664:. Additionally, their robust build means that they can withstand high pressure operations. They also produce turbulent conditions at low flow rates, increasing the heat transfer coefficient, and hence the rate of heat transfer. There are significant disadvantages however, the two most noticeable being their high cost in proportion to heat transfer area; and the impractical lengths required for high heat duties. They also suffer from comparatively high heat losses via their large, outer shells.
97:
443:
92:
For calculations involving the outer stream, the equivalent diameter (or mean hydraulic radius) is used in place of the geometric diameter, as the cross-sectional area of the annulus is not circular. Equivalent diameters are also used for irregular shapes such as rectangular and triangular ducts. For
667:
The simplest form is composed of straight sections of tubing encased within the outer shell, however, alternatives such as corrugated or curved tubing conserve space while maximising heat transfer area per unit volume. They can be arranged in series or in parallel depending on the heating
219:
683:
stream to limit the pressure drop. Beyond double stream heat exchangers, designs involving triple (or more) streams are common; alternating between hot and cool streams, thus heating/cooling the product from both sides.
206:
668:
requirements. Typically constructed from stainless steel, spacers are inserted to retain concentricity, while the tubes are sealed with O-rings, packing, or welded depending on the operating pressures.
73:
for both the inner and outer streams; given their diameters and velocities (or flow rates). For conditions where thermal properties vary significantly, such as for large temperature differences, the
593:
438:{\displaystyle {1 \over U_{o}}={R_{fo}}+{R_{fi}}\cdot {\frac {D_{o}}{D_{i}}}+{\frac {D_{o}}{2k_{w}}}\cdot \ln {\frac {D_{o}}{D_{i}}}+{1 \over h_{o}}+{1 \over h_{i}}\cdot {\frac {D_{o}}{D_{i}}}}
643:
488:
25:
are used in a variety of industries for purposes such as material processing, food preparation, and air-conditioning. They create a temperature driving force by passing
660:, is the simplicity of their design. As such, the insides of both surfaces are easy to clean and maintain, making it ideal for fluids that cause
57:
behaviour of concentric tube heat exchangers can be described by both empirical and numerical analysis. The simplest of these involve the use of
105:
770:
93:
concentric tubes, this relationship simplifies to the difference between the diameters of the shell and the outer surface of the inner tube.
851:
823:
798:
745:
493:
77:
is used. This model takes into consideration the differences between bulk and wall viscosities. Both correlations utilize the
505:
703:
657:
675:
method is more common. The preference is to pass the hot fluid through the inner tube to reduce heat losses, while the
602:
210:
After the heat transfer coefficients (h_{i} and h_{o}) are determined, knowing the resistance due to fouling and
70:
885:
34:
452:
672:
870:
447:
The length of heat exchanger required can then be expressed as a function of the rate of heat transfer:
61:
to model heat transfer; however, the accuracy of these predictions varies depending on the design. For
708:
653:
211:
214:
of the boundary material (k_{w}), the
Overall Heat Transfer coefficient (U_{o}) can be calculated.
30:
847:
819:
794:
766:
741:
38:
816:
Coulson & Richardson's
Chemical Engineering: Fluid Flow, Heat Transfer and Mass Transfer
82:
698:
86:
78:
74:
66:
21:
879:
693:
54:
42:
58:
89:
to be between 0.7 and 160, Seider-Tate applies to values between 0.7 and 16,700.
96:
713:
497:
17:
680:
62:
676:
201:{\displaystyle D_{\mathrm {eo} }={\frac {4\cdot Area}{WettedPerimeter}}}
661:
492:
Where A is the surface area available for heat transfer and ∆T is the
652:
The primary advantage of a concentric configuration, as opposed to a
500:
can be performed to calculate the heat exchanger’s effectiveness.
95:
26:
671:
While both co and counter configurations are possible, the
85:
is greater than 10,000. While Dittus-Boelter requires the
844:
Processing of Foods: Pasteurization and UHT Sterilization
588:{\displaystyle q_{max}\equiv C_{min}(T_{h,i}-T_{c,i})}
837:
835:
605:
508:
455:
222:
108:
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200:
763:Encyclopedia of Energy Engineering and Technology
738:Heat Transfer in Single and Multiphase Systems
842:Michael John Lewis and N. J. Heppell (2000).
8:
638:{\displaystyle E\equiv {\frac {q}{q_{max}}}}
814:J.M. Coulson and J. F. Richardson (1999).
818:(Sixth ed.). Butterworth Heinemann.
731:
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483:{\displaystyle A={\frac {Q}{U\Delta T}}}
725:
33:to each other, separated by a physical
784:
782:
648:Concentric tube heat exchanger design
7:
37:in the form of a pipe. This induces
471:
118:
115:
29:streams of different temperatures
14:
871:Thermodynamics of Heat Exchangers
494:log mean temperature difference
791:Heat Transfer Equipment Design
709:Plate and Frame Heat Exchanger
582:
544:
1:
704:Shell and tube heat exchanger
658:shell and tube heat exchanger
69:can be used to determine the
81:and are only valid when the
761:Barney L. Capehart (2007).
902:
496:. From these results, the
45:heat to/from the product.
679:is reserved for the high
71:heat transfer coefficient
65:, non-viscous fluids the
793:. Taylor & Francis.
736:Greg F. Naterer (2002).
789:Ramesh K. Shah (1988).
75:Seider-Tate Correlation
67:Dittus-Boelter Equation
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589:
484:
439:
202:
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212:thermal conductivity
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772:978-0-8493-3653-9
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148:
128:
123:
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890:
886:Heat exchangers
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218:
217:
149:
129:
109:
104:
103:
83:Reynolds number
51:
22:Heat Exchangers
20:Tube (or Pipe)
12:
11:
5:
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865:External links
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87:Prandtl number
79:Nusselt number
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853:0-8342-1259-5
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825:0-7506-4444-3
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800:0-89116-729-3
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765:. CRC Press.
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749:
747:0-8493-1032-6
743:
740:. CRC Press.
739:
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55:thermodynamic
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19:
846:. Springer.
843:
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809:
790:
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666:
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491:
449:
446:
216:
209:
102:
91:
59:correlations
52:
43:transferring
16:
15:
720:References
714:NTU method
498:NTU method
18:Concentric
681:viscosity
610:≡
564:−
526:≡
472:Δ
409:⋅
342:
336:⋅
277:⋅
134:⋅
63:turbulent
880:Category
688:See also
35:boundary
31:parallel
677:annulus
662:fouling
850:
822:
797:
769:
744:
597:where
49:Theory
654:plate
27:fluid
848:ISBN
820:ISBN
795:ISBN
767:ISBN
742:ISBN
53:The
656:or
882::
834:^
781:^
728:^
339:ln
41:,
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828:.
803:.
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750:.
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415:D
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