An experimental and numerical investigation of mixed convection from a heat generating element in a ventilated cavity

Radhakrishnan, T. V.; Verma, Ajeet Kumar; Balaji, C.; Venkateshan, S. P.

doi:10.1016/j.expthermflusci.2007.06.001

Cited by 58 publications

(13 citation statements)

References 16 publications

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“…Radhakrishnan et al (2007) reported a study on an experimental and numerical investigation of mixed convection from a vertical heat generating plate in a ventilation cavity. It was shown that the flow was not uniformly distributed in the room.…”

Section: List Of Symbolsmentioning

confidence: 99%

Simulation and performance enhancement of the air cooling system in the valve halls of a DC/AC power converter station

et al. 2010

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The present article reports on a ventilation system that uses impinging air jets to remove a portion of the heat generated in DC/AC converter towers. Each tower is a vertical stack of electronic components used in the power conversion. Airflow from the ventilation system enters the room through inlet ports located on the ground at two opposite sides of the DC/AC converter towers. The existing ventilation system circulates sufficient airflow in terms of the total heating load; however, elevated temperatures were reported within the towers due to poor air circulation. A numerical study has been conducted to investigate steady three-dimensional (3-D) turbulent mixed (combined free and forced) convection air cooling of vertical stacks of heat-generating blocks simulating typical towers in two valve halls of a DC/AC power converter station. The simulation results include the magnitudes of the net airflows for all the inter-block gaps, the maximum temperature in each gap, and the flow structure represented by streamlines at various locations of the 3-D domain. The location of the inlet, the inlet size and aspect ratio, and the location on the tower at which the airflow was aimed were varied parametrically to improve the ventilation relative to the existing design. These results demonstrate that, for fixed inlet mass flow rate, all the towers' heat generating surfaces can be kept under 60°C via simple modifications of the variables used in the parametric study.

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Section: List Of Symbolsmentioning

confidence: 99%

Simulation and performance enhancement of the air cooling system in the valve halls of a DC/AC power converter station

et al. 2010

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“…All the tested correlations available in the literature have proven to be unsuitable. The objective of this research is to obtain reliable and accurate models to calculate the heat transfer coefficient needed for the further design of the optimal cooling system of a hightemperature PEMFC stack that will be incorporated to the powerplant of a light UAV capable of reaching an altitude of 10,000 m. To this end, the energy supply technique [12,13] has been applied in experiments performed in two rectangular tunnels, for three different form factors, in conditions similar to those expected for the HT-PEMFC stack. For calculations, convective and radiative processes are considered.…”

Section: Latin Alphabetmentioning

confidence: 99%

“…However, the already discussed lack of models to accurately describe the heat transfer coefficient for the practical case studied in the present research, has forced to obtain the relation in Eq. (12), from a set of experiments specifically designed.…”

Section: Heat Transfer Analysis: Non-dimensional Considerationsmentioning

confidence: 99%

“…An example of this method is the determination of the surface temperature analyzing the emitted radiation intensity and wavelength using infrared cameras [10,11]. A direct heat transfer measurement method is the energy supply technique, in which the temperature of a solid surface is measured while actively providing heat [12,13]. Other methods for the direct measurement of the heat transfer coefficient are the use of thin film heat flux sensors [14e16] or the one based on naphthalene sublimation that has been used to measure the convective heat transfer coefficient on the horizontal roof of a real building [17].…”

Section: Introductionmentioning

confidence: 99%

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Experimental determination of the heat transfer coefficient for the optimal design of the cooling system of a PEM fuel cell placed inside the fuselage of an UAV

Barroso

Renau

Lozano

et al. 2015

Applied Thermal Engineering

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h i g h l i g h t sHeat transfer coefficients to refrigerate a HT-PEMFC stack are calculated. Experiments are performed in 2 wind tunnels, for 3 form factors and real conditions. The calculated heat transfer coefficient varies from 8 to 44 W m À2 K À1 . Results at sea level are suitably extrapolated for a target altitude of 10 km. Flow area is optimized as a function of the power required to cool the stack down. a b s t r a c tThe objective of this research is to calculate the heat transfer coefficients needed for the further design of the optimal cooling system of a high-temperature polymer electrolyte membrane fuel cell (HT-PEMFC) stack that will be incorporated to the powerplant of a light unmanned aerial vehicle (UAV) capable of reaching an altitude of 10,000 m. Experiments are performed in two rectangular tunnels, for three different form factors, in experimental conditions as close as possible to the actual ones in the HT-PEMFC stack. For the calculations, all the relevant thermal processes are considered (i.e., convection and radiation). Different parameters are measured, such as air mass flow rate, inlet and outlet air temperatures, and wall temperatures for bipolar plates and endplates. Different numerical models are fitted revealing the influence of the diverse relevant non-dimensional groups on the Nusselt number. Heat transfer coefficients calculated for the air cooling flow vary from 8 to 44 W m À2 K À1 . Results obtained at sea level are extrapolated for a flight ceiling of 10 km. The flow section is optimized as a function of the power required to cool the stack down to the temperature recommended by the membrane-electrode assembly (MEA) manufacturer using a numerical code specifically developed for this purpose.

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“…Oztop et al (2011) numerically examined the steady natural convection in an open cavity filled with porous media. Radhakrishnan et al (2007) reported experimental and numerical investigation of mixed convection from a heat generating element in a ventilated cavity. Zhao et al (2011) analyzed the characteristics of transition from laminar to chaotic mixed convection in a two-dimensional multiple ventilated cavity.…”

Section: Introductionmentioning

confidence: 99%

Numerical Study of the Cross Flow in a Non-isothermal Open Cavity

Ovando-Chacon

Ovando-Chacón

Prince-Avelino

et al. 2016

Recent Advances in Fluid Dynamics With Environmental Applications

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In the present work, the laminar steady state fluid dynamics and heat transfer, in a two-dimensional open cavity with a cross flow due to a secondary jet injected at the top wall, are analyzed. The numerical study is carried out for a Reynolds number of 500 with different Richardson and Prandtl numbers. A hot plate is provided on the bottom of the cavity which generates the heating of the fluid. In order to investigate the effect of the length of the plate two different plate sizes are considered. The governing equations of continuity, momentum and energy for incompressible flow are solved by the finite element method combined with the splitting operator scheme. It is studied the streamlines and isotherms inside the cavity and it is analyzed the average Nusselt number, the average temperature and the outlet temperature as a function of the Richardson and Prandtl numbers. It is observed that the Prandtl and Richardson numbers play a major role in the thermal and fluid behavior of the flow inside the cavity with a cross flow. Moreover the results indicate that a secondary jet injected at the top wall enhances the average Nusselt number.

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An experimental and numerical investigation of mixed convection from a heat generating element in a ventilated cavity

Cited by 58 publications

References 16 publications

Simulation and performance enhancement of the air cooling system in the valve halls of a DC/AC power converter station

Simulation and performance enhancement of the air cooling system in the valve halls of a DC/AC power converter station

Experimental determination of the heat transfer coefficient for the optimal design of the cooling system of a PEM fuel cell placed inside the fuselage of an UAV

Numerical Study of the Cross Flow in a Non-isothermal Open Cavity

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