Optimal design of an innovative microwave-based fluid heater

Abstract

New heating technologies are constantly being developed worldwide, specially the electrical ones that take advantage of renewable energy. In this paper, the Basic Cell of Energy Transference (BCET) is proposed as an innovative fluid heater, carrying a microwave-fed heat transfer plate for thermal contact. A fully-dimensional thermo-fluid analysis was implemented and validated to determine the key design parameters and operation features for heat transfer to temperature-sensitive working fluids.Circulation patterns were observed, when using certain fluids, in turn causing strong temperature non-uniformities. As fluid treatment in the heater relies on the thermal contact at its active plate, the model was used to ascertain the undesired excess/lack temperature range for quality/safety treatments, with reference to a final effective process temperature. Therefore, a geometry optimization by means of internal baffles was carried out which ensured variation to fluid pattern and more uniform active plate temperature. In a base case, the new design allowed to limit the uncontrolled temperature excess by almost 30%, while favouring the pressure drop reduction across the flow device by more than 10%.