Proposal of Performance Evaluation Indicator for Evaporation Cooling System

In this research, we focused on dry mist, which is an evaporative cooling system, and examined how to evaluate the effect of the system. The system effect seen in past research focused on the amount of change that the vaporization heat of mist brings to these effects, mainly because of factors such as improvement of thermal environment, energy saving, and influence on the behavior of passersby. In this study, we considered the concept of evaluation the system effect based on the total amount of heat of vaporization obtained from the released mist, while following the evaluation indexes shown in the previous research. We modeled the dry mist system introduced in the virtual block by using computational fluid dynamics and quantified it for each contributor of the effect on the total amount of vaporization heat of the released mist into the virtual block. The vaporization heat which contributed to the mitigation of hot weather environment and reduction of air conditioning heat load is suitable for the explicit installation effect of dry mist. In addition, the ratio of vaporization heat to the total amount is a useful index for determining system performance on the design and operation phases of this system. more

Study on Cooling System with using Water Mist: Control strategy for water mist system

This study aims to promote usage of cooling system with water mist. To achieve subject of this study, it is necessary to make clear for the proper operation and establish control scheme. The cooling system with water mist is controlled on/off by water pump; operation of turn on / turn off. Also, there are two control methods, manual and automatic. The automatically control will be needed when the getting wet resident face and cloth not permitted or water-drop must be prevented. In this paper, the control scheme for water mist system was evaluated and proposed proper control method based on empirical control scheme. 28.5 - 29 degree C of Dry-bulb and 70% of relative humidity are considered proper range to spray mist. more

Cooling System with Water Mist Sprayers for Mitigation of Heat-island

The purpose of this study is to establish the water mist (Dry-Mist) spraying system that improves environmental conditions in the cities. In Japan we have traditional method for cooling, which is called “Uchimizu” by utilizing the effect of water evaporation. This time we have developed the system which utilizes this effect more efficiently. This study is based on the idea that if the system is capable of supplying water mist whose size is small enough to evaporate, it could be possible to mitigate heat island phenomenon without depending on greening. more

Study on Cooling System by using Dry Mist System: Validation of cooling effectiveness and CFD simulation

The objective of this study is to propose a prediction technique for cooling effect of dry mist, and present useful data for design / control of a dry mist system. In this paper, the cooling effect of dry mist system was verified by two dry mist systems there were actually introduced and operated. One of the verified systems is a dry mist system that was installed into the air corridor on the site Aichi Expo. A cooling effect of this one was evaluated by using the field measurement data during three months. Another one is a dry mist system introduced into N university campus. We found out that the cooling effect by dry mist evaporative is presented about 3 degree Celsius of air temperature reduce and about 15 %RH of relative humidity increase. In addition, the cooling effect of the dry mist system was simulated with a CFD analysis code that is Fluent Ver. 6.3. The reproducibility was confirmed, and the possibility of the performance prediction of the dry mist system was shown. more

Study of Cooling System with Water Mist Sprayers: Fundamental examination of particle size distribution and cooling effects

A cooling system that sprays micro water droplets could prove useful in mitigating temperature increases in urban areas by using the heat of water evaporation, a process that consumes only small amounts of water and energy. If water mist is sprayed in a semi-outdoor area, for example, under a canopy, it could potentially improve conditions on hot days. However, there is little reference data concerning the design or control of such systems. In order to propose a method for designing and predicting the performance of a water mist system, we discuss differences in cooling effects in the context of particle size distribution of water mist. The results of numerical fluid analysis showed there is no significant difference in temperature reduction for different particle sizes. However, the water particles remained in a lower position with larger particles. more

Study on a Cooling System using Water Mist Sprayers: System control considering outdoor environment

This study examines the cooling effect of water mist in relation to variations in outside air temperature and humidity by using numerical fluid analysis. A semi-outdoor space under a canopy where the water mist is sprayed was modeled. The cooling effects of the various water mist sprays were simulated and reductions in the air temperature and the remaining water particle mass distribution were examined. As a result, acceptable conditions for spraying mist are suggested, and the utility of water mist cooling systems for representative cities in Japan is validated. more