Sihwan Lee

A Study on the Indoor Environment of the Main Building of the National Museum of Western Art, in Japan, for the Development of a Retrofit Scheme

Abstract The National Museum of Western Art is the only work of Le Corbusier in Japan and 50 years have already passed since its construction. In order to maintain the museum’s value as a cultural asset, there is an urgent need to draft a thorough retrofit plan both to maintain the building’s function as an art museum and to restore Le Corbusier’s original design concept. This study, which carried out an indoor environmental investigation for the purpose of developing such a retrofit plan in the main building, confirms the current airflow characteristics on the basis of a survey of factors such as the flow rates of the air conditioning system, internal pressures, and the age of air distribution. Because the exhaust flow rate was greater than the supply of fresh air into the building, there was concern about air infiltration. It was found that the age of air was highest in the exhibition space, comparatively lower in the entrance hall, and lowest in the restaurant. The adjacent wall air velocities varied greatly according to the locations and the highest values were around 0.7 m/s. In order to separate the exhibition space from the entrance hall to avoid possible disturbance from outdoors, glass partitions that were not part of Le Corbusier’s original design were added after the building was completed. CFD predictions were carried out to evaluate the air environment under the conditions of the original design using variable air conditioning zoning plans. Analysis indicated that if the original design were restored, using the present air conditioning zoning, there would be an increased risk of moisture condensation on the glass surface of the entrance hall. It was concluded, however, that this risk would be significantly reduced by subdividing the air conditioning zone and changing the air conditioning controls in each subdivided area.

Influence of vane angle on the effectiveness of air conditioning of wall-mounted split-type air conditioners in residential buildings

The purpose of this study is to accurately evaluate the effect of vane angle on the effectiveness of air conditioning of wall-mounted split-type air conditioners. First, to determine the detailed characteristics of airflow from an air conditioner opening, airflow rate, turbulence characteristics, and air distribution were measured according to the vane angle. Then, the detailed characteristics were calculated using a simplified opening model with boundary conditions obtained from the calculated results of a cross-flow fan model using the overset mesh technique to validate the computational fluid dynamics simulation. Finally, to evaluate the effectiveness of air conditioning, the effectiveness of air change was calculated under isothermal conditions by varying the vane angle and the setting position of the air conditioner by using the validated computational fluid dynamics model. The measurement results showed that when the vane was set at the middle position (rather than at the left or right positions), the airflow rate increased by 19.0%–20.9% in the high airflow rate mode. The simulation results verified that the simplified opening model was consistent with actual findings, and only a slight difference was observed between actual measurements and the computational fluid dynamics simulation results. Furthermore, installing the air conditioner at the center of a wall and setting the vane at the middle position improved the effectiveness of indoor air conditioning.

Performance comparison of conventional and local computer room air-conditioning systems in data centres by CFD analysis:

The maximum inlet air temperature and air recirculation ratio of information technology machines are important in evaluating the air-conditioning efficiency of data centres. In this study, evaluation models for estimating air and heat distributions were developed based on the thermal equilibrium in data centres, assuming conventional computer room air-conditioning and local computer room air-conditioning systems. The computer room air-conditioning cooling efficiency (η-index) was defined as the ratio of the effective cooling air volume of an information technology machine to the air volume of the computer room air-conditioning system. The recirculation ratio for an information technology machine (γ-index) was defined based on the air volume and thermal equilibrium. Several factors affecting air-conditioning efficiency, such as the mounting positions and heat load of the information technology machines and the ratio of the computer room air-conditioning system air volume to that of the information technology machine (V/Vm-index), were analysed using computational fluid dynamics. A mismatch was confirmed between the heat recirculation ratio (γm-index) and air recirculation ratio (γq-index), and the effect of heat transmission by the wall could be ignored in data centres. The mean γ values and inlet air temperatures (θ0m-index) could be reduced effectively by increasing the value of V/Vm and mounting the information technology machines at the bottom of each rack.

EXPERIMENTAL EVALUATION OF THE PERFORMANCE OF BATCH TYPE DESICCANT SYSTEM

The central thrust of this study involves developing a new desiccant-based energy recovery system useful for effective humidity control and featuring integrated design and analysis. The system heat source uses unutilized energy, heated water from solar panels and cool water from cooling towers. It consists of two air-water heat exchangers with adsorbent material coated on the fins and employs directly-heated desorption or directly-cooled adsorption for absorbent material created from the effective reuse of adsorbent materials. This paper describes the adsorption/desorption characteristics and performance of the air-water heat exchanger using the coating absorption material. Measurements involving the moist air being passed into the air-water heat exchanger via the coating of adsorbent material were conducted under various conditions. Consequently, the air-conditioning performance of the proposed system was found to be strongly dependent on the water temperature under constant air condition. The operating cycle of the system was also determined. The measured results make efficient use of the basic data from the numerical analysis model.