The Experts below are selected from a list of 225 Experts worldwide ranked by ideXlab platform
Giovanni A Longo - One of the best experts on this subject based on the ideXlab platform.
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Heat transfer and pressure drop during HFC refrigerant Saturated Vapour condensation inside a brazed plate heat exchanger
International Journal of Heat and Mass Transfer, 2020Co-Authors: Giovanni A LongoAbstract:This paper presents the heat transfer coefficients and the pressure drop measured during HFC refrigerants 236fa, 134a and 410A Saturated Vapour condensation inside a brazed plate heat exchanger: the effects of saturation temperature (pressure), refrigerant mass flux and fluid properties are investigated. The heat transfer coefficients show weak sensitivity to saturation temperature (pressure) and great sensitivity to refrigerant mass flux and fluid properties. A transition point between gravity controlled and forced convection condensation has been found for a refrigerant mass flux around 20 kg/m2s that corresponds to an equivalent Reynolds number around 1600-1700. At low refrigerant mass flux (Gr < 20 kg/m2s) the heat transfer coefficients are not dependent on mass flux and are well predicted by the Nusselt (1916) analysis for vertical surface: the condensation process is gravity controlled. For higher refrigerant mass flux (Gr > 20 kg/m2s) the heat transfer coefficients depend on mass flux and are well predicted by the Akers et al. (1959) equation: forced convection condensation occurs. In the forced convection condensation region the heat transfer coefficients show a 25-30% increase for a doubling of the refrigerant mass flux.\ud The frictional pressure drop shows a linear dependence on the kinetic energy per unit volume of the refrigerant flow and therefore a quadratic dependence on mass flux.\ud HFC-410A shows heat transfer coefficients similar to HFC-134a and 10% higher than HFC-236fa together with frictional pressure drops 40-50% lower than HFC-134a and 50-60% lower than HFC-236f
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Refrigerant R134a condensation heat transfer and pressure drop inside a small brazed plate heat exchanger
International Journal of Refrigeration, 2020Co-Authors: Giovanni A LongoAbstract:This paper presents the experimental tests on HFC-134a condensation inside a small brazed plate heat exchanger: the effects of refrigerant mass flux, saturation temperature and Vapour super-heating are investigated. A transition point between gravity controlled and forced convection condensation has been found for a refrigerant mass flux around 20 kg/m2 s. For refrigerant mass flux lower than 20 kg/m2 s, the Saturated Vapour heat transfer coefficients are not dependent on mass flux and are well predicted by the Nusselt [Nusselt, W., 1916. Die oberflachenkondensation des wasserdampfes. Z. Ver. Dt. Ing. 60, 541–546, 569–575] analysis for vertical surface. For refrigerant mass flux higher than 20 kg/m2 s, the Saturated Vapour heat transfer coefficients depend on mass flux and are well predicted by the Akers et al. [Akers, W.W., Deans, H.A., Crosser, O.K., 1959. Condensing heat transfer within horizontal tubes. Chem. Eng. Prog. Symp. Ser. 55, 171–176] equation. In the forced convection condensation region, the heat transfer coefficients show a 30% increase for a doubling of the refrigerant mass flux. The condensation heat transfer coefficients of super-heated Vapour are 8–10% higher than those of Saturated Vapour and are well predicted by the Webb [Webb, R.L., 1998. Convective condensation of superheated Vapour. ASME J. Heat Transfer 120, 418–421] model. The heat transfer coefficients show weak sensitivity to saturation temperature. The frictional pressure drop shows a linear dependence on the kinetic energy per unit volume of the refrigerant flow and therefore a quadratic dependence on the refrigerant mass flux
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Saturated Vapour condensation of hfc404a inside a 4 mm id horizontal smooth tube comparison with the long term low gwp substitutes hc290 propane and hc1270 propylene
International Journal of Heat and Mass Transfer, 2017Co-Authors: Giovanni A Longo, Giulia Righetti, Simone Mancin, Claudio ZilioAbstract:Abstract This paper presents the comparative analysis of HFC404A and its low GWP substitutes HC290, and HC1270 in Saturated Vapour condensation inside a 4 mm ID horizontal smooth tube. The experimental tests were carried out at 30, 35, and 40 °C of saturation temperatures, with refrigerant mass flux in the range 75–800 kg m −2 s −1 at decreasing Vapour quality. A transition point from gravity-dominated and forced convection condensation was found for an equivalent Reynolds number around 10,000. The experimental heat transfer coefficients in the forced convection condensation regime were very well predicted by the Akers et al. (1959) model, whereas the Friedel (1979) correlation was able to reproduce the frictional pressure drop data in the whole experimental range. HC290 and HC1270 exhibit heat transfer coefficients higher and frictional pressure drops lower than those of HFC404A; therefore both the HC refrigerants seem to be very promising as long-term low GWP substitutes for HFC404A.
