The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Eiji Hihara - One of the best experts on this subject based on the ideXlab platform.
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effect of Lubricating Oil on flow bOiling heat transfer of carbon dioxide
International Journal of Refrigeration-revue Internationale Du Froid, 2013Co-Authors: Chaobin Dang, Noburu Haraguchi, Takashi Yamada, Minxia Li, Eiji HiharaAbstract:Abstract The flow bOiling heat transfer of carbon dioxide with PAG-type Lubricating Oil entrained from 0% to 5% in horizontal smooth tubes was examined. Experiments were conducted using test tubes with inner diameter of 2–6 mm at mass fluxes of 360–1440 kg m −2 s −1 and heat fluxes of 4.5–36 kW m −2 . The saturation temperature was 15 °C. At low Oil concentrations of 0.5–1%, the heat transfer coefficient decreased to less than half that under Oil-free conditions. The heat transfer coefficient did not decrease further with increasing Oil concentration up to 5%. The heat flux positively influenced the heat transfer coefficient in low vapor quality regions, not the high vapor quality regions. The presence of Oil caused the mass flux to significantly influence the heat transfer coefficient at a low heat flux till dryout, while no significant influence of the mass flux at a high heat flux was observed. The dryout quality decreased at a large mass flux. The measured pressure drops increased monotonously because of the Lubricating Oil.
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effect of Lubricating Oil on the flow and heat transfer characteristics of supercritical carbon dioxide
International Journal of Refrigeration-revue Internationale Du Froid, 2012Co-Authors: Chaobin Dang, Keitaro Hoshika, Eiji HiharaAbstract:Abstract Effects of Lubricating Oil on heat-transfer performance of supercritical CO2 were studied by applying three lubricants: PAG, PVE, and ECP. Heat-transfer coefficient measurements and flow-pattern visualization were conducted in a horizontal tube of 2 mm I.D. at CO2 pressures from 8 to 10 MPa and mass fluxes from 800 to 1200 kg m−2 s−1. The solubility of lubricants with CO2 was found having remarkable influence on both the flow pattern and heat-transfer coefficient. For PVE, which has the highest CO2 solubility, Oil droplets can only be observed occasionally and the Oil film can hardly be identified at temperatures lower than Tpc, and the heat-transfer coefficient does not greatly change with Oil concentration. At higher temperatures, a decrease in the heat-transfer coefficient with increasing Oil concentration was observed for all three lubricants due to the formation of Oil film. The experiments show that while ECP is inferior to PVE, it provides better heat-transfer performance than PVG.
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effect of pag type Lubricating Oil on heat transfer characteristics of supercritical carbon dioxide cooled inside a small internally grooved tube
International Journal of Refrigeration-revue Internationale Du Froid, 2010Co-Authors: Chaobin Dang, Koji Iino, Eiji HiharaAbstract:Abstract Heat transfer characteristics of supercritical CO2 cooled inside a small internally grooved tube were investigated. The mean inner diameter (ID) and helix angle of this tube were 2 mm and 6.3°, respectively. Experiments were conducted in the pressure range of 8–10 MPa and mass flux range of 400–1200 kg m−2 s−1. The effect of PAG-type Lubricating Oil on the heat transfer characteristics was investigated by changing the Oil concentration from 0% to 5%. The drop in the heat transfer coefficient was 30–50% and 50–70% at Oil concentrations of 1% and 3%, respectively. The heat transfer coefficient of CO2 in the grooved tube was higher than that in the smooth tube at all Oil concentrations tested. The experimental results indicated that the grooved tube has a large heat transfer area and facilitates the breaking up of the Oil film.
