made to investigate the performance of rectifier using various fluids experimentally, few theoretical analysis has made without any constant from experimental data.
In this study in order to investigate the characteristic of rectifying process, experimental and analytical approach was made concerning plate-type rectifier. In the experiment, the effect of vapor flow rate and NH₃ mass concentration of solution on rectifying performance were investigated. And in the analysis the model of heat and mass transfer was proposed considering the distribution of mass concentration in boundary layer. As a result it was found that NH₃ mass concentration at rectifier outlet slightly decreased as vapor flow rate increased and that the model could predict NH₃ mass concentration in outlet vapor for various concentration in solution.

抄録全体を表示

Heat and mass transfer model for plate-type rectifier was presented in the previous paper and it was found that there existed the distribution of NH₃ concentration in boundary layer in vapor and solution phase, which was the resistance to heat and mass transfer. In order to enhance heat and mass transfer, packed tower-type rectifiers have been considered effective and used in the field of chemical engineering. And many data have been accumulated for each rectification-packing with give fluid to design packed tower. But it has rarely be seen to present heat and mass transfer model in order to evaluate the performance of packed tower rectifier without any experimental constant.
In this study heat and mass transfer model in packed tower-type rectifier was presented considering the specification of rectification-packing decided by surface area and porosity, and the calculation results were compared with experimental data. As a result it was found that over-all mass transfer coefficient increased as mass flow rate of vapor increased and that the model could expect over-all mass transfer coefficient within 30 [%] difference to experimental data. It was also cleared that mass transfer in packed-type rectifier was two to five times more enhanced than that in plate-type rectifier.

抄録全体を表示

This report refers to some static characteristics of the ammonia-water absorption refrigerator for low temperature refrigerating process which needs the temperature below the freezing point. Especially, the influence of evaporating temperature and cooling water temperature is clarified by the experimental investigation. In addition to this, the validity of constructed simulation model of this absorption refrigerator is mentioned. The validity of simulation model is verified by the comparison of experimental results and calculation.
To examine the characteristics, we conducted the performance test using the trial product of which the standard cooling capacity is 175kW. The performance is estimated according to cooling capacity and COP. As a result, the effects of the evaporating temperature and cooling water temperature on the cooling performance are clarified by the experimental research. Furthermore, the calculation of the static characteristics predicted by the simulation model is in good agreements with the experimental results.

抄録全体を表示

Experiments were performed on heat transfer and pressure drop for flow boiling of two non-azeotropic refrigerant mixtures of HFC-32/HFC-125/HFC-134a and HFC-32/HFC-134a at respectively certain compositions,which are expected to be alternatives to HCFC-22,in horizontal smooth and internally,spirally grooved tubes. Almost the same local heat transfer coefficients were obtained for both the mixtures in each tube. In the smooth tube,in the region where nucleate boiling contributes substantially to the heat transfer,the heat transfer coefficients for the mixtures were reduced down to about two-thirds of the value for HCFC-22,due to the effect of a mass transfer resistance on the heat transfer,while they were approximately equal to those for HCFC-22 in the forced convection dominated region. With the grooved tube,the heat transfer was enhanced over the smooth tube,but the enhancement was smaller than that for HCFC-22. In both the tubes,frictional pressure drops for the binary mixture were generally a few to 20 percent higher than those for the ternary mixture and the pure refrigerant,corresponding to the difference in the vapor density.

抄録全体を表示

Effect of the electric field on freezing of supercooled water was investigated, experimentally. The experiment was carried out by charging the electrode whose tip was inserted into supercooled water. It was found that supercooled water freeze instantly by applying the electric charge. There were many papers in the past which dealt with the effect of electrical field on freezing of supercooled water, but with a high voltage, order of a few kV. However, through this experimental study, it was found that the supercooled water can freeze at the voltage less than 100V, if D.C. voltage is applied directly to supercooled water. There was no deformation of water droplet or spark discharge as some papers suggest as a reason for the effect. It was also found that the probability of freezing depends upon the degree of supercooling, value of D.C. voltage applied, size of electrode and the distance between two electrods. The mechanism of this effect was discussed and suggested as follows: High electric field is formed locally due to the existence of surface edge or small projections on the surface. Water molecule which has a polarity is drawn near to the cluster on the surface whose motion is restricted by the existence of electric field. Therefore, embryo can transform to nucleus, instantly.

