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Maoqiong Gong - One of the best experts on this subject based on the ideXlab platform.
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experimental investigation on flow condensation of zeotropic mixtures of methane ethane in a horizontal smooth tube
International Journal of Refrigeration-revue Internationale Du Froid, 2018Co-Authors: Xiaoru Zhuang, Gaofei Chen, Xin Zou, Qinglu Song, Hao Guo, Qixiong Tang, Zhiqiang Yang, Maoqiong GongAbstract:Abstract An experimental investigation on condensation flow pattern and heat transfer coefficient of methane/ethane mixtures (0.27/0.73, 0.54/0.46 and 0.7/0.3 by mole) in a horizontal smooth tube with inner diameter of 4 mm was carried out. The tests were conducted at Saturation Pressure of 1.5–2.5 MPa with mass flux of 98–257 kg m −2 s −1 and heat flux of 15.1–44.4 kW m −2 over the entire vapor quality range. The effects of concentration, Saturation Pressure, heat flux, mass flux and vapor quality were analyzed and discussed. A new annular/non-annular flow pattern transition criteria on condensation for zeotropic mixtures was carried out. The new transition criteria took the influence of mass transfer resistance into consideration and had satisfactory predictive ability in present study. Moreover, the experimental data were compared with many condensation heat transfer correlations of mixtures. An improved heat transfer correlation for zeotropic mixtures based on flow patterns was proposed. The new correlation combined with the equilibrium method and introduced a new correction factor ( F m ). It achieves better predicting results with a mean absolute relative deviation of 8.02%.
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experimental investigation on two phase frictional Pressure drop of zeotropic mixtures of r50 r170 in a horizontal tube
Chinese Science Bulletin, 2017Co-Authors: Xiaoru Zhuang, Gaofei Chen, Xin Zou, Qinglu Song, Qixiong Tang, Zhiqiang Yang, Maoqiong GongAbstract:In recent years, due to the environmental issues, suitable substitutes are being searched to replace the traditional chlorinated refrigerants. With zero ozone depleting potential, low global warming potential and high thermodynamic performance, the hydrocarbons are suitable selections in refrigerators and heat pump systems. As hydrocarbons, R50 and R170 are also the important parts of the natural gas and often-used components in mixture refrigerants for the low-temperature Joule-Thomson refrigerator. As the flow characteristics play important parts in the design and optimization of the heat exchangers in refrigerators and air-conditioning systems, the two-phase frictional Pressure drop should be well examined and analyzed. Although there are massive experimental studies on two-phase frictional Pressure drop of hydrocarbons in horizontal tubes, the published experimental investigations for zeotropic mixtures of R50/R170 are rare. Therefore, it′s desirable to conduct an experimental investigation on two-phase frictional Pressure drop of zeotropic mixtures of R50/R170 in a horizontal tube and find a suitable correlation. In this paper, two-phase frictional Pressure drop of R50/R170 mixtures (0.27:0.73, 0.54:0.46 and 0.7:0.3 by mole) was studied experimentally in a horizontal tube with inner diameter of 4 mm. The tests were carried out at Saturation Pressures from 1.5 MPa to 2.5 MPa for mass fluxes from 99 kg m−2 s−1 to 255 kg m−2 s−1, vapor qualities from 0 to 0.9. The uncertainty for the Pressure drop was 40 Pa and the uncertainties for the vapor quality with a 95% confidence interval were less than 11.74% under the employed operation conditions. The effects of mass flux, Saturation Pressure, vapor quality and concentration on two-phase frictional Pressure drop were examined and analyzed. Some conclusions can be drawn that (1) the frictional Pressure drops increase with the increasing mass flux and the impact becomes more obvious when the vapor quality increases; (2) the frictional Pressure drops decrease with the increasing Saturation Pressure and the impact enhances when the vapor quality increases; (3) the frictional Pressure drops increase with the increasing vapor quality and then change to be smooth even decline at high vapor qualities. And the effect of vapor quality enhances as the mass flux increases and the Saturation Pressure decreases; (4) the frictional Pressure drops of pure R50 are lower than that of all R50/R170 mixtures and the frictional Pressure drops of the initial concentration of R50/R170 mixtures at 0.27:0.73 are also lower than that of other two initial concentrations of R50/R170 mixtures. Their differences are not obvious at low vapor qualities, while the differences enhance when the mass flux and vapor quality increase as well as the Saturation Pressure decreases. The influence of concentration may be mainly related to the difference of the vapor densities. In addition, the experimental data were compared with twenty well-known frictional Pressure drops correlations. The comparison results showed that the Friedel correlation showed the best agreement with a mean absolute relative deviation of 19.26% and 87.45% of points in the deviation bandwidth of ±30%.
