Polydimethylsiloxane (PDMS)-based microfluidic channel with integrated commercial pressure sensors

The precise characterisation of boiling in microchannels is essential for the optimisation of applications requiring two phase cooling. In this paper polydimethylsiloxane (PDMS) is employed to make microchannels for characterising microboiling. In particular the material properties of PDMS facilitate rapid prototyping and its optical transparency provides the capability to directly view any fluid flow. The production of microchannels is complicated by the need to integrate custom made sensors. This paper presents a PDMS microfluidic device with integrated commercial pressure sensors, which have been used to perform a detailed characterisation of microboiling phenomena. The proposed approach of integrating commercial pressure sensors into the channel also has potential applications in a range of other microsystems

Flow Boiling of Water in Square Cross Section Microchannel at Different Inlet Subcooling Conditions

The effect of inlet subcooling on flow boiling heat transfer of deionised water in a horizontal singlemicrochannel of square cross section 1.0 mm by 1.0 mm and 75 mm long was studied. Three inlet sub-cooling conditions of 50, 15 and 5 K were studied for the mass fluxes of 200, 400 and 600 kg/m2s with increasing base heat fluxes in the range of 105- 455 kW/m2. Flow boiling patterns were related to corresponding local heat transfer coefficient along the microchannel and pressure drop characteristics for each inlet sub-cooling condition. This study demonstrates that, inlet sub-cooling has a significant effect on the two-phase heat transfer rates, pressure drop and flow patterns in the range studied