Modeling of combustion of fluorine-containing refrigerants

Babushok, Valeri I.; Burgess, Donald R.; Kim, Dennis K.; Hegetschweiler, Michael J.; Linteris, Gregory T.

doi:10.6028/nist.tn.2170

Cited by 8 publications

(5 citation statements)

References 28 publications

(43 reference statements)

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“…Thus, the maximum expanded relative uncertainty (kuc/X) for the reported experimental burning velocities is 12%. This does not consider the uncertainty due to the selected data range for the extrapolation, which are discussed in detail for the present data in Kim et al [145].…”

Section: Data Reductionmentioning

confidence: 88%

Low-GWP non-flammable alternative refrigerant blends for HFC-134a :

Domanski

2023

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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 replace HFC-134a (GWP=1300) in military environmental control units (ECUs) and to demonstrate their performance. This work is a follow-on to the limited-scope project WP-2740, which used thermodynamic cycle simulation models alone to screen over 100 000 refrigerant blends and identified over 20 candidate HFC-134a replacements. In the present study we narrowed the pool of blend candidates down to three best blends, demonstrated their performance through drop-in tests in a military ECU in environmental chambers over a wide range of operating conditions, and extrapolated the laboratory-measured performance to that of ECUs equipped with modified compressor for each blend to provide the same system capacity while maintaining the isentropic efficiency of the original HFC-134a compressor. The project involved preliminary experimental and analytical tasks in support of the final project task. These included measurements of thermodynamic and transport properties of the novel fluids considered and an update of simulation methods for these properties, fundamental tests exploring the flammability characteristics including calculation methods, fundamental measurements and modeling of forced-convection heat transfer performance, and measurements of cycle performance of candidate blends in a laboratory mini-breadboard heat pump apparatus as the final qualification step of the best blends for full-scale testing in the ECU. The project s conclusion is that R-513A (GWP=573) and a blend we call Tern-1 [R-134a/1234yf/1234ze(E) (49.2/33.9/16.9*), GWP=640] are good replacement blends for HFC-134a offering a similar performance at GWP reduction of 66 % and 51 %, respectively. These fluids do not present any significant application difficulties. If greater reduction in GWP is desirable, R-515B (GWP=344) and CO2 (GWP=1) can be considered but they require further challenging research and developmental work. In the above blend selection, we adopted the ASTM E681 test method as stipulated by ASHRAE Standard 34 for qualifying non-flammability of refrigerants. If military requirements for non-flammability are more stringent than the E681 standard, a smaller reduction of GWP will be possible with qualifying blends.

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Section: Data Reductionmentioning

confidence: 88%

Low-GWP non-flammable alternative refrigerant blends for HFC-134a :

Domanski

2023

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“…As indicated, the mechanism does a very good job of predicting the burning velocity for these conditions. A similar comparison has been performed for other refrigerants [66][67][68]. The different data sets on each frame correspond to different molar ratios of the two constituents, as indicated on the curve labels.…”

Section: Improvements In Predictive Modelmentioning

confidence: 90%

“…Early work at NIST developed a detailed kinetic model for HFC fire suppressants [64,65] and recent work has extended it to flames of pure refrigerants and air [66][67][68]. In the present project, the mechanism was further refined and updated with new rates and thermodynamic data appearing in the literature.…”

Section: Improvements In Predictive Modelmentioning

confidence: 99%

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Low-GWP non-flammable alternative refrigerant blends for HFC-134a :