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study on two phase flow pattern of supercritical carbon dioxide with entrained pag type Lubricating Oil in a gas cooler
International Journal of Refrigeration-revue Internationale Du Froid, 2008Co-Authors: Chaobin Dang, Koji Iino, Eiji HiharaAbstract:Abstract In order to clarify the heat transfer mechanism of supercritical carbon dioxide flowing with a small amount of Lubricating Oil, visualization experiments were conducted using two sight glass tubes with inner diameters of 2 and 6 mm. The visualization images were recorded using a high-speed CCD camera with shutter speed changing from 500 to 10,000 pps (pictures per second). PAG-type Oil, which is partially miscible with supercritical carbon dioxide, was used. The experiments were conducted with Lubricating Oil concentrations of 1 and 5 wt%, pressures between 8 and 10 MPa, and mass fluxes between 200 and 1200 kg m−2 s−1. The visualization images revealed that the two-phase flow pattern inside the gas cooler was determined by many factors, including the tube diameter, Oil concentration, temperature, pressure, and mass flux. For a small size tube of 2 mm ID, the formation of both Oil droplets in the bulk region and an Oil film along the inner wall of the tube was confirmed. At low temperatures, a large number of Oil droplets were observed flowing with CO2 with a slip ratio of approximately 0.7. With an increase in the bulk temperature, both the dimension and number of Oil droplets entrained with CO2 decreased, and the flow of the Oil film became clearly visible. For a large tube of 6 mm ID, the flow pattern at a low mass flow rate was a separated wavy flow; with an increase in mass flow, the flow pattern changed to annular flow, which corresponds to a distinct decrease in the heat transfer coefficient due to the heat resistance of Oil layer. The transition of the flow pattern is considered due to the shear stress between the Oil layer and bulk CO2. In addition, the dissolution of CO2 into PAG Oil as well as the change in the solubility and thermodynamic properties of CO2 with the temperature and pressure makes the prediction of the flow patterns a challenging task. The relationship between the flow pattern and heat transfer characteristics was also discussed.
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effect of Lubricating Oil on cooling heat transfer of supercritical carbon dioxide
International Journal of Refrigeration-revue Internationale Du Froid, 2007Co-Authors: Chaobin Dang, Koji Iino, Ken Fukuoka, Eiji HiharaAbstract:Abstract In this research, the cooling heat transfer coefficient and pressure drop of supercritical CO 2 with PAG-type Lubricating Oil entrained were experimentally investigated. The inner diameter of the test tubes ranged from 1 to 6 mm. The experiments were conducted at Lubricating Oil concentrations from 0 to 5%, pressures from 8 to 10 MPa, mass fluxes from 200 to 1200 kg m −2 s −1 , and heat fluxes from 12 to 24 kW m −2 . In comparison to the Oil-free condition, when Lubricating Oil entrainment occurred, the heat transfer coefficient decreased and the pressure drop increased. The maximum reduction in the heat transfer coefficients—about 75%—occurred in the vicinity of the pseudocritical temperature. The influence of Oil was significant for a small tube diameter and a large Oil concentration. From visual observation, it was confirmed that this degradation in the heat transfer was due to the formation of an Oil-rich layer along the inner wall of the test tube. However, when the Oil concentration exceeded 3%, no further degradation in the heat transfer coefficient could be confirmed, which implies that the Oil flowing along with CO 2 in the bulk region does not influence the heat transfer coefficient and the pressure drops significantly. For a large tube at a lower mass flux, no significant degradation in the heat transfer coefficient was observed until the Oil concentration reached 1%. This is due to the transition of the flow pattern from an annular-dispersed flow to a wavy flow for a large tube, with CO 2 flowing on the upper side and the Oil-rich layer on the lower side of the test section.
Chaobin Dang - One of the best experts on this subject based on the ideXlab platform.
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effects of Lubricating Oil on thermal performance of water cooled carbon dioxide gas cooler
Applied Thermal Engineering, 2015Co-Authors: Baomin Dai, Chaobin DangAbstract:Abstract A water-cooled concentric gas cooler model was developed to examine the negative effects of the presence of polyalkylene glycol (PAG)–type Lubricating Oil on convective heat transfer. The model was used to analyze the gas cooler performance in detail at different Oil concentrations, tube diameters, operation pressures, mass flow rates, and inlet temperatures on the water side. The results show that the entrained Lubricating Oil had a dominant negative effect on gas coolers with a diameter of less than 2 mm. For CO2 heat pump/refrigeration systems equipped with water-cooled micro- or mini-channel gas coolers, the Lubricating Oil retained in the heat exchanger should be minimized. The negative effects of the Lubricating Oil are dominant for a wide range of operation pressures. However, the deterioration in thermal performance becomes more apparent as the pressure approaches the critical pressure value. Proper determination of the coolant fluid mass flow rate increases the thermal effectiveness of the gas cooler for a wide range of water inlet temperatures, but the reduced heat transfer performance is more pronounced at higher mass flow rates.
