Cheng-Liang Chang

Optimization Study of Small-Scale Solar Membrane Distillation Desalination Systems (s-SMDDS)

Membrane distillation (MD), which can utilize low-grade thermal energy, has been extensively studied for desalination. By incorporating solar thermal energy, the solar membrane distillation desalination system (SMDDS) is a potential technology for resolving energy and water resource problems. Small-scale SMDDS (s-SMDDS) is an attractive and viable option for the production of fresh water for small communities in remote arid areas. The minimum cost design and operation of s-SMDDS are determined by a systematic method, which involves a pseudo-steady-state approach for equipment sizing and dynamic optimization using overall system mathematical models. Two s-SMDDS employing an air gap membrane distillation module with membrane areas of 11.5 m2 and 23 m2 are analyzed. The lowest water production costs are

COOL THERMAL STORAGE COUPLED WITH WATER TREATMENT BY NORMAL FREEZING OF DILUTE AQUEOUS SOLUTIONS

5.92/m3 and

Simulation study of desalination performance for two large-scale air gap membrane distillation modules

5.16/m3 for water production rates of 500 kg/day and 1000 kg/day, respectively. For these two optimal cases, the performance ratios are 0.85 and 0.91; the recovery ratios are 4.07% and 4.57%. The effect of membrane characteristics on the production cost is investigated. For the commercial membrane employed in this study, the increase of the membrane mass transfer coefficient up to two times is beneficial for cost reduction.

Theoretical and experimental studies of flux enhancement with roughened surface in direct contact membrane distillation desalination

Mathematical models of normal freezing and zone melting are employed to describe the thickness and the solute distribution of solid crystal in a cool thermal storage process. The equations for estimating the optimum solidification thickness and operating time to remove the maximum amount of solute are derived. The estimation of optimal operating conditions has been illustrated with the temperature of free surface and the depth of aqueous solution as parameters. The temperature of free surface is an important factor in evaluating the efficiency and the pay-off of the process.

CFD simulation of the two-phase flow for a falling film microreactor

Abstract Being capable of utilizing low-grade thermal energy, membrane distillation (MD) has evolved as a promising technology for desalination. This paper reports the simulation study of two large-scale MD modules reported in the literature, a spiral wound type and a flat plate type. A mathematical model, which considers the heat and mass transfer mechanisms for all the composing layers of the module, is used. For both modules, the heat and mass transfer resistance and the performance enhancement by modifying design parameters and operating conditions are analyzed. The significant directions and quantitative potential of improvement are identified. Compared to the bases cases, the flux enhancement from modifying module parameters can be as high as about 10% for the spiral wound module and about 100% for the flat plate module. The flux enhancement from modifying operation conditions can be as high as about 50% for both modules.