Recently, several food refrigeration equipments that utilize magnetic field have attracted much attention from food production companies, consumers and mass media. However, the effectiveness of the freezers is not scientifically examined. Therefore, the effectiveness should be clarified by experiments or theoretical considerations. In this study, the effect of weak magnetic field (about 0.0005 T) on freezing process of several kinds of foods was investigated by using a specially designed freezer facilitated with magnetic field generator. The investigation included the comparison of freezing curves, drip amount, physicochemical evaluations on color and texture, observation of microstructure, and sensory evaluation. From the results of the control experiments, it can be concluded that weak magnetic field around 0.0005 T provided no significant difference on temperature history during freezing and on the qualities of frozen foods, within our experimental conditions.
In scroll compressors, oil injection to the compression chambers reduces refrigerant leakage loss in the compression process, while causes the heating loss in the suction process. In the previous experimental study where the relationship between the oil flow rate to the compression chambers and the compressor performance was investigated, we reported that the present R410A scroll compressor can be operated at higher efficiency as decreasing the oil flow rate. Based on this experimental result, we adopted a new oil supply device, which is the intermittent oil supply mechanism installed in the orbiting scroll, thus improving the efficiency. We studied theoretical oil flow rate of this new device, and addressing that this mechanism has excellent characteristics in oil flow control. Then we provided appropriate oil flow rate for the compression chambers with this new oil supply device, thus achieving higher performance on the R410A scroll compressor.
Tarako and Mentaiko are popular seafood products in Japan. They are prepared mainly from frozen Walleye Pollock roe which are mostly transported from Alaska or Russia. Fresh ovary as material for tarako products is generally believed to be of much better quality than frozen one, however it is yet to be scientifically evaluated. In this study, the effects of freezing rate on freeze-thaw ovarian quality were investigated through drip amount measurement, sensory test and morphological observation. Results showed that the freezing conditions (i.e. freezing rate and storage period) caused physical damage to the ovary resulting to the change its taste.
The ways to increase dehumidification capacity during the dehumidification operation reheated by refrigeration cycle on room air conditioners using R 410A was investigated, keeping electric power consumption lower, noise level lower and outlet air temperature constant. The indoor heat exchanger is divided into a condensing part and an evaporating part by a dehumidification valve which is located between these two heat exchangers. The cooled and dehumidified indoor air is heated by the condensing part. The noise occurred from the two-phase refrigerant flow passing through this valve. So the compressor rotational speed was increased properly to increase dehumidification capacity. Moreover a new dehumidification valve was developed to reduce the refrigerant flow noise. This valve has two expansion processes and each expansion process has plural notch throttles. As the result, 1.5 times dehumidification capacity was gained, keeping lower electric power consumption, lower noise level and constant outlet air temperature.
The new ways to control the humidity and the temperature of the room accurately during the dehumidification operation reheated by refrigeration cycle on room air conditioners using R 410A was investigated. The indoor heat exchanger is divided into a condensing part and an evaporating part by a dehumidification valve which is located between these two heat exchangers. The indoor air cooled and dehumidified by the evaporating part is heated by the condensing part. The dehumidification capacity increased according to increasing the compressor rotational speed. And the reheating capacity increased according to decreasing the outdoor fan rotational speed. So the humidity and the temperature of the room was controlled to the setting values exactly by regulating the compressor rotational speed and the outdoor fan rotational speed alternately.
As the carbon dioxides (CO2) is a high density refrigerant, the displacement volume of the CO2 compressor becomes smaller for a fixed cooling capacity, while the pressure difference between the adjacent compression chambers becomes larger. For developing a CO2 compressor with high efficiency, it was necessary to reduce the leakages through the clearances between the orbiting and fixed scrolls. The previous study for a R410A scroll compressor has addressed a new intermittent oil supply mechanism exhibiting the superior characteristics in oil flow control. In this study, therefore, the same intermittent oil supply mechanism was applied to a CO2 scroll compressor, where the relationship between the oil flow rate to the compression chamber and the corresponding performance was investigated in detail. As a result, it was made clear that the optimal ratio of the oil flow rate to the refrigerant flow rate in CO2 scroll compressor is about 5 % to achieve the higher efficiency, which is larger than that of the R410A scroll compressor.
The aim of the present study is to propose a convenient numerical calculation method combined with finite volume and temperature recovery methods, and to confirm the validity of the present numerical calculation method through a comparison with experiments and numerical calculation conducted by other researchers. In this paper, the details of the combined numerical calculation method have been first described. Secondary, the numerical results computed by the present proposed method has been compared with experimental and numerical calculation results obtained by other researchers in order to verify the effectiveness of the present combined numerical calculation method. As a result, present numerical calculation results for both the shape of ice formation and streamlines in unfrozen water were in good agreement with the experimental and numerical calculation ones previously obtained by other researchers.
