[home] [Personal Program] [Help]

---

Session: Poster Session and Sponsors Exhibition
Session starts: Thursday 22 September, 14:00

---

Andrea Spinelli (Dipartimento di Energia, Politecnico di Milano, Italy)
Vincenzo Dossena (Dipartimento di Energia, Politecnico di Milano, Italy)
Paolo Gaetani (Dipartimento di Energia, Politecnico di Milano, Italy)
Matteo Pini (Dipartimento di Energia, Politecnico di Milano, Italy)
Franco Marinoni (Dipartimento di Energia, Politecnico di Milano, Italy)

Abstract:
A blow-down, closed-loop wind tunnel for real gas applications has been designed, validated by means of dynamic simulation and finally constructed. The facility is aimed at characterizing an organic vapour stream, representative of expansions taking place in Organic Rankine Cycles (ORC) turbines, by independent measurements of pressure, temperature and velocity. ORC turbine performances are expected to strongly benefit from characterization of such a flow and from design tools validation provided by experimental data, which still lack in scientific literature. A straight axis planar convergent-divergent nozzle represents the test section for early tests, but the test rig can also accommodate linear blade cascades. A wide variety of working fluids can be tested with adjustable operating conditions up to maximum temperature and pressure of 400 °C and 50 bar. The test rig is batch-operating; the working liquid is stored and evaporated in a high pressure vessel (HPV), the vapour is then discharged through the test section (where the flow field is measured) and is collected and condensed within a low pressure vessel (LPV). The liquid compression to the HPV finally closes the loop. Despite the test rig operational mode is unsteady, the inlet nozzle pressure can be kept constant by a control valve. The work presented here discusses the commissioning of the facility, namely the performance of preliminary tests using air as working fluid and an orifice plate in place of the convergent-divergent nozzle. Even though the ordinary tests require the facility to be operated with organic compounds, the use of air allow a simpler operation of the plant; in fact, the fluid can be exhausted to the atmosphere with no need of vapour collection and condensation and tests can be performed at moderate temperatures. No measurement of the flow field through the orifice are performed. Indeed, the present work only aims at testing the plant sealing, the correct operation of the main plant components (with the exception of the pumps and of the condensing system), at verifying the simulated behaviour for the control system and finally at setting-up the control loop software. In order to perform this validation and, in particular, to test the operation of the control valve, the orifice plate design is such that the dynamics of the HPV air emptying mimics the one obtained by using the organic vapour taken as reference for the first actual experiment. The pressurized air required to carry out the commissioning tests has been provided by a reservoir array (fed by a compression station) storing about 6000 kg of dry air at the pressure of 200 bar. Several tests have been performed, allowing a satisfactory adjustment of the control loop and in particular the tuning of the parameters characterizing the PID regulators of both the heating system and the control valve.