CALCULATION OF COOLING CURVES o Sensible Heat: 0=W Cp Tin-Tout For constant Cp:Q=w(Hin-Hout otherwise ◆ latent heat:Q=Wλ o Multicomponent Cooling Curves: Requires point-by- point flash calculations /2499 Heat Exchanger desigr
8/24/99 Heat Exchanger Design 6 CALCULATION OF COOLING CURVES u Sensible Heat: Q = W Cp (Tin - Tout) (For constant Cp: Q = W (Hin - Hout) otherwise) u Latent Heat: Q = W l u Multicomponent Cooling Curves: Requires point-bypoint flash calculations
FEASIBLE COOLING CURVE PAIRINGS Corollary of the Second Law of Thermodynamics Heat can only be transferred from a higher temperature to a lower one For heat exchangers this means that the higher temperature cooling curve and the lower temperature heating curve cannot intersect. o When this condition is satisfied, the pairing of a heating and cooling curve is said to be feasible /2499 Heat Exchanger desigr
8/24/99 Heat Exchanger Design 7 FEASIBLE COOLING CURVE PAIRINGS u Corollary of the Second Law of Thermodynamics: Heat can only be transferred from a higher temperature to a lower one. u For heat exchangers this means that the higher temperature cooling curve and the lower temperature heating curve cannot intersect. u When this condition is satisfied, the pairing of a heating and cooling curve is said to be feasible