Condensation outside horizontal tubes

T = the tube loading, the condensate flow per unit length of tube, kg/m s. 

Using Kern s method, the mean coefficient for a tube bundle is given by  

For low-viscosity condensates the correction for the number of tube rows is generally ignored. 

A procedure for estimating the shell-side heat transfer in horizontal condensers is given in the Engineering Sciences Data Unit Design Guide, ESDU 84023. 

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Figure 8.14. Some arrangements of shell-and-tube condensers, (a) Condensate inside tubes, vertical upflow. (b) Inside tubes, vertical downflow, (c) Outside tubes, vertical downflow, (d) Condensate outside horizontal tubes. (HEDH, 1983, 3.4.3).

Condensation Outside Horizontal Tubes. Figure 8.14(d) shows a condenser with two tube passes and a shell side provided with vertically cut baffles that promote side to side flow of vapor. The tubes may be controlled partially flooded to ensure desired subcooling of the condensate or for control of upstream pressure by regulating the rate of condensation. Low-fin tubes often are advantageous, except when the surface tension of the condensates... 

Design the condenser of a steam power plant that has a thermal efficiency of 40 percent and generates 10 MW of net electric power. Steam enters the condenser as saturated vapor at 10 kPa, and it is to be condensed outside horizontal tubes through which cooling water from a nearby river flows. The temperature rise of the cooling water is limited to 8°C, and the velocity of the cooling water in the pipes is limited to 6 m/s to keep tile pressure drop at an acceptable level. Specify the pipe... 

Condensation outside Horizontal Tubes and Tube Banks.529... 

At low flow rates, a vapor may be condensed inside a horizontal or nearly horizontal tube under the condition that the condensate flhn drains down the inside surface of the tube by gravity and in laminar flow into the liquid pool at the bottom of the tube and then out the tube outlet. Kern [38] proposed a simple modification of the Nusselt equation for condensation outside horizontal tubes (see next section) that can be used for this case ... 

For shell-and-tube condensation related topics include evaporation (Section 16.11.4.1) and distillation (Section 16.11.4.2). Prefer condensation outside horizontal tubes use vertical tubes when condensing immiscible liquids to subcool the condensate. Assume pressure drop of 0.5 of the pressure drop calculated for the vapor at the inlet conditions. Baffle spacing is 0.2 to 1 times the shell diameter with the baffle window about 25%. Limit pressure drop for steam to 7 kPa on the shell side. U = 0.5 to 0.85 kW/m °C. 

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