Numerical Analysis of Convection Heat Transfer for Subsea Xmas Tree Assembly

2012 ◽  
Author(s):  
Kuang Ding ◽  
Hongwu Zhu ◽  
Jinya Zhang ◽  
Xuan Luo ◽  
Junyao Zhu ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Heat Loss ◽  
Convective Heat ◽  
Structural Reliability ◽  
Sea Water ◽  
Convective Heat Transfer Coefficient ◽  
Convection Heat Transfer ◽  
Water Velocity ◽  
Convection Heat

This study aims to investigate the convection heat transfer of a horizontal subsea Xmas tree assembly at a high spatial resolution. Such study is important for increasing the structural reliability design and flow assurance level of subsea Xmas tree. Computational fluid dynamics (steady Reynolds-averaged Navier-Stokes) is adopted to evaluate the forced convective heat transfer of the subsea Xmas tree assembly. The temperature, the convection heat loss and the convective heat transfer coefficient (CHTC) at the surfaces of the subsea Xmas tree assembly are numerically obtained with low-Reynolds number modeling (LRNM). The numerical results show that the outer surface temperatures of the subsea tree are close to that of the ambient cold sea water with the exception of the pipeline. The components along the internal production tubes are typical “hot spots,” which have high CHTHs and cause a great deal of heat loss. Under the designed water depth, the effects of installation orientation and sea water velocity on convective heat transfer are investigated. The overall average CHTCs and the local CHTC distribution of the subsea Xmas tree assembly are depended on the installation orientation. Meanwhile, with the increase of the sea water velocity, the growth rates of the CHTCs for individual components show great difference. Ultimately, for selected installation orientation, the CHTC-sea water velocity correlation is derived by using a power-law CHTC-Uin correlation.

Analysis of Convective Heat Transfer Coefficient on Shape Memory Alloy Actuatorunder Various Ambient Temperatures with Finite Difference Method

2015 ◽  
Vol 736 ◽  
pp. 127-133 ◽  
Author(s):  
Jaronie Mohd Jani ◽  
Sunan Huang ◽  
Martin Leary ◽  
Aleksandar Subic
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Convective Heat Transfer Coefficient ◽  
Convection Heat Transfer ◽  
Convection Heat ◽  
Ambient Temperatures ◽  
Sma Actuator

The demand for shape memory alloy (SMA) actuators for technical applications is steadily increasing; however SMA may have poor deactivation time due to relatively slow convective cooling. Convection heat transfer mechanism plays a critical role in the cooling process, where an increase of air circulation around the SMA actuator (i.e. forced convection) provides a significant improvement in deactivation time compared to the natural convection condition. The rate of convective heat transfer, either natural or forced, is measured by the convection heat transfer coefficient, which may be difficult to predict theoretically due to the numerous dependent variables. In this work, a study of free convective cooling of linear SMAactuators was conducted under various ambient temperatures to experimentally determine the convective heat transfer coefficient. A finite difference equation (FDE) was developed to simulate SMA response, and calibrated with the experimental data to obtain the unknown convectiveheat transfer coefficient, h. These coefficients are then compared with the available theoretical equations, and it was found that Eisakhaniet. almodel provides good agreement with the Experiment-FDE calibrated results. Therefore, FDE is reasonably useful to estimate the convective heat transfer coefficient of SMA actuator experiments under various conditions, with a few identified limitations (e.g. exclusion of other associative heat transfer factors).

A Study on the Influence of Sea Water Convective Heat Transfer Coefficient in Design Verification of Subsea HPHT Equipment

2017 ◽  
Author(s):  
Ali Sepehri ◽  
Stuart Harbert ◽  
Dave Holberry
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Sea Water ◽  
Convective Heat Transfer Coefficient ◽  
Design Verification ◽  
Section Viii ◽  
Advanced Analysis

As HPHT activity continues to grow and well conditions become more severe, more advanced analysis methods are required. Thermal/heat transfer and structural Finite Element Analyses (FEA) play a fundamental role in the design of subsea equipment for HPHT application. The objective of this study is to evaluate the effect of seawater convective heat transfer coefficient on design verification of a subsea drilling connector in the HPHT environment (bore pressure more than 15,000 psi, and/or bore temperature more than 300°F). The design verification work contains the elastic-plastic assessments including protection against plastic collapse (global), local failure, hydrotest and ratcheting criteria. The fatigue study is also performed per ASME Boiler & Pressure Vessel Code, Section VIII, Div. 3, Article KD-4 in compliance with API 17TR8. The effect of seawater convective heat transfer coefficient on the global, ratcheting and fatigue criteria is studied/presented. Results show that the higher value of heat transfer coefficient (convection) results in more thermal gradients through assembly causing higher stress and plastic strain deformation in the connector components and lower fatigue life.

