The Experts below are selected from a list of 231 Experts worldwide ranked by ideXlab platform
A Viedma - One of the best experts on this subject based on the ideXlab platform.
-
mixed convection heat transfer and isothermal pressure drop in corrugated tubes for laminar and Transition Flow
International Communications in Heat and Mass Transfer, 2004Co-Authors: P G Vicente, A Garcia, A ViedmaAbstract:We present an experimental investigation carried out in corrugated tubes for laminar and Transitional Flow. Employing water and ethylene glycol as test fluids, a wide range of Flow conditions was covered in order to use these results under the typical Flow conditions of the chemical and food industry. Laminar Flow heat transfer through horizontal corrugated tubes is produced by mixed convection where the Nusselt number depends on both natural convection and the entry region. Heat transfer results are presented in the form Nu = f(Ra,x*) and showed that at high Rayleigh numbers, enhancement produced by corrugated tubes can be up to 30%. Pressure drop results showed that friction factors in corrugated tubes are between 5 and 25% higher than the smooth tube ones. Moreover, it was observed that roughness accelerates Transition to critical Reynolds numbers below 1300
-
experimental study of mixed convection and pressure drop in helically dimpled tubes for laminar and Transition Flow
International Journal of Heat and Mass Transfer, 2002Co-Authors: P G Vicente, A Garcia, A ViedmaAbstract:Abstract This paper presents the experimental results carried out in dimpled tubes for laminar and Transition Flows and completes a previous work of the authors focused on the turbulent region. It was observed that laminar Flow heat transfer through horizontal dimpled tubes is produced in mixed convection, where Nusselt number depends on both the natural convection and the entry region. Employing water and ethylene glycol as test fluids, the following Flow range was covered: x ∗ =10 −4 –10 −2 and Ra=106–108. The experimental results of isothermal pressure drop for laminar Flow showed dimpled tube friction factors between 10% and 30% higher than the smooth tube ones. Moreover, it was perceived that roughness accelerates Transition to critical Reynolds numbers down to 1400. Correlations for the laminar friction factor f=f(Re,h/d) and for the critical Reynolds Recrit=Recrit(h/d) are proposed. The hydraulic behaviour of dimpled tubes was found to depend mainly on dimple height. In mixed convection, high temperature differences in the cross section were measured and therefore heat transfer was evaluated by a circumferentially averaged Nusselt number. Experimenal correlations for the local and the fully developed Nusselt numbers Nu x = Nu x (x ∗ ,Ra) and Nu ∞ = Nu ∞ (Ra) are given. Results showed that at low Rayleigh numbers, heat transfer is similar to the smooth tube one whereas at high Rayleigh, enhancement produced by dimpled tubes can be up to 30%.
P G Vicente - One of the best experts on this subject based on the ideXlab platform.
-
mixed convection heat transfer and isothermal pressure drop in corrugated tubes for laminar and Transition Flow
International Communications in Heat and Mass Transfer, 2004Co-Authors: P G Vicente, A Garcia, A ViedmaAbstract:We present an experimental investigation carried out in corrugated tubes for laminar and Transitional Flow. Employing water and ethylene glycol as test fluids, a wide range of Flow conditions was covered in order to use these results under the typical Flow conditions of the chemical and food industry. Laminar Flow heat transfer through horizontal corrugated tubes is produced by mixed convection where the Nusselt number depends on both natural convection and the entry region. Heat transfer results are presented in the form Nu = f(Ra,x*) and showed that at high Rayleigh numbers, enhancement produced by corrugated tubes can be up to 30%. Pressure drop results showed that friction factors in corrugated tubes are between 5 and 25% higher than the smooth tube ones. Moreover, it was observed that roughness accelerates Transition to critical Reynolds numbers below 1300
-
experimental study of mixed convection and pressure drop in helically dimpled tubes for laminar and Transition Flow
International Journal of Heat and Mass Transfer, 2002Co-Authors: P G Vicente, A Garcia, A ViedmaAbstract:Abstract This paper presents the experimental results carried out in dimpled tubes for laminar and Transition Flows and completes a previous work of the authors focused on the turbulent region. It was observed that laminar Flow heat transfer through horizontal dimpled tubes is produced in mixed convection, where Nusselt number depends on both the natural convection and the entry region. Employing water and ethylene glycol as test fluids, the following Flow range was covered: x ∗ =10 −4 –10 −2 and Ra=106–108. The experimental results of isothermal pressure drop for laminar Flow showed dimpled tube friction factors between 10% and 30% higher than the smooth tube ones. Moreover, it was perceived that roughness accelerates Transition to critical Reynolds numbers down to 1400. Correlations for the laminar friction factor f=f(Re,h/d) and for the critical Reynolds Recrit=Recrit(h/d) are proposed. The hydraulic behaviour of dimpled tubes was found to depend mainly on dimple height. In mixed convection, high temperature differences in the cross section were measured and therefore heat transfer was evaluated by a circumferentially averaged Nusselt number. Experimenal correlations for the local and the fully developed Nusselt numbers Nu x = Nu x (x ∗ ,Ra) and Nu ∞ = Nu ∞ (Ra) are given. Results showed that at low Rayleigh numbers, heat transfer is similar to the smooth tube one whereas at high Rayleigh, enhancement produced by dimpled tubes can be up to 30%.
A Garcia - One of the best experts on this subject based on the ideXlab platform.
