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Search Publications by: Gregory T. Linteris (Fed)

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Displaying 1 - 25 of 195

A DNS study of the impact of gravity on spherically expanding laminar premixed flames

September 25, 2023
Author(s)
Lukas Berger, Raik Hesse, Michael Hegetschweiler, Antonio Attili, Konstantin Kleinheinz, Joachim Beeckmann, Gregory T. Linteris, Heinz Pitsch
Determining laminar flame speeds from spherical flame experiments is dicult for low flame speeds, when the flame shapes quickly become non-spherical due to the influence of gravity. Direct Numerical Simulations (DNS) of spherically expanding laminar

A Microgravity Flame Speed Study on Refrigerant Mixtures of 2,3,3,3-Tetrafluoropropene (R1234yf) and Difluoromethane (R32)

September 25, 2023
Author(s)
Raik Hesse, Roman Glaznev, Christian Schwenzer, Valeri I. Babushok, Gregory T. Linteris, Heinz Pitsch, Joachim Beeckmann
Today's hydrofluorocarbon (HFC) refrigerants are designed to have a low global warming potential (GWP), resulting in fast atmospheric decomposition and increased reactivity. This causes them to be mildly flammable. The laminar flame speed SL,u ranks

Data Reduction Considerations for Spherical Constant Volume Flames of R32(CH2F2) with Air

September 25, 2023
Author(s)
Michael Hegetschweiler, Lukas Berger, Raik Hesse, Joachim Beeckmann, Chaimae Bariki, Heinz Pitsch, Gregory T. Linteris
The present work explores data reduction techniques for the measurement of the laminar burning velocities of R32(CH2F2)-air using a constant volume combustion device in which the pressure-time history is the only measured parameter. To allow clear

Elucidating the challenges in extracting ultra-slow flame speeds in a closed vessel - A CH2F2 microgravity case study using optical and pressure-rise data

September 25, 2023
Author(s)
Raik Hesse, Chaimae Bariki, Michael Hegetschweiler, Gregory T. Linteris, Heinz Pitsch, Joachim Beeckmann
Refrigerants with a low global warming potential (GWP) possess mild flammability. Hence, a fundamental understanding of their combustion characteristics is required to assess their fire-hazardous potential. The laminar burning velocity is one fundamental

Simultaneous Particle Image Velocimetry and Schlieren Measurements of Slow-burning Flames

September 25, 2023
Author(s)
Christian Schwenzer, Raik Hesse, Roman Glaznev, Valeri I. Babushok, Gregory T. Linteris, Heinz Pitsch, Joachim Beeckmann
The measurement of laminar flame speed is an essential factor in determining the reactivity, exothermicity, and diffusivity of a combustible mixture. In this study, the Schlieren method and Particle Image Velocimetry (PIV) were utilized simultaneously to

Flame Propagation in Blends of R152a, R134a, and R-1234yf with Air

September 13, 2023
Author(s)
Dennis Kim, Valeri I. Babushok, Michael Hegetschweiler, Gregory T. Linteris
Laminar burning velocity measurements have been made using a constant volume experiment with dry air and the refrigerant R152a (CH3CHF2), pure and blended with R134a (CH2FCF3), or R1234yf (CF3CFCH2). The resulting burning velocity data deduced from the

Non-flammable Low-GWP Refrigerant Blends to Replace HFC-134a

September 11, 2023
Author(s)
Harrison M. Skye, Piotr A. Domanski, Mark O. McLinden, Valeri I. Babushok, Ian Bell, Tara Fortin, Michael Hegetschweiler, Mark A. Kedzierski, Dennis Kim, Lingnan Lin, Gregory T. Linteris, Stephanie L. Outcalt, Vance (Wm.) Payne, Richard A. Perkins, Aaron Rowane
Non-flammable, lower global-warming-potential (GWP) refrigerants are needed to replace HFC-134a (GWP=1300) in military equipment. We previously used thermodynamic cycle simulations to screen 100 000+ refrigerant blends and identified 23 candidate

Lower-GWP Non-Flammable Refrigerant Blends to Replace HFC-134a

August 21, 2023
Author(s)
Harrison M. Skye, Piotr A. Domanski, Mark O. McLinden, Valeri I. Babushok, Ian Bell, Tara Fortin, Michael Hegetschweiler, Marcia L. Huber, Mark A. Kedzierski, Dennis Kim, Lingnan Lin, Gregory T. Linteris, Stephanie L. Outcalt, Vance (Wm.) Payne, Richard A. Perkins, Aaron Rowane
Non-flammable, lower global-warming-potential (GWP) refrigerants are needed to replace HFC-134a (GWP=1300) in military equipment. We previously used thermodynamic cycle simulations to screen 100 000+ refrigerant blends and identified 23 candidate

Low-GWP Non-Flammable Alternative Refrigerant Blends for HFC-134a: Final Report

January 27, 2023
Author(s)
Piotr A. Domanski, Mark O. McLinden, Valeri I. Babushok, Ian Bell, Tara Fortin, Michael Hegetschweiler, Marcia L. Huber, Mark A. Kedzierski, Dennis Kim, Lingnan Lin, Gregory T. Linteris, Stephanie L. Outcalt, Vance (Wm.) Payne, Richard A. Perkins, Aaron Rowane, Harrison M. Skye
This project addresses the objectives of the Statement of Need number WPSON-17-20 "No/Low Global Warming Potential Alternatives to Ozone Depleting Refrigerants." Its goal was to identify low global-warming-potential (GWP), non-flammable refrigerants to

