Parametric study of an active-passive system for cooling application in buildings improved with free cooling for enhanced solidification

The present study introduces an active-passive system (APS) with phase change material (PCM) integrated into the substructure of the internal walls and ceiling for cooling. To ensure sufficient cooling effect of the system during the daytime cycle, the system must solidify completely during the nighttime cycle and operation costs comparable to the ones of conventional cooling systems. An air gap was formed between the primary wall and ceiling and the PCM substructure and ventilated with the cool outdoor air during the nighttime cycle. A parametric study was performed using ANSYS Fluent followed by the energy performance and operation cost analysis. Different inlet air temperature scenarios (15-20 degrees C) were tested (suitable PCM thermal characteristics). The required solidification-time of PCM was determined. The model is validated against the experimental tests. The results show that with the current configuration, the PCM plates can be sufficiently solidified at supply air temperatures of 17 degrees C and below. If the system is ventilated with inlet air temperatures above 17 degrees C, additional cooling options must be considered. The study also determines the energy performance of the system under the chosen conditions and compares its feasibility to the conventional cooling systems (energy efficiency class A+++ and G air-conditioning device).

Automated summary

This study introduces an active-passive system with phase change material integrated into the internal walls and ceiling for cooling. The system solidifies during the nighttime cycle and provides sufficient cooling effect during the daytime cycle, with comparable operation costs to conventional cooling systems. The results show that the system can sufficiently solidify at supply air temperatures of 17 degrees C and below.