NUMERICAL INVESTIGATION OF FLOW AND THERMAL BEHAVIOR IN CHANNELS WITH PCM-FILLED THERMAL ENERGY STORAGE COLUMNS FOR POTENTIAL APPLICATION IN PHOTOBIOREACTORS

Microalgae has been identified as a potential source in the production of biofuel. Photobioreactors, which are used for microalgae production, normally experience temperature variations over the diurnal cycle due to changes in ambient conditions. Such temperature variations affect microalgae growth since microalgae are sensitive to these temperature variations. Hence, the thermal regulation of photobioreactors to minimize temperature variations will result in higher yield of microalgae. The present research is aimed to investigate an innovative approach to thermally regulate photobioreactors by introducing passive thermal energy storage using phase change materials (PCM) where the latent heat of the material is exploited as the energy storage. The present research uses a numerical approach to study the flow and thermal behaviors in a channel with a set of wall-confined, offset thermal storage columns. The research aims to investigate the melting behavior of the PCM inside these storage columns and the transient thermal response of the channel flow. Open source CFD software, OpenFOAM, is used to numerically simulate flow in a rectangular channel containing offset PCM columns. The model is validated against experimental data. A parametric analysis is performed to investigate the impact of various operating and geometric properties on the heat transfer to the PCM columns, with the aim to optimize the channel geometry to maximize the heat exchange between the PCM columns and the channel fluid.