Experimental Investigation of Non-Uniform Heating on Flow Boiling Instabilities in a Microchannels Based Heat Sink

Abstract

Two-phase flow boiling in microchannels is one of the most promising cooling technologies able to cope with high heat fluxes generated by the next generation of central processor units (CPU). If flow boiling is to be used as a thermal management method for high heat flux electronics it is necessary to understand the behaviour of a non-uniform heat distribution, which is typically the case observed in a real operating CPU. The work presented is an experimental study of two-phase boiling in a multi-channel silicon heat sink with non-uniform heating, using water as a cooling liquid. Thin nickel film sensors, integrated on the back side of the heat sinks were used in order to gain insight related to temperature fluctuations caused by two-phase flow instabilities under non-uniform heating. The effect of various hotspot locations on the temperature profile and pressure drop has been investigated, with hotspots located in different positions along the heat sink. It was observed that boiling inside microchannels with non-uniform heating led to high temperature non-uniformity in transverse direction.

Local measurement of flow boiling heat transfer in an array of non-uniformly heated microchannels

“…Past experimental efforts have studied the effects of non-uniform microchannel heating on flow boiling instabilities [17], pressure drop, and maximum wall temperatures [18][19][20]. It was found that hotspots near the inlet created a large transverse temperature variation across the heat sink due to nonuniform fluid distribution.…”