scholarly journals Influence of Coiling Direction of Helical Tube Bundles on the Thermal-Hydraulics of the HTGR Steam Generator

2021 ◽  
Vol 2048 (1) ◽  
pp. 012032
Author(s):  
Weikai Gao ◽  
Xiaoyang Xie ◽  
Xiaowei Li ◽  
Xinxin Wu
Keyword(s):  
Heat Transfer ◽  
Opposite Direction ◽  
Tube Bundle ◽  
Tangential Velocity ◽  
Transfer Coefficients ◽  
Direction Parallel ◽  
Helical Tube ◽  
Tube Bundles ◽  
Parallel Tube ◽  
Coiling Direction

Abstract Helical tube bundles were usually adopted in the steam generators (SGs) or intermediate heat exchangers (IHXs) of high temperature gas-cooled reactors (HTGRs). Heat transfer tubes in neighboring tube layers can be coiled in the same direction or in the opposite direction. The coiling direction has influences on the thermal-hydraulic performances of the SGs or IHXs. The cross flow convection over helical tube bundles with neighboring tube layers having the same coiled direction and opposite coiled direction were numerically investigated. Reynolds stress model with standard wall functions was used for the turbulence modeling. For a helical tube bundle with neighboring layers coiled in the same direction (parallel tube layers), the tangential velocity along the coiled circumferential direction could be observed obviously. For a helical tube bundle with neighboring layers coiled in the opposite direction (crossed tube layers), there is no average tangential velocity of the whole flow filed. And the streamlines of the fluid are very complex. The flow resistances and heat transfer coefficients over helical tube bundle with parallel tube layers and crossed tube layers were compared. Although the heat transfer over helical tube bundles with crossed tube layers was 9.39% smaller than that with parallel tube layers, the pressure drop over tube bundle with crossed tube layers was much smaller compared with those with parallel tube layers.

A New Heat Transfer Correlation and Flow Regime Map for Tube Bundles

1990 ◽  
Vol 112 (1) ◽  
pp. 150-156 ◽  
Author(s):  
Y. A. Hassan ◽  
T. K. Blanchat
Keyword(s):  
Heat Transfer ◽  
Flow Regime ◽  
Steam Generator ◽  
Tube Bundle ◽  
Nucleate Boiling ◽  
Heat Transfer Correlation ◽  
Transfer Coefficients ◽  
Tube Bundles ◽  
Regime Map ◽  
Flow Regime Map

A RELAP5/MOD2 computer code model for a once-through steam generator has been developed. The calculated heat transfer in the nucleate boiling flow was underpredicted as shown by a predicted superheat of only 11°C (20°F), whereas plant values range from 22–30°C (40–60°F). Existing heat transfer correlations used in thermal-hydraulic computer codes do not provide accurate predictions of the measurement-derived secondary convective heat transfer coefficients for steam generators because they were developed for flow inside tubes, not tube bundles. The RELAP5/MOD2 flow regime map was modified to account for flow across bundles. This modified flow regime map predicts better transition criteria between bubbly-to-slug and slug-to-annular flow. Consequently, improved saturated conditions for the fluid flow at the entrance to the boiler were obtained. A modified Chen-type heat transfer correlation was developed to predict the boiling heat transfer for steam generator tube bundle geometries. This correlation predicts better superheat.

Falling Film Evaporation of Water on Horizontal Configured Tube Bundles

2010 ◽  
Author(s):  
Wei Li ◽  
Xiaoyu Wu ◽  
Zhong Luo
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Transfer Enhancement ◽  
Inlet Temperature ◽  
Falling Film ◽  
Transfer Enhancement ◽  
Transfer Coefficients ◽  
Film Evaporation ◽  
Tube Bundles ◽  
Falling Film Evaporation

This paper reports an experimental study on falling film evaporation of water on 6-row horizontal configured tube bundles in a vacuum. Three types of configured tubes, Turbo-CAB-19fpi and −26fpi, Korodense, including smooth tubes for reference, were tested in a range of film Reynolds number from about 10 to 110. Results show that as the falling film Reynolds number increases, falling film evaporation goes from tubes partial dryout regime to fully wet regime; the mean heat transfer coefficients reach peak values in the transition point. Turbo-CAB tubes have the best heat transfer enhancement of falling film evaporation in both regimes, but Korodense tubes’ overall performances are better when tubes are fully wet. The inlet temperature of heating water has hardly any effects on the heat transfer, but the evaporation pressure has controversial effects. A correlation with errors within 10% was also developed to predict the heat transfer enhancement capacity.

