Shell-Side Heat Transfer and Pressure Drop Single Phase

The loss in terms of velocity heads can be estimated by counting the number of flow contractions, expansions, and reversals, and using the factors for pipe fittings to estimate the number of velocity heads lost. For two tube passes, there will be two contractions, two expansions, and one flow reversal. The head loss for each of these effects is contraction 0.5, expansion 1.0, 180° bend 1.5 so for two passes the maximum loss will be 

From this, it appears that Frank s recommended value of 2.5 velocity heads per pass is the most realistic value to use. 

Combining this factor with equation 12.19 gives 

Another source of pressure drop will be the flow expansion and contraction at the exchanger inlet and outlet nozzles. This can be estimated by adding one velocity head for the inlet and 0.5 for the outlet, based on the nozzle velocities. 

Note The friction factor/ is the same as the friction factor for pipes cf) (= (PJpu )). 

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Shell-Side Heat Transfer and Pressure Drop (Single Phase) Condensers... 

SHELL-SIDE HEAT TRANSFER AND PRESSURE DROP (SINGLE PHASE)... 

The geometry of coiled-tube heat exchangers can be varied widely to obtain optimum flow conditions for all streams and still meet heat transfer and pressure drop requirements. However, optimization of a coiled-tube heat exchanger design is very involved and complex. There are numerous variables, such as tube and shell flow velocities, tube diameter, tube pitch, and layer spacer diameter. Other considerations include single-phase and two-phase flow, condensation on either the tube or shell side, and boiling or evaporation on either the tube or shell side. Additional complications come into play when multicomponent streams are present, as in natural gas liquefaction, since mass transfer accompanies the heat transfer in the two-phase region. 

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