The Experts below are selected from a list of 288 Experts worldwide ranked by ideXlab platform

Hiroyuki Kumano - One of the best experts on this subject based on the ideXlab platform.

  • Flow and heat transfer characteristics of a tetra-n-butyl ammonium bromide hydrate slurry in the transition region
    International Journal of Refrigeration-revue Internationale Du Froid, 2012
    Co-Authors: Hiroyuki Kumano, Tetsuo Hirata, Yuki Kobayashi
    Abstract:

    Abstract The flow and heat transfer characteristics of a tetra-n-butyl ammonium bromide (TBAB) hydrate slurry were investigated experimentally. The characteristics in the transition region were examined in detail. Two types of hydrates form from TBAB solution of different concentrations. The hydrate type, Reynolds number and solid fraction were varied as experimental parameters and the coefficients of Pipe Friction and heat transfer were measured. In the low solid fraction region, it was found that the coefficients of Pipe Friction and heat transfer were constant and the values were the same as that for turbulent flow of the TBAB solution. However, for the high solid fraction region, a laminarization phenomenon occurs and the flow and heat transfer characteristics can be estimated from the laminar flow of the hydrate slurry. Moreover, the laminarization point for the solid fraction can be predicted using the apparent Reynolds number.

  • Study on flow and heat transfer characteristics in transition region for ice slurry.
    2012
    Co-Authors: Seigo Sawada, Fumito Tamura, Hiroyuki Kumano
    Abstract:

    The flow and heat transfer characteristics of ice slurry were investigated experimentally. The characteristics in the transition region were examined in detail. The ice slurry was produced from ethanol solution. Ice packing factor (IPF), Reynolds number and tube diameter were varied as experimental parameters and the coefficients of Pipe Friction and heat transfer were measured. In the low IPF region, it was found that the coefficients of Pipe Friction and heat transfer were constant and the values were the same as that for turbulent flow of the ethanol solution. However, for the high IPF region, a laminarization phenomenon occurs and the flow and heat transfer characteristics can be estimated from the laminar flow of the ice slurry. Moreover, the laminarization point for the IPF can be predicted using the apparent Reynolds number.

  • Effects of storage on flow and heat transfer characteristics of ice slurry
    International Journal of Refrigeration, 2012
    Co-Authors: Hiroyuki Kumano, Yosuke Hagiwara, Takuya Hirata, Fumito Tamura
    Abstract:

    The effect of storage on flow and heat transfer characteristics of ice slurry was investigated experimentally. After ice slurry had been stored in the storage tank, variations in ice particle size were measured using a microscope, and diameter distribution and average diameter determined. The ice packing factor, Reynolds number and storage time were varied as experimental parameters. The pressure drop and heat transfer coefficient were measured when the ice slurry flowed in the horizontal tube. For laminar flow, the ratios of Pipe Friction and heat transfer coefficient decreased with storage time. For more than 12 h storage time, the ice slurry could not flow in the tube. The adhesion between ice particles seemed to cause a blockage in the tube. On the other hand, for turbulent flow, the Pipe Friction and ice slurry heat transfer coefficients were similar to that of the ethanol solution, and the storage effect was insignificant. ?? 2011 Elsevier Ltd and IIR. All rights reserved.

  • Study on flow and heat transfer characteristics of ice slurry in the transition region
    International Journal of Refrigeration, 2012
    Co-Authors: Hiroyuki Kumano, Fumito Tamura, Seigo Sawada, Takahiko Asaoka
    Abstract:

    The flow and heat transfer characteristics of ice slurry were investigated experimentally. The characteristics in the transition region were examined in detail. The ice slurry was produced from ethanol solution. Ice packing factor (IPF), Reynolds number and tube diameter were varied as experimental parameters, and the coefficients of Pipe Friction and heat transfer were measured. In the low IPF region, the coefficients of the Pipe Friction and heat transfer were found to be constant with values that were the same as for turbulent flow in an ethanol solution. However, for the high IPF region, laminarization occurs and flow and heat transfer characteristics can be estimated from the laminar flow of the ice slurry. Moreover, the laminarization point can be estimated using the apparent Reynolds number.

  • experimental study on the flow and heat transfer characteristics of a tetra n butyl ammonium bromide hydrate slurry first report flow characteristics
    International Journal of Refrigeration-revue Internationale Du Froid, 2011
    Co-Authors: Hiroyuki Kumano, Tetsuo Hirata, Tomoya Kudoh
    Abstract:

    The flow characteristics of a tetra-n-butyl ammonium bromide hydrate slurry were investigated experimentally. Reynolds number, tube diameter and solid fraction were varied as the experimental parameters. For laminar flow, it was found that the ratio of the coefficients of Pipe Friction increases with solid fraction, and the rate of increase is high in the case of a low Reynolds number. For turbulent flow, the ratio of the coefficients of Pipe Friction was approximately 1 for all tube diameters at low solids fraction. It then decreased slightly at a particular solid fraction and increased again at high solid fraction. Theoretical analysis was carried out using the experimental results, and it was found that the flow characteristics of the hydrate slurry can be treated as those of a pseudoplastic fluid and clarified using the apparent Reynolds number.