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hfo1234ze z Saturated Vapour condensation inside a brazed plate heat exchanger
2014 Purdue Conferences. 15th International Refrigeration and Air-Conditioning Conference at Purdue., 2014Co-Authors: Giovanni A Longo, Claudio Zilio, Giulia Righetti, Steven J BrownAbstract:This paper presents the experimental heat transfer coefficients and pressure drop measured during HFO1234ze(Z) Saturated Vapour condensation inside a small commercial BPHE: the effects of refrigerant mass flux and saturation temperature were investigated. The heat transfer coefficients show weak sensitivity to saturation temperature and great sensitivity to refrigerant mass flux. At low refrigerant mass flux ( 15 kg m-2s-1) the heat transfer coefficients depend on mass flux and forced convection condensation occurs. The frictional pressure drop shows a linear dependence on the kinetic energy per unit volume of the refrigerant flow and therefore a quadratic dependence on the refrigerant mass flux. HFO1234ze(Z) shows heat transfer coefficients and frictional pressure drop higher than HFC236fa. The experimental results were compared against theoretical models for condensation heat transfer coefficients (Nusselt, 1916 and Akers et al., 1959) and a new linear correlation for two-phase frictional pressure drop was presented.
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The effect of Vapour super-heating on hydrocarbon refrigerant condensation inside a brazed plate heat exchanger
Experimental Thermal and Fluid Science, 2011Co-Authors: Giovanni A LongoAbstract:Abstract This paper investigates the effect of Vapour super-heating on hydrocarbon refrigerant 600a (Isobutane), 290 (Propane) and 1270 (Propylene) condensation inside a brazed plate heat exchanger. Vapour super-heating increases heat transfer coefficient with respect to Saturated Vapour, whereas no effect was observed on pressure drop. The super-heated Vapour condensation data shows the same trend vs. refrigerant mass flux as the Saturated Vapour condensation data, but with higher absolute values. A transition point between gravity controlled and forced convection condensation has been found for a refrigerant mass flux around 15–18 kg m −2 s −1 depending on refrigerant type. The super-heated Vapour heat transfer coefficients are from 5% to 10% higher than those of Saturated Vapour under the same refrigerant mass flux. The experimental heat transfer coefficients have been compared against Webb (1998) model for forced convection condensation of super-heated Vapour: the mean absolute percentage deviation between the experimental and calculated data is ±18.3%. HC-1270 shows super-heated Vapour heat transfer coefficient 5% higher than HC-600a and 10–15% higher than HC-290 together with total pressure drops 20–25% lower than HC-290 and 50–66% lower than HC-600a under the same mass flux.
Mingde Yang - One of the best experts on this subject based on the ideXlab platform.
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determination of Saturated Vapour pressure of aniline hydrochloride and Vapour liquid equilibrium of the water aniline hydrochloride system
Fluid Phase Equilibria, 2016Co-Authors: Husheng Hu, Yulong Wu, Mingde YangAbstract:Abstract The Vapour–liquid equilibrium (VLE) data for water (A)-aniline hydrochloride (B) binary system is the basis for the design of distillation columns for recovery of aniline hydrochloride from condensate aqueous solution produced during the dehydration of bischofite by aniline hydrochloride composite salt method or from the wastewater containing aniline hydrochloride. In this study, a new dynamic condensate-circulation still was designed and used for the determination of Saturated Vapour pressure of pure aniline hydrochloride and VLE and Vapour–liquid–solid equilibrium (VLSE) data for water (A)-aniline hydrochloride (B) binary system at 101.3 kPa. The phase diagrams of equilibrated Vapour-phase composition versus overall liquid-phase composition yB-xB (where subscript B denotes aniline hydrochloride) and equilibrated temperature versus overall liquid-phase or Vapour-phase composition T-xB(yB) were plotted by using the VLE and VLSE data and the data on solubility. The VLE data for this system were correlated with a binary non-electrolyte NRTL and an electrolyte-NRTL activity coefficient model respectively, and the results indicated that the use of electrolyte-NRTL gave satisfactory results (the root mean square deviations (RMSD) between predicted and measured are RMSD(ΔT) = 2.5 K, RMSD(ΔyB) = 0.0021).