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effect of Lubricating Oil on flow bOiling heat transfer of carbon dioxide
International Journal of Refrigeration-revue Internationale Du Froid, 2013Co-Authors: Chaobin Dang, Noburu Haraguchi, Takashi Yamada, Minxia Li, Eiji HiharaAbstract:Abstract The flow bOiling heat transfer of carbon dioxide with PAG-type Lubricating Oil entrained from 0% to 5% in horizontal smooth tubes was examined. Experiments were conducted using test tubes with inner diameter of 2–6 mm at mass fluxes of 360–1440 kg m −2 s −1 and heat fluxes of 4.5–36 kW m −2 . The saturation temperature was 15 °C. At low Oil concentrations of 0.5–1%, the heat transfer coefficient decreased to less than half that under Oil-free conditions. The heat transfer coefficient did not decrease further with increasing Oil concentration up to 5%. The heat flux positively influenced the heat transfer coefficient in low vapor quality regions, not the high vapor quality regions. The presence of Oil caused the mass flux to significantly influence the heat transfer coefficient at a low heat flux till dryout, while no significant influence of the mass flux at a high heat flux was observed. The dryout quality decreased at a large mass flux. The measured pressure drops increased monotonously because of the Lubricating Oil.
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effect of Lubricating Oil on the flow and heat transfer characteristics of supercritical carbon dioxide
International Journal of Refrigeration-revue Internationale Du Froid, 2012Co-Authors: Chaobin Dang, Keitaro Hoshika, Eiji HiharaAbstract:Abstract Effects of Lubricating Oil on heat-transfer performance of supercritical CO2 were studied by applying three lubricants: PAG, PVE, and ECP. Heat-transfer coefficient measurements and flow-pattern visualization were conducted in a horizontal tube of 2 mm I.D. at CO2 pressures from 8 to 10 MPa and mass fluxes from 800 to 1200 kg m−2 s−1. The solubility of lubricants with CO2 was found having remarkable influence on both the flow pattern and heat-transfer coefficient. For PVE, which has the highest CO2 solubility, Oil droplets can only be observed occasionally and the Oil film can hardly be identified at temperatures lower than Tpc, and the heat-transfer coefficient does not greatly change with Oil concentration. At higher temperatures, a decrease in the heat-transfer coefficient with increasing Oil concentration was observed for all three lubricants due to the formation of Oil film. The experiments show that while ECP is inferior to PVE, it provides better heat-transfer performance than PVG.
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effect of pag type Lubricating Oil on heat transfer characteristics of supercritical carbon dioxide cooled inside a small internally grooved tube
International Journal of Refrigeration-revue Internationale Du Froid, 2010Co-Authors: Chaobin Dang, Koji Iino, Eiji HiharaAbstract:Abstract Heat transfer characteristics of supercritical CO2 cooled inside a small internally grooved tube were investigated. The mean inner diameter (ID) and helix angle of this tube were 2 mm and 6.3°, respectively. Experiments were conducted in the pressure range of 8–10 MPa and mass flux range of 400–1200 kg m−2 s−1. The effect of PAG-type Lubricating Oil on the heat transfer characteristics was investigated by changing the Oil concentration from 0% to 5%. The drop in the heat transfer coefficient was 30–50% and 50–70% at Oil concentrations of 1% and 3%, respectively. The heat transfer coefficient of CO2 in the grooved tube was higher than that in the smooth tube at all Oil concentrations tested. The experimental results indicated that the grooved tube has a large heat transfer area and facilitates the breaking up of the Oil film.
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study on two phase flow pattern of supercritical carbon dioxide with entrained pag type Lubricating Oil in a gas cooler
International Journal of Refrigeration-revue Internationale Du Froid, 2008Co-Authors: Chaobin Dang, Koji Iino, Eiji HiharaAbstract:Abstract In order to clarify the heat transfer mechanism of supercritical carbon dioxide flowing with a small amount of Lubricating Oil, visualization experiments were conducted using two sight glass tubes with inner diameters of 2 and 6 mm. The visualization images were recorded using a high-speed CCD camera with shutter speed changing from 500 to 10,000 pps (pictures per second). PAG-type Oil, which is partially miscible with supercritical carbon dioxide, was used. The experiments were conducted with Lubricating Oil concentrations of 1 and 5 wt%, pressures between 8 and 10 MPa, and mass fluxes between 200 and 1200 kg m−2 s−1. The visualization images revealed that the two-phase flow pattern inside the gas cooler was determined by many factors, including the tube diameter, Oil concentration, temperature, pressure, and mass flux. For a small size tube of 2 mm ID, the formation of both Oil droplets in the bulk region and an Oil film along the inner wall of the tube was confirmed. At low temperatures, a large number of Oil droplets were observed flowing with CO2 with a slip ratio of approximately 0.7. With an increase in the bulk temperature, both the dimension and number of Oil droplets entrained with CO2 decreased, and the flow of the Oil film became clearly visible. For a large tube of 6 mm ID, the flow pattern at a low mass flow rate was a separated wavy flow; with an increase in mass flow, the flow pattern changed to annular flow, which corresponds to a distinct decrease in the heat transfer coefficient due to the heat resistance of Oil layer. The transition of the flow pattern is considered due to the shear stress between the Oil layer and bulk CO2. In addition, the dissolution of CO2 into PAG Oil as well as the change in the solubility and thermodynamic properties of CO2 with the temperature and pressure makes the prediction of the flow patterns a challenging task. The relationship between the flow pattern and heat transfer characteristics was also discussed.