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two phase flow patterns heat transfer and Pressure drop characteristics of r600a during flow boiling inside a horizontal tube
Applied Thermal Engineering, 2017Co-Authors: Zhiqiang Yang, Gaofei Chen, Xin Zou, Maoqiong Gong, Jun ShenAbstract:Abstract A detailed experimental study was carried out to investigate the flow boiling heat transfer and Pressure drop characteristics of R600a in a smooth horizontal tube with an inner diameter of 6 mm. The experiments were performed at conditions covering Saturation Pressures from 0.215 to 0.415 MPa, mass fluxes from 67 to 194 kg m −2 s −1 and heat fluxes from 10.6 to 75.0 kW m −2 . Based on an high speed camera, four main flow regimes can be observed: plug flow, stratified-wavy flow, slug flow and annular flow. Intermittent to annular flow transition was detected and plotted on flow pattern maps. Comparisons with available transition lines in the literature have been made. Furthermore, the influences of Saturation Pressure, mass flux and heat flux on heat transfer coefficient were analyzed. The experimental data was compared with the calculated data of seven well-known correlations. The results indicated that, the correlation of Liu and Winterton showed the best agreement with a mean absolute relative deviation of 11.5%. For two-phase frictional Pressure drop, mass flux had obviously positive effect on frictional Pressure drop, while negative effect was found for Saturation Pressure. Eight correlations were evaluated and the correlation of Muller-Steinhagen and Heck gave the best fit to the experimental data with a mean absolute relative deviation of 32.9%. A new correlation of Pressure drop which accounted for the influence of surface tension and gravitational force was developed on the basis of Muller-Steinhagen and Heck correlation and its mean absolute relative deviation was about 16.6% for the experimental data.
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experimental investigation on flow condensation of methane in a horizontal smooth tube
International Journal of Refrigeration-revue Internationale Du Froid, 2017Co-Authors: Xiaoru Zhuang, Gaofei Chen, Xin Zou, Qinglu Song, Maoqiong GongAbstract:Abstract An experimental investigation on flow visualization of adiabatic and condensation conditions as well as condensation heat transfer coefficient and Pressure drop of methane in a horizontal smooth tube was carried out. The tests were conducted at Saturation Pressure of 2–3.5 MPa with mass flux of 99–255 kg m −2 s −1 and fluid-to-wall temperature difference of 4.8–20.2 K throughout the vapor quality range. The effects of mass flux, Saturation Pressure, vapor quality and temperature difference were studied and discussed. In order to expand the range of temperature difference, some condensation heat transfer coefficients of ethane with larger temperature differences (19.7–39.2 K) were also reported in this paper. The experimental data were compared with many well-known correlations of condensation heat transfer coefficient and Pressure drop. An improved heat transfer correlation for different flow patterns was proposed and predicted the experimental results well with a mean absolute relative deviation of 6.86%.
V S Vorobev - One of the best experts on this subject based on the ideXlab platform.
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the Saturation Pressure for different objects in reduced variables and the justification of some empirical relations set from the van der waals equation
Chemical Physics Letters, 2014Co-Authors: E M Apfelbaum, V S VorobevAbstract:We analyse the Saturation Pressure (SP) behaviour along the coexistence curve liquid–gas in reduced variables, containing only the Zeno line parameters. Using experimental and simulation data for substances (Ar, N2, Hg, Cs) and two models (van der Waals and Lennard–Jones) we create a global 3D picture of SP dependence on temperature and density. We also show that the well-known empirical Timmermans relation and partly Riedel equation are the consequences of the van der Waals equation and the rectilinear diameter law.
