A plate heat exchanger (PHE) is used as an evaporator in ocean thermal energy conversion systems to generate electricity using seawater. A commonly used material for the PHE is titanium owing to its high corrosion resistance for seawater and ammonia, which are used as heat source and working fluid. To reduce the cost of the PHE, the authors propose using aluminum instead of titanium. However, as sufficient information on ammonia tolerance in aluminum materials is not available, a tolerance test was performed. A total of 15 test-pieces, including 5 aluminum pieces without coating (A1050, A3003, A5052, A5182, A6061), 7 coated aluminum pieces (PEEK film, WINKOTE film, Anodized, Anodized composite film), and 3 pieces made of other materials (Type 304 and 316 Stainless Steel, Titanium), were tested. The time taken to complete the test was approximately one hour, and the changes in mass and surface conditions were recorded. Pitting corrosion appeared on all test pieces without coating on the 7th day, and the A1050 experienced maximum mass reduction. However, the A1050 test pieces with anodized film exhibited no changes in mass and surface conditions for the duration of a year. Hence, anodized aluminum can be used in an ammonia-boiling environments.

For predicting hot tearing during casting process, viscosity properties and constitutive equations in the semi-solid region are required. In this research, viscosity properties of two alloys, which are Al-5mass%Mg alloy with Ti-B grain-refiner and Al-2mass%Cu alloy with Ti-B grain-refiner, are estimated using the image-based modelling method as suggested by Matsushita et al. As to the mechanical properties of the solid phase in semi-solid region, it is found that by using the temperature dependent value rather than the value just below the solidus temperature, the prediction accuracy of the viscosity value in semi-solid region has increased. By comparing the obtained numerical properties with the experimental properties, it is found that the method can predict the viscosity properties of Al5mass%Mg alloy and Al-2mass%Cu alloy in the semi-solid region at the solid fraction where hot tears are likely to occur.

The precursor foaming process is one of the fabrication processes used for the fabrication of aluminum foam. In this study, the shaping of the aluminum foam was conducted by press forming during foaming precursor. A pin screen mold was proposed for the die of the press forming. It was shown that the pin screen mold could be used for the die of the press forming of the aluminum foam, and star-shaped aluminum foam can be obtained. From X-ray computed tomography (CT) observation, there is little effect of press forming by using pin screen mold on the pore structures of the obtained aluminum foam.