Experimental Study of Flow Induced Vibration on Heat Transfer Helical Tube Bundle

2008 ◽  
Author(s):  
Lixia Gao ◽  
Jie Yang ◽  
Zilong Jiang ◽  
Jianzhong Ma ◽  
Song Li
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
High Pressure ◽  
Tube Bundle ◽  
Flow Induced Vibration ◽  
Steady State Operation ◽  
Helical Tube ◽  
Asme Code ◽  
Fatigue Evaluation ◽  
Large Flow

In this paper, the Flow Induced Vibration (FIV) tests of heat transfer helical tube bundle have been carried out. The results show that the more large flow velocity in tube becomes, the more high pressure drop of bundle is. The dynamic buckling of bundle does not occur during steady-state operation. The fatigue evaluation has been done according to ASME code and the structure is founded to satisfy the ASME code requirements.

Experimental Investigation on Natural Circulation in a Thermosyphon Reboiler

2010 ◽  
Author(s):  
Xing Luo ◽  
Yanming Gao ◽  
Stephan Kabelac
Keyword(s):  
Heat Transfer ◽  
Tube Bundle ◽  
Flow Boiling ◽  
Natural Circulation ◽  
Liquid Product ◽  
Pilot Scale ◽  
Vertical Tube ◽  
Transfer Coefficients ◽  
Two Phase ◽  
Set Up

Thermosyphon reboilers are widely used in refineries, petrochemical industries and other chemical processes. The liquid product stream coming from the bottom of the vapor-liquid separator is heated in an evaporator consisting of a vertical tube or tube bundle. When the evaporation occurs, the specific volume of the two-phase fluid increases. The upward buoyancy force caused by the density difference between the evaporator and down-flow pipe drives the fluid flowing through the evaporator in to the separator and forms a natural circulation. The experiments were conducted in a pilot scale thermosyphon system in which the evaporator consists of 7 steel tubes (outside diameter 30 mm, wall thickness 2 mm, length 4 m). A mathematical model was set up to simulate the heat transfer and pressure drop, in which empirical equations from literature were used. With the help of the simulation, the flow boiling heat transfer coefficients inside the tubes can be evaluated from a few measured local wall temperatures.

Different Type Tube Bundle Heat Transfer to Vertical Foam Flow

2007 ◽  
Author(s):  
Jonas Gylys ◽  
Stasys Sinkunas ◽  
Tadas Zdankus ◽  
Vidmantas Giedraitis
Keyword(s):  
Heat Transfer ◽  
Experimental Investigation ◽  
Flow Velocity ◽  
Void Fraction ◽  
Tube Bundle ◽  
Auxiliary Equipment ◽  
Foam Flow ◽  
Flow Parameters ◽  
Tube Bundles ◽  
Foam Generator

Gas-liquid foam due to especially large inter-phase contact surface can be used as a coolant. An experimental investigation of the staggered and in-line tube bundles’ heat transfer to the vertically upward and downward laminar foam flow was performed. The experimental setup consisted of the foam generator, vertical experimental channel, tube bundles, measurement instrumentation and auxiliary equipment. It was determined dependency of heat transfer intensity on flow parameters: flow velocity, direction of flow, volumetric void fraction of foam and liquid drainage from foam. Apart of this, influence of tube position in the bundle to heat transfer was investigated. Foam flow structure, distribution of the foam’s local void fraction and flow velocity in cross-section of the channel were the main factors which influenced on heat transfer intensity of the different tubes. Experimental investigation showed that the heat transfer intensity of the frontal and further tubes of the bundles to vertical foam flow is different in comparison with one-phase fluid flow. The results of the experimental investigation are presented in this paper.

Natural Convection From a Tube Bundle in a Thin Inclined Enclosure

2003 ◽  
Author(s):  
Wei Liu ◽  
Jane H. Davidson ◽  
F. A. Kulacki
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Tube Bundle ◽  
Storage System ◽  
Convection Heat Transfer ◽  
Constant Heat Flux ◽  
Working Fluid ◽  
Measured Temperature ◽  
Transfer Coefficients ◽  
Rectangular Array

Natural convection heat transfer coefficients for a rectangular array of eight tubes contained in a thin enclosure of aspect ratio 9.3:1 and inclined at 30 degrees to the horizontal are measured for a range of transient operating modes typical of a load side heat exchanger in unpressurized integral collector-storage systems. Water is the working fluid, and thermal charging is accomplished via a constant heat flux on the upper boundary. All other boundaries are well insulated. Results for isothermal and stratified enclosures yield the following correlation for the overall Nusselt number: NuD=(0.728±0.002)RaD0.25,4.0×105≤RaD≤1.4×107. The flow field in the enclosure is inferred from measured temperature distributions. The temperature difference that drives natural convection is also determined. The results extend earlier work for the case of a single tube and provide limiting case heat transfer data for a tube bundle that occupies the upper portion of the collector storage system.

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