Performance Analysis of a Multistage Centrifugal Pump Used in an Organic Rankine Cycle (ORC) System under Various Condensation Conditions

Abstract

In an Organic Rankine cycle (ORC) system, the working fluid pump plays an important role in the system performance. This paper focused on the operating characteristics of a multistage centrifugal pump at various speed and condensation conditions. The experimental investigation was carried out to assess the influence of the performance of the pump by the ORC system with special attention to actual net power output, thermal efficiency as well as back work ratio (BWR). The results showed that an increase in the pump speed led to an increase in the mass flow rate and expand in the operating range of the outlet pressure. The mass flow rate decreased nonlinearly with the increase of the outlet pressure from 0.22 to 2.41 MPa; the electric power consumption changed between 151.54 and 2409.34 W and the mechanical efficiency of the pump changed from 7.90% to 61.88% when the pump speed varied from 1160 to 2900 RPM. Furthermore, at lower pump specific speed the ORC system achieved higher thermal efficiency, which suggested that an ultra-low specific speed pump was a promising candidate for an ORC system. The results also suggested that the effects of condensation conditions on the pump performance decreased with the pump speed increasing and BWR was relatively sensitive to the condensation conditions, especially at low pump speed.

Techno-economic analysis on a small-scale organic Rankine cycle with improved thermal driven pump

“…Compared with the expander and heat exchanger, researches on electricity driven pump (EDP) for ORC is quite scare. Few related studies discussed the multistage centrifugal pump or gear pump which showed that the working efficiency had a remarkable influence on the system performance of ORC [23,24]. However, in some research cases, the pump work is often selectively ignored.…”

Experimental and Numerical Characterization of the Sliding Rotary Vane Expander Intake Pressure in Order to Develop a Novel Control-Diagnostic Procedure

“…In small scale ORC applications, pumps power consumption can severely affect the thermal efficiency and the net power output of the ORC system [30]. However, as pump efficiency is often very low [31], its improved off-design performance can play a key role in the reduction of the back work ratio [32]. Moreover, the cavitation problem can occur in off-design conditions and an overcharging of the working fluid is usually done, leading also to an improvement of the isentropic efficiency of the machine [33].…”