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application of the new scaling relations and global isomorphism to the study of liquid vapor Saturation Pressure
Journal of Physical Chemistry B, 2012Co-Authors: V S VorobevAbstract:We apply the new scaling relations and global isomorphism between continuous and discrete systems to find of Saturation Pressure. On this basis, we obtain the expression for the Saturation Pressure containing the critical, Z line parameters and two fitting parameters. First we calculate the Saturation Pressure for a number of model systems and real substances the critical parameters for which are known and verify that the accuracy is acceptable in a wide liquid–gas temperature domain. Then we discuss situation with the Saturation Pressure for metals (aluminum and iron), the critical parameters for which are unknown in advance and lie in the domain of parameters still inaccessible for experiments.
Gaofei Chen - One of the best experts on this subject based on the ideXlab platform.
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experimental investigation on flow condensation of zeotropic mixtures of methane ethane in a horizontal smooth tube
International Journal of Refrigeration-revue Internationale Du Froid, 2018Co-Authors: Xiaoru Zhuang, Gaofei Chen, Xin Zou, Qinglu Song, Hao Guo, Qixiong Tang, Zhiqiang Yang, Maoqiong GongAbstract:Abstract An experimental investigation on condensation flow pattern and heat transfer coefficient of methane/ethane mixtures (0.27/0.73, 0.54/0.46 and 0.7/0.3 by mole) in a horizontal smooth tube with inner diameter of 4 mm was carried out. The tests were conducted at Saturation Pressure of 1.5–2.5 MPa with mass flux of 98–257 kg m −2 s −1 and heat flux of 15.1–44.4 kW m −2 over the entire vapor quality range. The effects of concentration, Saturation Pressure, heat flux, mass flux and vapor quality were analyzed and discussed. A new annular/non-annular flow pattern transition criteria on condensation for zeotropic mixtures was carried out. The new transition criteria took the influence of mass transfer resistance into consideration and had satisfactory predictive ability in present study. Moreover, the experimental data were compared with many condensation heat transfer correlations of mixtures. An improved heat transfer correlation for zeotropic mixtures based on flow patterns was proposed. The new correlation combined with the equilibrium method and introduced a new correction factor ( F m ). It achieves better predicting results with a mean absolute relative deviation of 8.02%.
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experimental investigation on two phase frictional Pressure drop of zeotropic mixtures of r50 r170 in a horizontal tube
Chinese Science Bulletin, 2017Co-Authors: Xiaoru Zhuang, Gaofei Chen, Xin Zou, Qinglu Song, Qixiong Tang, Zhiqiang Yang, Maoqiong GongAbstract:In recent years, due to the environmental issues, suitable substitutes are being searched to replace the traditional chlorinated refrigerants. With zero ozone depleting potential, low global warming potential and high thermodynamic performance, the hydrocarbons are suitable selections in refrigerators and heat pump systems. As hydrocarbons, R50 and R170 are also the important parts of the natural gas and often-used components in mixture refrigerants for the low-temperature Joule-Thomson refrigerator. As the flow characteristics play important parts in the design and optimization of the heat exchangers in refrigerators and air-conditioning systems, the two-phase frictional Pressure drop should be well examined and analyzed. Although there are massive experimental studies on two-phase frictional Pressure drop of hydrocarbons in horizontal tubes, the published experimental investigations for zeotropic mixtures of R50/R170 are rare. Therefore, it′s desirable to conduct an experimental investigation on two-phase frictional Pressure drop of zeotropic mixtures of R50/R170 in a horizontal tube and find a suitable correlation. In this paper, two-phase frictional Pressure drop of R50/R170 mixtures (0.27:0.73, 0.54:0.46 and 0.7:0.3 by mole) was studied experimentally in a horizontal tube with inner diameter of 4 mm. The tests were carried out at Saturation Pressures from 1.5 MPa to 2.5 MPa for mass fluxes from 99 kg m−2 s−1 to 255 kg m−2 s−1, vapor qualities from 0 to 0.9. The uncertainty for the Pressure drop was 40 Pa and the uncertainties for the vapor quality with a 95% confidence interval were less than 11.74% under the employed operation conditions. The effects of mass flux, Saturation Pressure, vapor quality and concentration on two-phase frictional Pressure drop were examined and analyzed. Some conclusions can be drawn that (1) the frictional Pressure drops increase with the increasing mass flux and the impact becomes more obvious when the vapor quality increases; (2) the frictional Pressure drops decrease with the increasing Saturation Pressure and the impact enhances when the vapor quality increases; (3) the frictional Pressure drops increase with the increasing vapor quality and then change to be smooth even decline at high vapor qualities. And the effect of vapor quality enhances as the mass flux increases and the Saturation Pressure decreases; (4) the frictional Pressure drops of pure R50 are lower than that of all R50/R170 mixtures and the frictional Pressure drops of the initial concentration of R50/R170 mixtures at 0.27:0.73 are also lower than that of other two initial concentrations of R50/R170 mixtures. Their differences are not obvious at low vapor qualities, while the differences enhance when the mass flux and vapor quality increase as well as the Saturation Pressure decreases. The influence of concentration may be mainly related to the difference of the vapor densities. In addition, the experimental data were compared with twenty well-known frictional Pressure drops correlations. The comparison results showed that the Friedel correlation showed the best agreement with a mean absolute relative deviation of 19.26% and 87.45% of points in the deviation bandwidth of ±30%.
