In the presented study, a novel micro cooling system for electronic devices using a micro capillary groove evaporator was proposed. Based on experimental data in open(atmospheric) condition, we found that liquid level has an obvious influence on evaporating heat flux. For a given liquid level, there exists an optimum groove size, which maximizes evaporation heat transfer capacity. By using the optimum groove sizes in the open condition, two types of closed cooling sytems for CPU chips for personal computers were designed: one was for desktop models and the other for notebook models. Their cooling performance to keep CUP chip temperature belos 90℃ reached 3.35×105W/m2 and 2.51×105W/m2,respectively, for the desktop model by using ethanol and the notebook model by using methanol. Experimental results show that the maximum cooling capacities strongly depend on the condensation capacities of condensers in the closed cooling systems and volume fractions of working liquid in the evaporators.

A numerical analysis of flow and concentration fields of macromolecules in a slightly curved blood vessel was carried out. Based on these results, the effect of the bifurcation of a flow on the mass transport in a curved blood vessel was discussed. The macromolecules turned out to be easier to deposit in the inner part of the curved blood vessel near the critical Dean number. Once the Dean number is higher than the critical number, the bifurcation of the flow appears. This bifurcation can prevent macromolecules from concentrating in the inner part of the curved blood vessel. This result is helpful for understanding the possible correlations between the blood dynamics and atherosclerosis.

Analytical research was conducted to study the heat transfer from horizontal surfaces to normally impinging circular free-surface jets under arbitrary-heat-flux conditions. General expressions of heat transfer coefficients and recovery factor were obtained in the stagnation region and boundary layer region as well as viscous similarity region by the integral method. Then by using the analytical results, the conjugated heat transfer between a water jet and the impinged wall was numerically solved. Finally, an experimental study was also performed to characterize conjugated heat transfer coefficient on a thick copper target base impinged normally by circular free-surface jet. The present predictions of the mean conjugated heat transfer coefficient were good agreement with the experimental data.

The critical heat flux(CHF) is studied in a confined space both experimentally and analytically. The confined space is consisted of two horizontal surfaces with the lower surface heated and the upper mesh screen. The observation shows that the behaviors of the vapor mushroom over the mesh screen have not significant differences with that in the conventional pool boiling. However, the CHF reduces with the decrease of the space gap when it is narrower than someone critical value. The theoretical analyses show that the reduced CHF is related to the earlier dryout of macrolayer during the period of vapor mushroom because the initial thickness of the macrolayer reduces with the decrease of the space gap. However, for larger enough space, the CHF is reached due to the crisis of the local heat transfer by the microlayer model but not the macrolayer dryout. Analyses show that the heat transfer crisis(CHF) causedby the macrolayer dryout occurs only in advance of that by the microlyer model and the conventional macrolayer dryout model is a special case of the microlayer model. Theoretic prediction of CHF agrees reasonable well with experimental data.

The critical heat flux (CHF) of subcooled boiling is theoretically predicted by means of the microlayer model. The enhancement of heat transfer for subcooled boiling is mainly due to the augmented heat convection caused by the forming and collapsing of individual bubbles. For a uniform heat flux surface, CHF approaches a constant in the high subcooling region. For a uniform temperature surface, CHF increases with the subcooling. The evaporative heat transfer becomes small and the total heat flux is mainly due to the heat conduction outside the evaporating area as the subcooling is increased. The boiling crisis(CHF) is caused by the local dryout of microlayer at low subcooling and by the rapid increase of the duration of bubble condensation with the increase of wall superheat at high subcooling.