Natural Convection - Subsea Cooling: Theory, Simulations, Experiments and Design

2011 ◽  
Author(s):  
Brian R. Gyles ◽  
Bjarte Hægland ◽  
Tine Bauck Dahl ◽  
Arnaud Sanchis ◽  
Stig Grafsro̸nningen ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Test Facility ◽  
Design Parameters ◽  
Detailed Knowledge ◽  
Extensive Literature ◽  
Theoretical Studies ◽  
Testing Program ◽  
Special Geometry ◽  
Custom Made

In many future subsea projects, there will be a requirement to cool various fluid streams, either multi-phase or single phase. To meet this need, FMC Kongsberg Subsea AS (FMC) has undertaken a project to develop a practical and robust subsea cooler. The cooler is passive in that heat is transferred to the surrounding sea water by natural convection only. Because of the subsea application, the cooler must have a special geometry to meet requirements for modularization and easy installation/removal. The passive nature of the cooler means that the flow rate of the seawater coolant is not an independent variable, but is directly linked to the cooler geometry. Developing a design method for such coolers requires detailed knowledge of the important heat transfer parameters, to an accuracy far in excess of that normally required for industrial cooler design. This problem has been approached on several levels, including an extensive literature search, theoretical studies, and model testing. One of the first observations was that little research had been done previously on this type of cooler. Much information is available for various pieces of the problem, but it became clear that designing the cooler would require significant development work. Based on the knowledge gained during the initial theoretical studies, a theory for calculating cooler performance presuming one dimensional external coolant flow has been developed. While it is clear that the actual external flow is three-dimensional, the simplified theory gives important insights into how the various design parameters affect cooler performance. To fill in the gaps in theoretical knowledge, a series of model tests designed to quantify internal and external heat transfer coefficients for the special geometry is being proposed. The testing program covers several technical areas and has required the utilization of a number of advanced measurement techniques. For the next phase of the testing program, a complete new test facility has been constructed capable of testing coolers with cross-flows typical of ocean bottom currents. The cooler development program has provided new technology which will be used to construct robust and compact subsea coolers. Because of the emphasis on basic research, fundamental knowledge and insight of the heat transfer mechanisms governing the performance of this type of cooler are acquired. This knowledge gives FMC the capability to design and manufacture subsea coolers which are custom-made to match the exact requirements of a given application.

scholarly journals RESEARCH OF THE FUNCTIONING AND OPTIMIZATION PROCESS OF THE STRUCTURAL-TECHNOLOGICAL PARAMETERS

2020 ◽  
pp. 142-150
Author(s):  
Vitaliy Yaropud
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Flow Rate ◽  
Thermal Power ◽  
Design Parameters ◽  
Theoretical Studies ◽  
Technological Parameters ◽  
Air Flows ◽  
Counter Current ◽  
Pipe Heat

Domestic and foreign scientists in recent years have performed a considerable amount of scientific research on the biological justification of optimal combinations of microclimate parameters required for the normal development of animals. However, the results of the studies do not allow one to specify the optimal parameters for different species of animals, taking into account their age, sex, weight and level of feeding. While it is possible to specify rather wide limits of change of temperature and relative humidity of air at which productivity is maximum, and technical and economic efficiency is approximately the same. Providing microclimate regulations in livestock premises is associated with significant costs of electricity and heat, which is about 17% of the producers' costs. To create a microclimate in livestock premises based on the above technological parameters and the analysis of the design features of the recuperators, two design and technological schemes of the three-pipe recuperator, which differ in the directions of movement of air flows, are proposed. The purpose of the research is to increase the efficiency of the technological process of functioning of the three-pipe recuperator for livestock premises by substantiating its structural and mode parameters. The results of theoretical studies of pneumatic losses in the three-pipe recuperator determined the dependence of pressure and power losses on the length of the air duct of the three-pipe recuperator, the radius of the external duct and the volume flow rate of air. As a result of theoretical studies, a mathematical model of the heat transfer process in a three-pipe heat exchanger was developed, with condensation in it, which allows to determine the temperature distribution of air flows by its length and its thermal capacity. The results of theoretical studies of the process of heat transfer in the design and technological schemes of a three-pipe recirculator with counter-current and direct-current showed that the counter-current variant is more effective. Optimization of the results of theoretical studies allowed us to determine the dependence of the design parameters of the three-pipe heat exchanger on the volumetric flow rate of air, subject to the highest useful thermal power.