Some eggs are frozen for preservation and are thawed when they are used in microinsemination process such as ICSI. However, the elasticity of egg makes the manipulation difficult to perform. It may be possible to simplify the process by performing the manipulation for frozen egg, because there is no need to concern about the elasticity when eggs are in frozen state. Therefore, we propose a new type of microinsemination system, which is, a small hole is opened on a frozen egg by drilling and a sperm is injected into it. We developed a new system to establish this process. The ultimate objective of this system is to establish the microinsemination system for frozen egg of mouse. In the experiment we used immature eggs of a Silver whiting at first and then proceeded to the experiment of frozen mouse egg and succeeded to open a hole on it.
This study aims to clarify the adsorption / desorption behavior of water vapor onto / from a desiccant rotor in temperature swing. A magnetic suspension balance followed time variations of the weight of a small piece of desiccant rotor at various desorption temperature, adsorption / desorption time and their duration time ratio. Adsorption-desorption swing in steady state settled down at certain amplitude of the amount adsorbed keeping the balance of the adsorption and desorption rates averaged over each period. At low regeneration temperature around 40-50 oC, adsorption and desorption rates were affected considerably by the change of driving force of adsorption q*-q rather than the temperature dependence of the mass transfer coefficient. At constant adsorption and desorption air conditions, the adsorption /desorption rates could be summarized by the amount of adsorption and temperature, independently of the length of cycle time. Also, region of the amount of adsorption at which adsorption - desorption swing occurred was predicted considering the adsorption / desorption rates - amount adsorbed relationship and the adsorption / desorption duration ratio.
Adsorption / desorption behavior of water vapor in a desiccant rotor containing an iron aluminophosphate type zeolite FAM-Z01 (Functional Adsorbent Material Zeolite 01) was experimentally investigated for humidity swing. This rotor exhibited an S-shaped adsorption isotherm with its temperature dependence. Humidity swing, using a small piece of the rotor, could be usefully applied to interpret adsorption / desorption mechanisms by observing their rates. The most significant finding was that the adsorption / desorption rates in humidity swing could be described by the amount of adsorption, temperature and amplitude of the humidity swing, not by cycle time. Also, using the liner driving force (LDF) model, the overall mass transfer coefficient changed with the elapse of time or with the amount of adsorbed water. This implied that the LDF model, considering constant value of the overall mass transfer coefficient, was probably unable to explain the water adsorption / desorption behavior of FAM-Z01 desiccant rotor.
In this study, the specific heat of the water included in an adsorbent was analyzed by a differential scanning calorimeter, DSC, in the temperature range from -100°C to 50°C by direct measurement method and indirect measurement method. Zeolites with the various pore size were employed as an adsorbent and the measurement was performed with various water mass fractions to Zeolite. In this paper, the water was defined as it was composed of the adsorbed water and the free water which is not adsorbed in Zeolite. As a result, in the case that the temperature was under 0°C, the specific heat of the Zeolite adsorbing water decreased. In the case of the large amount of the water, the specific heat of Zeolite including the water became about the same specific heat of regular water. Furthermore Zeolite adsorbing the water has no phase transition. The specific heats of the adsorbed water and the free water were estimated from the above mentioned experimental values. It was found that the specific heat of the adsorbed water decreased with decreasing the temperature, and that the adsorbed water has no phase transition.
The desiccant air-conditioning will be suitable for effective use of the exhaust heat. We have reported high dehumidification efficiency of the proposed system that is composed of a sorbent rotor and a refrigerating cycle. In this study, to improve the sorption efficiency of the rotor, the double ventilation rotor is proposed. After the processing air is dehumidified at the sorption area 1 of the rotor, the air is cooled and has higher relative humidity. And then, the air is blew into the sorption area 2 from the rotor opposite. The double ventilation characteristics on the influence of the division area of the rotor, the flow rate, the recovery temperature, and the temperature of the air cooler were investigated. As a result, the behavior of the double ventilation rotor is clarified and it is found that the quantity of dehumidification of the rotor is greater in the case of 1:1:2 (sorption(1): sorption(2): desorption ) division rate of the rotor than that of 1:1:1.
The authors hope to develop an air-conditioning system that processes the latent heat load and the sensible heat load separately. This would enable the efficiency of the chilling unit to be improved because the temperature of the chilled water used for cooling would be higher than normal. However, if lukewarm water is used, there is insufficient cooling and dehumidification. Therefore, a dehumidifier such as a desiccant air-conditioning system is needed. Using the waste heat generated when the desiccant air-conditioning system is in operation increases efficiency. The authors are developing a prototype desiccant humidity control system that makes use of the waste heat generated by a water source heat pump. This paper describes the results of an experiment that was conducted for this prototype based on the assumption that it would be installed in an office building. The dehumidification performance achieved was sufficient to process the indoor latent heat load. The prototype was able to adjust the indoor relative humidity from 40% to 60% under conditions in which the indoor latent heat load varied. Humidification without the use of water was possible even in the absence of an indoor latent heat load when the outdoor absolute humidity was 3.5 g/kg' or more.
