Antifreeze-Permeation Behavior in a Small-Size Liquid Cooling System
Rintaro MINAMITANI and Shinji MATSUSHITA
Abstract:To ensure reliable operation and high performance of small-size liquid cooling systems, it is essential to evaluate the liquid-permeation behavior of polymer and to optimize the liquid weight in the system. Accordingly, the present study quantifies the liquid-permeation behavior of an isobutylene-isoprene rubber (IIR) tube and a nickel-plated syndiotactic polystyrene (SPS) plate in antifreeze, namely, a water-propyleneglycol solution. It was found that the IIR tube is permeable to only water in the antifreeze, not to propyleneglycol, because the water vapor pressure is 340 times higher than the propyleneglycol vapor pressure. Moreover, the nickel plated SPS plate has negligible low liquid-permeability, because the liquid barrier produced by the nickel plating is 10 times better than that by the non-plated SPS plate. Accordingly, after long-term operation of the small-size liquid cooling system, the above-mentioned selective water permeation in antifreeze leads to degradation of cooling performance. This is because the viscosity of the antifreeze and pressure losses in the cooling path increase as a result of the increased antifreeze concentration. These liquid-permeations and concentration changes of antifreeze must therefore be taken into consideration when specifying the required liquid weight in the liquid cooling system. Key Words:Liquid permeation, Polymer, Antifreeze, Vapor pressure, Liquid cooling system