Abstract
Makai Ocean Engineering has been developing Thin Foil Heat Exchangers (TFHX) for use in seawater-refrigerant, air-water, and water-water applications. This report summarizes work performed between August 2021 – June 2022.
In this period, Makai’s efforts focused on improving TFHX fabrication success, developing TFHX production quality control methods, and continuing with thermal, hydraulic, and mechanical/structural characterization.
TFHX Design and Characterization. In this period, Makai introduced different materials and additional weld parameters and designs that expanded TFHX pressure capacity and channel sizes and began geometric and mechanical characterization of these new combinations. A welding analysis tool was also developed to guide optics and weld parameter selection. A new insert and sealing method, which is compatible for high operating temperatures and pressures, was also tested.
TFHX Fabrication. Makai focused fabrication efforts on improving success rates to achieve reliable, repeatable, high-quality TFHX plates. This required revisions to improve existing fabrication equipment and fixturing and new tooling and methods to monitor, evaluate, and repair TFHX plates during and after fabrication. Makai also commissioned the cutting station to remove the excess foil after a TFHX plate is fabricated.
All-Welded Design. Makai advanced the all-welded TFHX (AW-TFHX) technology by demonstrating the internal manifold weld. Makai completed the design and procurement of fixturing to weld and pressure test stacks of all-welded plates.
Stand-Alone TFHX Demonstration. In this period, Makai tested three ammonia-seawater (OTEC) TFHXs and three seawater-seawater (SWAC) TFHXs. Makai also started a long-term biofouling test.