Design and performance of multi port mini channel compact condensers for multistage flash thermal desalination

Tube bank condensers used to recuperate heat into brine in stages of Multistage Flash (MSF) desalination plants are expensive and large. In this study, the potential for use of compact Multiport Mini channel Condensers (MMC) for MSF is assessed using experiments and parametric modeling. Experiments are performed on a single MMC plate, as well as a bank of 5 MMC plates arranged in two rows, for various liquid flow rates and vapor side subcooling temperatures. The impact of using hydrophobic coating on the performance of the single and 5 plate bank is also assessed. Experimental results indicate that there is a significant improvement in performance of the MMC, especially at higher liquid flow rates, by using the coating. A minimum spacing is needed to ensure that vapor flow in the 5-plate MMC is not constricted. Data from experiments are used to validate a resistance-based model. The model, validated to within 10% of experiments, is then used to design an MMC for MSF, and its performance is compared against baseline tube bank using three non-dimensional parameters- heat transfer coefficient ratio, pressure drop ratio, and volume ratio. Results indicate that it is possible to obtain between 9 and 11 times smaller MMC condenser operating at lower pressure drop compared to the tube bank, along with an 18% reduction in flash chamber volume. • Multiport Minichannel Condenser (MMC) for multi-stage flash desalination proposed. • Minimum condenser plate spacing controlled by vapor flow characterized. • Hydrophobic coating can reduce condenser plate spacing increasing compactness. • Model validated with experimental results to within 10%. • Hydrophobic MMC can be 11× smaller volume at 80% of tube-bundle pressure drop. • Polymer MMC designs that perform better than metal tube bundle identified.