Flow boiling of 1-methoxyheptafluoropropane (HFE 7000) in 222 m hydraulic diameter channels containing a single row of 24 inline 100 m pin fins was studied for mass fluxes from 350 kg /m2 s to 827 kg /m2 s and wall heat fluxes from 10 W /cm2 to 110 W /cm2. Flow visualization revealed the existence of isolated bubbles, bubbles interacting, multiple flow, and annular flow. The observed flow patte...

In this study, one type of nano-engineered heat transfer fluids: Water/AOT/Polyalphaolefin (PAO) nanoemulsion fluids are prepared, and their phase change heat transfer properties have been investigated. The Water/AOT/Polyalphaolefin nanoemulsion heat transfer fluids which are thermodynamically stable are spontaneously generated by a self-assembly of dispersed water nanodroplets The results, exp...

Flow boiling of water across a bank of circular staggered micro-pin fins, 250 lm long and 100 lm diameter with pitch-to-diameter ratio of 1.5, was experimentally studied for mass fluxes ranging from 346 kg/m s to 794 kg/m s and surface heat fluxes ranging from 20 W/cm to 350 W/cm. Local temperature measurements were used to elucidate the two-phase heat transfer coefficients. The flow was visual...

This paper is the second of a two-part study concerning two-phase flow and heat transfer characteristics of R134a in a micro-channel heat sink incorporated as an evaporator in a refrigeration cycle. Boiling heat transfer coefficients were measured by controlling heat flux (q00 = 15.9 93.8W/cm) and vapor quality (xe = 0.26 0.87) over a broad range of mass velocity. While prior studies point to e...

Cryogenic fluids have found many practical applications in today’s world, from cooling superconducting magnets to fueling launch vehicles. In many of these applications the cryogenic fluid is initially introduced into piping systems that are in excess of 150 degrees Kelvin higher than the fluid. This leads to voracious evaporation of the fluid and significant pressure fluctuations, which is acc...

Flow boiling in miniand microchannels offer very high heat transfer capabilities and find applications in many emerging technologies, such as electronics cooling and fuel cells. The low flow rate employed in such geometries, coupled with the small flow channels, often results in a laminar flow with all flow as liquid. Since the single-phase flow with all liquid is in the laminar range, the flow...

The enhancement of boiling heat transfer, the most powerful energy-transferring technology, will lead to milestones in the development of high-efficiency, next-generation energy systems. Perceiving nano-inspired interface functionalities from their rough morphologies, we demonstrate interface-induced liquid refreshing is essential to improve heat transfer by intrinsically avoiding Leidenfrost p...

In recent years, water (R718) as a kind of natural refrigerant—which is environmentally-friendly, safe and cheap—has been reconsidered by scholars. The systems of using water as the refrigerant, such as water vapor compression refrigeration and heat pump systems run at sub-atmospheric pressure. So, the research on water boiling heat transfer at sub-atmospheric pressure has been an important iss...