Tube Spacing

Turbulent Flow The correlation by Grimison (Trans. ASME, 59, 583—.594 [1937]) is recommended for predicting pressure drop for turbulent flow (Re > 2,000) across staggered or in-hne tube banks for tube spacings [(a/Dt), (b/Dt)] ranging from 1.25 to 3.0. The pressure drop is given by... 

For banks of in-line tubes,/for isothermal flow is obtained from Fig. 6-43. Average deviation from available data is on the order of 15 percent. For tube spacings greater than 3D(, the charts of Gram, Mackey, and Monroe (Trans. ASME, 80, 25—35 [1958]) can be used. As an approximation, the pressure drop can be taken as 0.32 velocity head (based on V ) per row of tubes (Lapple, et al.. Fluid and Paiiicle Mechanics, University of Delaware, Newark, 1954). 

For a single row of tubes, the friction fac tor is given by Curve B in Fig. 6-44 as a function of tube spacing. This curve is based on the... 

Convection tube spacing is important when the fuel is residual oil or coal, especially co with low asn-fusion or high ash-fouling tendencies. The amount of the ash and, even more important, the characteristics of the ash must be specified for design. 

The tube diameter, d(, and tube spacing influence the film coefficient, hp. The work of Oldshue [29] covers a practical range about as large and as small as is industrially used. The tube spacing of 2 to 4 tube diameters produced consistent results. 

G is the single tube mass velocity through the (p-d) tube space, defined as ... 

This is the exchanger where heat flows from the room return or mixed air to cold refrigerant or to chilled water. It is an arrangement of finned tubes normally of aluminum fins on copper tubes, but copper fins can be specified for corrosive atmosphere. Performance characteristics are controlled by fin and tube spacing. If the room rh is high, dehumidification may be brought into use by operating the coil or one of a number of parallel coils at a low temperature. If the room s sensible heat load is low reheat must be allowed to operate at the same time. 

A boiler bank is also included. The boiler-bank tube bundle provides sufficient heat transfer surface area to provide the rated capacity for saturated steam. Boiler-bank tube spacing and dimensions are arranged so that a steam-water circulation subsystem connects the top and bottom drums with subcooled water passing down the tubes farthest from the furnace and returning as a steam-water mixture. 

In a tube bundle the vapour rising from the lower rows of tubes passes over the upper rows. This has two opposing effects there will be a tendency for the rising vapour to blanket the upper tubes, particularly if the tube spacing is close, which will reduce the heat-transfer rate but this is offset by the increased turbulence caused by the rising vapour bubbles. Palen and Small (1964) give a detailed procedure for kettle reboiler design in... 

Tube spacing and tube inside and outside diameters (Df, D0). 

The tube spacing promotes turbulence and hence good heat transfer. 

FIG. 6-45 Friction factors for transition region flow across tube banks. (Pitch is the minimum center-to-center tube spacing.) (From Bergelin, Brown, and Doberstein, Trans. ASME, 74, 953 [1952].)... 

A cube of data sized (mxnxp) can be unfolded in three different directions along the row space, along the column space, and along the third direction of the cube, also called the tube space. The three unfolding procedures give a row-wise... 

UNFOLD KEEPING TUBE SPACE INTACT for z=0 nsam-l... 

In Eqs. (33) and (34), best results are obtained if xT is between 1.5 and 4.0. For design purposes, the range can be extended down to 1.25. When the Reynolds number is between 2000 and 10,600 with tubes in line, f for a given tube spacing can be assumed to be constant at the value obtained when the Reynolds number is 10,060. 

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