Organic Rankine Cycle for Vehicles: Control Design and Experimental Results

Abstract

The system considered here is an organic Rankine cycle for recovering waste heat from a heavy-duty diesel engine. Because of the highly transient conditions these systems are subject to, control plays a fundamental role to enable the viability and efficiency of those systems. In this context, this paper investigates the problem of control design for superheating (SH) and pressure at evaporator outlet. Based on a moving boundary heat exchanger model, a first controller, which consists of a dynamic feedforward combined to a gain-scheduled PID, is implemented on the pump speed to maintain the SH close to the set-point value. Experimental results illustrate the enhanced performance in terms of disturbance rejection. Then, a second controller based on nonlinear state estimation is proposed. This is a nonlinear feedback law, which allows to adjust the evaporating pressure to time-varying demand with a good accuracy.

Recent developments of control strategies for organic Rankine cycle (ORC) systems

“…Recently, more details have been demonstrated in Peralez et al (2017), some experimental results on superheating control testify the effectiveness of the proposed compound algorithm that integrates gain scheduling PID, FFC and EKF together. Simulation results on pressure control have been illustrated rather than experimental results.…”

Axial Turbo-Expander Design for Organic Rankine Cycle Waste-Heat Recovery With Comparative Heavy-Duty Diesel Engine Drive-Cycle Performance Assessment

“…Furthermore, electrical turbocompoundingcan contribute to fuel saving of over 5% (Hopman, 2004). In recent years, WHR systems based on ORC systems have been at the focal point of research for road vehicle applications (Peralez et al, 2017). ORC systems offer potentially higher efficiencies, for on-road vehicle engines, than turbocompound and TEG (Jeihouni et al, 2016).…”

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

“…Further strategies involve the control of the speeds of the pump and the expander [36] and cooling water mass flow rate [37]. In order to achieve the evaporating pressure and superheating degree, a first controller constituted by the combination of a dynamic feed-forward and a gain-scheduled proportional integrative derivative (PID) is implemented on the pump [38]. A control system based on a multi-linear approach has also been proposed [39], subdividing the non-linear behavior of the system in local operating regimes as an equivalent linear system.…”