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two phase flow patterns heat transfer and Pressure drop characteristics of r600a during flow boiling inside a horizontal tube
Applied Thermal Engineering, 2017Co-Authors: Zhiqiang Yang, Gaofei Chen, Xin Zou, Maoqiong Gong, Jun ShenAbstract:Abstract A detailed experimental study was carried out to investigate the flow boiling heat transfer and Pressure drop characteristics of R600a in a smooth horizontal tube with an inner diameter of 6 mm. The experiments were performed at conditions covering Saturation Pressures from 0.215 to 0.415 MPa, mass fluxes from 67 to 194 kg m −2 s −1 and heat fluxes from 10.6 to 75.0 kW m −2 . Based on an high speed camera, four main flow regimes can be observed: plug flow, stratified-wavy flow, slug flow and annular flow. Intermittent to annular flow transition was detected and plotted on flow pattern maps. Comparisons with available transition lines in the literature have been made. Furthermore, the influences of Saturation Pressure, mass flux and heat flux on heat transfer coefficient were analyzed. The experimental data was compared with the calculated data of seven well-known correlations. The results indicated that, the correlation of Liu and Winterton showed the best agreement with a mean absolute relative deviation of 11.5%. For two-phase frictional Pressure drop, mass flux had obviously positive effect on frictional Pressure drop, while negative effect was found for Saturation Pressure. Eight correlations were evaluated and the correlation of Muller-Steinhagen and Heck gave the best fit to the experimental data with a mean absolute relative deviation of 32.9%. A new correlation of Pressure drop which accounted for the influence of surface tension and gravitational force was developed on the basis of Muller-Steinhagen and Heck correlation and its mean absolute relative deviation was about 16.6% for the experimental data.
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experimental investigation on flow condensation of methane in a horizontal smooth tube
International Journal of Refrigeration-revue Internationale Du Froid, 2017Co-Authors: Xiaoru Zhuang, Gaofei Chen, Xin Zou, Qinglu Song, Maoqiong GongAbstract:Abstract An experimental investigation on flow visualization of adiabatic and condensation conditions as well as condensation heat transfer coefficient and Pressure drop of methane in a horizontal smooth tube was carried out. The tests were conducted at Saturation Pressure of 2–3.5 MPa with mass flux of 99–255 kg m −2 s −1 and fluid-to-wall temperature difference of 4.8–20.2 K throughout the vapor quality range. The effects of mass flux, Saturation Pressure, vapor quality and temperature difference were studied and discussed. In order to expand the range of temperature difference, some condensation heat transfer coefficients of ethane with larger temperature differences (19.7–39.2 K) were also reported in this paper. The experimental data were compared with many well-known correlations of condensation heat transfer coefficient and Pressure drop. An improved heat transfer correlation for different flow patterns was proposed and predicted the experimental results well with a mean absolute relative deviation of 6.86%.
Xin Zou - One of the best experts on this subject based on the ideXlab platform.
