Rate Constants for the Reactions of OH Radical with the (E)/(Z) Isomers of CF3CF═CHCl and CHF2CF═CHCl

Tokuhashi, Kazuaki; Uchimaru, Tadafumi; Takizawa, Kenji; Kondô, Shigeo

doi:10.1021/acs.jpca.7b11923

Cited by 14 publications

(16 citation statements)

References 26 publications

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“…However, a simple procedure to estimate the ODP seems to be also valuable. In a previous report, 4 we used 0.00047 as the modified ODP of (E)-CF 3 CH=CHCl based on the difference in the rate constants reported by Sulbaek Andersen et al 11 and recommended by Burkholder et al 13 Using the modified ODP of (E)-CF 3 CH=CHCl, we estimated the ODPs of (E)-CFCl=CFCl and (Z)-CFCl=CFCl using the following simple scaling procedure…”

Section: Resultsmentioning

confidence: 99%

“…In addition, calculations of the IR spectra were carried out in the same manner as described in our previous paper. 4 The geometry optimizations of the molecules and their frequency calculations were carried out using the DFT M062X functional and the aug-cc-pVTZ basis set. The calculated vibrational frequencies were scaled using the factors prescribed by Laury et al 7 More specifically, factors of 0.9698 and 0.9574 were applied for scaling the lower (below 1000 cm −1 ) and the higher frequencies, respectively.…”

Section: Resultsmentioning

confidence: 99%

“…The experimental apparatus and procedure for the measurements of the reaction rate constants and IR spectra have been described previously. ,, Briefly, the reaction rate constants were measured under pseudo-first-order conditions with a large excess of sample (( E )- or ( Z )-CFCl=CFCl or ( E )-CHF=CHF) relative to the initial concentration of OH radicals. OH radicals were produced by either the flash photolysis (FP) or laser photolysis (LP) method.…”

Section: Methodsmentioning

confidence: 99%

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Rate Constants for the Reactions of OH Radicals with the (E)/(Z) Isomers of CFCl=CFCl and (E)-CHF=CHF

et al. 2019

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The rate constants for the OH radical reactions with halogenated ethenes were investigated experimentally and computationally. The rate constants for the reactions of OH radicals with (E)-CFCl=CFCl (k 1 ), (Z)-CFCl=CFCl (k 2 ), and (E)-CHF=CHF (k 3 ) were measured using flash and laser photolysis methods. The temporal profile of the OH radical was monitored by a laser-induced fluorescence technique. Kinetic measurements were carried out over the temperature range of 250−430 K. Arrhenius rate constants were determined to be kThe quoted uncertainties are 95% confidence levels and do not include systematic errors. Infrared absorption spectra were measured at room temperature. The atmospheric lifetimes and the global warming potentials of (E)-CFCl=CFCl, (Z)-CFCl=CFCl, and (E)-CHF=CHF were estimated to be 4.3, 4.2, and 1.2 days and 0.035, 0.036, and 0.0056, respectively. The ozone depletion potentials of (E)-CFCl=CFCl and (Z)-CFCl=CFCl were determined to be 0.00011 and 0.00010, respectively. The photochemical ozone creation potentials of the halogenated ethenes were less than 1/4 that of ethene. In addition, the (E)/(Z) differences in the energy and IR spectra of the CFCl=CFCl and CHF=CHF molecules were computationally examined. The reactivities of these halogenated ethenes toward OH radicals were investigated through the combination of DFT and ab initio computations. The rate constants calculated for the OH radical reactions of these halogenated ethenes showed reasonable agreement with the experimentally determined values. Our computational results for the CFCl=CFCl and CHF=CHF (E)/(Z) isomeric pairs indicated that the rate constants toward OH radicals are larger for the higher-energy geometrical isomers than for the lower-energy counterparts.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Rate Constants for the Reactions of OH Radicals with the (E)/(Z) Isomers of CFCl=CFCl and (E)-CHF=CHF

et al. 2019

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“…The properties of HCFO-1224 yd are given in Table 1 along with those of HFE-347 pc-f for MSC (Kano, 2019) and HFE-7100 for MC (Al-Zaidi, 2019). The global warming potential (GWP) of HCFO-1224 yd is less than 1 (Tokuhashi, 2018) while constant values of the thermal conductivity, specific heat, and latent heat are assumed. The standard boiling point of HCFO-1224 yd is 15 °C, which makes the fluid suitable for high boiling heat transfer at low wall temperatures.…”