A multi-divided rotary adsorber was proposed to realize a double-stage dehumidification in 2-rotor desiccant cooling process. In this process, once dehumidified and cooled air was dehumidified again at the different adsorption zone of the same desiccant rotor. Four process flow configurations were experimentally tested for investigations of the appropriate outside air inlet position and rotating directions of the rotary adsorber and rotary heat exchanger. It was found that dehumidifying performance was strongly influenced by the supply position of outside air to the adsorbent rotor. Humid outside air should be supplied to the latter half of the adsorption zone and once dehumidified air should be sent to the first half of the adsorption zone. This is because the increase in the amount adsorbed at the first half of the adsorption step resulted in a poor adsorbabilty at the latter half of the adsorption step for the once dehumidified dry air. Therefore, the effective use of the adsorbent rotor could be done by considering the angular distribution of the amount of adsorbed. Consequently, 30% larger amount of dehumidification than that of conventional processes under a humid summer condition was confirmed. Regarding the product air temperature, the process configurations at which secondary dehumidified air was cooled at the first half of the sensible rotor produced roughly 5 °C lower temperature air than that of the other. This implied that the directions of rotation of the adsorbent rotor and the rotary heat exchanger, or dehumidification - cooling sequence, also had a great impact on the product air condition.
The study investigated fixed bed desiccant units for ventilation and air-conditioning. The system mainly dehumidifies the outdoor fresh air to be supplied to an air-conditioned room. Hence, the airconditioning load of the air-conditioner in the room can be mitigated. Several adsorbents were compared from the viewpoints of humidity ratio at the outlet of the desiccant unit, dehumidified quantity per unit volume, and dehumidified quantity per unit adsorbent mass. The performance of the desiccant unit was predicted by simulation which was validated by comparison with experiment. The results revealed the most suitable adsorbent to reduce the desiccant unit size. It was also found that the humidity ratio at the outlet of the desiccant unit could be lowered by shortening the dimensionless switching time.
The study investigated fixed bed desiccant units for ventilation and air-conditioning. The role of the system is the dehumidification of the outdoor fresh air to be supplied to an air-conditioned room. Hence, the latent heat load of the air-conditioner in the room can be mitigated. The system consisted of two pairs of a desiccant unit and a heat storage unit. The microwave irradiation to the desiccant unit was examined as a candidate of the regeneration method of the system, and the performance of the microwave regeneration was compared with that of the hot air regeneration in terms of the supply air humidity ratio, outdoor air based COP, and the process air temperatures. The results revealed the effects of the switching time and the irradiation timing on the performance of the microwave irradiation.
The objective of this study is to develop a paper-base for the desiccant rotor by using Wakkanai siliceous shale (WSS), which have a high ability of water adsorption / desorption. The paper containing WSS was made by using chemical fibers and WSS fine particles, which was prepared by a ball-milling treatment. In addition, a coating material was prepared by the mixing of WSS fine particles, the resin-emulsion as a binder, a chloride solution for increasing the water adsorption ability. The water adsorption amount of the paper containing WSS showed two times higher than that of the original paper, at the over 70%RH of high humidity range, because of capillary condensation by the meso-pore in the WSS. The water adsorption amount of paper containing WSS evaluated from the cyclic test gave 22 g/m2 by the impregnation of chloride solutions. The initial water adsorption speed also increased by using coating material. It was recognized that the application of the coating material to the paper surface accompanied with the impregnation of chloride solutions improved the water adsorption speed and amount.
The aim of this study is to develop a desiccant system using Wakkanai siliceous shale. A honeycombed desiccant rotor containing this shale's powder and chlorides was made and evaluated. However a specific surface area and a pore volume were smaller than a silica-gel rotor or a zeolite rotor, the maximum amount of water adsorption was twice as other rotors. We have verified the function of this desiccant rotor concerning adsorption and desorption of moisture from the draft experiments. The rotor containing the shale could adsorb moisture stably in the cyclic test, and be regenerated by 40°C air under this experimental condition. This means that the exhaust heat from the heat pump can be used for regenerating rotor. Furthermore, the numerical simulation was carried out on the assumption that this rotor was used for a dehumidification for the residential air conditioning in Tokyo. This rotor could adsorb 37.1% moisture of the required dehumidification amount for the hottest day in 2008. When we employed a pre-cooling before dehumidification, the amount of adsorption increased to 66.2%.