Internal Bearing Chamber Wall Heat Transfer as a Function of Operating Conditions and Chamber Geometry

1999 ◽  
Author(s):  
Stefan Busam ◽  
Axel Glahn ◽  
Sigmar Wittig
Keyword(s):  
Heat Transfer ◽  
Operating Conditions ◽  
Chamber Wall ◽  
Test Facility ◽  
Detailed Knowledge ◽  
Wall Heat Transfer ◽  
Transfer Coefficients ◽  
Two Phase ◽  
Dimensional Parameter ◽  
Secondary Air

Increasing efficiencies of modern aero-engines are accompanied by rising turbine inlet temperatures, pressure levels and rotational speeds. These operating conditions require a detailed knowledge of two-phase flow phenomena in secondary air and lubrication oil systems in order to predict correctly the heat transfer to the oil. It has been found in earlier investigations that especially at high rotational speeds the heat transfer rate within the bearing chambers is significantly increased with negative effects on the heat to oil management. Furthermore, operating conditions are reached where oil coking and oil fires are more likely to occur. Therefore, besides heat sources like bearing friction and churning, the heat transfer along the housing wall has to be considered in order to meet safety and reliability criteria. Based on our recent publications as well as new measurements of local and mean heat transfer coefficients, which were obtained at our test facility for engine relevant operating conditions, an equation for the internal bearing chamber wall heat transfer is proposed. Nusselt numbers are expressed as a function of non-dimensional parameter groups covering influences of chamber geometry, flow rates and shaft speed.

scholarly journals Experimental and Numerical Study of Heat Transfer Performance for an Engine Representative Two-Pass Rotating Internal Cooling Channel

2016 ◽  
Author(s):  
Zhi Wang ◽  
Roque Corral ◽  
Francois Chedevergne
Keyword(s):  
Heat Transfer ◽  
Aspect Ratio ◽  
Heat Transfer Performance ◽  
Numerical Results ◽  
Test Facility ◽  
Design Parameters ◽  
Internal Cooling ◽  
Surprising Result ◽  
Transfer Performance ◽  
Cooling Channel

This paper investigates, both experimentally and computationally, the heat transfer performance on an engine representative varying aspect ratio two-pass internal cooling channel, in both stationary and rotating conditions. The test geometry and design parameters were suggested by SNECMA as a representative HPT blade two-pass internal cooling channel. The cooling channel has radially outward flow in the first passage with an aspect ratio of 1:2.25 and after a 180 degree sharp turn, a radially inward flow in the second passage with an aspect ratio of 1:1.85. One side of the two passages is equipped with 45 degree angled rib turbulators with a rib spacing P/e=7 and blockage ratio e/Dh =0.116. The other side is smooth in order to have optical access for experiment. The experiment was performed at three Reynolds numbers: 15,000, 25,000, and 35,000. Both forward and backward rotating directions were tested in order to study the heat transfer performance of the ribbed surface as trailing wall or leading wall individually. The tested Rotation numbers were Ro=±0.3 at Re=15,000 and Re=25,000, whereas the Rotation number was reduced to ±0.22 at Re=35,000, due to restrictions of the test facility. Infrared thermography technology is used to capture the temperature field for further evaluation of heat transfer performance. Numerical simulations for all experimental cases were conducted using the same geometry including the air feeding system, applying the experimental wall temperature distribution in order to properly capture inlet and buoyancy effects, with the k–ω–SST turbulence model. Numerical results show overall agreement and similar trends than the experimental data. Numerical results also show that the rotation effects alter the internal flow significantly, resulting in different surface heat transfer distributions. Particularly, it is shown that heat transfer performance of the pressure side is not enhanced by the rotation in this study, which is a surprising result. This behavior was captured both in the experiments and the numerical predictions.

