Experimental assessment of a PCM to air heat exchanger storage system for building ventilation application

• The objective is to withdraw the heat pump from the grid during the 2 h of electrical peak power.
• Design of a new heat exchanger with PCM integrated in an air ventilation system.
• Laboratory experiment to analyze the heat exchanger efficiency.
• Dimensionless analyses to have general conclusions on the system design.

This paper presents a heat exchanger prototype containing PCM material designed to provide a 1 kW heating power during 2 h (i.e. energy storage of 2 kWh). The exchanger is tested in a closed-loop wind tunnel, used to provide constant airflow rates with temperature changes selected so that the PCM is allowed to melt, then to solidify. Temperature and air velocity measurements are achieved for eight airflow rates and the heating power is estimated. The second objective of this work is to provide detailed results suitable with the validation of numerical models. Therefore, the geometry of the exchanger is detailed and the uncertainty associated with the heating power measurement is given. Results show that enough energy is stored in the exchanger, yet the heating power is lower than 1 kW before 2 h because of the use of a constant airflow rate during the tests. On the other hand, the global behaviour of the heat exchanger is rather simple, which gives confidence in using a simplified approach in further work and help with optimizing the current prototype.