Extended-surface heat

Figure 10-147. Shell-side jn factors for bundles. One sealing strip per 10 rows of tubes and TEMA clearances. (Source Engineering Data Book, 2" Ed., 1960. Wolverine Tube, Inc. Used by permission Kern, D. Q., and Kraus, A. D. Extended Surface Heat Transfer, p. 506, 1972. McGraw-Hill, Inc. All rights reserved.)...

Kern, D. Q. and Kraus, A. D., Extended Surface Heat Transfer, McGraw-Hill Book Go. (1972). 

Extended surface heat exchanger tubing to improve heat transfer... 

Step 13. In this step, Ux, the step 1 assumed value, and the overall extended surface heat-transfer coefficient are calculated ... 

Still another method of evaluating fin performance is discussed in Prob. 2-68. Kern and Kraus [8] give a very complete discussion of extended-surface heat transfer. Some photographs of different fin shapes used in electronic cooling applications are shown in Fig. 2-13. 

Kern, D. Q., and A. D. Kraus Extended Surface Heat Transfer," McGraw-Hill Book Company, New York, 1972. 

Ethvlene reactor, 573.574.588.593 circulating sand, 593 flame reactor, 573 Evaporators, 208-211 backward and forward feed, 211 heat transfer coefficients, 211 sketches, 209-211 thermal economy, 210 Extended surfaces, heat transfer, 188... 

Kern, D.Q. Kraus, A.D. Extended surface heat transfer. New York McGraw-Hill 1972... 

Actual heat transfer from extended surface Heat transfer from wall without fin... 

In an extended surface heat exchanger, heat transfer takes place from both the fins (r /< 100 percent) and the primary surface (%= 100 percent). In that case, the total heat transfer rate is evaluated through a concept of total surface effectiveness or extended surface efficiency T 0 defined as... 

Vol. 5 Madassar Manzoor Heat Flow Through Extended Surface Heat Exchangers... 

Most air coolers are either induced-draft or forced-draft, as shown in Fig. 19.1, the more common arrangement being forced-draft. The air is moved by rather large fans. The tubes are surrounded with foil-type fins, typically 1 inch high. The surface area of the fins as compared to the surface area of the tubes is typically 12 to 1. That is why we call an air cooler an extended-surface heat exchanger. 

Since cryogenic nitrogen-removal systems typically operate at temperatures as low as 115 to 80K (-250° to -310°F) in their coldest sections, it is necessary to remove impurities which might form solid phases to very low levels. Gaseous components which require removal, with their freezing points and typical allowable concentrations, are listed in Table 16-18. Particulate impurities, such as dust from a molecular sieve unit and entrained compressor lubrication oil, must also be removed to a very low level to minimize fouling of extended surface heat exchangers. 

Collins-type concentric extended surface heat exchanger manufactured by the Joy Manufacturing Company, Michigan City, Ind. 

Both concentric tube and extended surface heat exchangers are widely used in small-scale operations. The extended surface types are very efficient but also tend to be relatively expensive. Their high cost tends to make them impractical for large-scale use. 

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