Estimation of Gas-Phase Heat Capacities for Hydrofluoroethers with Two Carbon Atoms

Blowers, Paul; Tetrault, Kyle Franklin; Trujillo-Morehead, Yirla

doi:10.1021/ie070724k

Cited by 5 publications

(6 citation statements)

References 27 publications

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“…Emissions of CO 2 -equiv would be slightly lower than the HFC basecase if the heat capacity were overestimated by 20%. However, our prior computations showed that our error in heat capacity for similar species was only about 3%, so this parameter is unlikely to change the results.…”

Section: Resultsmentioning

confidence: 85%

“…Figure 2d shows how results would vary for the HFE if the predicted gas-phase heat capacity were different from that used based on our prior work (23). If the predicted heat capacity were lower, impacts would be lower due to both the reduced energy requirement and the reduced material flow that would occur due to the lower liquid phase heat capacity, as discussed earlier.…”

Section: Resultsmentioning

confidence: 90%

“…Computational chemistry and statistical thermodynamics were used to predict heat capacities for the existing HFE data points and were in close agreement with the measurements. The same approaches were used to predict the heat capacity of CF 3 OCH 3 (23). Corresponding states equations estimated the liquid heat capacity from the gas-phase heat capacity functions.…”

Section: Methodsmentioning

confidence: 99%

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Carbon Dioxide Emission Implications if Hydrofluorocarbons are Regulated: A Refrigeration Case Study

Blowers

Lownsbury

2010

Environ. Sci. Technol.

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The U.S. is strongly considering regulating hydrofluorocarbons (HFCs) due to their global climate change forcing effects. A drop-in replacement hydrofluoroether has been evaluated using a gate-to-grave life cycle assessment of greenhouse gas emissions for the trade-offs between direct and indirect carbon dioxide equivalent emissions compared to a current HFC and a historically used refrigerant. The results indicate current regulations being considered may increase global climate change.

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Section: Resultsmentioning

confidence: 85%

Section: Resultsmentioning

confidence: 90%

Section: Methodsmentioning

confidence: 99%

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Carbon Dioxide Emission Implications if Hydrofluorocarbons are Regulated: A Refrigeration Case Study

Blowers

Lownsbury

2010

Environ. Sci. Technol.

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“…The liquid isobaric specific heat capacity of PBA is calculated by the Sternling–Brown equation [ 26 ], as shown in Equation (5). The ideal gas state isobaric specific heat capacity of PBA is calculated by Equation (6) [ 27 ].

where

(J·g −1 ·K −1 ) is the specific heat capacity at constant pressure for PBAs in their ideal gas state,

(J·g −1 ·K −1 ) is the specific heat capacity at constant pressure for PBAs in the liquid state.…”

Section: Modeling Methodsmentioning

confidence: 99%

Behavior Characteristics and Thermal Energy Absorption Mechanism of Physical Blowing Agents in Polyurethane Foaming Process

2023

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Polyurethane rigid foam is a widely used insulation material, and the behavior characteristics and heat absorption performance of the blowing agent used in the foaming process are key factors that affect the molding performance of this material. In this work, the behavior characteristics and heat absorption of the polyurethane physical blowing agent in the foaming process were studied; this is something which has not been comprehensively studied before. This study investigated the behavior characteristics of polyurethane physical blowing agents in the same formulation system, including the efficiency, dissolution, and loss rates of the physical blowing agents during the polyurethane foaming process. The research findings indicate that both the physical blowing agent mass efficiency rate and mass dissolution rate are influenced by the vaporization and condensation process of physical blowing agent. For the same type of physical blowing agent, the amount of heat absorbed per unit mass decreases gradually as the quantity of physical blowing agent increases. The relationship between the two shows a pattern of initial rapid decrease followed by a slower decrease. Under the same physical blowing agent content, the higher the heat absorbed per unit mass of physical blowing agent, the lower the internal temperature of the foam when the foam stops expanding. The heat absorbed per unit mass of the physical blowing agents is a key factor affecting the internal temperature of the foam when it stops expanding. From the perspective of heat control of the polyurethane reaction system, the effects of physical blowing agents on the foam quality were ranked in order from good to poor as follows: HFC-245fa, HFC-365mfc, HFCO-1233zd(E), HFO-1336mzzZ, and HCFC-141b.

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“…They also described how molecular structure can be manipulated to reduce environmental impacts due to global warming. Blowers et al [196] estimated the gas-phase heat capacities of nine HFEs containing two carbon atoms (CH 3 OCH 2 F, CH 3 OCHF 2 , CHF 2 OCHF 2 , CH 3 OCF 3 , CH 2 FOCHF 2 , CHF 2 OCHF 2 , CH 2 FOCF 3 , CHF 2 OCF 3 , and dimethyl ether) using the B3LYP/6-31G(d) method. They found close agreement with experimental values for the two HFEs and a good agreement over a wide temperature range for dimethyl ether.…”

Section: Global Warming Potentialmentioning

confidence: 99%

Assessment of theoretical methods for the study of hydrogen abstraction kinetics of global warming gas species during their degradation and byproduct formation (IUPAC Technical Report)

Ramasami

Abdallah

Archibong

et al. 2013

Pure and Applied Chemistry

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Global climate change is a major concern as it leads to an increase in the average temperature of the earth's atmosphere. The existence and persistence of some gaseous species in the atmosphere contribute to global warming. Experimental techniques are used to study the kinetics and degradation of global warming gases. However, quantum mechanical methods are also useful for the kinetic and radiative forcing study of global warming species and can precede experimental investigations. Research has also been targeted to develop more adapted procedures using ab initio and density functional theory (DFT) methods. This report provides a global perspective, in simplified manner, of the theoretical studies of the degradation of gas species in the atmosphere with an emphasis on the hydrogen abstraction kinetics of global warming gas species during their degradation and byproduct formation. En route, the results obtained from these studies are analysed and compared with experimental data where available. Our analyses indicate that the theoretical predictions are in agreement with experimental findings but the predicted parameters are dependent on the method being used. Theoretical methods are used to predict the thermodynamic parameters of reactions, and, with relevance to this report, the global warming potential (GWP) index can also be calculated. This report can be useful for future investigations involving global warming gaseous species while providing suggestions on how computations can fill in data gaps when experimental data are unavailable.

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Estimation of Gas-Phase Heat Capacities for Hydrofluoroethers with Two Carbon Atoms

Cited by 5 publications

References 27 publications

Carbon Dioxide Emission Implications if Hydrofluorocarbons are Regulated: A Refrigeration Case Study

Carbon Dioxide Emission Implications if Hydrofluorocarbons are Regulated: A Refrigeration Case Study

Behavior Characteristics and Thermal Energy Absorption Mechanism of Physical Blowing Agents in Polyurethane Foaming Process

Assessment of theoretical methods for the study of hydrogen abstraction kinetics of global warming gas species during their degradation and byproduct formation (IUPAC Technical Report)

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