An Analysis of Natural Convection in Leading Edge Wing Compartments

2008 ◽  
Author(s):  
V. Egan ◽  
D. Moore ◽  
D. Newport ◽  
V. Lacarac ◽  
B. Estebe
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Convection Heat Transfer ◽  
Internal Heat ◽  
Leading Edge ◽  
Test Facility ◽  
Civil Aircraft ◽  
Aeronautical Industry ◽  
Building Ventilation ◽  
Good Agreement

Enclosure natural convection has applications in many engineering disciplines such as electronic component cooling, building ventilation and heating, and renewable energy systems such as solar collectors. To date there has been little research on its application in the aeronautical industry where it plays an important role in aircraft heat transfer. Standard civil aircraft comprise of a number of vented and non-vented compartments. One such compartment is the leading edge which houses the main aircraft bleed duct and several electronic devices. Natural convection heat transfer in the leading edge compartment is important during aircraft turn around while systems are running and the exterior of the aircraft is subjected to solar loading. The objective of this paper is to investigate the heat transfer in a leading edge. The effect of an internal heat generating source, a bleed duct, is also investigated. A dimensional analysis of the governing equations is carried out to determine the appropriate scaling groups for the natural convection cases and a numerical simulation is run on a commercial CFD package. The numerical results are compared with experimental measurements obtained from a leading edge test facility. The effect of bleed duct placement is also investigated both experimentally and numerically with good agreement achieved. It was found that bleed duct placement can have a significant effect on the overall temperature distribution within a leading edge compartment. The results provide a basis for the optimisation of natural convection in such aircraft wing compartments.

Internal Bearing Chamber Wall Heat Transfer as a Function of Operating Conditions and Chamber Geometry

2000 ◽  
Vol 122 (2) ◽  
pp. 314-320 ◽  
Author(s):  
Stefan Busam ◽  
Axel Glahn ◽  
Sigmar Wittig
Keyword(s):  
Heat Transfer ◽  
Operating Conditions ◽  
Chamber Wall ◽  
Test Facility ◽  
Detailed Knowledge ◽  
Wall Heat Transfer ◽  
Transfer Coefficients ◽  
Two Phase ◽  
Dimensional Parameter ◽  
Secondary Air

Increasing efficiencies of modern aero-engines are accompanied by rising turbine inlet temperatures, pressure levels and rotational speeds. These operating conditions require a detailed knowledge of two-phase flow phenomena in secondary air and lubrication oil systems in order to predict correctly the heat transfer to the oil. It has been found in earlier investigations that especially at high rotational speeds the heat transfer rate within the bearing chambers is significantly increased with negative effects on the heat to oil management. Furthermore, operating conditions are reached where oil coking and oil fires are more likely to occur. Therefore, besides heat sources like bearing friction and churning, the heat transfer along the housing wall has to be considered in order to meet safety and reliability criteria. Based on our recent publications as well as new measurements of local and mean heat transfer coefficients, which were obtained at our test facility for engine relevant operating conditions, an equation for the internal bearing chamber wall heat transfer is proposed. Nusselt numbers are expressed as a function of non-dimensional parameter groups covering influences of chamber geometry, flow rates and shaft speed. [S0742-4795(00)02202-X]

Experimental Studies of Natural Convection in Partitioned Enclosures With a Trombe Wall Geometry

1995 ◽  
Vol 117 (1) ◽  
pp. 16-21 ◽  
Author(s):  
R. O. Warrington ◽  
T. A. Ameel
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Experimental Studies ◽  
Heat Transfer Fluid ◽  
Test Facility ◽  
Fluid Temperature ◽  
Nusselt Numbers ◽  
Trombe Wall ◽  
Passive Solar ◽  
Wall Geometry

Natural convection heat transfer was investigated in a scaled test facility of a Trombe wall geometry. A silicone oil was employed as the convecting medium to obtain large Rayleigh numbers (up to 1.5 × 1010, based on enclosure height) characteristic of full-scale Trombe wall in a passive solar building. The main objectives were to study effects of Trombe wall nonisothermality and location on heat transfer, fluid temperature and fluid flow patterns. As expected, Nusselt numbers were slightly larger on the Trombe wall space side than on the living space side. Nusselt numbers increased slightly as the mass transfer gaps in the Trombe wall were increased. The results were verified, for the zero gap case, by comparing with previous studies. Physical understanding of the convection process was enhanced by flow visualization data. The information obtained should be useful to designers in optimizing overall building performance for passive solar heating.

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