Exchanger double-pipe exchangers

Minimum Area. The limit of minimum network area is presented in References 2 and 3. If idealized double-pipe exchangers are used, a heat-exchange network having minimum area can quickly be developed for any In the limiting case, where all heat-transfer coefficients are assumed to be equal, the area for this network can easily be obtained from the composite streams by... 

Double-pipe exchangers are often piped in complex series-parallel arrangements on both sides. The MTD to be used has been derived for some of these arrangements and is reported in Kern (Process Heat Transfer, McGraw-Hill, New York, 1950). More complex cases may require trial-and-error balancing of the heat loads ana rate equations for subsections or even for individual exchangers in the bank. 

Longitudinal fins are commonly used in double-pipe exchangers upon the outside of the inner tube. U-tube and conventional removable tube bundles are also made from such tubing. The ratio of external to internal surface generally is about 10 or 15 1. 

Heat Exchanger - Shell and tube and double pipe exchangers, where the cooler side can be blocked in full of liquid while the hot side fluid flow continues, must be protected by either ... 

A double-pipe exchanger is made up of one pipe containing the tube fluid concentric with another pipe, which serves as the shell. The tube is often finned to give additional surface area. The double-pipe exchanger was developed to fit applications that are too small to economicall apply the requirements of TEMA for shell and tube exchangers. 

Double-pipe exchangers - the simplest type, used for cooling ind heating. 

Double-pipe exchangers-the simplest type with concentric pipe arrangement used for cooling and heating several units can be connected in series to extend their capacity. ... 

Figure 10-4B. Cutaway view of finned double-pipe exchanger. (Used by permission ALCO Products Co., Div. of NITRAM Energy, Inc.)...

Fluids in Anniilus of Tube-in-Pipe or Double Pipe Exchanger, Forced Convection... 

The longitudinal finned tube usually is adapted to double pipe exchangers but is used in the conventional bundle design with special considerations. 

For a double pipe exchanger (one finned tube in each of two shells), see Figure 10-4A, the heat flow resistances are ... 

The outer and inner tubes extend from separate stationary tube sheets. The process fluid is heated or cooled by heat transfer to/from the outer tube s outside surface. The overall heat transfer coefficient for the O.D. of the inner tube is found in the same manner as for the double-pipe exchanger. The equivalent diameter of the annulus uses the perimeter of the O.D. of the inner tube and the I.D. of the inner tube. Kem presents calculation details. 

Double-pipe exchanger is competitive at duties requiring 100-200 sqft. 

Solvent cooler double pipe exchanger, heat transfer area 2 m2, materials stainless steel. 

Figure 12.67. Double-pipe exchanger (constructed for weld fittings)...

Some designs of double-pipe exchanger use inner tubes fitted with longitudinal fins. 

Design a double-pipe exchanger for this duty, using standard carbon steel pipe and fittings. Use pipe of 50 mm inside diameter, 55 mm outside diameter for the inner pipe, and 75 mm inside diameter pipe for the outer. Make each section 5 m long. The physical properties of the caustic solution are ... 

Figure 8.4. Example of tubular heat exchangers (see also Fig. 8.14). (a) Double-pipe exchanger, (b) Scraped inner surface of a double-pipe exchanger, (c) Shell-and-tube exchanger with fixed tube sheets, (d) Kettle-type reboiler, (e) Horizontal shell side thermosiphon reboiler, (f) Vertical tube side thermosiphon reboiler, (g) Internal reboiler in a tower, (h) Air cooler with induced draft fan above the tube bank, (i) Air cooler with forced draft fan below the tube bank.

Double-pipe exchangers have largely lost out to shell-and-tube units in recent years, although Walker (1982) lists 70 manufacturers of them. They may be worth considering in these situations ... 

The process design of double-pipe exchangers is practically the simplest heat exchanger problem. Pressure drop calculation is straightforward. Heat transfer coefficients in annular spaces have been investigated and equations are rated in Table 8.10. A chapter is devoted to this equipment by Kern (1950). 

A typical double-pipe exchanger is shown in Fig. 2. It consists of two concentrically arranged pipes or tubes, with one fluid flowing in the inner pipe and the other in the annulus between the pipes. Special end fittings are used to get the fluids into and out of their respective flow channels and keep them from leaking to the atmosphere. Additional... 

FIG. 11 -42 Double-pipe-exchanger section with longitudinal fins. (Brown Fin-tube Co.)... 

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