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experimental investigation on flow condensation of zeotropic mixtures of methane ethane in a horizontal smooth tube
International Journal of Refrigeration-revue Internationale Du Froid, 2018Co-Authors: Xiaoru Zhuang, Gaofei Chen, Xin Zou, Qinglu Song, Hao Guo, Qixiong Tang, Zhiqiang Yang, Maoqiong GongAbstract:Abstract An experimental investigation on condensation flow pattern and heat transfer coefficient of methane/ethane mixtures (0.27/0.73, 0.54/0.46 and 0.7/0.3 by mole) in a horizontal smooth tube with inner diameter of 4 mm was carried out. The tests were conducted at Saturation Pressure of 1.5–2.5 MPa with mass flux of 98–257 kg m −2 s −1 and heat flux of 15.1–44.4 kW m −2 over the entire vapor quality range. The effects of concentration, Saturation Pressure, heat flux, mass flux and vapor quality were analyzed and discussed. A new annular/non-annular flow pattern transition criteria on condensation for zeotropic mixtures was carried out. The new transition criteria took the influence of mass transfer resistance into consideration and had satisfactory predictive ability in present study. Moreover, the experimental data were compared with many condensation heat transfer correlations of mixtures. An improved heat transfer correlation for zeotropic mixtures based on flow patterns was proposed. The new correlation combined with the equilibrium method and introduced a new correction factor ( F m ). It achieves better predicting results with a mean absolute relative deviation of 8.02%.
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experimental investigation on two phase frictional Pressure drop of zeotropic mixtures of r50 r170 in a horizontal tube
Chinese Science Bulletin, 2017Co-Authors: Xiaoru Zhuang, Gaofei Chen, Xin Zou, Qinglu Song, Qixiong Tang, Zhiqiang Yang, Maoqiong GongAbstract:In recent years, due to the environmental issues, suitable substitutes are being searched to replace the traditional chlorinated refrigerants. With zero ozone depleting potential, low global warming potential and high thermodynamic performance, the hydrocarbons are suitable selections in refrigerators and heat pump systems. As hydrocarbons, R50 and R170 are also the important parts of the natural gas and often-used components in mixture refrigerants for the low-temperature Joule-Thomson refrigerator. As the flow characteristics play important parts in the design and optimization of the heat exchangers in refrigerators and air-conditioning systems, the two-phase frictional Pressure drop should be well examined and analyzed. Although there are massive experimental studies on two-phase frictional Pressure drop of hydrocarbons in horizontal tubes, the published experimental investigations for zeotropic mixtures of R50/R170 are rare. Therefore, it′s desirable to conduct an experimental investigation on two-phase frictional Pressure drop of zeotropic mixtures of R50/R170 in a horizontal tube and find a suitable correlation. In this paper, two-phase frictional Pressure drop of R50/R170 mixtures (0.27:0.73, 0.54:0.46 and 0.7:0.3 by mole) was studied experimentally in a horizontal tube with inner diameter of 4 mm. The tests were carried out at Saturation Pressures from 1.5 MPa to 2.5 MPa for mass fluxes from 99 kg m−2 s−1 to 255 kg m−2 s−1, vapor qualities from 0 to 0.9. The uncertainty for the Pressure drop was 40 Pa and the uncertainties for the vapor quality with a 95% confidence interval were less than 11.74% under the employed operation conditions. The effects of mass flux, Saturation Pressure, vapor quality and concentration on two-phase frictional Pressure drop were examined and analyzed. Some conclusions can be drawn that (1) the frictional Pressure drops increase with the increasing mass flux and the impact becomes more obvious when the vapor quality increases; (2) the frictional Pressure drops decrease with the increasing Saturation Pressure and the impact enhances when the vapor quality increases; (3) the frictional Pressure drops increase with the increasing vapor quality and then change to be smooth even decline at high vapor qualities. And the effect of vapor quality enhances as the mass flux increases and the Saturation Pressure decreases; (4) the frictional Pressure drops of pure R50 are lower than that of all R50/R170 mixtures and the frictional Pressure drops of the initial concentration of R50/R170 mixtures at 0.27:0.73 are also lower than that of other two initial concentrations of R50/R170 mixtures. Their differences are not obvious at low vapor qualities, while the differences enhance when the mass flux and vapor quality increase as well as the Saturation Pressure decreases. The influence of concentration may be mainly related to the difference of the vapor densities. In addition, the experimental data were compared with twenty well-known frictional Pressure drops correlations. The comparison results showed that the Friedel correlation showed the best agreement with a mean absolute relative deviation of 19.26% and 87.45% of points in the deviation bandwidth of ±30%.
