Side coefficient

T. Single liquid drops in gas, gas side coefficient =2 + ANiS,Ni [E] Used for spray drying (arithmetic partial pressure difference). [88] p. 489... 

U. Single water drop in air, liquid side coefficient / jy l/2 ki = 2 ), short contact times / J 1 lcontact times dp [T] Use arithmetic concentration difference. Penetration theory, t = contact time of drop. Gives plot for k a also. Air-water system. [lll]p.. 389... 

Overall coefficients are determined hke shell and tube exchangers that is, sum all the resistances, then invert. The resistances include the hot-side coefficient, the cold-side coefficient, the fouhng factor (usually only a total value not individual values per fluid side) and the wall resistance. 

Only data on thermal properties of the fluid are necessarv to calculate mixer side coefficients in most... 

A, = area of inside of. surface for heat transfer, such as coil, flat surface, or other barrier, sq ft/ft h = inside heat transfer fluid side coefficient, in coil, flat plate, or otlier barrier, Btu/hr/sq fl/°F ro = fouling resistance (factor) associated wTth fluid on outside (tank process side) of heat transfer... 

Example If the shell-side coefficient of a unit is 25 Btu/hr (ft )(°F) and velocity in the shell is doubled, read the new shell-side coefficient, h as 36 (line a). If the tube-side coefficient is 25 and velocity is doubled, read the new tube coefficient, h, as 43.1 (line a). In other cases, pressure drop would increase by a factor of 4. Note This may be used in reverse for reduced flow. 

Shell-side coefficient vapor desuperheating or cooling. 

If the tube bundle is to be large in diameter, it is possible that the liquid head will suppress the boiling in the lower portion of the horizontal bundle thereby actually creating a liquid heating in this region, with boiling above this. Under such situations, the boiling in the unit cannot be considered for the full volume hence, there should be two shell-side coefficients calculated and the resultant areas added for the total. 

Determine net free flow area for air across bundle, and determine air linear velocity. Compare air side coefficients for same linear velocities. 

When processing (tube side) coefficients referred to the bare outside tube are less than 200 Btu/hr (fti) (°F), the... 

It is shown in Section 9.9.5 that, with the existence of various bypass and leakage streams in practical heat exchangers, the flow patterns of the shell-side fluid, as shown in Figure 9.79, are complex in the extreme and far removed from the idealised cross-flow situation discussed in Section 9.4.4. One simple way of using the equations for cross-flow presented in Section 9.4.4, however, is to multiply the shell-side coefficient obtained from these equations by the factor 0.6 in order to obtain at least an estimate of the shell-side coefficient in a practical situation. The pioneering work of Kern(28) and DoNOHUE(lll who used correlations based on the total stream flow and empirical methods to allow for the performance of real exchangers compared with that for cross-flow over ideal tube banks, went much further and. 

The water-side coefficient may now be calculated using equation 9.218, although here, use will be made of the ji, factor. 

It is known from previous measurements under similar conditions that the oil side coefficients of heat transfer for a velocity of 1 m/s. baaed on a diameter of 38 mm. vary with the temperature of the oil as follows ... 

This section is concerned with the UA xtiT — Text) term in the energy balance for a stirred tank. The usual and simplest case is heat transfer from a jacket. Then A xt refers to the inside surface area of the tank that is jacketed on the outside and in contact with the fluid on the inside. The temperature difference, T - Text, is between the bulk fluid in the tank and the heat transfer medium in the jacket. The overall heat transfer coefficient includes the usual contributions from wall resistance and jacket-side coefficient, but the inside coefficient is normally limiting. A correlation applicable to turbine, paddle, and propeller agitators is... 

The complex flow pattern on the shell-side, and the great number of variables involved, make it difficult to predict the shell-side coefficient and pressure drop with complete assurance. In methods used for the design of exchangers prior to about 1960 no attempt was made to account for the leakage and bypass streams. Correlations were based on the total stream flow, and empirical methods were used to account for the performance of real exchangers compared with that for cross flow over ideal tube banks. Typical of these bulk-flow methods are those of Kern (1950) and Donohue (1955). Reliable predictions can only be achieved by comprehensive analysis of the contribution to heat transfer and pressure drop made by the individual streams shown in Figure 12.26. Tinker (1951, 1958) published the first detailed stream-analysis method for predicting shell-side heat-transfer coefficients and pressure drop, and the methods subsequently developed... 

Shell i.d. 387, baffle spacing 77.9 mm, 15% cut. Tube-side coefficient 851 W/m2oC, clean. 

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