Parallel microchannels

Kleiner et al. [23] theoretically and experimentally investigated forced air-cooling, which employs microchannel parallel plate fin heat sinks and tubes. Optimization was performed and design trade-off was studied. Tube sizes were observed to have a significant impact on optimum heat sink design. Air-cooled heat sinks are used for micro channel heat sinks with heat loads less than 100 W/cm. ... 

Today, much of the product development conducted in pharmaceutical company laboratories is carried out in microflow systems that allow a total conversion of reactant to product that is rapid, efficient and selective on a scale of 1-100 g for activity testing. The past few years have seen several groups seek to develop electrolysis cell designs that can be used in such equipment. The Southampton group have attempted to develop cells that combine good performance with an appearance similar to other equipment used for routine microfiow synthesis. This led to a cell based on a single-patterned microchannel, parallel... 

The front opening of such a microchannel element has a diameter of only a few microns, but it is only one element of a whole multichannel array (Figure 31.2). Whereas the orifice to one micro-channel element covers an area of only a few square microns, an array of several thousand parallel elements covers a much larger area. In particular, the area covered by the array must be larger than... 

Hetsroni G, Mosyak A, Pogrebnyak E, Yarin LP (2005c) Heat transfer in micro-channels comparison of experiments with theory and numerical results. Int J Heat Mass Transfer 48 5580-5601 Hetsroni G, Mosyak A, Segal Z, Pogrebnyak E (2003b) Two-phase flow patterns in parallel microchannels. Int J Multiphase Flow 29 341-360... 

Sobhan CB, Garimella SV (2001) A comparative analysis of studies on heat transfer and fluid flow in micro-channels. Microscale Thermophys Eng 5 293-311 Steinke M, Kandlikar SG (2003) Flow boiling and pressure drop in parallel flow micro-channels. In Kandlikar SG (ed) Proceedings of 1st International Conference on Micro-channels and Mini-channels, Rochester, 24-25 April 2003, pp 567-579 Thome JR (2006) State-of-the-art overview of boiling and two-phase flows in microchannels. Heat Transfer Eng 27(9) 4-19... 

Mala GM, Li D, Werner C (1997b) Flow characteristics of water through a micro-channel between two parallel plates with electro kinetic effects. Int J Heat Fluid Flow 18 491 96 Male van P, Croon de MHJM, Tiggelaar RM, Derg van den A, Schouten JC (2004) Heat and mass transfer in a square micro-channel with asymmetric heating. Int J Heat Mass Transfer 47 87-99 Maranzana G, Perry I, Maillet D (2004) Mini- and micro-channels influence of axial conduction in the walls. Int J Heat Mass Transfer 47 3993 004 Maynes D, Webb BW (2003) Full developed electro-osmotic heat transfer in microchannels. Int J Heat Mass Transfer 46 1359-1369... 

Two-phase flow in parallel micro-channels, feeding from a common manifold shows that different flow patterns occur simultaneously in different microchannels. The probability of appearance of different flow patterns should be taken into account for developing flow pattern maps. 

Hetsroni G, Mosyak A, Segal Z, Pogrebnyak E (2003) Two-phase flow pattern in parallel microchannels. Int J Multiphase Flow 29 344-360... 

Li HY, Tseng FC, Pan C (2004) Bubble dynamics in micro-channels. Part II two parallel microchannels. Int J Heat Mass Transfer 47 5591-5601 Li J, Cheng P (2004) Bubble cavitation in a micro-channel. Int J Heat Mass Transfer 47 2689-2698 Liu D, Lee PS, Gaiimella SV (2005) Prediction of the onset of nucleate boiling in microchannel flow. Int J Heat Mass Transfer 48 5134-5149... 

Numbering up microchannels to large-scale capacity reactors is driven by a rigorous understanding of pressure drop in every parallel circuit Passive flow distribution permits sufficient flow to each channel. No serious evaluation of microvalves or actuators has been undertaken for high-capacity systems with thousands to tens... 

For most medium- and large-scale micromanifold structures, where one passage feeds multiple parallel channels, flow traverses through turbulent and transition flows in the micromanifold region. This fluid in turbulent to transition flow also turns in the micromanifold region as it drops flow into parallel microchannels, which are primarily in the laminar flow regime. 

Figure 11.3 Two microchannel layers which form a complete flow circuit including a micromanifold region and connecting channels. The bottom layer is placed on the first to create a common plenum that connects to six submanifolds. Each submanifold connects to 12 parallel microchannels.

The application of microchannel technology is a natural fit for the production of synthetic fuels via the FT process. The primary limitations of conventional FT technology include the removal of process heat that can produce hot spots and severely shorten catalyst life, and effective management of two-phase flow as synthesis gas transforms into hquid hydrocarbons. Both these issues can be addressed with microchaimel technology, which greatly improves heat transfer and precisely controls flow through thousands of parallel chaimels. 

Figure 11.19 Manufacturing scale-up device with submanifolds for passive flow distribution to feed thousands of parallel microchannels. Flow is mapped using ranges to show variations from a normalized value.

Kikutani, Y, Horiuchi, T., Uchiyama, K., Hisamoto, H., Tokeshi, M., Kitamori, T, Glass microchip with three-dimensional microchannel network for 2x2 parallel synthesis. Lab. Chip 2 (2002) 188-192. 

Figure 36.2. Left cross section of a microchannel with an inlet port, a channel, an outlet port and integrated gold electrodes. Right a cartridge containing eight parallel microchannels, embedded in a white polymer support, serving as rigidifier, guide and reservoir.

As an example, Fig. 36.5 presents a calibration curve for the determination of Interleukin IB in plasma sample. The insert in Fig. 36.5 shows the row data obtained for the parallel detection of p-aminophenol in a series of eight individually addressable microchannels as a function of time, and the resulting calibration points are given by the slope at the origin of these different curves. 

Immusoft is a software that has been developed to perform computer-driven assays in our microchips. This software has a user-friendly graphical user interface, and it enables control of the pump, the valves and the electrochemical detection system, as well as the development of specific assay protocols, the running of simultaneous or sequential experiments in eight parallel microchannels, the automatic read-out of the results and the processing of the obtained data. These different functions are managed by way of three main menus, named Method, Analysis and Results, and the software also comprises two additional items dedicated to the setting of the computing parameters and to the maintenance of the instrumentation. 

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