Fouling freezing

If measured pressure drops are significantly lower than calculated drops, this might indicate fluid bypassing, which could occur either on tube side or shell side. On the other hand, if measured pressure drop is too high, this is often caused by severe fouling, freezing, or slug flow for two-phase flows. 

Freezing fouling. Overcoohng of a fluid below the fluids freezing point at the heat-transfer surface causes solidification and coating or the heat-transfer surface. 

Synonym dithiocarbonic anhydride Formula CS2 MW 76.13 CAS [75-15-0] used in the manufacture of rayon and soil disinfectants and as a solvent colorless liquid with a strong foul odor boils at 46.5°C freezes at -111.6°C density 1.263 g/mL at 20°C slightly soluble in water (0.22% at 20°C) miscible with alcohol, ether, benzene, and chloroform highly toxic and flammable (Patnaik, 1992). 

Fouling factors, heat transfer, 180 data, 183, 184, 186 Fourier equation, 169 Fractionation. See Distillation Fractionator conntrol lower ends, 49,50 upper ends, 51,52 Freeze drying, 639 cvcle lengths. 639 products 646 Friction, 93 Friction factor, 92 Colebrook equation, 94 granular beds, 117 non-Newtonian fluids, 109 Rounds equation, 94... 

The knowledge of wall temperature in a heat exchanger is essential to determine localized hot spots, freeze points, thermal stresses, local fouling characteristics, or boiling/condensing coefficients. Based on the thermal circuit of Fig. 17.22, when R. is negligible, TKk = Tw%c = T is computed from... 

Intermediate pressure. Noncorrosive vapor. Severe coolant or moderate vapor fouling. Can handle freezing condensate. Tube vibration problems. Multipassing and variable baffle spacing can be used for total condensation. Good venting control. 

Any action in mitigating flow maldistribution must be preceded by an identification of possible reasons that may cause the performance deterioration and/or may affect mechanical characteristics of the heat exchanger. The possible reasons that affect the performance are [131,147] (1) deterioration in the heat exchanger effectiveness and pressure drop characteristics, (2) fluid freezing, as in viscous flow coolers, (3) fluid deterioration, (4) enhanced fouling, and (5) mechanical and tube vibration problems (flow-induced vibrations as a consequence of flow instabilities, wear, fretting, erosion, corrosion, and mechanical failure). 

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