GB2462098A

GB2462098A - Thermal management device comprising heat pipes

Info

Publication number: GB2462098A
Application number: GB0813487A
Authority: GB
Inventors: Ryan James Mcglen; James Robson; Kevin Victor Lynn
Original assignee: Individual
Current assignee: Individual
Priority date: 2008-07-23
Filing date: 2008-07-23
Publication date: 2010-01-27
Also published as: GB0813487D0

Abstract

A thermal management device comprises a fin stack 1, heat pipes 2, 3, and attachment means 7 to facilitate connection to electronic communication equipment, or other heat generating equipment. The thermal performance of the device is enhanced to ensure that the equipment will work at temperatures below 0°C. The fin design and geometry may be modified, by providing separating features 4 or incorporating separate fin stacks 5, to optimise the heat pipe performance at ambient temperatures below 0°C. Two types of heat pipes comprising conventional heat pipes 2, containing water, and alternative fluid heat pipes 3, containing a fluid that does not freeze below 0°C, may be attached between the fin stack and an evaporator block 6 connected to a heat source 8. Preferably, the heat created by the heat source is absorbed by the evaporator block and transferred to all the heat pipes such that the alternative fluid heat pipes maintain the temperature of the conventional heat pipes above 0°C to prevent freezing and enable continued operation.

Description

I

Variable Thermal Conductance Cooling_Device This invention relates to a device, the purpose of which is to prevent the thermal "run-away" of a piece of cooling apparatus by extending the operational range of water filled heat pipes at temperatures lower than 0°C.

Many electronic communication devices are increasingly deployed in an open environment where the effects of the local climate can be quite extreme. Even in these extreme conditions, the communication devices require the cooling apparatus to ensure that the associated electronic and electrical equipment within these devices continues to function within these environments and in particular, at temperatures below freezing.

If conventional cooling techniques and apparatus are used to provide the cooling for the electronic and electrical equipment, then at temperatures below freezing, the cooling apparatus will cease to function and the electronic and electrical equipment will be damaged. When using water as the working fluid, the removal of the two-phase heat transfer mechanism results in only heat transfer by conduction through the walls of the apparatus. This may cause electronic component temperatures to exceed their maximum temperature limits over a short period of time, resulting in failure or permanent damage. By integrating additional heat pipes into the apparatus containing a working fluid that operates below 0°C, the thermal operational range of the cooling apparatus can be significantly improved. As well as employing additional beat pipes with a different working fluid, the performance of the apparatus is further enhanced by careful design considerations of the fin area and geometry.

Conventional cooling techniques have a relatively narrow operational temperature range, but by employing this device, the operating range is significantly increased. The performance of conventional cooling apparatus reduces as the ambient temperature reduces. However, by using this device the performance at lower ambient temperatures is improved which will significantly enhance overall system performance. As the ambient temperature around a water filled heat pipe reduces, the power transporting capability of the heat pipe also reduces. The "nesting" of the alternative working fluid beat pipes along side the water filled heat pipes, increases the temperature of the water filled heat pipes and allows them to transport more power than they The nesting of heat pipes with the same working fluid (e.g. water) in regional boundaries, also benefits from this invention by raising the temperature locally around each heat pipe and ensuring a wider operational range.

The invention will now be described solely by way of examples and with reference to the accompanying drawings in which: Figure 1 Shows a the typical configuration of the heat pipes and fin stack utilising this device In figure 1, the fin stack 1 is attached directly to the conventional heat pipes 2 and the alternative fluid heat pipes 3. Integrated into the fin design are separating features 4, which divide the fin stack into sections, or separate fin stacks 5 can be incorporated into the main fin stack.

The heat pipes are formed to connect with the evaporator block 6, which in turn has mounting features for connection to the heat source. The heat created by heat source 8 is absorbed by the evaporator block and transferred to all heat pipes. Heat pipe 3 containing a working fluid that does not freeze below 0°C is positioned alongside the water filled heat pipe 2. The fin area around the heat pipe 2 and 3 is separated into regions by features incorporated into the fins.

When heat pipe 2 and 3 are nested together in one region, heat pipe 3 will maintain the temperature of the heat pipe 2 above 0°C and therefore these are allowed to continue to function below 0°C.

The slots or regionalisation slots are so configured to maintain the fin area resulting in the maximum cooling effect without loss of surface area.

The connection of fins to heat pipes can be made by various means which include mechanical, solder or adhesive. The fin geometry can be altered to improve all aspects of device performance in a range of diverse operating conditions.

Figure 2 Shows the device incorporated into a heat sink In figure 2, the heat pipes 1 and 2 are connected directly to the heat sink 4. The method of connection varies and can include, although not limited to; solder, adhesive or mechanical means. Regional separation is achieved by the slots 3 incorporated into the heat sink base 4. The slots provide the same function as that identified in figure 1.

Figure 3 Shows the device incorporated into a folded fin configuration In figure 3, the heat pipes 1 and 2 are connected directly to the folded fin structure. The method of connection varies and can include, although not limited to; solder, adhesive or mechanical means. Regional separation is achieved by the slots 3 incorporated into the folded fins 4. The slots provide the same function as that identified in figure 1.

Claims

Claims 1. A thermal management device comprising various attachment means to facilitate connection to electronic communication equipment or other heat generating equipment, enhanced device thermal performance to ensure that electronic equipment or heat generating equipment will work at temperatures below 0°C.
2. A thermal management device according to claim 1, in which the fin design and geometry is modified to optimise heat pipe performance ambient temperatures below 0°C.
3. A thermal management device according to claim 1, in which an integral heat collector will transfer the collected heat into the two types of heat pipe, thus ensuring the heat is removed from the heat source efficiently and quickly.
4. A thermal management device according to claim 1, which transfers heat via heat pipes of 2 different types, thus ensuring performance below ambient temperatures of 0°C when traditional cooling technologies would cease to function.
5. A thermal management device according to claim 1, that can elevate the temperature of selected heat pipes by configuring the fin area, should all heat pipes utilise the same
6. A thermal management device according to claim 1, which enables the fin area to be maintained for the folded and "c" fin geometries by careful design of the slots as spacer features.