PSI University Application Notes Page
Power Electronics are the most critical components in a large number of applications; including power generation and operational equipment. Power Electronics module manufacturers invest millions of dollars to make these devices as effcient as possible, aiming primarily to reduce waste heat. However, even with effciency gains at the module level, overall waste heat is rising across the industry due to more system and user driven functional requirements. Increased system capability leads to higher power densities and more waste heat! Selecting off the shelf thermal solutions is no longer a viable option for applications that are pushing the envelope on power and operating effciency.
Investing in an optimal thermal solution can be the design change with the largest payback potential in a high power system. If properly designed, the thermal management system should not only meet performance requirements, but do so while minimizing energy usage. This eBook provides a guide for designers looking to expand the operating limits of traditional air and liquid cooled thermal solutions.
All electronics dissipate waste heat. In typical high-power electronics cabinets this waste heat can become significant, in the range of 100’s to 1,000’s of Watts. At these levels dissipating the waste heat becomes a critical design issue. Most cabinets that operate in controlled indoor environments use fan filter systems, which duct ambient air through the cabinet, because they are the most eective and ecient way of dissipating the waste heat load. This is also feasible for some outdoor applications assuming rain guards and filters are used.
However, in many applications such as dirty / dusty environments, hose down / wash down facilities in the food industry, harsh outdoor applications, and many others it is not possible or advisable to allow ambient air to flow through and cool the sensitive and expensive components inside your enclosure. The best way to protect electronics is to use a sealed cabinet that does not allow any contaminated ambient air, even filtered air, from entering the cabinet. This is where sealed air-to-air heat exchangers, or sealed enclosure coolers, become an invaluable part of the overall system.
ADVANCED COOLING TECHNOLOGIES, INC. (ACT) HAS WORKED EXTENSIVELY ON HEAT PIPE PRODUCT RELIABILITY. This guide provides information for designing, modeling, and practical reliability surrounding copper/water heat pipes.
A heat pipe is a two phase heat transfer device with very high “effective” thermal conductivity. It is a vacuum tight device consisting of an envelope, a working fluid, and a wick structure. As shown below, the heat input vaporizes the liquid working fluid inside the wick in the evaporator section. The saturated vapor, carrying the latent heat of vaporization, flows towards the colder condenser section. In the condenser, the vapor condenses and gives up its latent heat. The condensed liquid returns to the evaporator through the wick structure by capillary action. The phase change processes and two phase flow circulation continue as long as the temperature gradient between the evaporator and condenser are maintained.