Nanofluids, stabilized suspensions of nanoparticles typically < 100 nm in conventional fluids, are evolving as potential enhanced heat transfer fluids due to their better thermal conductivity, increase in single phase heat transfer coefficient and significant increase in critical boiling heat flux. In the present paper, we investigate the overall thermal resistance of a closed two-phase thermos...

Nucleate boiling heat transfer coefficients may be strongly reduced by scale formation, even for conditions where the bulk foulant concentration is well below the saturation concentration. Due to the mechanism of micro-layer evaporation, the local concentration at the heat transfer surface can be considerably increased, causing the formation of scale and changes in bubble frequency and bubble d...

A two-part experimental study is conducted on pool boiling heat transfer over enhanced cylindrical microchannel test surfaces with water at atmospheric pressure. In this Part II of the study, the effects of circumferential V-groove microchannels and axial rectangular microchannels are reported. These experiments were performed in the horizontal as well as vertical orientations. The heat transfe...

This two-part study concerns the development of a generalized approach to predicting both Nucleate Boiling dominated and Convective Boiling dominated heat transfer in mini/micro-channel flows. Both heat transfer regimes exhibit substantial reduction in the heat transfer coefficient at the location of partial annular liquid film dryout, hence the need to ascertain the occurrence of this importan...

Boiling heat transfer is a superior heat transfer technology using the latent heat transport with phase-change. However, it has been difficult to employ as a cooling technology for electronics because the unstable transition boiling and film boiling with excessive high temperature are impossible to control. In highly subcooled boiling, the coalescing bubbles formed on the heating surface collap...

Experiments were conducted to determine the influence of local vapor quality on local heat transfer coefficient in flow boiling in an array of microchannels. Additionally, the variation of local heat transfer coefficient along the length and width of the microchannel heat sink for given operating conditions was investigated over a range of flow parameters. Each test piece includes a silicon par...

Slush nitrogen (SN(2)) is a mixture of solid nitrogen and liquid nitrogen, with an average temperature of -207 °C. To investigate whether plunging a French plastic straw (commonly used for sperm cryopreservation) in SN(2) substantially increases cooling rates with respect to liquid nitrogen (LN(2)), a numerical simulation of the heat conduction equation with convective boundary condition was us...

Pool boiling heat transfer characteristics of Al2O3 -water nanofluids is studied experimentally using a NiCr test wire of 36 standard wire guage diameter. The experimental work mainly concentrated on (1) change of critical heat flux with different volume concentrations of nanofluid and (2) flow visualization of pool boiling using a fixed concentration of nanofluid at different heat flux values....