THERMAL MANAGEMENT


In-house thermal management


ccurate real-world measurement of airfl ow and enclosure impedance is essential when designing forced-air cooling systems in equipment racks and enclosure. Engineers use the consolidated data they collect to calculate the amount of thermal energy generated by the electrical and electronics components in the equipment when it’s operating and use the data to reduce cooling over-design, minimise noise levels and generally help determine the best fan(s) for the application. After adjusting for external factors such as solar gain and the cooling effects of natural convection, and accounting for ambient temperate versus target operating temperature, engineers are able to determine the amount of heat that forced airfl ow ventilation in the equipment will need to dissipate, and build-in the required safety margin.


Selecting the ideal fan(s) and deciding on their positioning and arrangement in the enclosure is more complex: Computational fl uid dynamics (CFD) is used to model the enclosure and its internal components for their resistance to air fl ow, and the impedance curve of the enclosure is plotted. Complex as it can be, CFD modelling on its own will still only provide a theoretical result. A real-world result can only be determined by a physical airfl ow/impedance test. The usual approach is for engineers to apply a mixture of theoretical impedance calculation and estimations, usually arriving at a result with a strong incentive to ere on the side of caution. Accordingly, engineers often over design the cooling system and opt to try out fans simply because they mechanically fi t the enclosure and deliver the airfl ow needed. This approach is not ideal: It can be time consuming and does not always deliver the optimum noise, energy effi ciency and vibration result.


Physical airfl ow/impedance testing The engineer can always turn to external testing laboratories for help in selecting the optimal cooling architecture, but it


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optimisation of racks and enclosures


By Tim Coxhill, business development manager, EAO A


Figure 1 - Example of fan tester and equipment setup


may be costly, and its rarely convenient to setup and transport equipment to an independent lab with the skills and facilities needed to carry out the tests. Further, once out of the manufacturing facility it can be diffi cult to make design tweaks or fan changes to determine the optimal fan performance during testing. The alternative and much more convenient approach is to bring a portable airfl ow tester and the target enclosure together in the customer’s own lab. Using the Sanyo Denki DCAT (dual chamber air tester) EAO engineers are quickly able to determine the system impedance (resistance to airfl ow), the operating airfl ow (the actual airfl ow when the cooling the fan is mounted) and the airfl ow versus static pressure (P-Q) performance of a target populated enclosure and download the plotted results in a simple Excel graphical form. They are able to quickly determine the impedance of the customer’s enclosure and measure the real-world airfl ow that the chosen fan(s) fi tted within it is/are producing. The P-Q curves of fans from other manufacturers may also be easily digitised and overlaid onto any graph for comparison purposes.


FEBRUARY 2026 | ELECTRONICS FOR ENGINEERS


Before arriving on-site, the EAO team will need a drawing of the equipment to be tested detailing the size of the vents and their position so they can determine how best to attach the DCAT to the enclosure. Once an airtight linkage duct has been created - think rigid foamboard with manual cut-outs and gaffer tape to securely seal any gaps! - the testing starts using the fan model(s) and/or fan layout confi gurations prepared for the test.


Post test analysis and identifying the Optimum fan.


Once the tests have been performed, the EAO team uses the company’s proprietary Cooling Architecture Software (CAS) that contains digitised P-Q curves for the Sanyo Denki family of dual ball-bearing fans, together with integrated data analysis and simulation algorithms. The dataset in the CAS includes data for blower fans from 52mm to 160mm sizes, for axial fans from 38mm to 200mm, for high static pressure counter rotating fans from 38mm to 172mm, and for centrifugal fans from 70mm to 270mm. For rugged application the CAS also includes data on Sanyo Denki family of ‘endurance’


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