Fluid Knocking

Vertical in-tube condensers are often designed for reflux or knock-back application in reactors or distillation columns. In this case, vapor flow is upward, countercurrent to the hquid flow on the tube wall the vapor shear ac4s to tliicken and retard the drainage of the condensate film, reducing the coefficient. Neither the fluid dynamics nor the heat transfer is well understood in this case, but Sohman, Schuster, and Berenson [J. Heat Transfer, 90, 267-276... 

ETHYL FLUID see MOTOR FUEL ANTI-KNOCK COMPOUND ... 

The basic principle of a diffusion pump can be explained with a simple single-stage mercury diffusion pump (see Fig. 7.21). On the system side of the pump (at about 10 2 to 10 3 torr, or better), gas molecules wander around, limited by their mean free path and collisions with other molecules. The lowest section of this diffusion pump is an electric heater that brings the diffusion pump liquid up to its vapor pressure temperature. The vapors of the diffusion pump liquid are vented up a central chimney where, at the top, they are expelled out of vapor jets at supersonic speeds (up to 1000 ft/sec). Below these jets is a constant rain of the pumping fluid (mercury or low vapor-pressure oil) on the gases within the vacuum system. Using momentum transfer/ gas molecules are physically knocked to the bottom of the pump, where they are trapped by the vapor jets from above. Finally, they are collected in a sufficient quantity to be drawn out by the auxiliary (mechanical) pump. 

Momentum transfer is possible because momentum = (mass) x (velocity), and the velocity of the diffusion pump fluid (when it leaves the pump jets) is typically at supersonic speeds. Thus, it is easy for the diffusion pump liquid to knock around any size molecule. 

The iron, with its melting point depressed to about 1,100°C by dissolved carbon (m.p. of pure iron 1,535°C), drips through the charge and collects on the hearth. Being the denser fluid product of the blast furnace, it forms a lower phase as it accumulates on the hearth. Molten pig iron is periodically withdrawn from this accumulation by drilling or knocking out a clay plug placed in a lower tap hole in the side of the hearth. 

Zhang W, Xiong H, Callaghan D, Liu H, Jones A, Pei K et al (2013) Blood-brain barrier transport of amyloid beta peptides in efflux pump knock-out animals evaluated by in vivo optical imaging. Fluids Barriers CNS 10 13... 

The discharge of copious quantities of chemicals directly to atmosphere can give rise to secondary hazards, especially if the materials are toxic and can form flammable atmosphere in air (e.g., vapor or mist). In such cases, the provision of a knock-out device (scrubber, dump tank) of adequate size to contain the aerated/foaming fluid will be required. 

Viewed in a multiverse context, we may imagine a world in which, say, the mass of the electron is different. Tliis would have a knock-on effect on all the above properties N of them, say. Tims, as the mass changes, these properties cease to assume biofriendly values. So on the face of it, we may invoke a standard multiverse/anthropic explanation for why water is biofriendly. But this is a bit of a cheat. We still need to explain why any values for the electron mass exist in which aWN of the key properties realize their biofriendly values simultaneously. My point is that the said N qualities are not independent, but interrelated through physics and chemistry. You can t change each of them in isolation without changing the others. So we are left with the mystery of why any universe in the multiverse contains any fluid that enjoys, in conjunction, all the properties needed for life. 

Something smashed into the middle of his back, knocking him forwards completely off balance. He went crashing painfully onto the ground. Auto-balance and unarmed combat programs went primary, interfacing to roll him smoothly to one side. He regained his feet in a fluid motion. 

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