An experimental study on the thermal performance of a novel hydrodynamic cavitation reactor

The hydrodynamic cavitation technique has been widely considered to have great potential for many environmental, chemical, and biological industrial-scale applications. This paper presents an experimental investigation of the thermal performance, i.e., heat generation rate and thermal efficiency of a novel, advanced, rotational 15 kW class hydrodynamic cavitation reactor (HCR). The cavitation generation mechanism of the HCR was analyzed according to flow visualization. The thermal performance was tested in 20 experiments with various rotational speeds of the rotor (2700, 3000, 3300, and 3600 rpm) and pump pressure settings (0.0, 0.5, 0.7, 1.0, and 1.5 bar gauge pressure) without controlling the flow rate. The HCR achieved a maximum heat generation rate of 48.15 MJ/h (i.e., 13.375 kW) and a maximum thermal efficiency of 82.18%. To evaluate the independent effects of the operational conditions, the thermal performance was also evaluated under various flow rates (6, 8, and 10 L/min), pump pressure settings (0.5, 0.8, 1.1, and 1.4 bar), and inlet water temperatures (15, 25, 35, and 45 °C). The results showed that increasing the rotational speed, flow rate, and pump pressure setting gave rise to higher heat generation rate and thermal efficiency of the HCR. Moreover, the thermal performance decreased with increasing water temperature. Compared with the conventional and advanced rotational HCRs introduced in previous research, the HCR in this study provided more outstanding thermal performance and stable operational state and has great development potential for various large-scale applications.