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 June 2023 – January 2024.
In this period, Makai’s efforts included improving TFHX fabrication methods; continued characterization of TFHX thermal and structural/mechanical performance, and investigation of biofouling mitigation methods.
TFHX Design
Development Makai introduced a new cassette design for large-scale (> 2 MWthermal) heat exchangers that require large stacks of plates. The cassette design is expected to reduce the total unit cost by eliminating individual modules and improve performance by eliminating two 90° turns in the seawater path.
Makai also delivered an air cooling unit (TFAC) to Blue Ocean Mariculture (BOM) and will be tracking performance once BOM installs it.
TFHX Fabrication
Makai continued to improve the fabrication fixtures, parameters, and quality control capabilities to reduce the fabrication time while improving plate success rates.
TFHX Characterization
Makai’s characterization efforts were focused on better understanding the parameters that affect fatigue life. In addition to the pattern design, Makai also evaluated the impact of process parameters such as the expansion pressure and incorporation of an extra unsupported expansion step on fatigue life.
TFHX Performance
Testing Makai fabricated four TFHXs for seawater-ammonia testing. Three of the four heat exchangers have been tested, each as an evaporator and a condenser. One heat exchanger remains to be tested.
Biofouling
Makai tested an automated in situ cleaning prototype. A baseline test for wider plate spacings was also initiated.