Capillary pumping

These two time constants overlap assuring that film liquid exchange by capillary pumping or suction can keep pace with the pore-wall stretching and squeezing of the film during flow through several constrictions. On the other hand, based on a linear stability analysis summarized in Appendix A for a free,... 

The instrumental setup for capillary HPLC-NMR coupling is shown in Figure 4.6. The capillary pump is connected via 50 pm capillaries between the capillary HPLC pump, the UV detector, and the NMR flow probe. 

See also Gas chromatography Capillary gel electrophoresis (CGE), in microfluidic assays, 26 971 Capillary hydrodynamic flow (CHDF) techniques, 16 291 20 381 Capillary microfiltration/ultrafiltration (MF/UF) technology, 26 83-84 Capillary number, 11 746 Capillary optics, 26 438 Capillary pumped loops (CPLs),... 

FIGURE 3.33 Geometry and hydrodynamic characteristics of the microfluidic capillary system (CS). (a) top view of a CS. (b) The flow of liquid (arrows) is superimposed on the cross section (not to scale) of the CS. CRV capillary retention valve CP, capillary pump [459]. Reprinted with permission from the American Chemical Society. 

Sample analysis was performed by using an Applied Biosystems (Foster City, CA) API 3000 triple quadrupole mass spectrometer equipped with a TurboIonSpray source and an Agilent 1100 capillary HPLC system (Palo Alto, CA). The capillary HPLC system included a binary capillary pump with an active micro flow rate control system, an online degasser, and a microplate autosampler. The analytical column was a 300 pm I.D.x 150 mm Zorbax C18 Stablebond capillary column (pore size 100 A and particle size 3.5 pm). The injection volume was 5 pL, and a needle ejection rate of 40 pL/min was used. The pLC flow rate was 6 pL/min. In order to minimize dead volume before the column, the autosampler was programmed to bypass the 8 pL sample loop 1.5 min after injection. The mobile phase consisted of (A) 2 mM ammonium acetate (adjusted to pH 3.2 with formic acid) in 10 90 acetonitrile-water, and (B) 2 mM ammonium acetate in 90 10 acetonitrile-water. The percentage of mobile phase B was held at 32 % for the first minute, increased to 80 % over 8 min, and then increased tol00% over the following 1 min. 

Capillary pumped loops are attractive alternative for heat regulation [15]. The capillary pumped evaporator is used instead of the boiler. A capillary pumped evaporator is more flexible with the point of view of its orientation in space and is more compact. This principal difference of vapour generating gives the possibility to use the evaporator in higher level that condensers. 

Evaporation of the liquid from the defined surface area of a capillary pump. With the exception of the last-mentioned method, all these methods are used for... 

Figure 6 Chip component of the MicroChannel assay system, (a) Overview of the entire chip, (b) detail of capillary pumps, which provide autonomous filling of each channel by capillary action, (c) each capillary retention valve prevents drainage of a channel s reaction zone after the fill port has emptied, and (d) a chip with an attached PDMS cube is fdled by a standard pipette. By placing the chip on 2 aluminum blocks, whose temperature is individually controlled by 2 Peltier elements, differential evaporation allows extremely low flow rates...

Fine fiber bundle wicks have a good capillary pumping head, but have low permeability and high effective thermal resistance (low thermal conductivity) across the wick. They have the... 

Yu. Maidanik, Yu. Fershtater, V. Pastukhov " Some results of Development of Loop Heat Pipes" in Proceedings of the CPL-96 Workshop on Capillary pumped Two-phase Loops, Noordwijk, Netherlands, 1996. ... 

Meyer, E., Dasgupta, S., Shaddock, D., Tucker, J. and Pillion, R., 1993, A Silicon-Carbide Micro-Capillary Pumped Eoop for Cooling High Power Devices, 9 Semiconductor Thermal Measurement and Management Symposium, pp. 364-368. 

Vestad T, Marr D, Oakey J (2004) Flow control for capillary-pumped microfluidic systems. J Micromech Microeng 14 1503... 

In a gravitational environment, the normal and axial hydrostatic pressure terms may either assist or hinder the capillary pumping process depending on whether the tilt of the heat pipe promotes or hinders the flow of liquid back to the evaporator (i.e., the evaporator lies either below or above the condenser). In a zero-g environment, both this term and the normal hydrostatic pressure drop term can be neglected because of the absence of body forces. 

Composite wicking structures accomplish the same type of effect in that the capillary pumping and axial fluid transport are handled independently. In addition to fulfilling this dual purpose, several wick structures physically separate the liquid and vapor flow. This results from an attempt to eliminate the viscous shear force that occurs during countercurrent liquid-vapor flow. 

Pettigrew K, Kirshberg J, Yerkes K, Trebotich D, Liepmann D (2001) Performance of a MEMS based micro capillary pumped loop for chip-level temperature control. In 14th IEEE international conference on micro electro mechanical systems, Interlaken, Switzerland, pp 427-430, 21-25 Jan 2001... 

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