Heat transfer chlorine cooler

In a chlorine cooler, flows usually are single-pass and nearly countercurrent, but the behavior of the At is highly nonlinear and its mean is not calculable simply from end conditions. The composition of the gas phase also changes drastically as it passes through the cooler. This causes the heat-transfer coefficient to drop to a fraction of its value at the entrance to the cooler. This effect is discussed below in Section 9.1.3.2. 

Design of hydrogen coolers must provide for a steady decrease in the heat-transfer coefficient as diffusion of the remaining water to a cold surface becomes more difficult. Because of the generally higher diffusion coefficients in hydrogen systems, the effect is less marked here than in the case of chlorine cooling. 

As noted above, a second exchanger cooled with chilled water is often added to increase the removal of water. All the problems referred to above with increasing mass-transfer resistances occur in this second exchanger as well. Added to this problem is the fact that the gas entering the exchanger is much leaner in water. The net result is that unit heat fluxes in chlorine chillers are much lower than those in the coolers, perhaps by a factor of five or ten. 

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