Investigation and Optimization of Wavy Channel Liquid Cooler for Power Electronics
Authors
Rasmussen, Niels Christian ; Joensen, Simon
Term
4. term
Education
Publication year
2026
Submitted on
2026-05-27
Pages
98
Abstract
As power electronics pack more power into smaller spaces, getting heat out becomes critical. Liquid cooling with wavy fins is a versatile approach that can transfer more heat than straight fins, but it is still mostly confined to laboratory studies. This thesis examines wavy-fin water blocks at the system level, including how the electronics are mounted, the inlet and outlet flow conditions, and thermal interface resistances. The aim is to use a thermal–hydraulic trade-off to identify promising fin design parameters. We combined laboratory measurements with CFD (computer simulations of fluid flow and heat transfer) to validate a model, then improved the inlet manifold. We investigated how flow rate affects performance for one fin geometry across channel Reynolds numbers from 600 to 10,000 (a dimensionless measure of flow regime). Using a selected operating point, we varied fin width and the number of waves per fin to build a Pareto front—a curve that shows the best trade-offs between cooling and pumping power (the thermal–hydraulic trade-off). Results show that this trade-off is effective for selecting an optimal flow rate for a given fin structure. For the geometry studied, a Reynolds number of about 2300 provided strong heat transfer while keeping pumping power relatively low. Designs with a high fin-width-to-channel-width ratio performed well, and a moderate number of waves per fin gave the best overall performance; too few waves reduced heat transfer, whereas too many greatly increased pressure losses. Overall, the thermal–hydraulic trade-off is a practical tool for choosing water-block designs and operating conditions that minimize pumping power for a given heat load. This work lays the groundwork for more comprehensive studies of fin optimization and flow behavior in liquid-cooled power electronic systems.
Når effektelektronik bliver mere kompakt og effektiv, bliver effektiv varmehåndtering afgørende. Væskekøling med bølgede ribber er en lovende metode, der kan flytte mere varme end traditionelle lige ribber, men bruges stadig mest i laboratoriet. Denne afhandling undersøger bølgede ribbestrukturer på systemniveau, inklusive integration med elektronikken, indløbs- og udløbsforhold samt termiske grænseflademodstande. Målet er at bruge en termisk–hydraulisk afvejning til at pege på optimale ribbeparametre. Vi kombinerede eksperimenter med CFD (computersimuleringer af strømning og varme) for at sikre, at modellen fanger den relevante fysik, og forbedrede derefter indløbsmanifolden. Vi undersøgte, hvordan flowhastigheden påvirker ydelsen for en given ribbegeometri over et Reynolds-tal-interval på 600–10.000 (et dimensionsløst mål for strømningen). Med et valgt driftspunkt varierede vi ribbebredde og antal bølger pr. ribbe og opstillede en Pareto-front—en kurve, der viser de bedste kompromiser mellem køleeffekt og pumpearbejde (den termisk–hydrauliske afvejning). Resultaterne viser, at denne afvejning er effektiv til at finde en optimal flowhastighed for en given ribbestruktur. For den undersøgte geometri gav et Reynolds-tal omkring 2300 høj varmeoverførsel med relativt lav pumpeeffekt. Geometrier med et højt forhold mellem ribbebredde og kanalbredde var fordelagtige, og et moderat antal bølger pr. ribbe gav den bedste samlede ydelse; for få bølger reducerede varmeoverførslen, mens for mange bølger øgede tryktabene markant. Samlet set er den termisk–hydrauliske afvejning et nyttigt værktøj til at vælge vandblokdesign og driftsbetingelser, der minimerer pumpeeffekt for en given varmeafledning. Arbejdet lægger grunden for mere omfattende studier af ribbeoptimering og strømningsadfærd i væskekølede effektelektroniske systemer.
[This apstract has been rewritten with the help of AI based on the project's original abstract]
Keywords