• Clean Technology
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• v.20 no.1
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• pp.13-21
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• 2014

Because of the water scarcity caused by the increase of salinity in the underground water, seawater desalination stands out as one of the most promising solution. As there are so much energy costs in operating desalination plants, new hybrid process which is more effective should be researched. A geothermal VMD (vacuum membrane distillation) hybrid process is a competitive alternative for seawater desalination. Because geothermal energy has significant characteristics of high capacity factor to operate the power plant at full capacity for 24 hour per day, it can be a priority heat source of VMD superior to any other renewable energies such as solar and wind power. In this study, we design a geothermal VMD hybrid process, analyze it economically and finally compare the result with a case of conventional VMD process. Geothermal VMD hybrid process generates $23,822,409 of NPV (net present value) more than the conventional VMD process in case of 5% discount rate. The break-even point between these processes is 5.36 year. Sensitivity analysis indicates that steam cost is the most decisive influence variable to the economic outcome.

• Journal of the Korean Solar Energy Society
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• v.34 no.5
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• pp.23-31
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• 2014

This study was accomplished to get the foundation design data of VMD(Vacuum Membrane Distillation) system for Solar Thermal VMD plant. VMD experiment was designed to evaluate thermal performance of VMD using PVDF(polyvinylidene fluoride) hollow fiber hydrophobic membranes. The total membrane surface area in a VMD module is $5.3m^2$. Experimental equipments to evaluate VMD system consists of various parts such as VMD module, heat exchanger, heater, storage tank, pump, flow meter, micro filter. The experimental conditions to evaluate VMD module were salt concentration, temperature, flow rate of feed sea water. Salt concentration of feed water were used by aqueous NaCl solutions of 25g/l, 35g/l and 45g/l concentration. As a result, increase in permeate flux of VMD module is due to the increasing feed water temperature and feed water flow rate. Also, decrease in permeate flux of VMD module is due to increasing salinity of feed water. VMD module required about 590 kWh/day of heating energy to produce $1m^3/day$ of fresh water.

• Journal of Korean Society of Water and Wastewater
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• v.30 no.3
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• pp.313-319
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• 2016

In this study, the performance experiment was conducted to compare the permeate flux of hollow fiber Vacuum Membrane Distillation module according to leak problem between module housing and membrane bundle. For the permeate flux performance experiment of the two Vacuum Membrane Distillation modules, the Lab-scale experimental equipment was built in the capacity of $1m^3/day$. The performance test of the two Vacuum Membrane Distillation modules were analyzed according to the feed water conditions. As a result, it was analyzed that the leak VMD module decreased about 14% of permeate flux than normal VMD module.

• Journal of Korean Society of Water and Wastewater
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• v.31 no.4
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• pp.339-346
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• 2017

In this study, thermal performance test of VMD module was performed, prior to the construction of the demonstration plant using the vacuum membrane distillation (VMD) module of the capacity of $400m^3/day$ and to the commercialization of the VMD module. For the thermal performance test, the experimental equipment of capacity of $2m^3/day$ was constructed. The permeate flux test and thermal performance test according to feed water conditions such as temperature and flow rate were conducted. The VMD module used in the study was manufactured by ECONITY Co., LTD with PVDF hollow fiber membrane. As a result, the Performance Ratio (PR) of the VMD module showed the maximum value of 0.904 under the condition of feed water temperature of $75^{\circ}C$ and flow rate of $8m^3/h$. PR value of the VMD module using PVDF hollow fiber membrane showed linearly increasing relationship with feed water temperature and flow rate. Also, The permeate flux of the VMD module was analyzed to have maximum value of 18.25 LMH and the salt rejection was 99.99%.