Showing papers on "Fin (extended surface) published in 1996"

Combined natural convection-conduction and radiation heat transfer in a discretely heated open cavity

Abstract: Combined natural convection, conduction, and radiation heat transfer in an open-top upright cavity containing a discrete heat source has been modeled numerically. The surface emissivity has been varied and its effects on the flow and thermal fields have been determined for different values of Rayleigh number. The complex interaction of the three modes of heat transfer mechanisms is explored by solving the coupled convection, conduction, and radiation equations. It is noted that the inclusion of radiation has a significant effect on the flow, resulting in the formation of a recirculation zone within the cavity. Comparison of the local heat transfer coefficients for the conjugate analysis and no radiation case reveals that the inclusion of radiation has a negligible effect on the heat transfer performance of the heat source. However, comparison of the numerical results with experimental observations shows that accurate prediction of the flow and thermal fields is strongly dependent on the consideration of radiation heat transfer in the numerical case.

Heat transfer and friction correlations for wavy plate fin-and-tube heat exchangers

Abstract: This paper deals with heat exchangers having plate fins of herringbone wave configuration. Correlations are developed to predict the air-side heat transfer coefficient and friction factor as a function of flow conditions and geometric variables of the heat exchanger. Correlations are provided for both staggered and in-line arrays of circular tubes. A multiple regression technique was used to correlate 41 wavy fin geometries by Beecher and Fagan (1987), Wang et al. (1995) and Beecher (1968). For the staggered layout, 92% of the heat transfer data are correlated within {+-}10%, and 91% of the friction data are correlated within {+-}15%.

Semiconductor device and semiconductor module

Abstract: It is an object to downsize a device while maintaining a high breakdown voltage. An external terminal (7) protrudes to the outside from the side wall of a sealing resin (2) and a heat sink (1) is exposed in the bottom of the sealing resin (2). A step surface (21) retracted from the exposed surface of the heat sink (1) is formed in the part of the sealing resin (2) surrounding the periphery of the heat sink (1). When using this semiconductor device, the exposed surface of the heat sink (1) is brought into surface contact with the flat surface (41a) of the radiation fin (41) and an insulation sheet (31) is interposed between the step surface (21) and the flat surface (41a), and which is pressed therebetween. The insulation sheet (31) is disposed to cover the region facing the external terminal (7) in the flat surface (41a). Accordingly, it is possible to set the height of the external terminal (7) from the exposed surface of the heat sink (1) lower than the spatial distance determined on the basis of the rated voltage while keeping the breakdown voltage between the external terminal (7) and the radiation fin (41) as the rated voltage.

Heat sink device having radial heat and airflow paths

Abstract: A heat sink device is disclosed which provides a large surface area in order to facilitate heat transfer into the surrounding air and which also allows cooling air to impinge directly upon the integrated circuit device being cooled. The heat sink device is constructed having a relatively large central region which is adapted to contact the integrated circuit device. This large central region facilitates conduction of heat from the integrated circuit device into the heat sink device. Extending outwardly from the central region are a plurality of cooling fins which facilitate the conduction of heat out of the central region and which provide a large surface area to enhance heat transfer into the surrounding air.

Egr gas cooler

Abstract: PROBLEM TO BE SOLVED: To provide an exhaust gas recirculating(EGR) gas cooler using a heat conductive pipe where the cause of the bad conditions of an engine is removed beforehand by providing a projection within the heat conductive face, and increasing the disorder of the flow thereby raising the heat conductivity. SOLUTION: This is an EGR gas cooler where a group of heat conductive pipes consisting of plural pipes are fixed and arranged at a tube sheet 3, and the pipes are set and supported in the through holes of a supporting plate 5 whose periphery is fixed at plural places to the inwall of a drum pipe 1, and end caps which have an inflow port 8 and an outflow port 9 for EGR gas are fixed to outside of both ends of the drum pipe, and the drum pipe of which is provided with cooling medium inflow and outflow ports, and the heat conductive pipe has at least one spiral rib within, and this rib is processed from outside of the heat conductive pipe, and further a plate-shaped fin made of a band- shaped plate or a corrugated plate is inserted into the heat conductive pipe to touch internally the rib, or the plate-shaped fin is made, being twisted in the opposite direction to the spiral direction of at least one spiral rib of the heat conductive pipe. COPYRIGHT: (C)1999,JPO

Cold plate having uniform pressure drop and uniform flow rate

Abstract: A system for cooling electronic components includes a cold plate having a channel through which a fluid coolant is transported, a plurality of bosses each receiving an electronic, optical, or other heat-generating component, and a plurality of fin structures, at least three of which are adjacently disposed in a sequential order on the cold plate. Each fin structure contacts a boss, and has a fin inlet and a fin outlet in fluid communication with a section of the channel for supplying the area around the boss with coolant and cooling the component seated on the boss. A portion of the channel defines a serpentine path for transporting the fluid coolant to the at least three sequential fin structures in a non-sequential order. Sections of the channel in the serpentine path further transport the coolant in opposite directions, thus enhancing heat transfer and temperature equilibration across the cold plate. The system can further include a plurality of such cooling plates disposed in a vertical stack, and a manifold delivering coolant to the cooling plates. When the cooling plates are stacked, the flow rate and pressure drop across each plate is substantially uniform, thus providing a cold plate having a substantially isothermal surface across a portion of the cold plate.