Domanski

2023

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This project addresses the objectives of the Statement of Need number WPSON-17-02 for "No/Low Global Warming Potential Alternatives to Ozone Depleting Refrigerants" issued by the Strategic Environmental Research and Development Program (SERDP), the U.S. Department of Defense (DoD) environmental science and technology program, planned and executed in full partnership with the U.S. Department of Energy and the U.S. Environmental Protection Agency. The goal of this Statement of Need was to identify low global-warming-potential (GWP), nonflammable refrigerants to replace HFC-134a (GWP = 1300) in military equipment.This work is a follow-on to the SERDP limited-scope project WP-2740, carried out at NIST, which used thermodynamic cycle simulation models alone to screen over 100 000 refrigerant blends and identified over 20 candidate HFC-134a replacements. In the present study we narrowed the pool of blend candidates down to three "best" blends, demonstrated their performance through "drop-in" tests in a military environmental control unit (ECU) in environmental chambers over a wide range of operating conditions. Through simulation the laboratory-measured performance was extrapolated to that of ECUs equipped with a compressor modified for each blend to provide the same system capacity while maintaining the isentropic efficiency of the original HFC-134a compressor.The project involved preliminary experimental and analytical tasks in support of the final project task. These included measurements of thermodynamic and transport properties of the novel fluids considered and an update of simulation methods for these properties, fundamental tests exploring the flammability characteristics including calculation methods, fundamental measurements and modeling of forced-convection heat transfer performance, and measurements of cycle performance of candidate blends in a laboratory mini-breadboard heat pump apparatus as the final qualification step of the "best" blends for full-scale testing in the ECU. The project's conclusion is that R-513A (GWP = 573) and a blend we call Tern-1 [R-134a/1234yf/1234ze(E) (49.2/33.9/16.9 * ), GWP = 640] are good replacement blends for HFC-134a offering a similar capacity and coefficient of performance at GWP reduction of 66 % and 51 %, respectively. These fluids do not present any significant application difficulties. If greater reduction in GWP is desirable, R-515B (GWP = 344) can be considered but it requires further challenging research and developmental work.The GWP reduction also depends on the stringency of the military requirements for "nonflammability". At the time of execution of the project, military requirements for nonflammability had not been established. For this reason, we used the ASTM E681 test method as stipulated by ASHRAE Standard 34 for qualifying non-flammability. If military requirements for 'non-flammability' are more stringent than the E681 standard, a smaller reduction of GWP will be possible with qualifying blends.

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“…We are developing a larger kinetics model with additional reactions that are needed to describe the combustion of other hydrofluorocarbon (HFC) fuels and HFC-doped hydrocarbon flames. 21 The chemistry involves reactions of species containing carbon, hydrogen, oxygen, and fluorine. By analogy to methane combustion, one expects little formation of species larger than C 2 under conditions of current interest, thus limiting the necessary reactions.…”

Section: Overview Of Chemical Kinetic Mechanismmentioning

confidence: 99%

A chemical kinetic mechanism for combustion and flame propagation of CH₂F₂/O₂/N₂ mixtures

Burgess

Babushok

Manion

2021

Int J of Chemical Kinetics

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In this work, we compiled and evaluated rate expressions for reactions relevant to the decomposition and combustion of CH 2 F 2 (difluoromethane, refrigerant R-32) in CH 2 F 2 /O 2 /N 2 flames. The recommended values have been used in premixed flame calculations, reported elsewhere, to model experimentally derived burning velocities determined using a constant volume spherical flame method. In this work, we also provide a detailed description of the reaction pathways for decomposition and combustion of CH 2 F 2 . This work is part of a larger effort at NIST to characterize and predict the flammability of new refrigerant working fluids and their blends for consideration as replacements of current refrigerants with high global warming potentials.

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Modeling of combustion of fluorine-containing refrigerants

Cited by 8 publications

References 28 publications

Low-GWP non-flammable alternative refrigerant blends for HFC-134a :

Low-GWP non-flammable alternative refrigerant blends for HFC-134a :

Low-GWP non-flammable alternative refrigerant blends for HFC-134a :

A chemical kinetic mechanism for combustion and flame propagation of CH₂F₂/O₂/N₂ mixtures

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Modeling of combustion of fluorine-containing refrigerants

Cited by 8 publications

References 28 publications

Low-GWP non-flammable alternative refrigerant blends for HFC-134a :

Low-GWP non-flammable alternative refrigerant blends for HFC-134a :

Low-GWP non-flammable alternative refrigerant blends for HFC-134a :

A chemical kinetic mechanism for combustion and flame propagation of CH2F2/O2/N2 mixtures

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A chemical kinetic mechanism for combustion and flame propagation of CH₂F₂/O₂/N₂ mixtures