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two phase flow patterns heat transfer and Pressure drop characteristics of r600a during flow boiling inside a horizontal tube
Applied Thermal Engineering, 2017Co-Authors: Zhiqiang Yang, Gaofei Chen, Xin Zou, Maoqiong Gong, Jun ShenAbstract:Abstract A detailed experimental study was carried out to investigate the flow boiling heat transfer and Pressure drop characteristics of R600a in a smooth horizontal tube with an inner diameter of 6 mm. The experiments were performed at conditions covering Saturation Pressures from 0.215 to 0.415 MPa, mass fluxes from 67 to 194 kg m −2 s −1 and heat fluxes from 10.6 to 75.0 kW m −2 . Based on an high speed camera, four main flow regimes can be observed: plug flow, stratified-wavy flow, slug flow and annular flow. Intermittent to annular flow transition was detected and plotted on flow pattern maps. Comparisons with available transition lines in the literature have been made. Furthermore, the influences of Saturation Pressure, mass flux and heat flux on heat transfer coefficient were analyzed. The experimental data was compared with the calculated data of seven well-known correlations. The results indicated that, the correlation of Liu and Winterton showed the best agreement with a mean absolute relative deviation of 11.5%. For two-phase frictional Pressure drop, mass flux had obviously positive effect on frictional Pressure drop, while negative effect was found for Saturation Pressure. Eight correlations were evaluated and the correlation of Muller-Steinhagen and Heck gave the best fit to the experimental data with a mean absolute relative deviation of 32.9%. A new correlation of Pressure drop which accounted for the influence of surface tension and gravitational force was developed on the basis of Muller-Steinhagen and Heck correlation and its mean absolute relative deviation was about 16.6% for the experimental data.
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experimental investigation on flow condensation of methane in a horizontal smooth tube
International Journal of Refrigeration-revue Internationale Du Froid, 2017Co-Authors: Xiaoru Zhuang, Gaofei Chen, Xin Zou, Qinglu Song, Maoqiong GongAbstract:Abstract An experimental investigation on flow visualization of adiabatic and condensation conditions as well as condensation heat transfer coefficient and Pressure drop of methane in a horizontal smooth tube was carried out. The tests were conducted at Saturation Pressure of 2–3.5 MPa with mass flux of 99–255 kg m −2 s −1 and fluid-to-wall temperature difference of 4.8–20.2 K throughout the vapor quality range. The effects of mass flux, Saturation Pressure, vapor quality and temperature difference were studied and discussed. In order to expand the range of temperature difference, some condensation heat transfer coefficients of ethane with larger temperature differences (19.7–39.2 K) were also reported in this paper. The experimental data were compared with many well-known correlations of condensation heat transfer coefficient and Pressure drop. An improved heat transfer correlation for different flow patterns was proposed and predicted the experimental results well with a mean absolute relative deviation of 6.86%.
Xiaoru Zhuang - One of the best experts on this subject based on the ideXlab platform.
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experimental investigation on flow condensation of zeotropic mixtures of methane ethane in a horizontal smooth tube
International Journal of Refrigeration-revue Internationale Du Froid, 2018Co-Authors: Xiaoru Zhuang, Gaofei Chen, Xin Zou, Qinglu Song, Hao Guo, Qixiong Tang, Zhiqiang Yang, Maoqiong GongAbstract:Abstract An experimental investigation on condensation flow pattern and heat transfer coefficient of methane/ethane mixtures (0.27/0.73, 0.54/0.46 and 0.7/0.3 by mole) in a horizontal smooth tube with inner diameter of 4 mm was carried out. The tests were conducted at Saturation Pressure of 1.5–2.5 MPa with mass flux of 98–257 kg m −2 s −1 and heat flux of 15.1–44.4 kW m −2 over the entire vapor quality range. The effects of concentration, Saturation Pressure, heat flux, mass flux and vapor quality were analyzed and discussed. A new annular/non-annular flow pattern transition criteria on condensation for zeotropic mixtures was carried out. The new transition criteria took the influence of mass transfer resistance into consideration and had satisfactory predictive ability in present study. Moreover, the experimental data were compared with many condensation heat transfer correlations of mixtures. An improved heat transfer correlation for zeotropic mixtures based on flow patterns was proposed. The new correlation combined with the equilibrium method and introduced a new correction factor ( F m ). It achieves better predicting results with a mean absolute relative deviation of 8.02%.
