Simulation and measurements of a new PCM storage system using night cold air for daytime free cooling of buildings

A PCM cold storage battery has been built with two small PCM cells integrated in an air flow heat exchanger. The idea is to use it as a portable device that can be placed outside on summer nights to charge cold and discharge it indoors the following day. The prototype realization is described with its major issues in low power ventilation of the heat exchanger and efficient heat transfer between the air flow and the PCM with thermal conductivity < 0.2 W m-1 K-1. A parallel and a serial setup of the two cells have been built and the charge, storage and discharge properties have been compared. Cooling powers of 71W and 129W were obtained with flows of 24m3/h and 44m3/h, respectively for a total storage potential between 15°C and 30°C of 176 Wh. The thermal profile of the PCM battery has been investigated along the air flow channel and the neighboring PCM zone for charge/discharge and storage processes and was compared with finite element simulations. A critical analysis of the measurement and simulation results is presented together with the usage perspectives of such batteries in residential building environments.