Pressure Pulsation and Cavitation Phenomena in a Micro-ORC System

Abstract

Micro-ORC systems are usually equipped with positive displacement machines such as expanders and pumps. The pumping system has to guarantee the mass flow rate and allows a pressure rise from the condensation to the evaporation pressure values. In addition, the pumping system supplies the organic fluid, characterized by pressure and temperature very close to the saturation. In this work, a CFD approach is developed to analyze from a novel point of view the behavior of the pumping system of a regenerative lab-scale micro-ORC system. In fact, starting from the liquid receiver, the entire flow path, up to the inlet section of the evaporator, has been numerically simulated (including the Coriolis flow meter installed between the receiver and the gear pump). A fluid dynamic analysis has been carried out by means of a transient simulation with a mesh morphing strategy in order to analyze the transient phenomena and the effects of pump operation. The analysis has shown how the accuracy of the mass flow rate measurement could be affected by the pump operation being installed in the same circuit branch. In addition, the results have shown how the cavitation phenomenon affects the pump and the ORC system operation compared to control system actions.

Design Multistage External Gear Pumps for Dry Sump Systems: Methodology and Application

“…Driving shaft loads schematic (b). [16,17], this software is able to catch the transient phenomena as well as the cavitation issues, showing a good agreement with the experimental results. e computational model used for the analysis is reported in Figure 6.…”

“…e presented procedure has been applied to a case study constituted by a three-stage gear pump, where the flexibility of the method has been proved. With the purpose of ascertaining the performances of the designed pump, a CFD analysis has been performed with reference to the models reported in [16] and [17]. e results show the achievement of the target performances, validating the calculation methodology and proving its robustness and accuracy.…”

“…e stationary domain is composed of about 1 million elements. Since no experimental data are available, the computational analysis accuracy was set up with the reference of the models reported in [16,17].…”

Organic Rankine Cycle for Energy Recovery System

“…This book contains the successful invited submissions [1][2][3][4][5][6][7][8][9] to a Special Issue of Energies entitled "Organic Rankine Cycle for Energy Recovery System", focusing on a modern technology committed to energy saving and thus capable of producing positive environmental outcomes. Indeed, the organic Rankine cycle (ORC) is a thermodynamic concept already demonstrated as an engineering viable solution for waste heat recovery systems.…”

“…Casari et al [9] numerically investigate specific fluid dynamic issues, related with pressure oscillations and flow cavitation, which may occur in a pump of a micro-ORC system operated with organic fluids.…”