Conversion of Thermally Amplified Hydraulic Shock for Power Generation: Modeling and Experimental Analyses

Abstract

Abstract Hydraulic shock, also colloquially known as hydram, or hydraulic ram pump, or water hammer, or fluid hammer is a high-pressure shock wave that propagates at the speed of sound through a piping system when a fluid in motion is forced to change direction or stop abruptly. This destructive force can be converted into useful work, i.e., to pump the water to higher elevation, thereby increasing its potential energy, i.e., lifts the water using the high-pressure shockwave. Its low performance combined with affordability of fuels has put this otherwise longstanding technology in the backburner of science and research for a long time, yielding to electric or fuel powered pumps. However, growing concerns about the impacts of fossil fuel use on the environment as well as the rising price of electricity has generated a renewed interest in such technology. The ram pump’s operation in remote areas where the power grid is not available adds research value to the technology. In this paper, a novel approach, i.e., adding thermal energy to the flow to assist the water hammer pressure was modeled. Computational fluid dynamics (CFD) simulations were conducted using ansys. The results were validated experimentally in a 32 mm (27 mm internal diameter) drive pipe and a supply head of 2.18 m ram pump. The exhaust pressure can also be used to produce power using a hydraulic turbine, hence our claim of multi-purpose application as a theme of this project. The results between simulation and experiment were consistent, with only 6.99% error for pressure, and 10.16% for flowrate. The results show that pressure increased from 183.33 kPa to 342.32 kPa when thermally assisted to reach 106.75 °C. The experimental discharge flow increased from 11.72 l/min to 16.41 l/min for the corresponding temperature, a 42.01% increase. The system in power mode produced 91.28 W and 35.81 W with and without thermal infusion, respectively. The Rankine efficiency of thermally assisted hydraulic ram for combined application was above 10% whereas with power generation only, the efficiency was 1.4% at a net delivery head of 5 m for both scenarios. It was observed that in general, the efficiency increases proportionally with delivery flow.