Bundling effect

Palen recommendation corrects single tube boiling data (outside) to the bundle effect in a horizontal reboiler by ... 

C. M. Chu and J. M. McNaught, Tube Bundle Effects in Crossflow Condensation on Low-Finned Tubes, Proc. 10th Int. Heat Transfer Conf, Brighton, 3, pp. 293-298,1994. 

In a way, the limit set is thus the entire funnel between the two extreme cases qlc, and g o, Fig. 5. This effect is called Takens-chaos, [21, 5, 7]. As a consequence of this theorem each momentum uncertainty effects a kind of disintegration" process at the crossing. Thus, one can reasonably expect to reproduce the true excitation process by using QCMD trajectory bundles for sampling the funnel. To realize this idea, we have to study the full quantum solution and compare it to suitable QCMD trajectory bundles. 

Fig. 5. Protein folding. The unfolded polypeptide chain coUapses and assembles to form simple stmctural motifs such as -sheets and a-hehces by nucleation-condensation mechanisms involving the formation of hydrogen bonds and van der Waal s interactions. Small proteins (eg, chymotrypsin inhibitor 2) attain their final (tertiary) stmcture in this way. Larger proteins and multiple protein assembhes aggregate by recognition and docking of multiple domains (eg, -barrels, a-helix bundles), often displaying positive cooperativity. Many noncovalent interactions, including hydrogen bonding, van der Waal s and electrostatic interactions, and the hydrophobic effect are exploited to create the final, compact protein assembly. Further stmctural...

Fypass Flow Effects. There are several bypass flows, particularly on the sheUside of a heat exchanger, and these include a bypass flow between the tube bundle and the shell, bypass flow between the baffle plate and the shell, and bypass flow between the shell and the bundle outer shroud. Some high temperature nuclear heat exchangers have shrouds inside the shell to protect the shell from thermal transient effects. The effect of bypass flow is the degradation of the exchanger thermal performance. Therefore additional heat-transfer surface area must be provided to compensate for this performance degradation. 

Entrance andExit SpanXireas. The thermal design methods presented assume that the temperature of the sheUside fluid at the entrance end of aU tubes is uniform and the same as the inlet temperature, except for cross-flow heat exchangers. This phenomenon results from the one-dimensional analysis method used in the development of the design equations. In reaUty, the temperature of the sheUside fluid away from the bundle entrance is different from the inlet temperature because heat transfer takes place between the sheUside and tubeside fluids, as the sheUside fluid flows over the tubes to reach the region away from the bundle entrance in the entrance span of the tube bundle. A similar effect takes place in the exit span of the tube bundle (12). 

This implies that the LMTD or M I D as computed in equations 20 through 26 may not be a representative temperature difference between the two heat-transferring fluids for aU tubes. The effective LMTD or M ID would be smaller than the value calculated, and consequentiy would require additional heat-transfer area. The tme value of the effective M I D may be determined by two- or three-dimensional thermal—hydrauUc analysis of the tube bundle. Baffle—Tube Support PlateXirea. The portion of a heat-transfer tube that passes through the flow baffle—tube support plates is usuaUy considered inactive from a heat-transfer standpoint. However, this inactive area must be included in the determination of the total length of the heat-transfer tube. 

Miscellaneous Effects. Depending on individual design characteristics, there are other miscellaneous effects to consider in the determination of the final sizing of a heat exchanger. These include effects of flow maldistribution of both the sheUside and tubeside fluids, stagnant or inactive regions in the tube bundle, and inactive length of the tube in tubesheets. These effects should be individuaUy assessed and appropriate additional areas should be provided. 

Commercially, stabilization is accomplished by controlled heating in air at temperatures of 200—300°C. A variety of equipment has been proposed for continuous stabilization. One basic approach is to pass a fiber tow through heated chambers for sufficient time to oxidize the fiber. Both Mitsubishi and Toho patents (23,24) describe similar continuous processes wherein the fiber can pass through multiple ovens to increase temperature and reaction rate as the thermal stabiUty of the fiber is increased. Alternatively, patents have described processes where the fiber passes over hot roUs (25) and through fluidized beds (26) to provide more effective heat transfer and control of fiber bundle temperature. 

These equations apply to single tubes or to flat surfaces in a large pool. In tube bundles the equations are only approximate, and designers must rely upon experiment. Palen and Small [Hydrocarbon Process., 43(ll), 199 (1964)] have shown the effect of tube-bundle... 

Find the correction factor for bundle-bypassing effects Jb from Fig. 11-12... 

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