Bypassing inefficiencies

Inefficient contacting due to solids movement and the bypassing of solids by bubbles. 

The electrical and heat analysis, as discussed in Section 15.3, will show the relationship between power and heat and how this varies over time. It may be necessary to use steam bypass and stations or dump condenser, as discussed in Section 15.2. The uses of dump condensers for meeting part-load requirement is inefficient and should be avoided. It is more acceptable to reduce turbine power output accordingly and import or top-up from an alternative supply. 

Spillback bypasses the compressor discharge gas, back to the compressor suction. This is a relatively energy-inefficient way to increase the evaporator temperature. Spillback is discussed in Chap. 28, Centrifugal Compressors and Surge. ... 

The second method for removing atmospheric gases involves sweeping air out of the apparatus by a flush of inert gas. The factors which influence this type of process are discussed in detail in Chapter 2. For the present, it is adequate to note that a continuous flush of inert gas, which pushes the atmospheric gases from one extreme of the apparatus to an outlet on another extreme, as in Fig. 1.1, is most efficient. This so-called plug flow is difficult to achieve with singleneck flasks and similar apparatus. A flow of inert gas which bypasses part of the apparatus is relatively inefficient. 

The design calculations highlighted the shortcomings of the Kern method of exchanger design. The Kern method fails to account for shell-side inefficiencies such as bypassing, leakage, crossflow losses, and window losses. This leads to a marked overestimate of the shell-side heat-transfer coefficient and shell-side pressure drop. The Bell method is recommended to correct these deficiencies. 

This trinuclear complex is an example of how coupling to a photosensitizer may improve the performance of a luminophore by (i) increasing the cross-section for light absorption, (ii) achieving visible spectral sensitization, (iii) bypassing the inefficient intersystem crossing step of the luminophore. Light... 

The other type of classifier inefficiency is apparent bypass, a. If, because of mutual interference or other reasons, some of the feed material bypasses the separation and reports to either the fine or the coarse streams, then a certain percentage of one of the product streams will have the same particle size distribution as the feed materiaL Both the apparent bypass and the sharpness index dictate the performance of classifiers. 

Some areas of investigation are restricted by the requirement for purified proteins because these may be limited in quantity of source material and their purification often involves tedious and inefficient procedures. Elder et al. have reported a unique approach that bypasses some of these restrictions in their studies of viral and plasma membrane proteins. After separation of proteins by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, they remove the gel slice containing the protein band of interest and radioiodinate it by chloramine-T while still in the gel. This application should prove to be useful in other systems. 

Altered intestinal motility produces diarrhea by three mechanisms reduction of contact time in the small intestine, premature emptying of the colon, and bacterial overgrowth. Chyme must be exposed to intestinal epithelium for a sufficient time period to enable normal absorption and secretion processes to occur. If this contact time decreases, diarrhea results. Intestinal resection or bypass surgery and drugs (such as metoclopramide) cause this type of diarrhea. On the other hand, an increased time of exposure allows fecal bacteria overgrowth. A characteristic small intestine diarrheal pattern is rapid, small, coupling bursts of waves. These waves are inefficient, do not allow absorption, and rapidly dump chyme into the colon. Once in the colon, chyme exceeds the colonic capability to absorb water. 

Choi, J.Y. and Guengerich, F.P. (2006) Kinetic evidence for inefficient and error-prone bypass across bulky... 

Phosphoglycolate is subsequently dephosphorylated and passed into organelles called the peroxisomes where it is further oxidized, the glyoxylate is amidated, and glycine is produced. This process is referred to as photorespiration and it occurs under conditions where the oxygen concentration is high. The C4 cycle, which occurs in so-called C4 plants, bypasses some of the inefficiency of photosynthesis arising from photorespiration. 

---