- مبلغ: ۸۶,۰۰۰ تومان
- مبلغ: ۹۱,۰۰۰ تومان
The maximum theoretical boiling heat transfer rate qmax is set by interface unidirectional thermal vapor flux, and quest continues for achieving a high fraction of it under saturated liquid flow. We introduce the flow-boiling canopy wick (FBCW) employing film (meniscus) evaporation and perforated screenlayer separating the liquid stream from the underlying vapor space. The vapor vents continuously through periodic perforations, in contrast to plain surface which becomes completely covered by vapor at high heat flux. The FBCW allows streamwise liquid tracks on the screenlayer between perforations providing capillary liquid flow toward heated surface and evaporation on high-effective-conductivity monolayer wick. Under extreme heat flux, various hydrodynamic limits prevent liquid supply and vapor removal, i.e., the capillary-viscous, wick superheat, perforation pressure drop and chocking and liquid-vapor stability limits. The liquid and vapor inertiae control the streamwise continuous liquid track (with isolated and/or merged vapor track) and for saturated water at 1 atm CFD and wick pressure drop predict heat flux up to 0.1qmax = 20 MW/m2 , an order-of-magnitude larger than the nucleate flow-boiling limit. The concept of replacing the chaotic nucleated bubbles with the structured, continuous vapor venting in the periodic FBCW transforms boiling heat transfer and its upper limit.
We have shown that FBCW, a boiling metamedium, enables extreme heat transfer by controlling heat transfer/vapor generation and hydrodynamics of the vapor and liquid tracks. FBCW separates and directs these tracks to ensure the highest liquid supply rate and smallest thermal resistance. Heat flux up to 0.1qmax is predicted, and the increase of the liquid velocity extends the isolated-vapor track coverage, and gradually leads to the streamwise local vapor compressibility limit. The FBCW transforms boiling heat transfer using unit-cell, 3-D capillary structure under saturated liquid flow and is capable of achieving record fraction of the theoretical maximum heat flux limit.