Xingyu Liang - One of the best experts on this subject based on the ideXlab platform.
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effect of Lubricating Oil on the particle size distribution and total number concentration in a diesel engine
Fuel Processing Technology, 2013Co-Authors: Lihui Dong, Xingyu LiangAbstract:Abstract In this paper, the characteristics of particle size distribution in the exhaust gas of a diesel engine lubricated by two kinds of Lubricating Oil are investigated. The experiments are conducted in a turbocharged direct-injection diesel engine with Fast Particulate Spectrometer DMS 500 connected to the exhaust pipe. Two kinds of commonly used commercial Lubricating Oil, Kunlun API CF-4 15W40 and Mobil API CI-4 15W40, are chosen for the experiments. Particle size distribution and total number concentration are measured under medium load (100 Nm) and full load. Barring a few exceptions, the results indicate that total particle number concentration is almost the same, while particle size distribution shows great difference.
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effect of Lubricating Oil additives on particle size distribution and total number concentration in diesel engine
Lubrication Science, 2012Co-Authors: Lihui Dong, Xingyu Liang, Yuesen WangAbstract:This paper investigates the characteristics of particle size distribution in exhaust gas of engine fuelled with pure diesel and with diesel mixed with base Oil or with Oil additives. The experiments are conducted on a turbocharged diesel engine with fast particulate spectrometer DMS 500 connected to the exhaust pipe. Base Oil and two kinds of commonly used Lubricating Oil additives, antioxidant additives and antifoaming additives, are chosen to be added into the fuel, with the concentrations being 0.5%, 1.0% and 1.5% of fuel weight individually. The particle size distribution is measured under medium load (100 Nm) and full load at different speeds. The results indicate that the existence of base Oil or Oil additives shows great influence on particle size distribution. Copyright © 2012 John Wiley & Sons, Ltd.
Koji Iino - One of the best experts on this subject based on the ideXlab platform.
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effect of pag type Lubricating Oil on heat transfer characteristics of supercritical carbon dioxide cooled inside a small internally grooved tube
International Journal of Refrigeration-revue Internationale Du Froid, 2010Co-Authors: Chaobin Dang, Koji Iino, Eiji HiharaAbstract:Abstract Heat transfer characteristics of supercritical CO2 cooled inside a small internally grooved tube were investigated. The mean inner diameter (ID) and helix angle of this tube were 2 mm and 6.3°, respectively. Experiments were conducted in the pressure range of 8–10 MPa and mass flux range of 400–1200 kg m−2 s−1. The effect of PAG-type Lubricating Oil on the heat transfer characteristics was investigated by changing the Oil concentration from 0% to 5%. The drop in the heat transfer coefficient was 30–50% and 50–70% at Oil concentrations of 1% and 3%, respectively. The heat transfer coefficient of CO2 in the grooved tube was higher than that in the smooth tube at all Oil concentrations tested. The experimental results indicated that the grooved tube has a large heat transfer area and facilitates the breaking up of the Oil film.
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study on two phase flow pattern of supercritical carbon dioxide with entrained pag type Lubricating Oil in a gas cooler
International Journal of Refrigeration-revue Internationale Du Froid, 2008Co-Authors: Chaobin Dang, Koji Iino, Eiji HiharaAbstract:Abstract In order to clarify the heat transfer mechanism of supercritical carbon dioxide flowing with a small amount of Lubricating Oil, visualization experiments were conducted using two sight glass tubes with inner diameters of 2 and 6 mm. The visualization images were recorded using a high-speed CCD camera with shutter speed changing from 500 to 10,000 pps (pictures per second). PAG-type Oil, which is partially miscible with supercritical carbon dioxide, was used. The experiments were conducted with Lubricating Oil concentrations of 1 and 5 wt%, pressures between 8 and 10 MPa, and mass fluxes between 200 and 1200 kg m−2 s−1. The visualization images revealed that the two-phase flow pattern inside the gas cooler was determined by many factors, including the tube diameter, Oil concentration, temperature, pressure, and mass flux. For a small size tube of 2 mm ID, the formation of both Oil droplets in the bulk region and an Oil film along the inner wall of the tube was confirmed. At low temperatures, a large number of Oil droplets were observed flowing with CO2 with a slip ratio of approximately 0.7. With an increase in the bulk temperature, both the dimension and number of Oil droplets entrained with CO2 decreased, and the flow of the Oil film became clearly visible. For a large tube of 6 mm ID, the flow pattern at a low mass flow rate was a separated wavy flow; with an increase in mass flow, the flow pattern changed to annular flow, which corresponds to a distinct decrease in the heat transfer coefficient due to the heat resistance of Oil layer. The transition of the flow pattern is considered due to the shear stress between the Oil layer and bulk CO2. In addition, the dissolution of CO2 into PAG Oil as well as the change in the solubility and thermodynamic properties of CO2 with the temperature and pressure makes the prediction of the flow patterns a challenging task. The relationship between the flow pattern and heat transfer characteristics was also discussed.