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Determination of Saturated Vapour pressure of aniline hydrochloride and Vapour–liquid equilibrium of the water- aniline hydrochloride system
Fluid Phase Equilibria, 2016Co-Authors: Husheng Hu, Yulong Wu, Mingde YangAbstract:Abstract The Vapour–liquid equilibrium (VLE) data for water (A)-aniline hydrochloride (B) binary system is the basis for the design of distillation columns for recovery of aniline hydrochloride from condensate aqueous solution produced during the dehydration of bischofite by aniline hydrochloride composite salt method or from the wastewater containing aniline hydrochloride. In this study, a new dynamic condensate-circulation still was designed and used for the determination of Saturated Vapour pressure of pure aniline hydrochloride and VLE and Vapour–liquid–solid equilibrium (VLSE) data for water (A)-aniline hydrochloride (B) binary system at 101.3 kPa. The phase diagrams of equilibrated Vapour-phase composition versus overall liquid-phase composition yB-xB (where subscript B denotes aniline hydrochloride) and equilibrated temperature versus overall liquid-phase or Vapour-phase composition T-xB(yB) were plotted by using the VLE and VLSE data and the data on solubility. The VLE data for this system were correlated with a binary non-electrolyte NRTL and an electrolyte-NRTL activity coefficient model respectively, and the results indicated that the use of electrolyte-NRTL gave satisfactory results (the root mean square deviations (RMSD) between predicted and measured are RMSD(ΔT) = 2.5 K, RMSD(ΔyB) = 0.0021).
W Wagner - One of the best experts on this subject based on the ideXlab platform.
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measurement and correlation of the p ρ t relation of ethane ii Saturated liquid and Saturated Vapour densities and Vapour pressures along the entire coexistence curve
The Journal of Chemical Thermodynamics, 2002Co-Authors: M Funke, Reiner Kleinrahm, W WagnerAbstract:Abstract Comprehensive and accurate measurements of the Saturated-liquid and Saturated-Vapour densities together with the Vapour pressure of pure nitrogen were carried out from the temperature T =64 K (triple-point temperature T t =63.151 K) to 0.0222 K below the critical temperature. The typical values of the total uncertainties of the measurements are: −4 · p σ ∣ for the Vapour pressures, −4 ·ρ′∣ for the Saturated-liquid densities, and −4 ·ρ″∣ for the Saturated-Vapour densities. The critical constants (T c =126.192 K, ρ c =313.3 kg·m −3 , ρ c =3.3958 MPa) and the isothermal compressibilities in the critical region close to the phase boundary have also been determined from these measurements. Comparisons with experimental results of previous workers are presented. Based on the new values of this work, new correlation equations for the Vapour pressure, the Saturated-liquid density, and the Saturated-Vapour density have been established.
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measurement and correlation of the p ρ t relation of sulphur hexafluoride sf 6 ii Saturated liquid and Saturated Vapour densities and Vapour pressures along the entire coexistence curve
The Journal of Chemical Thermodynamics, 2002Co-Authors: M Funke, Reiner Kleinrahm, W WagnerAbstract:Abstract Comprehensive and accurate measurements of the Saturated-liquid and Saturated-Vapour densities together with the Vapour pressure of pure sulphur hexafluoride were carried out from the temperature T = 224 K (triple-point temperature Tt = 223.555 K) to 0.033 K below the critical temperature ( Tc = 318.723 K). Typical values of the total uncertainties of the measurements are: ⩽ ± 0.01 percent for the Vapour pressures,⩽ ± 0.015 percent for the Saturated-liquid densities, and⩽ ± 0.016 percent for the Saturated-Vapour densities. The values for the critical density and the critical pressure ( ρc = 742.26 kg · m − 3, pc = 3.7550 MPa) and the isothermal compressibilities in the critical region close to the phase boundary have also been determined from these measurements. Comparisons with experimental results of previous workers are presented. Using the new values of this work, new correlation equations for the Vapour pressure, the Saturated-liquid density, and the Saturated-Vapour density have been established.
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measurement and correlation of the pressure density temperature relation of carbon dioxide ii Saturated liquid and Saturated Vapour densities and the Vapour pressure along the entire coexistence curve
The Journal of Chemical Thermodynamics, 1990Co-Authors: W Duschek, Reiner Kleinrahm, W WagnerAbstract:Abstract Comprehensive measurements of the Saturated-liquid and -Vapour densities together with the Vapour pressure of pure carbon dioxide were carried out from the triple-point temperature (216.580 K) up to about 0.1 K below the critical temperature. The critical constants ( T c = 304.136 K, ϱ c = 467.6 kg · m −3 , p c = 7.3773 MPa) and the isothermal compressibilities in the critical region close to the phase boundary were also determined from these measurements. Comparisons with the experimental results of previous studies are presented. Based on the new values of this work, new correlation equations for the Vapour pressure, the Saturated-liquid density, and the Saturated-Vapour density have been established. These correlation equations are compared with three current equations of state for carbon dioxide and with several correlation equations for the saturation properties. Furthermore, the influence of condensation in capillaries and pores on the measurements of the Saturated-Vapour densities is described.