Honeycomb sandwich panel with built in heat pipes

Abstract: A sandwiched honeycomb panel with built in heat pipes includes a radiating fin which is integral with an envelope having a heat pipe formed therein. A heat block may be used in place of the radiating fin.

Heat dissipation apparatus and method

Abstract: A heat dissipation apparatus (51) has a lid (12) and an optimized fin arrangement (16) located in a cavity (57) of a base (11). Semiconductor chips (41, 42, 43, 44, 45, and 46) are coupled to the lid (12), and a heat conducting medium (47) is forced into the cavity (57) through a port (13) and out of the cavity (57) through a different port (14). Heat generated by the semiconductor chips (41, 42, 43, 44, 45, and 46) is thermally conducted into the fin arrangement (16) and then transferred into the heat conducting medium (47).

Thermal Performance Reduction in Air-Cooled Heat Exchangers Due to Nonuniform Flow and Temperature Distributions

Abstract: The effect of nonuniform (or maldistributed) inlet airflow and temperature on the thermal performance of cross-flow air-cooled heat exchangers, with both fluids unmixed, and taking into consideration differences in performance characteristics of individual tube rows, is addressed in this article. The latter may be due to different fin pitches or other geometric variations or row effects due to changes in air turbulence. Downstream tube rows in such a multirow tube bundle experience higher performance reductions than the tube row at the air inlet. A nonuniform air velocity distribution to a tube row leaves the row with a distorted temperature profile. This temperature nonuniformity increases as the air passes through subsequent tube rows, and causes the downstream rows to be progressively less effective. The present analysis is used to evaluate the performance of the individual tube rows and ultimately the entire bundle. Velocity distributions which have been measured on air-cooled heat exchanger models ar...

Heat transfer and friction characteristics of convex-louver fin-and-tube heat exchangers

Abstract: Experiments were carried out to study the heat transfer and pressure drop characteristics of convex-louver fin-and-tube heat exchangers. In all, 12 samples of heat exchangers, including nine convex-louver, a wavy fin, a louver-fin, and a plate-fin configuration were tested and compared in the present investigation. The effects of row number and fin pitch on the thermal-hydraulic characteristics of the convex-louver were also investigated. Results are presented as plots of Fanning friction factor f and Colburn j factor against Reynolds number based on tube collar diameters in the range of 400 to 8,000. The data were also compared to the louver, wavy, and plain fin geometries. It was found that the number of rows has a small effect on the Colburn j factor only at Reynolds numbers less than 1,000. Also, it is shown that the row effect on the friction factors is negligible.

Numerical and experimental evaluation of planar and staggered heat sinks

Abstract: The performance of an air-cooled planar and staggered bonded heat sink is evaluated using both experimental and numerical approaches. The performance is evaluated for three power settings of 100, 150, and 200 W and for three approach velocities at 200, 400, and 600 ft/min. The comparison of the measurements and predictions shows good agreement, indicating that computational methods of the type employed in this work are a cost effective means of designing and evaluating high-performance heat sinks. The results demonstrate that the thermal performance of the staggered fin configuration is superior over the planar fin configuration by approximately 8% over the power and flow ranges examined herein. This enhanced thermal performance, however, was realized at the expense of an additional pressure drop of 10 to 20%.

Fin strip and heat exchanger construction

Abstract: A corrugated fin strip for heat exchanger tubes has interfacing parallelogram shaped fin panels joined by successive parallel crests, all fin panels having the same parallelogram shape selected in accordance with a desired configuration of the heat exchanger In one embodiment, these parallel crests extend obliquely between the longitudinal edges of a rectilinear metal strip from which the fin strip is formed, and are adapted to be alternatively attached to the flat face of a heat exchanger tube in oblique relation to parallel sides of the tube, thereby defining an air flow direction oblique to the length thereof In a second embodiment, the successive parallel crests extend perpendicularly to the opposite edges of the rectilinear metal strip, are displaced alternately therefrom by a selected distance, and are adapted to be attached alternately to the opposed flat faces of a pair of longitudinally parallel heat exchanger tubes, thereby displacing one tube transversely from the other The fin strip of either embodiment is adapted to be wound in a helix around a cylindrical heat exchanger tube with alternate parallel crests attached to the tube in axial alignment therewith and with each other