Fumito Tamura - One of the best experts on this subject based on the ideXlab platform.

  • Study on flow and heat transfer characteristics in transition region for ice slurry.
    2012
    Co-Authors: Seigo Sawada, Fumito Tamura, Hiroyuki Kumano
    Abstract:

    The flow and heat transfer characteristics of ice slurry were investigated experimentally. The characteristics in the transition region were examined in detail. The ice slurry was produced from ethanol solution. Ice packing factor (IPF), Reynolds number and tube diameter were varied as experimental parameters and the coefficients of Pipe Friction and heat transfer were measured. In the low IPF region, it was found that the coefficients of Pipe Friction and heat transfer were constant and the values were the same as that for turbulent flow of the ethanol solution. However, for the high IPF region, a laminarization phenomenon occurs and the flow and heat transfer characteristics can be estimated from the laminar flow of the ice slurry. Moreover, the laminarization point for the IPF can be predicted using the apparent Reynolds number.

  • Effects of storage on flow and heat transfer characteristics of ice slurry
    International Journal of Refrigeration, 2012
    Co-Authors: Hiroyuki Kumano, Yosuke Hagiwara, Takuya Hirata, Fumito Tamura
    Abstract:

    The effect of storage on flow and heat transfer characteristics of ice slurry was investigated experimentally. After ice slurry had been stored in the storage tank, variations in ice particle size were measured using a microscope, and diameter distribution and average diameter determined. The ice packing factor, Reynolds number and storage time were varied as experimental parameters. The pressure drop and heat transfer coefficient were measured when the ice slurry flowed in the horizontal tube. For laminar flow, the ratios of Pipe Friction and heat transfer coefficient decreased with storage time. For more than 12 h storage time, the ice slurry could not flow in the tube. The adhesion between ice particles seemed to cause a blockage in the tube. On the other hand, for turbulent flow, the Pipe Friction and ice slurry heat transfer coefficients were similar to that of the ethanol solution, and the storage effect was insignificant. ?? 2011 Elsevier Ltd and IIR. All rights reserved.

  • Study on flow and heat transfer characteristics of ice slurry in the transition region
    International Journal of Refrigeration, 2012
    Co-Authors: Hiroyuki Kumano, Fumito Tamura, Seigo Sawada, Takahiko Asaoka
    Abstract:

    The flow and heat transfer characteristics of ice slurry were investigated experimentally. The characteristics in the transition region were examined in detail. The ice slurry was produced from ethanol solution. Ice packing factor (IPF), Reynolds number and tube diameter were varied as experimental parameters, and the coefficients of Pipe Friction and heat transfer were measured. In the low IPF region, the coefficients of the Pipe Friction and heat transfer were found to be constant with values that were the same as for turbulent flow in an ethanol solution. However, for the high IPF region, laminarization occurs and flow and heat transfer characteristics can be estimated from the laminar flow of the ice slurry. Moreover, the laminarization point can be estimated using the apparent Reynolds number.

  • Effects of storage on flow and heat transfer characteristics of ice slurry
    International Journal of Refrigeration-revue Internationale Du Froid, 2011
    Co-Authors: Hiroyuki Kumano, Yosuke Hagiwara, Tetsuo Hirata, Fumito Tamura
    Abstract:

    Abstract The effect of storage on flow and heat transfer characteristics of ice slurry was investigated experimentally. After ice slurry had been stored in the storage tank, variations in ice particle size were measured using a microscope, and diameter distribution and average diameter determined. The ice packing factor, Reynolds number and storage time were varied as experimental parameters. The pressure drop and heat transfer coefficient were measured when the ice slurry flowed in the horizontal tube. For laminar flow, the ratios of Pipe Friction and heat transfer coefficient decreased with storage time. For more than 12 h storage time, the ice slurry could not flow in the tube. The adhesion between ice particles seemed to cause a blockage in the tube. On the other hand, for turbulent flow, the Pipe Friction and ice slurry heat transfer coefficients were similar to that of the ethanol solution, and the storage effect was insignificant.

Koichi Kaizu - One of the best experts on this subject based on the ideXlab platform.