Wind Induced Heat Transfer Coefficient From Flat Horizontal Surfaces Exposed to Solar Radiation

2007 ◽  
Author(s):  
Subhash C. Mullick ◽  
Suresh Kumar ◽  
Basant K. Chourasia
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Convective Heat Transfer ◽  
Heat Loss ◽  
Convective Heat ◽  
Solar Collector ◽  
Convective Heat Transfer Coefficient ◽  
Loss Coefficient ◽  
Operating Conditions

Upward heat losses have strong effect on the performance of flat plate solar collectors under different operating conditions. Suitable equations for estimation of top heat loss coefficient have already been proposed [1,2]. The top heat loss coefficient is a function of wind induced convective heat transfer coefficient in a flat plate solar collector. It is, therefore, important to choose appropriate values of this convective heat transfer coefficient for correct estimation of the top heat loss coefficient. Researchers [3–6] have suggested different wind speed based correlations for estimation of the wind induced convective heat transfer coefficient. These correlations give different values of wind heat transfer coefficient thus resulting in variation in values of the top heat loss coefficient of a solar collector under same operating conditions. In present study, an attempt has been made to measure and study the wind induced convective heat transfer coefficient from exposed flat horizontal surfaces in real wind. For this purpose, three unglazed test plates of similar construction and different sizes were employed. Experiments were conducted on the three test plates over rooftop of a building in built environment. From experimental data of the test plate, of size 925mm × 865mm × 2mm, a correlation between wind heat transfer coefficient and wind speed has been obtained by linear regression. The obtained correlation has also been compared with work of other researchers [3–6]. Results obtained from experimental data of the three test plates provide some interesting information about wind induced convective heat transfer coefficient.

Natural Convection Heat Transfer Between Bodies and Their Spherical Enclosure

1983 ◽  
Vol 105 (3) ◽  
pp. 440-446 ◽  
Author(s):  
R. E. Powe ◽  
R. O. Warrington
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Convection Heat Transfer ◽  
Natural Convection Heat Transfer ◽  
Convection Heat ◽  
Average Deviation ◽  
Eccentric Cylinders ◽  
Different Shapes

The natural convective heat transfer phenomena which occur between a body and its spherical enclosure have been experimentally investigated. Bodies of several different shapes were employed, so the results should have broad applicability. New temperature field and heat transfer results, in the form of natural convection from cubical inner bodies to a spherical enclosure, have been combined with previously available enclosure data. By considering all of the data combined, trends in the behavior of the convective heat transfer phenomena have been established, thus enabling a much more reliable analysis of enclosed body problems than is now possible. A very general heat transfer correlation has been developed which predicts the natural convection heat transfer from spheres (concentric and eccentric), cylinders, and cubes to a spherical enclosure with an average deviation of less than 12 percent. Although these results are strictly valid only for a spherical outer body, they should give a preliminary indication of expected behavior for other shapes.

Experimental Study of Forced Convection Heat Transfer of Water in a Short Micro Duct at Turbulent Reynolds Number

2009 ◽  
Author(s):  
Iltesham Z. Syed ◽  
Abhijit Mukherjee
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Convective Heat Transfer Coefficient ◽  
Large Diameter ◽  
Convection Heat Transfer ◽  
Outer Wall ◽  
Turbulent Reynolds Number ◽  
Prandtl Numbers

The present study deals with experimental investigation of cooling of machining tools, by water flowing through a microduct at the tip of the tool. The microduct is of diameter of around 200μm and the flow takes place at turbulent Reynolds number. The outer wall temperature of microduct and the temperature of water at inlet and exit have been measured. The convective heat transfer coefficient is calculated at different wall temperatures and varying liquid mass flux. The experimental results shows that the average Nusselt numbers for the short micro-duct are higher than those predicted by conventional correlations for large diameter ducts. A correlation has been proposed to compute convective heat transfer during turbulent flow through a short microduct of a particular geometry for a range of Reynolds and Prandtl numbers.

Natural Convection Heat Transfer in Moderate Aspect Ratio Enclosures

1979 ◽  
Vol 101 (4) ◽  
pp. 655-659 ◽  
Author(s):  
B. A. Meyer ◽  
J. W. Mitchell ◽  
M. M. El-Wakil
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Rayleigh Number ◽  
Aspect Ratio ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Convection Heat Transfer ◽  
Natural Convection Heat Transfer ◽  
Convection Heat ◽  
Aspect Ratios

Local and average heat transfer coefficients for natural convection between parallel plates separated by slats to create enclosures of moderate aspect ratio have been experimentally determined using an interferometric technique. The effects of Rayleigh number, tilt and slat angle, and aspect ratio on the Nusselt number have been determined. The Rayleigh number range tested was up to 7 × 104, and the aspect ratio (ratio of enclosure length to plate spacing) varied between 0.25 and 4. The angles of tilt of the enclosure with respect to the horizontal were 45, 60 and 90 deg. Slat angles of 45, 60, 90 and 135 deg were studied. The results obtained in a previous investigation [1] for aspect ratios of 9 to 36 are included to show continuity. The results indicate that the convective heat transfer is a strong function of the aspect ratio for aspect ratios less than 4. For aspect ratios in the range of 0.5 to 4, spacers between the plates increase, rather than decrease, natural convection heat transfer compared to that for long enclosures. Slat angles less than 90 deg (i.e., oriented downward) reduce convective heat transfer.

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