System having stackable heat sink structures

Abstract: Electronic systems utilizing a plurality of integrated circuit packages having a stackable heat sink assembly is formed by press-fit assembly of two or more identical fin layers. Each fin layer is formed using powdered metallurgy and has a button-like projection extending from its bottom surface and a recess opening in its top surface. The button-like projection and recess opening are sized and shaped such that an interference fit is formed when the buttonlike projection of one fin layer is pressed into the recess of another fin layer. The use of an adaptor to increase or decrease the effective size of the button-like projection of the bottom-most fin layer is described. Relieving gases that may be entrapped in the recess during assembly is described. Circular, elliptical and polygonal shapes (outlines) for the fin layers are described.

Aluminum fin material for heat exchanger

Abstract: PURPOSE: To provide an aluminum fin material for a heat exchanger which is excellent in affinity to water (hydrophilic sustainance), anticorrosiveness (especially alkali resistance) and machinability. CONSTITUTION: An anticorrosive film is formed on the surface of an aluminum or aluminum alloy sheet and an anticorrosive hydrophilizing coating layer which is obtained by applying and drying a primer treating agent containing polyvinyl pyrolidone, a crosslinking agent and hardening promoter on an upper layer of the film to make an aluminum fin material for a heat exchanger. COPYRIGHT: (C)1996,JPO

Contact resistance in air-cooled plate fin-tube air-conditioning condensers

Abstract: Test equipment and procedures have been developed to measure the heat transfer performance of an industry-standard wavy plate fin-tube condenser, and to compare it with alternative designs. Two test rigs were employed: one used direct electric heating, and the other used an R22 thermosyphon. Analysis revealed that the standard production heat exchanger suffered from excessive fin-tube resistance. This was confirmed by sectioning and microscopic examination. Seven different designs were compared at the same Reynolds number. The results were analysed to isolate the air-side heat transfer coefficient.

Heat sink assembly for an integrated circuit

Abstract: A heat sink assembly for an integrated circuit comprises a base plate defining a central opening and an integrated circuit receiving slot, a fin plate defining a downwardly extending protrusion, a fan fixedly mounted on a top of the fin, and screws for connecting the fin plate and the base plate together whereby the downwardly extending protrusion of the fin plate is extended through the opening of the base plate.

Single-Phase and Boiling Cooling of Small Pin Fin Arrays by Multiple Nozzle Jet Impingement

Abstract: Experimental measurements of multiple nozzle submerged jet array impingement single-phase and boiling heat transfer were made using FC-72 and 1 cm square copper pin fin arrays, having equal width and spacing of 0.1 and 0.2 mm, with aspect ratios from 1 to 5. Arrays of 25 and 100 nozzles were used, with diameters of 0.25 to 1.0 mm providing nozzle area from 5 to 20 mm2 (5 to 20% of the heat source base area). Flow rates of 2.5 to 10 cm3 /s (0.15 to 0.6 l/min) were studied, with nozzle velocities from 0.125 to 2 m/s. Single nozzles and smooth surfaces were also evaluated for comparison. Single-phase heat transfer coefficients (based on planform area) from 2.4 to 49.3 kW/m2 K were measured, while critical heat flux varied from 45 to 395 W/cm2 . Correlations of the single-phase heat transfer coefficient and critical heat flux as functions of pin fin dimensions, number of nozzles, nozzle area and liquid flow rate are provided.

Stacked fin heat sink construction and method of manufacturing the same

Abstract: A heat sink is constructed from a plurality of fin elements each of which has upper and lower heat dissipating surfaces The upper surface is provided with a centrally located nesting recess while the lower surface is provided with a centrally located nesting shoulder which is complementary in shape to the recess The fin elements are assembled in interfitting stacked relation such that the nesting shoulder of one fin element is received in nested relation within the recess of an adjacent fin element and further assembled such that the outer side and bottom walls of the shoulder are in intimate facing thermal contact with the inner side and bottom walls of the recess The side walls of the shoulder and recess of consecutively nested fin elements are consecutively longer in length, ie the recess is deeper and shoulder higher, so that the heat dissipating surfaces of the adjacent fin elements are maintained in spaced relation The nesting formations of the fin elements are preferably formed by stamping the center portion of the fin elements to produce a recess on the stamped side while also forming the complementary shoulder on the opposing side During assembly of the various fin elements, the nested formations are bonded together using a bonding technique appropriate to the particular metal used for the fin elements The heat dissipating surfaces of the fin elements are also preferably provided with embossed surface formations to increase the effective heat dissipating surface area of the fin elements