Ph.d.-forsvar Gennaro Criscuolo

Two-phase cooling of power electronics - An investigation on flow boiling of refrigerants in narrow channels

The operation of many electronic devices relies on the thermal management system that dissipates heat generation. With the continuous advancement of components, miniaturization, and the increasing need for energy-efficient solutions, novel thermal management approaches will be necessary for many fields. In this context, cooling electronics by refrigerant flow boiling, i.e. boiling a refrigerant that flows in small-scale channels, is one of the most promising solutions. The Ph.D. thesis presents an experimental investigation on the heat transfer characteristics of small-scale heat sinks for the cooling of power electronics. In particular, the study was oriented to the cooling of electronics in electric vehicles. The heat sinks comprised channels with a width of 200 µm and 300 µm, micro-milled over a footprint area of 1 cm2. The effect of the operating conditions on the thermal performance and the heat transfer mechanisms was studied by investigating a broad set of experimental conditions. Flow visualization was adopted to clarify the relationship with the two-phase flow characteristics. The thermal performance was analyzed by considering the channel heat transfer coefficients, critical heat fluxes, and the overall cooling performance. For a limit temperature of 165 °C, the investigation showed that the heat sinks could dissipate footprint heat fluxes well above what electric vehicles need. The Ph.D. thesis analyses and discusses several aspects related to the heat transfer performance of the heat sinks, primarily dependent on the heat dissipation and secondarily on the operating mass flow rate. The role of the geometric parameters and fluid on the cooling performance at the footprint is highlighted. Existing empirical models were considered for the prediction of the heat transfer performance.

Principal supervisor: Associate Professor Wiebke Brix Markussen, DTU Mechanical Eng., DK
Co-supervisor: Senior Researcher Martin Ryhl Kærn, DTU Mechanical Eng., DK
Co-supervisor: Professor Björn Palm, KTH Royal Institute of Technology, Sweden

Examiners:
Associate Professor Kurt Engelbrecht, DTU Dept. of Energy Conversion and Storage, DK
Professor Tassos Karayiannis, Brunel University London, UK
Professor Luigi Pietro Maria Colombo, Politecnico di Milano, Italy

Chairperson at defense:
Associate Professor Emeritus, Arne Jørgensen Egelund, DTU Mechanical Eng., DK

 

 

Tidspunkt

tir 26 okt 21
13:00 - 16:00

Arrangør

DTU Mekanik

Hvor

DTU Lyngby Campus, Bygning 421, Aud. 74