Modeling of horizontal tube-bundle absorbers of absorption cooling systems
A simplified-coupled model was developed for the analysis and design of horizontal tubular absorbers. The analysis included film-flow over tubes, drop and jet flow between tubes and the serpentine flow of the coolant. The predictions of the model were compared with experimental data and the predictions of a numerical simulation model. Both models included inter-tube flow and absorption. There is good agreement between the predictions of the two models, particularly when spatially varying heat and mass transfer coefficients are used in the simplified model. There is reasonable trend-wise agreement between the predictions of the two models and the experimental data. The simplified model was used to extract heat and mass transfer coefficients from published experimental data. The approximate expressions obtained for the exponents in the simplified model agreed well with exact analysis. The modeling of round tubes as vertical plate segments result in significant deviations in the predictions of the solution temperature and concentration. Partial wetting of the absorber tubes by the solution has a marked effect on the predictions of the two models.