Water desalination by membrane distillation is restricted by calcium carbonate precipitation on the membrane surface, what resulted in a progressive decline of the permeate flux. The module rinsing by HCl solution removed this deposit, however, such operation could cause the membrane wettability, associated with lowering of the permeate flux. This phenomenon was inhibited when the membrane modules with prefiltration element, assembled directly at the inlet to module, were used. The salt deposits were formed mainly on the surface of the filtration element (nets area constituted over 10% of the membranes area), what protected the membranes assembled inside the module. The filter efficiency decreased when the deposit layer covered the entire surface of pre-filter element, and after a few hours (period of 10-20 h) the formation of crystallite on the membrane surface was also observed. Therefore, the formed deposit was systematically removed (at every 5 h) from this pre-filter by 3 wt.% HCl solutions. The periodical rinsing of nets by acid did not have a negative influence on the membrane.
Badano efektywność wykorzystania ciepła w procesie destylacji membranowej w modułach kapilarnych o różnej konstrukcji. Sprawność termiczną określono jako stosunek ilości ciepła zużywanego na wytworzenie pary do całkowitej ilości ciepła wymienionej w module membranowym. Zbadano wpływ sposobu ułożenia membran w obudowie modułu oraz warunków jego eksploatacji (temperatura i natężenie przepływu strumieni) na wielkość ocenianego parametru.
EN
The influence of a capillary module design on the effectiveness of heat utilization in the membrane distillation (MD) process has been evaluated. Heat efficiency was defined as a ratio of the latent heat consumed in the evaporation to the total heat exchanged in the membrane module. The dependence of this parameter on the membrane arrangement within the MD capillary module and the working conditions (temperature and flow rates of streams) was investigated.
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