CLUSTER OF INCLINED STRUCTURES

Abstract

The present invention involves both the geometrical specification of a structure and positioning the structure in the cluster layout to achieve rapid heating/cooling as a medium transverses through them, and with little pressure drop penalty.

Description

FIELD OF THE INVENTION

The present invention involves both the geometrical specification of a structure and positioning of the structure in the cluster layout to achieve rapid heating/cooling as a medium transverses through them, with little pressure drop penalty.

BACKGROUND OF THE INVENTION

This invention builds upon prior art: PCT/SG2010/000169—An Enhanced Heat Sink, but encompasses a wider range of applications and configurations.

PCT/SG2010/000169 description: A heat sink device for dissipating heat from an electronic component mounted there to, the device comprising: an inlet for receiving a fluid; an outlet for venting said fluid; a heat dissipation zone intermediate the inlet and outlet; said zone including a plurality of transverse channels and a plurality of oblique channels extending between adjacent transverse channels; wherein said oblique and transverse channels define a fluid path for said fluid from the inlet to the outlet.

The prior art clearly states itself as a ‘heat sink device’. This invention is not limited to a ‘heat sink device’ and its purpose of heat dissipation. This invention includes any cluster of inclined objects arranged for the purpose of enhanced heat transfer or disruption of thermal or hydrodynamic boundary layers, such as battery cooling and wind distribution in a cluster of buildings.

The purpose of the prior art is the dissipation of heat from a secondary ‘electronic component’ mounted on the prior art invention. This invention is not limited to the case of heat dissipation from a secondary ‘electronic component’. The secondary component can be non-electronic in nature such as in the case of engine cooling. In some cases, the primary objective of heat transfer can be the inclined objects themselves, such as in the case of battery cooling presented in the summary of invention.

The prior art comprises of inlet and outlet vents. The invention does not limit itself to configurations and applications involving an inlet and outlet vent. Similarly, the invention includes cases, in which the cluster of inclined structures is not enclosed as otherwise depicted by the prior art.

The prior art makes claims for angles of inclinations from 20 to 45 degrees. This invention expands the angles of inclinations to 0 to 90 degrees.

The prior art only makes claims for flow within the transverse and/or oblique channels when Reynolds Number is less than 2300. This invention is not limited to any range of Reynolds Number.

The prior art only makes claims for structures with sharp edges. This invention also includes inclined structures with rounded edges.

SUMMARY OF THE INVENTION

The present invention involves both the geometrical specification of a structure and positioning of the structure in the cluster layout to achieve rapid heating/cooling as a medium transverses through them, and with little pressure drop penalty. The geometry of each structure and the positioning of each structure in the cluster is depicted in FIGS. 1 and 2.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of the inclined structures of the present invention arranged in a cluster.

FIG. 2 is a plan view of the cluster of the present invention showing fluid flow pattern.

FIG. 3 illustrates geometric parameters of the cluster of the present invention.

FIG. 4 illustrates inclined structures of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention involves both the geometrical specification of a structure and the positioning of the structure in the cluster layout to achieve rapid heating/cooling as a medium transverses through them, with little pressure drop penalty. The geometry of each structure and the positioning of each structure in the cluster is depicted in FIGS. 1 and 2.

As seen from FIG. 2, the fluid flow comprises two channel streams, namely the mainstream flow, which is parallel to the direction of mainstream flow, and diverted flow, which is diverted from the mainstream flow by an inclined slope of between 0 to 90 degrees. The diverted flows cause the boundary layers at the leading edge of each structure to be re-initialized, thus reducing boundary layer thickness. The re-initialization causes the mainstream flow to maintain a thermally developing state throughout the channel, resulting in better heat transfer. The diverted channels divert a small fraction of flow away from the main channel, thus improving fluid mixing. Improved fluid mixing further enhances heat transfer. In addition, a pressure recovery effect is also noticed in the diverted channel, which minimizes the pressure drop penalty for the increased heat transfer.

Compared with a conventional arrangement of prismatic structures, inclined structures and its arrangement in the aforementioned cluster layout have much higher heat transfer capacity between the structures and the cooling medium. This improved efficiency in heat transfer can be key enablers for the successful development of electric vehicles/hybrid-electric vehicles with or without fast charging capabilities. This is because the efficiency and life-cycle of batteries are dependant on their temperature. The cooling medium in this application includes but is not limited to natural airflow and induced-air flow by a fan. Other applications of this invention include the geometrical optimization and positioning of buildings, the walls of buildings or racks in data centers for improved airflow for cooling.

