Investigation of the performance for a heat generator using hydrodynamic cavitation

Abstract

Cavitation occurs typically when pressure is lower than the saturated vapor pressure. Generally, cavitation used to be a phenomenon engineer should avoid when they design fluid machinery because it creates erosion, vibration and noise that make performance of the machineries worse. Recently, study about generating energy with cavitaion is being proceeded like heat generating machinery which is the most typical. There is little academic research, although study about these has some commercial documents or patents. In this study, we proceed experimental study for the heat generator connected to electrical motor which generates heat from cavitaion using a fast rotating device. We used 15 kW and 55 kW electric motors to rotate the generator. The experiments performed changing flow conditions such as pressure at entering position by using a booster pump and rotating velocity of the motors by an inverter. We analyzed heat production and thermal efficiency according to the flow conditions. The front cover of the heater is made of acrylic plate so that we can use high speed photography to observe the relation between cavitation and generator shape. We made sure that these conditions can affect performance and especially pressure at entrance or rotating velocity affect heat production. Existing theory of cavitation and results of this study were discussed. These results could be useful for design process of the machine using cavitation such as a cavitation heat generator and a chemical reactor etc. Copyright © 2011 by ASME.