Summary The objective of this study is to examine the new absorption refrigeration cycle using ionic liquid with LCST-type phase transition. This study selected [P4444][CF3COO] as the ionic liquid. The solution of the ionic liquid separates water from itself over the temperature of 55℃ and solve it under the temperature. This ionic liquid allows the separation process of refrigerant from the working fluid at heat source temperature of 60℃, which implies effective utilization of low temperature heat sources. The new absorption refrigeration cycle involves reverse osmosis process. This study investigates the behavior of the proposed cycle from the viewpoints of cooling output, COP, required pressure for the reverse osmosis to transfer the refrigerant of water from the absorbent to the ionic liquid solution, an area of membrane, mass transfer coefficient by cycle simulation. It is also discussed that the possibility of power recovering when the absorbent solution passes between reverse osmosis process and the absorber. The results of the cycle calculation and the sensitivity analysis show that there exists a mass flow rate of the ionic liquid which maximizes the cooling capacity with respect to the mass flow rate of the absorbent. The COP is expected to be 0.46 or more when sufficient area of the membrane is provided. On the other hand, high pressure of 33 MPa is required for the reverse osmosis process.

The objective of this study is to develop a desiccant system using Wakkanai Siliceous Shale (WSS). In the previous study, we planned highly efficiency desiccant unit for household which consists of a total heat exchange element (T-HEX), a heating coil, a precooling coil and WSS desiccant rotor. And so, we improved this unit to accommodate small/medium-sized buildings. In this paper,we conducted a demonstration test to clarify the energy saving effect of a WSS desiccant system. Firstly, we improved an air conditioner to be a sensible heat treatment unit by increasing of evaporating temperature 8^oC to 15^oC. the demonstration test was carried out inside a factory site. Furthermore, the performance prediction by simple regression analysis was carried out to clarify the energy saving effect of the desiccant system. As a result, we confirmed that the desiccant system is capable to treat the sensible heat load and latent heat load separately. Cooling capacity and energy consumption of the air conditioner are reduced by the evaporation temperature control. WSS descant system can reduce the 28.6 % of energy consumption by compared with the conventional air conditioning system. Finally, by the regression analysis, the energy saving effect for cooling using the WSS desiccant system showed 39.7 % for the whole system in the summer season.

The authors have been developing a desiccant ventilation unit, which consist of a static total heat exchanger and Wakaknai siliceous shale (WSS) rotor. In this study, toluene, ammonia and formaldehyde were used as a model odor gas, and the odor transfer from the RA to SA were evaluated by using the gas sensor and gas detected tubes. Transfer of toluene gas were not observed in the total heat exchanger and WSS rotor, because of the limit of detector concentration. The ammonia transfer rate of THEX showed a high transfer rate of 50% at the higher humidity conditions. It was indicated that the ammonia transfer was depended on the water content in THEX. The WSS rotor gave the transfer rate of 33% with ammonia and 46% with formaldehyde. During the ammonia supply into the RA, lot of ammonia gas was adsorbed and maintained in the rotor.

A desiccant rotor divided into four sectors realizes a double-stage dehumidification or regeneration in one adsorbent rotor. In this study, the amount of dehumidification and efficiency of two typical configurations of the four-divided silica gel rotor, one is called “adjacent type” whose adsorption or regeneration zones are adjacent to each other and the other is called “diagonal type” in which adsorption or regeneration zones located diagonally opposite to each other, were experimentally investigated and compared with a conventional configuration. It was found that the dehumidifying performance of the “adjacent type” was the highest among these three configurations and the inlet air temperature of 2nd regeneration zone significantly influenced on the amount of dehumidification. Also, measurement of air temperature profiles along with the rotating and axial directions of the rotor helps to understand a simultaneous heat and water vapor transfer occurred in the four-divided silica gel rotor.

This paper presents experimental data of heat and mass transfer characteristics of the gas-liquid contactor for a liquid desiccant air-conditioning system. In this study, finned-tube type internally heated regenerator is newly proposed. Furthermore, aqueous solution of ionic liquid is used as absorbent solution. Heat and mass transfer characteristics of the combination of proposed finned-tube type gas-liquid contactor and ionic liquid have yet to be revealed. Effects of air side Reynolds number and solution film Reynolds number upon air side heat transfer coefficient, solution side mass transfer coefficients and air side friction factor are experimentally investigated, and also, in order to obtain these data, numerical simulations are conducted. As a result, experimental data of these transfer coefficients and friction factor were obtained and the relationship between transfer coefficients and Reynolds numbers are quantitatively revealed. Moreover, these experimental results revealed that the mass transfer in the solution falling film is more dominant than that in the air side in almost entire experimental conditions.