  • Friction welding technique and joint properties of thin walled Pipe Friction welded joint between type 6063 aluminum alloy and aisi 304 austenitic stainless steel
    The International Journal of Advanced Manufacturing Technology, 2016
    Co-Authors: Masaaki Kimura, Masahiro Kusaka, Koichi Kaizu, Kazuhiro Nakata, Kimiaki Nagatsuka
    Abstract:

    The joint characteristics of thin-walled Pipe Friction-welded joint between AA6063 aluminum alloy (A6063) and AISI 304 stainless steel (SUS304) were investigated. The Pipe had a thickness of 1.5 mm, and the joint was made with a Friction speed of 27.5 rps and a Friction pressure of 30 MPa. The joint, which was made by a continuous drive Friction welding machine, had heavy deformation on the A6063 side during braking. To prevent deformation until rotation stop with braking, the joint was made by a technique in which the relative speed between both specimens instantly decreased to 0 when the setting Friction time was finished, and consequently, the joining could be successfully achieved. The joint with a Friction pressure of 30 MPa and a Friction time of 0.4 s did not have the intermetallic compound (IMC) layer (interlayer) at the weld interface, although that with a Friction time of 1.6 s had it. However, the joint with a forge pressure of 150 MPa had the A6063 side buckling. Moreover, the joint efficiency of the joint with flash was higher than that of the joint without flash because the inner flash of A6063 was stuck to the inner surface of the SUS304 side. Therefore, the joint should be made with the opportune Friction time without the IMC interlayer and with the opportune forge pressure without buckling, and the accurate joint efficiency should be evaluated without flash.

  • joint properties and their improvement of aisi 310s austenitic stainless steel thin walled circular Pipe Friction welded joint
    Materials & Design, 2012
    Co-Authors: Masaaki Kimura, A Ichihara, Masahiro Kusaka, Koichi Kaizu
    Abstract:

    Abstract This paper describes the joint properties and their improvement in thin walled circular Pipe Friction welded joint for an AISI 310S austenitic stainless steel. Pipes were welded with the combination of the same thickness and outer diameter by a continuous drive Friction welding machine that has an electromagnetic clutch. Then, when the clutch was released, the relative speed between both specimens instantly decreased to zero. When the joint with a Pipe thickness of 1.50 mm was made at a Friction pressure of 120 MPa, the joining could be successfully achieved and that had 100% efficiency with the base metal fracture. However, the joining became difficult with decreasing Pipe thickness, and it was not successful at a Pipe thickness of 0.50 mm. On the other hand, when the joint with a Pipe thickness of 0.50 mm was made at a Friction pressure of 30 MPa, the joining could be successfully achieved, although that did not have 100% efficiency. Then, when the joint was made under a Friction time of 0.6 s, i.e. the Friction torque reached just after the initial peak, and a forge pressure of 60 MPa, it had 100% efficiency with the base metal fracture. However, when that was made with high forge pressure such as 120 MPa, the joining could not be achieved because the adjacent region of the weld interface had heavy buckling. To obtain the successful joining and 100% joint efficiency with the base metal fracture for the thin walled circular Pipe, the joint should be made with opportune Friction welding condition as follows: low Friction pressure, a Friction time of just after the initial peak of the Friction torque, and a forge pressure of double value of a Friction pressure.

Marco Ferrante - One of the best experts on this subject based on the ideXlab platform.

  • velocity profiles and unsteady Pipe Friction in transient flow
    Journal of Water Resources Planning and Management, 2000
    Co-Authors: Bruno Brunone, Bryan W Karney, Michele Mecarelli, Marco Ferrante
    Abstract:

    Transient conditions in closed conduits have traditionally been modeled as 1D flows with the implicit assumption that velocity profile and Friction losses can be accurately predicted using equivalent 1D velocities. Although more complex fluid models have been suggested, there has been little direct experimental basis for selecting one model over another. This paper briefly reviews the significance of the 1D assumption and the historical approaches proposed for improving the numerical modeling of transient events. To address the critical need for better data, an experimental apparatus is described, and preliminary measurements of velocity profiles during two transient events caused by valve operation are presented. The velocity profiles recorded during these transient events clearly show regions of flow recirculation, flow reversal, and an increased intensity of fluid turbulence. The experimental pressures are compared to a water hammer model using a conventional quasi-steady representation of head loss an...

Takahiko Asaoka - One of the best experts on this subject based on the ideXlab platform.

  • Study on flow and heat transfer characteristics of ice slurry in the transition region
    International Journal of Refrigeration, 2012
    Co-Authors: Hiroyuki Kumano, Fumito Tamura, Seigo Sawada, Takahiko Asaoka
    Abstract:

    The flow and heat transfer characteristics of ice slurry were investigated experimentally. The characteristics in the transition region were examined in detail. The ice slurry was produced from ethanol solution. Ice packing factor (IPF), Reynolds number and tube diameter were varied as experimental parameters, and the coefficients of Pipe Friction and heat transfer were measured. In the low IPF region, the coefficients of the Pipe Friction and heat transfer were found to be constant with values that were the same as for turbulent flow in an ethanol solution. However, for the high IPF region, laminarization occurs and flow and heat transfer characteristics can be estimated from the laminar flow of the ice slurry. Moreover, the laminarization point can be estimated using the apparent Reynolds number.