-
mixed convection heat transfer and isothermal pressure drop in corrugated tubes for laminar and Transition Flow
International Communications in Heat and Mass Transfer, 2004Co-Authors: P G Vicente, A Garcia, A ViedmaAbstract:We present an experimental investigation carried out in corrugated tubes for laminar and Transitional Flow. Employing water and ethylene glycol as test fluids, a wide range of Flow conditions was covered in order to use these results under the typical Flow conditions of the chemical and food industry. Laminar Flow heat transfer through horizontal corrugated tubes is produced by mixed convection where the Nusselt number depends on both natural convection and the entry region. Heat transfer results are presented in the form Nu = f(Ra,x*) and showed that at high Rayleigh numbers, enhancement produced by corrugated tubes can be up to 30%. Pressure drop results showed that friction factors in corrugated tubes are between 5 and 25% higher than the smooth tube ones. Moreover, it was observed that roughness accelerates Transition to critical Reynolds numbers below 1300
-
experimental study of mixed convection and pressure drop in helically dimpled tubes for laminar and Transition Flow
International Journal of Heat and Mass Transfer, 2002Co-Authors: P G Vicente, A Garcia, A ViedmaAbstract:Abstract This paper presents the experimental results carried out in dimpled tubes for laminar and Transition Flows and completes a previous work of the authors focused on the turbulent region. It was observed that laminar Flow heat transfer through horizontal dimpled tubes is produced in mixed convection, where Nusselt number depends on both the natural convection and the entry region. Employing water and ethylene glycol as test fluids, the following Flow range was covered: x ∗ =10 −4 –10 −2 and Ra=106–108. The experimental results of isothermal pressure drop for laminar Flow showed dimpled tube friction factors between 10% and 30% higher than the smooth tube ones. Moreover, it was perceived that roughness accelerates Transition to critical Reynolds numbers down to 1400. Correlations for the laminar friction factor f=f(Re,h/d) and for the critical Reynolds Recrit=Recrit(h/d) are proposed. The hydraulic behaviour of dimpled tubes was found to depend mainly on dimple height. In mixed convection, high temperature differences in the cross section were measured and therefore heat transfer was evaluated by a circumferentially averaged Nusselt number. Experimenal correlations for the local and the fully developed Nusselt numbers Nu x = Nu x (x ∗ ,Ra) and Nu ∞ = Nu ∞ (Ra) are given. Results showed that at low Rayleigh numbers, heat transfer is similar to the smooth tube one whereas at high Rayleigh, enhancement produced by dimpled tubes can be up to 30%.
Haiting Zhang - One of the best experts on this subject based on the ideXlab platform.
-
water holdup measurement of oil water two phase Flow with low velocity using a coaxial capacitance sensor
Experimental Thermal and Fluid Science, 2017Co-Authors: X Chen, Hongxia Zhang, Haiting ZhangAbstract:Abstract This paper is devoted to measuring water holdup of oil-water two-phase Flow with low velocity using a coaxial capacitance sensor. We first investigated the distribution characteristics of the coaxial capacitance sensor via the finite element method (FEM) and optimized its geometry size. Afterward, we carried out a vertical upward oil-water two-phase Flow experiment in a pipe with a 20-mm inner diameter (ID) to obtain the responses of four Flow patterns: Transition Flow (TF), dispersed oil-in-water slug Flow (D OS/W), dispersed oil-in-water Flow (D O/W) and very fine dispersed oil-in-water Flow (VFD O/W). The sensor outputs were normalized to equivalent water holdup and compared with the set values from a quick closing valve (QCV) method. Finally, we studied the time-frequency dynamic characteristics of different Flow patterns based on the Adaptive Optimal Kernel Time-Frequency Representation (AOK-TFR) algorithm to further analyze the evolution of oil-water two-phase Flow with low velocity. The results show that the coaxial capacitance sensor can be effectively applied in the measurement of water holdup under moderate and low water-cuts as well as uncovering discrepancies regarding different Flow patterns.
Lu-sheng Zhai - One of the best experts on this subject based on the ideXlab platform.
-
Flow measurement of oil water two phase Flow at low Flow rate using the plug in conductance sensor array
Sensors, 2019Co-Authors: Yiyu Zhou, Xinghe Liang, Dayang Wang, Lu-sheng ZhaiAbstract:In order to improve the Flow measurement accuracy of oil-water two-phase Flow at low Flow rate, this paper presents a plug-in conductance sensor array (PICSA) for the measurement of water holdup and cross-correlation velocity. Due to the existence of the insert body in PICSA, the effect of slippage and the non-uniform distribution of dispersed phase on the measurement of oil-water two-phase Flow at low Flow rate can be reduced. The finite element method is used to analyze the electric field distribution characteristics of the plug-in conductance sensor, and the sensor geometry is optimized. The dynamic experiment of oil-water two-phase Flow is carried out where water cut Kw and mixture velocity Um are set in the range of 10–98% and 0.0184–0.2580 m/s respectively. Experimental results show that the PICSA has good resolution in water holdup measurement for dispersed oil-in-water slug Flow (D OS/W), Transition Flow (TF), dispersed oil-in-water bubble Flow (D O/W) and very fine dispersed oil-in-water bubble Flow (VFD O/W). In addition, the cross-correlation velocity of the oil-water two-phase Flow is obtained by using the plug-in upstream and downstream conductance sensor arrays. The relationship between the cross-correlation velocity and mixture velocity is found to be sensitive to the change of Flow pattern, but it has a good linear relationship under the same Flow pattern. Based on the Flow pattern identification, a good prediction result of the mixture velocity is obtained using kinematic wave theory. Finally, a high precision prediction of the individual phase volume fraction of oil-water two-phase Flow at low Flow rate is achieved by using the drift flux model.