In this study, a two-vessel circulating-fluidized-bed in which particulate sorbents are circulated by air was created to confirm that moisture could be transferred between two air flows continuously, and to investigate its basic behavior. The amount of humidification and dehumidification, which means the amount of moisture transferred between two air flows, was evaluated when changing the air flow velocity and humidity conditions of the air flow. As a result of the experiments, it was found that the amount of humidification and dehumidification influences by the circulating amount of particulate sorbents, and there is an optimum condition for the circulating amount. As the air flow velocity increases, the moisture transfer amount increases because the amount of circulating sorbents also increases. On the other hand, if the amount of circulation sorbents is too large, the moisture transfer amount decreases. Moreover, even if the air flow humidity is changed, no significant difference is found in the circulation amount, but it was found the amount of humidification and dehumidification increases as the relative humidity difference between the two air flows increases.

The objective of this study is to investigate the effect of frequency of acoustic wave on the adsorption enhancement. Experimental measurements were conducted, which results were analyzed to derive the condition of acoustic wave in which the adsorption rate is increased. 3 cases with different frequency which corresponding to the resonance mode indicated that the enhancement rate would depend on the frequency. It was also found that the critical velocity amplitude of the acoustic wave above which the enhancement effect was observed would increase as the frequency is higher. The authors proposed a model that the enhancement effect occurs when the effective displacement amplitude of the oscillation flow is larger than the certain value. Mathematical analysis of the model suggested the critical velocity amplitude would be expressed in a linear function with the frequency, which was verified based on the observation of the experimental results. It revealed that the mechanism of the enhancement effect would be explained by the model.

Adsorption/desorption rate of vapor to adsorbent on an adsorption heat exchanger is one of the important characteristics in order to design and improve the performance of adsorption chillers and dehumidifying/humidifying desiccant systems effectively. In the present study, for a silica gel thin film adsorbent coated on an aluminum plate in a cross-fin tube heat exchanger, measurement of equilibrium adsorption of water vapor by TGA and measurement of adsorption/desorption rate by gravimetric method under different flow velocities of moist air were performed. The equilibrium adsorption was formulated with function of relative humidity. In addition, the overall mass transfer resistance related to both the mass diffusion in the film and the mass transfer in the boundary layer on the film was investigated. It was clarified that the influence of the resistance on the reaction rate appeared only at the beginning of reaction, and the resistance decreased with the increase of the velocity, especially in adsorption. Furthermore, the resistance in desorption was less than half in adsorption. Consequently, the resistance in the boundary layer was a negligible quantity for desorption when the flow rate was above 0.1 m･s^-1. Finally, correlations were proposed to predict these resistances.

This paper provides an analysis of the adsorption kinetics by using image processing algorithm. Rapid adsorption kinetics is increasingly important because it offers a good mass transfer hence improves the efficiency of the sorption system. For adsorption kinetics, it is required to determine the first stage of the measurement precisely. Therefore, selecting the proper method becomes essential. Simple experimental setup was developed for evaluating adsorption equilibrium and adsorption kinetics of Silica gel/water pair. The test apparatus comprises of adsorption cell, evaporator/condenser, piping line, and measurement devices for temperature and pressure. Silica gel types A was employed in the present study as the adsorbent material. A new method is proposed to calculate the adsorption kinetics by using the digital image analyzing. Algorithm for image analysis could semantically segment the adsorption process by creating images which represented the dataset for water level changes inside the evaporator.

Electric vehicle doesn’t generate much amount of waste heat. Therefore, electric vehicles consume a relatively larger amount of electricity for heating. Normally, dry and low-temperature winter air is heated and supplied to the vehicle cabin to avoid water condensation on the windows. This results in further reduction of the vehicle cruising range. This paper discusses the applicability of a thermally regenerative desiccant block for dehumidification and heating of electric vehicles. Regenerated desiccant block adsorbs the water vapor generated by the passengers, therefore fogging of the windows can be avoided without air ventilation. Also, simultaneously generated heat due to heat of adsorption can support the heating. Experimental results employing a commercialized silica gel honeycomb block indicated that the regeneration time of the block was much shorter than dehumidification duration. This must be a suitable feature for the actual use. A field-test using a silica gel honeycomb block of four-liters set in a real vehicle cabin with two passengers showed anti-fogging effect during 30 min or more. This desiccant dehumidification and heating could reduce the heating load by 40 percent or more comparing to the conventional heating and ventilation.