The interfacial instabilities important to the modeling of critical heat flux (CHF) in reduced-gravity systems are sensitive to even minute body forces, especially for small coolant velocities. Understanding these effects is of paramount importance to both the reliability and safety of two-phase thermal management loops proposed for future space and planetary-based thermal systems. Unfortunatel...

This paper is the first of a two-part study concerning measurement and prediction of saturated flow boiling heat transfer in a water-cooled micro-channel heat sink. In this paper, new experimental results are discussed which provide new physical insight into the unique nature of flow boiling in narrow rectangular micro-channels. The micro-channel heat sink contained 21 parallel channels having ...

Local heat transfer coefficients and pressure drops during boiling of the dielectric liquid fluorinert FC-77 in parallel microchannels were experimentally investigated in recent work by the authors. Detailed visualizations of the corresponding two-phase flow regimes were performed as a function of a wide range of operational and geometric parameters. A new transition criterion was developed for...

This paper is Part II of a two-part study devoted to measurement and prediction of the saturated flow boiling heat transfer coefficient in water-cooled micro-channel heat sinks. Part I discussed the experimental findings from the study, and identified unique aspects of flow boiling in micro-channels such as abrupt transition to the annular flow regime near the point of zero thermodynamic equili...

in this work, the characteristics of flow and heat transfer of a fluid containing nano particles of aluminum oxide with the water volume fraction (0.1-0.2-0.3)(v/v) percent of the reports. the overall heat transfer coefficient, heat transfer and the average heat transfer fluid containing nano water - aluminum oxide in a horizontal double pipe counter flow heat exchanger under turbulent flow con...

An experimental study is presented for droplets containing an alcohol-resistant aqueous film forming foam (AR-AFFF) impacting and boiling on a heated stainless steel surface. Experiments with solutions of 3% (volume fraction) AR-AFFFldistilled water were compared to ones with distilled water and 3% AR-AFFF/simulated seawater. The latter experiments were motivated by the practice of mixing AR-AF...

the ali-abad porphyry copper deposit is located in the central iranian magmatic belt. as a result of subduction magmatism, oligo-miocene leucogranitoid rocks have intruded into conglomerates of lower cretaceous age. due to contact metamorphism the following mineral assemblage has occurred in the altered conglomerate: garnet (andradite-grossular) + epidote+ quartz + calcite + pyrite skarnificati...

An experimental facility is developed to investigate critical heat flux (CHF) of saturated flow boiling of Refrigerant-123 (R-123) in microchannels. Six parallel Microchannels with cross sectional area of 0.2 mm × 0.2 mm are fabricated on a copper block, and a Polyvinyl Chloride (PVC) cover is then placed on top of the copper block to serve as a transparent cover through which flow patterns and...

In this paper, a numerical scheme has been developed for primary and secondary fluids adopting Euler–Cauchy method to find the temperature distribution of the primary fluid relative to the secondary fluid and vice–versa and to obtain an optimum boiling length of the tube in the vertical inverted U–tube steam generator (UTSG).

Experiments were performed to examine the effects of body force on flow boiling CHF. FC-72 was boiled along one wall of a transparent rectangular flow channel that permitted photographic study of the vapor-liquid interface just prior to CHF. High-speed video imaging techniques were used to identify dominant CHF mechanisms corresponding to different flow orientations and liquid velocities. Six d...