Section: Methodsmentioning

confidence: 99%

Experimental study on heat transfer enhancement in subcooled flow boiling under pressurized conditions

Shiono

Kano

2021

JTST

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In this study, the cooling capabilities of flow boiling heat transfer aided by electrohydrodynamic (EHD) force and diamond-electrodeposited boiling surface is investigated in a micro-slit channel (MSC). The MSC uses a two-phase flow cooling system, in which an electric field is applied to a dielectric liquid using a slit electrode. To reduce the wall temperature below 60 °C and promote cooling in electronic devices, a dielectric liquid with a saturation temperature of 15 °C HCFO-1224yd (AGC, AMOLEA, CF 3 CF = CHCI) was selected as a working fluid. Moreover, the entire system was pressurized using nitrogen gas to suppress liquid flow instabilities due to the generation of cavitation at the saturated system pressure. To enhance boiling heat transfer, the surface was electrically deposited with fine diamond particles (mixture of particles with diameters 20 and 1.5 m), and an electric field of −5 kV/mm was applied between the surface and slit electrode. The experiments were conducted under various system pressures (75-230 kPa), mass flow rates (1.67-5.00 g/s), and degrees of subcooling (5-15 K) to evaluate the heat transfer performance. The electric field was effective in increasing both the critical heat flux (CHF) and heat transfer coefficient (HTC). The high electric field enhanced the boiling heat transfer until the inflow liquid entirely evaporated. Increasing the mass flow rate was also effective in increasing the CHF and HTC at lower wall temperatures, resulting in a maximum of 101 W/cm 2 at 64 °C and 37 kW/m 2 •K at 52 °C, respectively. Increasing the system pressure improved the HTC but elevated the wall temperature. Subcooling was effective in increasing HTC. Increase in either pressure or subcooling did not change the CHF because the entire inflow liquid evaporated in the MSC chamber due to the electric field effect.

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“…Both R514A and R1224yd(Z) are proposed replacements for R123 and R245fa with zero ODP. The GWP for R514A is 2 (Myhre et al, 2013) and that for R1224yd(Z) is 0.88 (Tokuhashi et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Pool Boiling of R514A, R1224yd(Z), and R1336mzz(E) on a Reentrant Cavity Surface; Extensive Measurement and Analysis

Kedzierski¹,

Lin²

2020

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This paper quantifies the pool boiling performance of R514A, R1224yd(Z), and R1336mzz(E) on a flattened, horizontal Turbo-ESP surface for airconditioning applications for heat fluxes between roughly 10 kWm-2 and 100 kWm-2. R514A, R1224yd(Z), and R1336mzz(E) are replacements for R123 and R245fa. All of these replacement refrigerants had measured boiling heat fluxes that were larger than that for R123 for most heat fluxes. For example, for heat fluxes between 10 kWm-2 and 80 kWm-2 , R514A, R1224yd(Z), and R1336mzz(E) exhibited average heat fluxes that were 30 %, 57 %, and 13 % larger than that for R123 for a saturation temperature of 277.6 K. For the same comparison done at a saturation temperature of 298.2 K, the average heat flux for R514A was roughly 43 % larger than that for R123. A pool boiling model, that was previously developed for pure and mixed refrigerants on the Turbo-ESP surface, was compared to the measured boiling performance. The model predicted the measured superheats of the mixed refrigerants and the single component refrigerants to within ± 0.7 K and ± 0.45 K, respectively.

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Rate Constants for the Reactions of OH Radical with the (E)/(Z) Isomers of CF₃CF═CHCl and CHF₂CF═CHCl

Cited by 14 publications

References 26 publications

Rate Constants for the Reactions of OH Radicals with the (E)/(Z) Isomers of CFCl=CFCl and (E)-CHF=CHF

Rate Constants for the Reactions of OH Radicals with the (E)/(Z) Isomers of CFCl=CFCl and (E)-CHF=CHF

Experimental study on heat transfer enhancement in subcooled flow boiling under pressurized conditions

Pool Boiling of R514A, R1224yd(Z), and R1336mzz(E) on a Reentrant Cavity Surface; Extensive Measurement and Analysis

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