alex huerta | Instituto de Pesquisas Energéticas e Nucleares (IPEN-CNEN/SP) (original) (raw)
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Instituto Tecnológico y de Estudios Superiores de Monterrey (ITESM)
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A numerical model has been developed to simulate the effects of the oil on the performance of cap... more A numerical model has been developed to simulate the effects of the oil on the performance of capillary tubes considering a separated flow model for refrigerants R-12 and R-134a. The numerical simulation integrates the one dimensional governing equations for the fluid flow (continuity, momentum and energy), using a step by step numerical method The presence of oil in the refrigerant modifies the properties of the mixture. The separated flow model considers the two phases to be segregated with different properties and different mean velocities. This numerical model was used to illustrate several effects of the oil presence on the capillary tube · design parameters and on value of the flow rates. The results show good agreement with experimental data. NOMENCLATURE A == area [m 2 ] f.J = dynamic viscosity [Pa.s] c = liquid fraction of oil in the liquid mixture v = specific volume (m/kg] CL = liquid fraction of oil in the mixture p = density [kglm] D = tube inner diameter [m] u = surfac...
Applied Thermal Engineering, 2013
h i g h l i g h t s < Experimental study on the metastable flow of R-410A through adiabatic capil... more h i g h l i g h t s < Experimental study on the metastable flow of R-410A through adiabatic capillary tubes. < Correlation for predicting underpressure of vaporisation for R-410A with average error similar to literature for other fluids. < Inclusion of the proposed correlation in a capillary tube simulation model previously developed by the authors. < Validation of modified simulation model presented a very good agreement between experimental data and numerical results.
This document has been made available through Purdue e-Pubs, a service of the Purdue University L... more This document has been made available through Purdue e-Pubs, a service of the Purdue University Libraries. Please contact epubs@purdue.edu for additional information. Complete proceedings may be acquired in print and on CD-ROM directly from the Ray W. Herrick Laboratories at
Applied Thermal Engineering, 2009
This work presents the results of an experimental study on pure refrigerant R-134a and refrigeran... more This work presents the results of an experimental study on pure refrigerant R-134a and refrigerant-oil mixtures flowing through capillary tubes in order to analyse the oil influence in component performance. Tests were carried out for capillary tubes internal diameters of 0.69 mm and 0.82 mm, condensing temperatures ranging from 40°C to 50°C, and subcooling degrees between 3°C and 12°C. Pure refrigerant flow measurements were compared to those for refrigerant-oil mixtures with oil concentrations of 1.0% and 3.0%.
Experimental Thermal and Fluid Science, 2007
This work presents the results of an experimental study with pure refrigerants R-134a and R-600a ... more This work presents the results of an experimental study with pure refrigerants R-134a and R-600a and refrigerantoil mixtures flowing through capillary tubes in order to analyse the metastable flow. A large number of experiments were carried out to verify the influence of several ...
… thermal and fluid …, 2002
This paper presents an experimental study on HCFC 22 alternative refrigerant mixtures flow throug... more This paper presents an experimental study on HCFC 22 alternative refrigerant mixtures flow through capillary tubes. Results for R-410A and R-407C show that the main operational parameters affect in a similar way the performance of capillary tubes for both refrigerants. The ...
A numerical model has been developed to simulate the effects of the oil on the performance of cap... more A numerical model has been developed to simulate the effects of the oil on the performance of capillary tubes considering a separated flow model for refrigerants R-12 and R-134a. The numerical simulation integrates the one dimensional governing equations for the fluid flow (continuity, momentum and energy), using a step by step numerical method The presence of oil in the refrigerant modifies the properties of the mixture. The separated flow model considers the two phases to be segregated with different properties and different mean velocities. This numerical model was used to illustrate several effects of the oil presence on the capillary tube · design parameters and on value of the flow rates. The results show good agreement with experimental data. NOMENCLATURE A == area [m 2 ] f.J = dynamic viscosity [Pa.s] c = liquid fraction of oil in the liquid mixture v = specific volume (m/kg] CL = liquid fraction of oil in the mixture p = density [kglm] D = tube inner diameter [m] u = surfac...
Applied Thermal Engineering, 2013
h i g h l i g h t s < Experimental study on the metastable flow of R-410A through adiabatic capil... more h i g h l i g h t s < Experimental study on the metastable flow of R-410A through adiabatic capillary tubes. < Correlation for predicting underpressure of vaporisation for R-410A with average error similar to literature for other fluids. < Inclusion of the proposed correlation in a capillary tube simulation model previously developed by the authors. < Validation of modified simulation model presented a very good agreement between experimental data and numerical results.
This document has been made available through Purdue e-Pubs, a service of the Purdue University L... more This document has been made available through Purdue e-Pubs, a service of the Purdue University Libraries. Please contact epubs@purdue.edu for additional information. Complete proceedings may be acquired in print and on CD-ROM directly from the Ray W. Herrick Laboratories at
Applied Thermal Engineering, 2009
This work presents the results of an experimental study on pure refrigerant R-134a and refrigeran... more This work presents the results of an experimental study on pure refrigerant R-134a and refrigerant-oil mixtures flowing through capillary tubes in order to analyse the oil influence in component performance. Tests were carried out for capillary tubes internal diameters of 0.69 mm and 0.82 mm, condensing temperatures ranging from 40°C to 50°C, and subcooling degrees between 3°C and 12°C. Pure refrigerant flow measurements were compared to those for refrigerant-oil mixtures with oil concentrations of 1.0% and 3.0%.
Experimental Thermal and Fluid Science, 2007
This work presents the results of an experimental study with pure refrigerants R-134a and R-600a ... more This work presents the results of an experimental study with pure refrigerants R-134a and R-600a and refrigerantoil mixtures flowing through capillary tubes in order to analyse the metastable flow. A large number of experiments were carried out to verify the influence of several ...
… thermal and fluid …, 2002
This paper presents an experimental study on HCFC 22 alternative refrigerant mixtures flow throug... more This paper presents an experimental study on HCFC 22 alternative refrigerant mixtures flow through capillary tubes. Results for R-410A and R-407C show that the main operational parameters affect in a similar way the performance of capillary tubes for both refrigerants. The ...