SATURATED UP-FLOW BOILING IN A VERTICAL INTERNAL THREE-DIMENSIONAL FIN-TUBE AT MODERATE PRESSURES

1994 ◽  
Author(s):  
Hong-Ji Zhang ◽  
Si-Li Shao ◽  
Ming-Wei Tong
Keyword(s):  
Flow Boiling ◽  
Three Dimensional ◽  
Fin Tube

Numerical Analysis of a Compressor Type of Dehumidifier: (I) Fluid Flow

2017 ◽  
Vol 25 (02) ◽  
pp. 1750011 ◽  
Author(s):  
Xuan Quang Duong ◽  
Jae Dong Chung
Keyword(s):  
Physical Model ◽  
High Performance ◽  
Three Dimensional ◽  
Computation Time ◽  
Object A ◽  
Porous Model ◽  
Two Factors ◽  
Fin Tube ◽  
Dimensional Simulation ◽  
Actual Shape

A three-dimensional simulation of a compressor dehumidifier was conducted by applying a porous model for condenser and evaporator, and a moving reference frame for the fan. A physical model was simulated for the unit cell of the actual shape of a fin-tube, and the parameters of viscous resistance and initial resistance were obtained. With these values, the porous model showed close agreement with the physical model within a reasonable computation time. A uniform flow across the evaporator and the condenser is desirable for high performance of the dehumidifier. Surface averaged velocity, standard deviation of velocity, and uniformity were chosen as indicators of the design object. A case study showed that two factors, (i) reducing the space between the evaporator and the condenser and (ii) introducing a cover to reduce the by-passing air flow, have the strongest influence on the air distribution in this dehumidifier.

Development and Application of a UTSG Thermal-Hydraulic Analysis Code

2014 ◽  
Author(s):  
Tenglong Cong ◽  
Guanghui Su ◽  
Wenxi Tian ◽  
Suizheng Qiu
Keyword(s):  
Steam Generator ◽  
Structural Integrity ◽  
Tube Bundle ◽  
Flow Boiling ◽  
Three Dimensional ◽  
Hydraulic Parameters ◽  
Two Phase ◽  
Drift Flux ◽  
Thermal Hydraulic Analysis ◽  
Secondary Side

Structural integrity of steam generator should be maintained during operation, since it performs as the pressure and heat transfer boundary of primary side coolant. Localized thermal-hydraulic parameters of secondary side are essential for the analysis of tube wastage, fatigue and failure. In this paper, a three-dimensional thermohydraulics analysis code, named STAF, is developed based on FLUENT. With STAF code, three-dimensional thermohydraulics of secondary side of AP1000 steam generator are generated. This code is developed based on the porous media theory. In this code, the drift flux two-phase model coupled with a simplified flow boiling model is utilized to present two-phase flow among the U-tube bundle. Downcomer, tube bundle, support plates and primary separators in steam generator are considered in STAF code. The calculated results are compared with a general steam generator thermohydraulic analysis code ATHOS, which is developed by EPRI steam generator group. The comparison indicates that STAF code performs well in evaluating thermal-hydraulic parameters in steam generator. The results show that the flow field varies significantly at different position in AP1000 steam generator. Flow vapor quality at the inlet of primary separators varies significantly, which is a severe challenge to the capacity design of separators.

Flow Boiling Characteristics of R410A in Horizontal Annuli of Enhanced Surface Tubes

2019 ◽  
Author(s):  
Zhi-chuan Sun ◽  
Wei Li ◽  
Xiang Ma ◽  
Yuansheng Lin ◽  
Zhiwu Ke ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Boiling Heat Transfer ◽  
High Speed ◽  
Flow Boiling ◽  
Saturation Temperature ◽  
Outer Tube ◽  
Annular Gap ◽  
Penalty Factor ◽  
Fin Tube

