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Cooling performance of tube X-COOLER shaped by MIM technology
Technical Paper: PIM International, Vol.2 No. 3 September 2008, pages 64-68, 2477 words
[1] FOTEC Forschungs- und Technologietransfer GmbH, Viktor Kaplan-Strasse 2, 2700 Wiener Neustadt, Austria
[2] Institute of Chemical Technologies and Analytics, Getreidemarkt 9/164, 1060 Wien, Austria
[3] Institute for Multidisciplinary Studies of the University of Belgrade, Kneza Viseslava 1a, 11000 Belgrade, Serbia
Abstract
An advanced X-COOLER was produced by MIM (metal injection moulding) technology as a regular array of thin Cu tubes on a carrier copper plate used as motherboard plate. This cooler was designed to serve as a CPU active and passive heat sink. Its thermal properties were measured and compared to those of Cu heat sinks produced by precision forging technology of copper and Al heat sinks produced by the cold forging technology of aluminium, with pins arranged in a similar matrix array. Measurements were done for input heat generated on a heater placed at the bottom side of the motherboard plate and conducted by two dissipation modes: natural air convection and forced air flow cooling by a CPU ventilator (axial fan). Ventilator RPMs and volume air flow or 'wind' velocities were varied through the input voltage and calibrated by an additional wind meter. Two variations of the fan-generated air flow in the cooler were tested, siphoning or upward and blowing or downward. Thermal resistance [Rth], thermal conductivity [ëeff] and the heat transfer value W/tT for all three cooler types were determined and compared. All results were normalised by the heat sink outer volume, active surface and material volume to show the advantage of the novel MIM shaped heat sink in the volume-specific thermal conductivity.] and the heat transfer value W/tT for all three cooler types were determined and compared. All results were normalised by the heat sink outer volume, active surface and material volume to show the advantage of the novel MIM shaped heat sink in the volume-specific thermal conductivity.
Introduction
A novel tube X-COOLER was realised as an array of thin Cu tubes arranged on the copper carrier plate using advanced MIM technology and custom Cu feedstock, as described in patent [1] and article [2]. A special, very complex multi injection point production tool was produced, which contains a programmable heater inside, to maintain a homogeneous feedstock temperature and ensure simultaneous solidification of the green sample in the tool. Debinding and sintering processes were also optimised to achieve high quality samples of maximum density, low tube deformation and low concentration of micro cracks. Fig. 1 shows the CPU heat sink shaped by MIM Cu (pure copper) with fan.
The tube X-COOLER produced by MIM is compared to two other types of coolers (similar in size, geometry and purpose). The coolers are given in Fig. 2: the MIM copper cooler is given in Fig. 2a, the aluminium cooler is given in Fig. 2b (produced by precision cold forging technology of aluminium), and the copper cooler in Fig. 2c (similar to the aluminium cooler and produced by precision cold forging technology of copper).
For better comparison, the Cu MIM cooler was machined to have a 40 x 40 mm basal plate by milling off one row of tubes. Thus, all the coolers have the same (external) dimensions but the design was different. The bearing faces of the heat sinks used for the measurements were polished down to a surface roughness of Rz < 4-6 ìm. The main properties of the coolers are given in Table 1.
In this work, the coolers were compared in different ways......
Further sections of this article include:
- Experimental field
- Results and Discussion
- Conclusion
- Acknowledgment
- References
Figures and Tables:Fig. 1 CPU heat sink shaped by MIM (pure copper) with fan: base plate area 50 x 50 mm2, height 30 mm, 96 'tubes' with wall thickness 0.3 mm Fig. 2 Heat sink selection Fig. 3 Schematic of heat transfer measuring device Fig. 4 Different cases of active cooling prepared for measurements a); b) Fig. 5 Fan Calibration Fig. 6 Thermal resistance for all three coolers as a function of the air flow velocity (blowing mode) Fig. 7 Volumetric thermal resistance for the all three coolers (blowing mode) Fig. 8 Air flow difference (velocity loss) between fan with and without cooler, respectively for the three coolers Fig. 9 Thermal conductivity of coolers vs. temperature (calculated from thermal diffusivity data) Table 1 The main properties of the coolers Table 2 Thermal resistance for natural convection Rth [K/W] Table 3 Thermal Resistance of the coolers for different operating modes of the fan Table 4 Comparison of the air flow loss to the fan air blowing velocity Table 5 Comparison of thermal properties of the coolers at ambient temperature (W/m K) |
__________________________________ Also available from PIM International: Micro-channelled heat exchanger manufactured by Ceramic Injection Moulding and co-firing (PDF Store) Metal and ceramic injection moulding: A guide for designers and end-users (Free feature) ______________________________________ |