Husheng Hu - One of the best experts on this subject based on the ideXlab platform.
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determination of Saturated Vapour pressure of aniline hydrochloride and Vapour liquid equilibrium of the water aniline hydrochloride system
Fluid Phase Equilibria, 2016Co-Authors: Husheng Hu, Yulong Wu, Mingde YangAbstract:Abstract The Vapour–liquid equilibrium (VLE) data for water (A)-aniline hydrochloride (B) binary system is the basis for the design of distillation columns for recovery of aniline hydrochloride from condensate aqueous solution produced during the dehydration of bischofite by aniline hydrochloride composite salt method or from the wastewater containing aniline hydrochloride. In this study, a new dynamic condensate-circulation still was designed and used for the determination of Saturated Vapour pressure of pure aniline hydrochloride and VLE and Vapour–liquid–solid equilibrium (VLSE) data for water (A)-aniline hydrochloride (B) binary system at 101.3 kPa. The phase diagrams of equilibrated Vapour-phase composition versus overall liquid-phase composition yB-xB (where subscript B denotes aniline hydrochloride) and equilibrated temperature versus overall liquid-phase or Vapour-phase composition T-xB(yB) were plotted by using the VLE and VLSE data and the data on solubility. The VLE data for this system were correlated with a binary non-electrolyte NRTL and an electrolyte-NRTL activity coefficient model respectively, and the results indicated that the use of electrolyte-NRTL gave satisfactory results (the root mean square deviations (RMSD) between predicted and measured are RMSD(ΔT) = 2.5 K, RMSD(ΔyB) = 0.0021).
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Determination of Saturated Vapour pressure of aniline hydrochloride and Vapour–liquid equilibrium of the water- aniline hydrochloride system
Fluid Phase Equilibria, 2016Co-Authors: Husheng Hu, Yulong Wu, Mingde YangAbstract:Abstract The Vapour–liquid equilibrium (VLE) data for water (A)-aniline hydrochloride (B) binary system is the basis for the design of distillation columns for recovery of aniline hydrochloride from condensate aqueous solution produced during the dehydration of bischofite by aniline hydrochloride composite salt method or from the wastewater containing aniline hydrochloride. In this study, a new dynamic condensate-circulation still was designed and used for the determination of Saturated Vapour pressure of pure aniline hydrochloride and VLE and Vapour–liquid–solid equilibrium (VLSE) data for water (A)-aniline hydrochloride (B) binary system at 101.3 kPa. The phase diagrams of equilibrated Vapour-phase composition versus overall liquid-phase composition yB-xB (where subscript B denotes aniline hydrochloride) and equilibrated temperature versus overall liquid-phase or Vapour-phase composition T-xB(yB) were plotted by using the VLE and VLSE data and the data on solubility. The VLE data for this system were correlated with a binary non-electrolyte NRTL and an electrolyte-NRTL activity coefficient model respectively, and the results indicated that the use of electrolyte-NRTL gave satisfactory results (the root mean square deviations (RMSD) between predicted and measured are RMSD(ΔT) = 2.5 K, RMSD(ΔyB) = 0.0021).
Vaclav Svoboda - One of the best experts on this subject based on the ideXlab platform.
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calculation of heats of vaporization of selected groups of organic compounds containing oxygen sulphur or nitrogen by using Saturated Vapour pressure data
Fluid Phase Equilibria, 1993Co-Authors: Pavlina Basařova, Vaclav Svoboda, Zdenka KolskaAbstract:Abstract Basařova P., Svoboda V. and Kolska Z., 1992. Calculation of heats of vaporization of selected groups of organic compounds containing oxygen, sulphur or nitrogen by using Saturated Vapour pressure data. Using the Clapeyron equation the data on the temperature dependence of vaporization heats were calculated for selected groups of non-associating and weakly associated organic compounds, like ethers, esters, phenols, carbonyl compounds, amines, nitriles, sulphides, thiols, heterocyclic and miscellaneous compounds containing oxygen, sulphur or nitrogen. The parameters of the Wagner equation for Vapour pressure correlation and of the modified Redlich-Kwong-Soave equation of state are given as well.
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calculation of heats of vaporization of halogenated hydrocarbons from Saturated Vapour pressure data
Fluid Phase Equilibria, 1991Co-Authors: Pavlina Basařova, Vaclav SvobodaAbstract:Abstract Basařova P. and Svoboda V., 1991. Calculation of heats of vaporization of halogenated hydrocarbons from Saturated Vapour pressure data. The Clapeyron equation was employed for calculating the data on the temperature dependence of heats of vaporization for a group of seventy five halogenated hydrocarbons. The calculated parameters of the Wagner equation and the Redlich-Kwong-Soave equation are given as well.