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effect of Lubricating Oil on cooling heat transfer of supercritical carbon dioxide
International Journal of Refrigeration-revue Internationale Du Froid, 2007Co-Authors: Chaobin Dang, Koji Iino, Ken Fukuoka, Eiji HiharaAbstract:Abstract In this research, the cooling heat transfer coefficient and pressure drop of supercritical CO 2 with PAG-type Lubricating Oil entrained were experimentally investigated. The inner diameter of the test tubes ranged from 1 to 6 mm. The experiments were conducted at Lubricating Oil concentrations from 0 to 5%, pressures from 8 to 10 MPa, mass fluxes from 200 to 1200 kg m −2 s −1 , and heat fluxes from 12 to 24 kW m −2 . In comparison to the Oil-free condition, when Lubricating Oil entrainment occurred, the heat transfer coefficient decreased and the pressure drop increased. The maximum reduction in the heat transfer coefficients—about 75%—occurred in the vicinity of the pseudocritical temperature. The influence of Oil was significant for a small tube diameter and a large Oil concentration. From visual observation, it was confirmed that this degradation in the heat transfer was due to the formation of an Oil-rich layer along the inner wall of the test tube. However, when the Oil concentration exceeded 3%, no further degradation in the heat transfer coefficient could be confirmed, which implies that the Oil flowing along with CO 2 in the bulk region does not influence the heat transfer coefficient and the pressure drops significantly. For a large tube at a lower mass flux, no significant degradation in the heat transfer coefficient was observed until the Oil concentration reached 1%. This is due to the transition of the flow pattern from an annular-dispersed flow to a wavy flow for a large tube, with CO 2 flowing on the upper side and the Oil-rich layer on the lower side of the test section.
Lihui Dong - One of the best experts on this subject based on the ideXlab platform.
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effect of Lubricating Oil on the particle size distribution and total number concentration in a diesel engine
Fuel Processing Technology, 2013Co-Authors: Lihui Dong, Xingyu LiangAbstract:Abstract In this paper, the characteristics of particle size distribution in the exhaust gas of a diesel engine lubricated by two kinds of Lubricating Oil are investigated. The experiments are conducted in a turbocharged direct-injection diesel engine with Fast Particulate Spectrometer DMS 500 connected to the exhaust pipe. Two kinds of commonly used commercial Lubricating Oil, Kunlun API CF-4 15W40 and Mobil API CI-4 15W40, are chosen for the experiments. Particle size distribution and total number concentration are measured under medium load (100 Nm) and full load. Barring a few exceptions, the results indicate that total particle number concentration is almost the same, while particle size distribution shows great difference.
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effect of Lubricating Oil additives on particle size distribution and total number concentration in diesel engine
Lubrication Science, 2012Co-Authors: Lihui Dong, Xingyu Liang, Yuesen WangAbstract:This paper investigates the characteristics of particle size distribution in exhaust gas of engine fuelled with pure diesel and with diesel mixed with base Oil or with Oil additives. The experiments are conducted on a turbocharged diesel engine with fast particulate spectrometer DMS 500 connected to the exhaust pipe. Base Oil and two kinds of commonly used Lubricating Oil additives, antioxidant additives and antifoaming additives, are chosen to be added into the fuel, with the concentrations being 0.5%, 1.0% and 1.5% of fuel weight individually. The particle size distribution is measured under medium load (100 Nm) and full load at different speeds. The results indicate that the existence of base Oil or Oil additives shows great influence on particle size distribution. Copyright © 2012 John Wiley & Sons, Ltd.
