A design supporting simulation system for predicting and evaluating the cool microclimate creating effect of passive evaporative cooling walls

As a passive cooling strategy to control increased surface temperatures and create cooler urban environments, we have developed a passive evaporative cooling wall (PECW) constructed of pipe-shaped ceramics that possess a capillary force to absorb water up to a level higher than 130 cm. The current paper presents a simulation system to predict and evaluate microclimatic modifying effects of PECWs in urban locations where PECW installation is under consideration at the design stage. This simulation system is composed of a CFD simulation tool and a 3D-CAD-based thermal simulation tool. Simulation methodology of coupling the two simulation tools was developed and described in this paper. Numerical models for simulating surface temperatures and evaporation of PECWs were proposed based on analysis results of experimental data. Validation of the proposed numerical models was confirmed by comparing simulated results with measured data. In order to demonstrate the applicability of the proposed simulation system, a case study was then performed to predict and evaluate the microclimate in a rest station where PECWs were assumed to be installed. Spatial distributions of air temperature, airflow, moisture and surface temperature in the rest station were simulated under a sunny weather condition in the summer of Tokyo. Furthermore, thermal comfort indexes (mean radiant temperature and new standard effective temperature) were used to evaluate thermal comfort in the human activity spaces of the rest station. Simulation results show that this simulation system can provide quantitative predictions and evaluations of microclimatic modifying effects resulting from the application of PECWs.