抄録全体を表示

Room temperature controllers of air conditioners make increasing progress, because some newer computer software technologies, such as ″Fuzzy-Logic″and ″Neural-Network″, are applied in order to satisfy user's comfort. However, it is difficult to design these controllers using conventional experimental methods, because of their very complicated structures. Thus, we need some simple dynamic simulation models of room temperature control system for tuning them efficiently.
The purpose of this study is to make a linear-discrete model for the room temperature control system of air conditioners using the system identification method. And we discuss effects of the air conditioner load on controlled system dynamics on the basis of these simulation models.

抄録全体を表示

In recent years, air-conditioners for domestic use has a "Fuzzy logic controller" to maintain desired room temperature. This is quite effective to adapt many different environments, area of the rooms, structure of the walls, weather, and so on. However, it is not easy to design an optimized Fuzzy logic controller, because it has many variable parameters and complex structures, hence many controller experiments are required.
We proposed a design method to optimize the controller by applying Genetic AIgorithms (GA), and developed the air-conditioner with the room temperature controller designed by this method.

抄録全体を表示

Mixing of refrigerant with refrigeration oil has great influence on viscosity and foaming of the oil in refrigerant compressors. This paper dealt with transient characteristics of mixing process of refrigerant into refrigeration oil. The mixing phenomena were investigated by using an experimental apparatus which modeled process of the oil-refrigerant mixing in a casing of refrigerant compressors. Mass of refrigerant dissolved into the oil stored in a cylindrical vessel was recorded continuously under different conditions of pressure, temperature, amount of the oil, diameter of the vessel and combination of the refrigerant and the oil. On the other hand, the mixing phenomena were analyzed theoretically by two mathematical models, one is a one-dimensional diffusion model and the other is a mass transfer model. Based on the comparison of theoretical and experimental results, values of apparent diffusion coefficient and mean mass transfer coefficient were decided. The mixing process can be easily predicted by these models, but an applicable range of mass transfer model is wider than that of diffusion model. The mixing characteristics were correlated by a non-dimensional equation composed of Schmidt number, Grashof number and aspect ratio in the diffusion model and by another non-dimensional equation composed of Sherwood number, Schmidt number and Grashof number in the mass transfer model.

抄録全体を表示

The distribution of ice-rich layer in an ice storage tank is an important factor to estimate the thermal performance of a dynamic-type ice storage system. The ice-rich layer distribution and the water permeability were tested by using cylindrical tanks. The accumulation of ice-rich layer was predicted by a model analysis in which Darcy's law was applied. From the results of both experiments and analyses, the effect of water flow rate on the time history of the ice-rich layer formation were revealed. An average downward superficial velocity in the ice-rich layer is a dominant factor in the component design for an efficient use of an ice storage tank. This calculation model for the distribution of ice-rich layer can be considered to be applicable to realize the high thermal performance for large-scaled ice storage tanks.

抄録全体を表示

About 90 points of diffusion coefficient of lithium bromide (LiBr) in aqueous solution were measured by holographic interferometry in the temperature range of 20∼50°C and the concentration range of 0.4∼55mass%.
A correlation among concentration, temperature and diffusion coefficients was done, and an empirical equation to calculate the diffusion coefficient in the concentration and the temperature ranges mentioned above was proposed. Differences between experimental values and correlated expression were almost within±2%.
Accuracy of the measured diffusion coefficients was discussed and the measurements are shown to be made within error of ±6.8%.

抄録全体を表示