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experimental investigation on two phase frictional Pressure drop of zeotropic mixtures of r50 r170 in a horizontal tube
Chinese Science Bulletin, 2017Co-Authors: Xiaoru Zhuang, Gaofei Chen, Xin Zou, Qinglu Song, Qixiong Tang, Zhiqiang Yang, Maoqiong GongAbstract:In recent years, due to the environmental issues, suitable substitutes are being searched to replace the traditional chlorinated refrigerants. With zero ozone depleting potential, low global warming potential and high thermodynamic performance, the hydrocarbons are suitable selections in refrigerators and heat pump systems. As hydrocarbons, R50 and R170 are also the important parts of the natural gas and often-used components in mixture refrigerants for the low-temperature Joule-Thomson refrigerator. As the flow characteristics play important parts in the design and optimization of the heat exchangers in refrigerators and air-conditioning systems, the two-phase frictional Pressure drop should be well examined and analyzed. Although there are massive experimental studies on two-phase frictional Pressure drop of hydrocarbons in horizontal tubes, the published experimental investigations for zeotropic mixtures of R50/R170 are rare. Therefore, it′s desirable to conduct an experimental investigation on two-phase frictional Pressure drop of zeotropic mixtures of R50/R170 in a horizontal tube and find a suitable correlation. In this paper, two-phase frictional Pressure drop of R50/R170 mixtures (0.27:0.73, 0.54:0.46 and 0.7:0.3 by mole) was studied experimentally in a horizontal tube with inner diameter of 4 mm. The tests were carried out at Saturation Pressures from 1.5 MPa to 2.5 MPa for mass fluxes from 99 kg m−2 s−1 to 255 kg m−2 s−1, vapor qualities from 0 to 0.9. The uncertainty for the Pressure drop was 40 Pa and the uncertainties for the vapor quality with a 95% confidence interval were less than 11.74% under the employed operation conditions. The effects of mass flux, Saturation Pressure, vapor quality and concentration on two-phase frictional Pressure drop were examined and analyzed. Some conclusions can be drawn that (1) the frictional Pressure drops increase with the increasing mass flux and the impact becomes more obvious when the vapor quality increases; (2) the frictional Pressure drops decrease with the increasing Saturation Pressure and the impact enhances when the vapor quality increases; (3) the frictional Pressure drops increase with the increasing vapor quality and then change to be smooth even decline at high vapor qualities. And the effect of vapor quality enhances as the mass flux increases and the Saturation Pressure decreases; (4) the frictional Pressure drops of pure R50 are lower than that of all R50/R170 mixtures and the frictional Pressure drops of the initial concentration of R50/R170 mixtures at 0.27:0.73 are also lower than that of other two initial concentrations of R50/R170 mixtures. Their differences are not obvious at low vapor qualities, while the differences enhance when the mass flux and vapor quality increase as well as the Saturation Pressure decreases. The influence of concentration may be mainly related to the difference of the vapor densities. In addition, the experimental data were compared with twenty well-known frictional Pressure drops correlations. The comparison results showed that the Friedel correlation showed the best agreement with a mean absolute relative deviation of 19.26% and 87.45% of points in the deviation bandwidth of ±30%.
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experimental investigation on flow condensation of methane in a horizontal smooth tube
International Journal of Refrigeration-revue Internationale Du Froid, 2017Co-Authors: Xiaoru Zhuang, Gaofei Chen, Xin Zou, Qinglu Song, Maoqiong GongAbstract:Abstract An experimental investigation on flow visualization of adiabatic and condensation conditions as well as condensation heat transfer coefficient and Pressure drop of methane in a horizontal smooth tube was carried out. The tests were conducted at Saturation Pressure of 2–3.5 MPa with mass flux of 99–255 kg m −2 s −1 and fluid-to-wall temperature difference of 4.8–20.2 K throughout the vapor quality range. The effects of mass flux, Saturation Pressure, vapor quality and temperature difference were studied and discussed. In order to expand the range of temperature difference, some condensation heat transfer coefficients of ethane with larger temperature differences (19.7–39.2 K) were also reported in this paper. The experimental data were compared with many well-known correlations of condensation heat transfer coefficient and Pressure drop. An improved heat transfer correlation for different flow patterns was proposed and predicted the experimental results well with a mean absolute relative deviation of 6.86%.
