Enhanced boiling heat transfer in mesochannels

• Published in: International journal of heat and mass transfer Vol. 52; no. 25; pp. 5802 - 5813
• Main Authors: Schwarzkopf, John D., Penoncello, Steven G., Dutta, Prashanta
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.12.2009; Elsevier
• Subjects: Applied sciences; Boiling; Channels; Design. Technologies. Operation analysis. Testing; Droplets; Electronics; Electronics cooling; Enhanced boiling; Exact sciences and technology; Fluid flow; Heat flux; Heat transfer; Integrated circuits; Mathematical models; Mesochannels; Minichannels; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Surface temperature; Mesochannels; Electronics cooling; Minichannels; Enhanced boiling; Flow boiling; Two phase flow; Mesoscale; Pipe flow; Electronic component; Cooling system; Theoretical study; Spray cooling; Heat transfer coefficient; Experimental study; Thermophysical properties; Heat transfer
• ISSN: 0017-9310; 1879-2189
• DOI: 10.1016/j.ijheatmasstransfer.2009.07.022

Heat transfer characteristics are studied for a hybrid boiling case that combine features of spray cooling and flow boiling. In such a hybrid system, a liquid is atomized and the surrounding vapor is entrained into the droplet cone to provide an initial quality for enhanced boiling. An in-house experimental setup was developed to obtain surface temperature and heat flux measurements in a series of converged mesochannels for hybrid boiling. To compare the heat transfer performance of this hybrid technique, a flow boiling module was also developed using the same series of converged mesochannels. The inlet and exit hydraulic diameter of the mesochannels was 1.55 and 1.17 mm, respectively. The heat flux was in the range of 15–45 kW/m 2 and the estimated mass flux varied from 45 kg/m 2s at the channel inlet to 110 kg/m 2s at the channel outlet. Moreover, a model was presented to predict surface temperatures and heat transfer coefficients for flow boiling and hybrid boiling in mesochannels. This model was developed based on Chen’s formulation (1966) [21] but with two essential modifications. First, the laminar entry length effect was taken into consideration for heat transfer coefficient calculation. Second, the boiling enhancement factor was calculated based on the fluid properties. The model was compared to the experimental data and several other correlations for both cases. This model shows good agreement with the experimental data (mean deviations on the order of 12–16%).