The enhancement in heat transfer in the present invention was verified through a benchmarking study conducted using computational fluid dynamics (CFD) analysis, for cases in which (1) normal prismatic structures and the instant invention—(2) inclined structures that are placed in a cluster of 4 by 4 in an enclosure. The volume of both the normal prismatic and inclined structures were kept the same for a fair comparison. However the inclined shape of the structure results in a 22.86% increase in total volume occuppied by the cluster. The detailed geometric parameters are listed in Table 1. FIG. 3 also shows the geometric parameters in the clusters. The air of temperature 20° C. flows into the enclosure with uniform velocity of 0.1068 m/s and exits at the other end with an environment pressure of 101325 Pa. A volumetric heat flux of 17771 W/m³ was supplied to each structure to give 40 W/structure and a thermal conductivity of 3.4 W/m²K and volumetric specific heat capacity of 12.17 J/m³K were applied to the structures.

TABLE 1
Geometric parameters of the structures
				Space	Space
				between	between
				Structure	Structure		Additional
	Structure	Structure	Structure	in x-	in y-	Inclined	Volume
Structure	Width	Length	Height	direction	direction	Angle	of Cluster
Shape	(mm)	(mm)	(mm)	(mm)	(mm)	(°)	(%)
Normal	80.5	116.5	240	8	6	—	—
Prismatic
Inclined	80.5	228	240	8	6	35.66	22.86

Table 2 shows the comparison of temperature data between the two cases: (1) normal prismatic structures and (2) inclined structures.

TABLE 2
Temperature and Pressure data of (1) Normal
Prismatic and (2) Inclined Structures
				Bulk	Pressure
	Minimum	Maximum	Temper-	Average	Drop
	Temper-	Temper-	ature	Temper-	across
Structure	ature	ature	Difference	ature	enclosure
Shape	(° C.)	(° C.)	(° C.)	(° C.)	(Pa)
Normal	32.02	79	46.98	64.88	15.9
Prismatic
Inclined	27.25	71.26	44.01	54.04	19.1

The inclined structures cluster has a Bulk Average Temperature of more than 10° C. lower than that of the normal prismatic structures cluster, and also displays a lower Maximum Temperature and Temperature Difference. This is at the expense of a 20% increase in pressure drop and a 22.86% of additional volume required. However, with a larger cluster, the additional volume will become a smaller proportion of total volume. Pressure drop proportion will also decrease due to the reduction in proportion of additional flow length.

Even though the value for the angle of inclination in this simulation is 35.66 degrees, the range of angles where there will be cooling benefits is between 0 to 90 degrees. This invention also covers varied designs of the structures. One variation of this invention is shown in FIG. 4, where the edges of the structures are rounded while the mainstream channels, diverted channels and inclined slopes of the structures are maintained.

Optimization of the incline angle depends on several factors—heat dissipation and pressure drop requirements, type of cooling medium, space required between the structures. We have however determined 35.66 degrees to be one of the optimal configurations for use of air as a fluid for the purpose of cooling battery cells.

The present invention contemplates the optimization of dimensions for the mainstream and diverted channels, dimensions for inclined structures, range of incline angle, flow velocity of cooling medium and dimensions of the whole cluster.

Claims

1. An array structure and its positioning in the cluster layout comprising one or more shape edges arranged to achieve rapid heating/cooling as a medium transverses through them, and with little pressure drop penalty.

2. The array structure according to claim 1, wherein said each shape edges are positioned at an angle to the transverse edge in the range 1° to 89°.

3. The array structure according to claim 1, wherein a cross-sectional area of any one of sloped gaps is less than a cross-section area of transverse gaps between which the sloped channel extends.

4. The array structure according to claim 1, wherein elements of a heat dissipation zone separating one or more channels are heat dissipation sources.

5. The array structure according to claim 1, wherein sloped gaps are uniformly spaced from each other within a heat dissipation zone.

6. The array structure of claim 1 capable of use as a heat sink device, wherein oblique channels are uniformly spaced from each other within a heat dissipation zone.

7. The array structure of claim 1 capable of use as a heat sink device, further comprising at least one heat concentration zone within a heat dissipation zone, such that spacing of oblique channels within the at least one heat concentration zone is less than the spacing of the oblique channels within a remaining portion of the heat dissipation zone.

8. The array structure of claim 1 capable of use as a heat sink device, further comprising at least one heat concentration zone within the heat dissipation zone, such that spacing of transverse channels within the at least one heat concentration zone is less than the spacing of the transverse channels within a remaining portion of the heat dissipation zone.

9. The array structure of claim 8 capable of use as a heat sink device, further comprising a plurality of heat concentration zones within the heat dissipation zone.