A Kinetic Mechanism for CF3I Inhibition of Methane-Air Flames

January 12, 2022
Author(s)
Valeri I. Babushok, Donald R. Burgess Jr., Gregory T. Linteris
The influence of CF3I on the burning velocity of methane–air flame is experimentally and numerically studied. Experimental results demonstrate that the inhibition effectiveness of CF3I is very close to that of CF3Br. A detailed kinetic model of flame

Modeling of Combustion of Fluorine-Containing Refrigerants

November 17, 2021
Author(s)
Valeri I. Babushok, Donald R. Burgess Jr., Dennis Kim, Michael Hegetschweiler, Gregory T. Linteris
A gas-phase chemical kinetic model for the combustion of C1-C3 fluorine-containing refrigerants is presented, including a list of relevant species, their thermodynamic and transport properties, and the Arrhenius parameters for their reactions. Also

Low-GWP Alternative Refrigerant Blends for HFC-134a: Interim Report

October 13, 2021
Author(s)
Piotr A. Domanski, Mark O. McLinden, Valeri I. Babushok, Ian Bell, Tara Fortin, Michael Hegetschweiler, Mark A. Kedzierski, Dennis Kim, Lingnan Lin, Gregory T. Linteris, Stephanie L. Outcalt, Richard A. Perkins, Aaron Rowane, Harrison M. Skye
This project addresses the objectives of the Statement of Need number WPSON-17-20 "No/Low Global Warming Potential Alternatives to Ozone Depleting Refrigerants." Its goal is to identify and demonstrate performance of low global-warming-potential (GWP), non

Data Reduction Tool for Spherical Constant Volume Flame Experiments

April 2, 2021
Author(s)
Michael Hegetschweiler, Gregory T. Linteris
A data reduction tool was developed to conveniently post-process spherical constant volume flame experiments. Such experiments are employed to obtain laminar flame velocities in a premixed gas mixture. The setup is relatively simple and the only recorded

Low global-warming-potential refrigerant CH2F2 (R-32): Integration of a radiation heat loss correction method to accurately determine experimental flame speed metrics

August 22, 2020
Author(s)
Gregory T. Linteris, Raik Hesse, Lukas Berger, Michael Hegetschweiler, Heinz Pitsch, Joachim Beeckmann
Due to their high global warming potential (GWP), hydrofluorocarbon refrigerants (HFCs) are systematically being phased out. Replacements with low GWP exist, but give rise to safety hazards as they are found to be mildly flammable. The assessment of the

Numerical and Experimental Studies of Extinguishment of Cup-Burner Flames by C6F12O

August 1, 2020
Author(s)
Fumiaki Takahashi, Viswanath R. Katta, Valeri I. Babushok, Gregory T. Linteris
The extinguishment processes of cup-burner flames by adding a halon-replacement fire-extinguishing agent C6F12O (Novec 1230) to coflowing air in normal gravity have been studied computationally and experimentally. The time-dependent, axisymmetric numerical

Measurements and Modeling of Spherical CH2F2-Air Flames

July 27, 2020
Author(s)
Michael J. Hegetschweiler, John L. Pagliaro, Lukas Berger, Raik Hesse, Joachim Beeckmann, Heinz Pitsch, Gregory T. Linteris
The burning velocity of mixtures of the refrigerant R-32 (CH2F2) with air over a range of equivalence ratios are studied via spherically expanding flames SEFs in a large, optically accessible spherical chamber at constant pressure. Shadowgraph images from

Flammable Refrigerant Safety

April 22, 2020
Author(s)
Gregory T. Linteris, Peter Sunderland
Most refrigerants currently in use have relatively high Global Warming Potential (GWP). For example, the GWPs of R-134a and R-410a are 1300 and 2088. Leaks to the atmosphere are common – typically about 10% of the total charge annually. This has motivated

Effects of Stretch and Radiation on the Laminar Burning Velocity of R-32-Air Flames

March 4, 2020
Author(s)
Michael Hegetschweiler, John Pagliaro, Lukas Berger, Raik Hesse, Joachim Beeckmann, Heinz Pitsch, Gregory T. Linteris
Experiments are performed for outwardly propagating spherical flames of R-32/air mixtures at constant pressure. A high-speed video camera captures shadowgraph images from which the flame radius as a function of time is extracted. Direct numerical

The hunt for refrigerant blends to replace R-134a

August 1, 2019
Author(s)
Ian H. Bell, Piotr A. Domanski, Gregory T. Linteris, Mark O. McLinden
We investigated refrigerant blends as possible low GWP (global warming potential) alternatives for R-134a in an air-conditioning application. We carried out an extensive screening of the binary, ternary, and four-component blends possible among a list of

R-152a/air and R-134a/oxygen constant volume spherical flame burning velocity measurements

March 25, 2019
Author(s)
Robert R. Burrell, Gregory T. Linteris, Donald R. Burgess Jr., Michael J. Hegetschweiler, Jeffrey A. Manion, Valeri I. Babushok
Many presently used refrigerants are non-flammable but are being phased out due to concerns about their strong global warming potential (GWP). Replacements with low GWP exist but tend to be flammable with a maximum burning velocity in air between 1 cm/s