The objective of this research is to combine renewable solar thermal energy and seawater membrane di stillation desa lination systems into green processes. The units of the systems include so lar collectors, heat exchangers and membrane distillation modules. In order to assess the economic design point of the process, the Aspen Custom Molder (ACM) was lIsed to build the mathematical model to describe each unit of so lar membrane distillation desa linat ion systems. Simulation results show that the optimal total annual costs (lAC) of direct contact (DeMD) and vacuum membrane di stillation (VMD) modules for 2000 kglhr water production are $844,200 and $576,359, respectively. The fundamental differences between De MD and VMD are driven by temperature and pressure difference between either side of the membrane. A larger temperature difference between the hot and cold sides of the membrane will require an increased heat supply from the so lar co llector and the heat exchanger. This wi ll calise a dramatic increase in cost of the so lar collector and the heat exchanger for De MD systems. The control structures of DCMD and VMD systems were built in order to maintain the water production rate. The operability ana lys is in the optimal design points were done for De MO and VMD systems with a typical summer solar intensity curve. For a short-term one day operability analysis in Taiwan, the 1.2 times overdesign of heat storage tank will handle the processes we ll either in De MO or VMD systems. Finally, the dynamic simulations of DeMO and VMD systems in summer are demonstrated to validate the operability analysis results. The water production amounts per day are 37.17 tOllS and 35.39 tons, respectively.
FILTRATION AND SEPARATION SYMPOSIUM 2013, pp.161-166