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Experimental Heat Transfer Correlations For A Liquid-Liquid Two Phase System In A Compact Heat Exchanger

S.Ramachandran, P.Kalaichelvi, S.Sundaram

Heat transfer using new generation compact heat exchangers in two-phase process streams are increasingly encountered in process industries. Investigation of the rates of momentum and heat transfer for two phase systems is a must for an optimal design of the heat exchanger. Experimental studies in laminar range were conducted in a spiral plate heat exchanger with hot water as the heating fluid and the two-phase mixture of waternitrobenzene in different mass fractions and flow rates as the process fluid. The experimental heat transfer coefficients on the process side were correlated with Reynolds numbers and were fitted into an equation h = a Re m, adopting an approach available in literature for two phase fluid flow studies. The heat transfer coefficients were also related to the mass fraction of nitrobenzene for identical Reynolds numbers. The two-phase multiplier (ratio of the heat transfer coefficient of the two phase fluid and that of the single phase fluid - Ï•L) was correlated with the Lockhart Martinelli parameter (χtt 2) in the form Ï•L=1+C/χtt+1/χtt 2. This correlation enables calculation of the two-phase heat transfer coefficients using single-phase data. The calculated coefficients showed a variance of ± 8 % over the experimental values.