Abstract An experimental study on the flow boiling heat transfer in a horizontal annular passage outside the single tube using R410A. The tested tubes contain a smooth tube, a 1EHT tube (dimpled tube) and a herringbone micro-fin tube with the same outside diameter of 12.70 mm. Tests were carried out at a saturation temperature of 6 °C for a mass flux range of 8∼107 kg/m2s with a fixed inlet quality of 0.1 and three different outlet qualities (0.4, 0.6, 0.8). Changes in vapor quality and annular gap size are found to have a significant impact on boiling heat transfer in the concentric annulus. For tests in the annuli with a 25.4-mm-ID outer tube, the HTC of the herringbone micro-fin tube is highest together with the largest pressure drop. Both the annulus of 1EHT tube and the annulus of herringbone micro-fin tube show a higher boiling HTC at an outlet quality of 0.6. The larger penalty factor is found at an outlet quality of 0.8. For flow boiling in the annuli having different annular gap sizes, it is found that the heat transfer enhancement ratio decreases sharply with the increasing average quality. When the inner diameter of outer tube is 19.0 mm, HTC decreases at first and then rises slowly. The huge bubbles occurred at the low mass fluxes and the scouring effect on the heated annulus walls of high-speed flow may be responsible.

Single-Side Heated Monoblock, High Heat Flux Removal Using Water Subcooled Flow Boiling

2003 ◽  
Author(s):  
Ronald D. Boyd ◽  
Ali Ekhlassi ◽  
Penrose Cofie ◽  
Richard Martin ◽  
Hongtao Zhang
Keyword(s):  
Heat Flux ◽  
Wall Temperature ◽  
Test Section ◽  
Flow Boiling ◽  
Three Dimensional ◽  
High Heat ◽  
High Heat Flux ◽  
Subcooled Flow Boiling ◽  
Subcooled Flow ◽  
Single Side

Plasma-facing components for fusion reactors and other high heat flux heat sinks are usually subjected to a peripherally non-uniform heat flux. The configuration under study is related to these applications and consists of a single-side heated monoblock cross-section test section with a circular coolant channel bored through the center. The monoblock test section has a heated length of 180.0 mm and has 10.0 mm and 30.0 mm inside diameter and outside square sides, respectively. It was subjected to a constant heat flux on one side only, and the remaining portion of the outside surfaces is not exposed to a heat flux. The inlet channel water temperature was held near at 26.0°C, the exit pressure was maintained at 0.207 MPa, and the mass velocity was 0.59 Mg/m2s. The results consist of three-dimensional monoblock test section wall temperature distributions and a clear display of both critical heat flux and post-critical heat flux for this single-side heated configuration. These results are very encouraging in that they are among the first full set of truly three-dimensional monoblock test section wall temperature measurements for a one-side heated monoblock flow channel which contains the effects of conjugate heat transfer for turbulent, subcooled flow boiling. Comparisons are made between these results for the monoblock test section and those for a single-side heated circular test section.

Numerical Study of Single Bubble Dynamics During Flow Boiling

2007 ◽  
Vol 129 (7) ◽  
pp. 864-876 ◽  
Author(s):  
Ding Li ◽  
Vijay K. Dhir
Keyword(s):  
Bubble Dynamics ◽  
Numerical Study ◽  
Flow Boiling ◽  
Three Dimensional ◽  
Horizontal Surface ◽  
Single Bubble ◽  
Bulk Liquid ◽  
Interface Heat Transfer ◽  
Single Bubble Dynamics ◽  
Energy Equations

Three-dimensional numerical simulation of single bubble dynamics during nucleate flow boiling is performed in this work. The range of bulk liquid velocities investigated is from 0.076to0.23m∕s. The surface orientations at earth normal gravity are varied from an upward facing horizontal surface to vertical through 30, 45, and 60deg. The gravity levels on an upward facing horizontal surface are varied from 1.0ge to 0.0001ge. Continuity, momentum, and energy equations are solved by finite difference method and the level set method is used to capture the liquid-vapor interface. Heat transfer within the liquid micro layer is included in this model. The numerical results have been compared with data from experiments. The results show that the bulk flow velocity, heater surface orientation, and gravity levels influence the bubble dynamics.

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