Pneumatic system for pressure probe measurements in transient flows of non-ideal vapors subject to line condensation

Conti, Camilla Cecilia; Fusetti, Alberto; Spinelli, Andrea; Gaetani, Paolo; Guardone, Alberto

doi:10.1016/j.measurement.2022.110802

Cited by 9 publications

(5 citation statements)

References 11 publications

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“…The pneumatic system documented in Conti et al. ( 2022 ) involving nitrogen flushing was implemented to allow probes insertion in the TROVA test section while avoiding the above issues. The configuration was experimentally optimized to minimize the overall volume (including tubing, fittings and transducers volumes) to ensure a response time that is appropriate for resolving the blowdown dynamics of the plant.…”

Section: Methodsmentioning

confidence: 99%

“…The present authors also developed a pneumatic system for pressure probe measurements in flows of organic vapors in non-ideal conditions that sets the foundation for future directional pressure probes calibration and use in the characterization of such flows (Conti et al 2022), and which is indeed the basis of the work here documented.…”

Section: Introductionmentioning

confidence: 95%

“…Since siloxane MM is liquid at room temperature and considered operating pressures during tests, unheated pneumatic lines are subject to condensation, leading to poor measurement quality related to the presence of vapor-liquid menisci, hydrostatic head and time delay due to mass sink effects. The pneumatic system documented in Conti et al (2022) involving nitrogen flushing was implemented to allow probes insertion in the TROVA test section while avoiding the above issues. The configuration was experimentally optimized to minimize the overall volume (including tubing, fittings and transducers volumes) to ensure a response time that is appropriate for resolving the blowdown dynamics of the plant.…”

Section: Nitrogen-flushed Pneumatic Systemmentioning

confidence: 99%

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Shock loss measurements in non-ideal supersonic flows of organic vapors

et al. 2022

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This paper presents the first ever direct measurements of total pressure losses across shocks in supersonic flows of organic vapors in non-ideal conditions, so in the thermodynamic region close to the liquid–vapor saturation curve and the critical point where the ideal gas law is not applicable. Experiments were carried out with fluid siloxane MM (hexamethyldisiloxane, C$$_6$$ 6 H$$_{18}$$ 18 OSi$$_2$$ 2 ), commonly employed in medium-/high-temperature organic Rankine cycles (ORCs), in the Test Rig for Organic VApors (TROVA), a blowdown wind tunnel at the Laboratory of Compressible fluid dynamics for Renewable Energy Applications (CREA lab) of Politecnico di Milano. A total pressure probe was inserted in superheated MM vapor flow at Mach number $$\sim 1.5$$ ∼ 1.5 with total conditions in the range $$215-230~^\circ \hbox {C}$$ 215 - 230 ∘ C and $$2-12~\hbox {bar}$$ 2 - 12 bar at varying levels of non-ideality, with a compressibility factor evaluated at total conditions between $$Z_\text {T}=0.68-0.98$$ Z T = 0.68 - 0.98 . These operating conditions are representative of the first-stage stator of ORC turbines. Measured shock losses were compared with those calculated from pre-shock quantities by solving conservation equations across a normal shock, with differences always below $$2 \%$$ 2 % attesting a satisfactory reliability of the implemented experimental procedure. An in-depth analysis was then carried out, highlighting the direct effects of non-ideality on shock intensity. Even at the mildly non-ideal conditions with $$Z_\text {T}\gtrsim 0.70$$ Z T ≳ 0.70 considered here, non-ideality was responsible for a significantly stronger shock compared to the ideal gas limit at same pre-shock Mach number, with differences as large as $$6\%$$ 6 % . Graphical abstract

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 95%

Section: Nitrogen-flushed Pneumatic Systemmentioning

confidence: 99%

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Shock loss measurements in non-ideal supersonic flows of organic vapors

et al. 2022

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“…Moreover, the frequency response much decreases due to the very low vapor mass flow rate feeding the line. These issues can be solved by periodically flushing the lines (Head 2021, Conti et al 2022a). If the flow is subsonic, the total pressure can be measured directly with a pressure probe, while for supersonic flows additional data are needed to solve the jump relation across the probe-induced bowed shock (Manfredi et al 2023).…”

Section: Derived Measurementmentioning

confidence: 99%

Nonideal Compressible Fluid Dynamics of Dense Vapors and Supercritical Fluids

Guardone,

Colonna,

Pini

et al. 2024

Annu. Rev. Fluid Mech.

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The gas dynamics of single-phase nonreacting fluids whose thermodynamic states are close to vapor-liquid saturation, close to the vapor-liquid critical point, or in supercritical conditions differs quantitatively and qualitatively from the textbook gas dynamics of dilute, ideal gases. Due to nonideal fluid thermodynamic properties, unconventional gas dynamic effects are possible, including nonclassical rarefaction shock waves and the nonmonotonic variation of the Mach number along steady isentropic expansions. This review provides a comprehensive theoretical framework of the fundamentals of nonideal compressible fluid dynamics (NICFD). The relation between nonideal gas dynamics and the complexity of the fluid molecules is clarified. The theoretical, numerical, and experimental tools currently employed to investigate NICFD flows and related applications are reviewed, followed by an overview of industrial processes involving NICFD, ranging from organic Rankine and supercritical CO2 cycle power systems to supercritical processes. The future challenges facing researchers in the field are briefly outlined.

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“…All thermodynamic variables were obtained using the fluid database program REF-PROP developed by NIST using the pressure and temperature measurements. For the Pitot probe data reduction, the scheme and the program explained in detail by Gori [18] and Conti [19] were applied. The relative uncertainty level of the pressure measurements was of order ∆p/p = 0.5% up to 1.6%.…”

Section: Data Reduction and Uncertainty Analysismentioning

confidence: 99%

Profile Loss Prediction for Organic Rankine Cycle Turbines: An Experimental Case Study

Hake,

Sundermeier,

Wiesche

2023

IJTPP

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The results of profile loss measurements, including trailing edge flow details, are presented for the flow of an organic vapor through a linear turbine cascade. The so-called VKI-I blade profile from the open literature was chosen for the cascade, and the working fluid was NOVEC 649. Pitot probes and hot-wire anemometry were employed to measure the flow field up and downstream of the cascade. Details of the unsteady flow caused by the trailing edge of the blades and the turbulent spectrum were investigated using hot-wire anemometry. The new organic vapor flow results were compared with the literature data obtained for air and with the prediction of conventional literature loss models. It was found that, under certain thermodynamic conditions, specific traditional loss models can reasonably predict organic Rankine cycle (ORC) turbines’ profile loss. Still, significant deviations between the loss models and the experimental data can also occur.

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Pneumatic system for pressure probe measurements in transient flows of non-ideal vapors subject to line condensation

Cited by 9 publications

References 11 publications

Shock loss measurements in non-ideal supersonic flows of organic vapors

Shock loss measurements in non-ideal supersonic flows of organic vapors

Nonideal Compressible Fluid Dynamics of Dense Vapors and Supercritical Fluids

Profile Loss Prediction for Organic Rankine Cycle Turbines: An Experimental Case Study

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