Prediction and experimental investigation of heat and mass transfer characteristics of a horizontal tube bundle absorber

摘要

One of the main obstacles in the design process of absorption chillers is the accurate prediction of the heatand mass transfer coefficients for all the heat exchangers. This refers especially for the absorber, where thelowest heat transfer coefficients are expected due to the coupled heat and mass transfer process duringabsorption. Appropriate correlations for the calculation of the heat and mass transfer coefficients ofhorizontal tube bundle absorbers are discussed by literature research in this work and are applied on the heatexchanger’s geometry of a self-designed and constructed absorption chiller. The correlations are discussedconcerning their dependence on the solution mass flow rate and the considered physical properties. Theresults of the correlations are validated with experimental data of the self-designed absorption chiller.It is shown that the dependence of the heat transfer coefficient on the material properties is taken intoaccount in the same way in all correlations. In contrast to this, there is no agreement in the correlations onwhich way the mass transfer is affected by the material properties. Due to different flow regimes in the filmwhich are considered in particular correlations, no uniform influence of the solution mass flow rate on theheat and mass transfer is identified. Basically all correlation overestimate heat transfer coefficients or do notshow the same dependence of the heat transfer coefficient on the solution mass flow rate compared toexperimental data. Only the results of one of the correlations for heat transfer are suitable, but only for lowsolution flow rates.