• Mustapha, Karkri
• Sobolčiak, Patrik
• Abdulgader, Asma
• Bart, Hans-Jörg
• Popelka, Anton
• Aboukhlewa, Abdelnasser A.
• Krupa, Igor
• Mrlik, Miroslav
• Abdala, Ahmed A.
• Kiepfer, Hendrik

Abstract

<jats:p>Composites of high-density polyethylene (HDPE) and expanded graphite (EG) are prepared for heat exchangers in multi-effect distillation (MED) desalination. At 50 wt.% EG loading, the thermal conductivity of HDPE was increased by 372%. Moreover, the surface wettability of the HDPE/EG composite was enhanced by corona and RF plasma treatment as demonstrated by the increase in surface free energy from 28.5 mJ/m2 for untreated HDPE/EG to 55.5 and 54.5 mJ/m2 for HDPE/EG treated by corona and RF plasma, respectively. This enhanced surface wettability was retained over a long time with only a 9% and 18% decrease in RF and corona plasma-treated samples’ surface energy after two months. The viscoelastic moduli and the complex viscosity profiles indicated that EG content dictates the optimum processing technique. At loading below 30 wt.%, the extrusion process is preferred, while above 30 wt.% loading, injection molding is preferred. The plasma treatment also improved the HDPE/EG composite overall heat transfer coefficient with an overall heat transfer coefficient of the composite reaching about 98% that of stainless steel. Moreover, the plasma-treated composite exhibited superior resistance to crystallization fouling in both CaSO4 solution and artificial seawater compared to untreated composites and stainless-steel surfaces.</jats:p>

Topics

• density
• impedance spectroscopy
• surface
• stainless steel
• extrusion
• composite
• viscosity
• injection molding
• thermal conductivity
• crystallization
• surface energy
• distillation