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Ocean Thermal Energy Conversion (OTEC) Heat Exchanger Development (August 2022 to May 2023)

Report

Title: Ocean Thermal Energy Conversion (OTEC) Heat Exchanger Development (August 2022 to May 2023)
Author:
Makai Ocean Engineering
Publication Date:
Pages:
60
Sponsoring Organization:
Hawaii Natural Energy Institute
Technology:
OTEC
Collection Method:
Lab Data, Modeling
Operations:
Fouling
Engineering:
Performance
Language:
English

Document Access

Website:
External Link
Attachment: Access File
Notice: This material may be protected by Copyright Law.
(4.2 MB)

Citation

Makai Ocean Engineering (2023). Ocean Thermal Energy Conversion (OTEC) Heat Exchanger Development (August 2022 to May 2023). Report for Hawaii Natural Energy Institute.
TY - RPRT
TI - Ocean Thermal Energy Conversion (OTEC) Heat Exchanger Development (August 2022 to May 2023)
AU - Makai Ocean Engineering
AB - 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 2022 – May 2023.In this period, Makai’s efforts included introduction of new TFHX designs; implementation of weld defect identification and repair method; continued characterization of TFHX thermal and structural/mechanical performance, and initiation of biofouling mitigation methods.TFHX Design Makai introduced two new designs, one intended for seawater application with a different form factor (TFPX) and a pass-through design intended for air cooling (TFAC). Makai also established operating ranges and sizes for the existing modular design.TFHX Fabrication Makai completed the disassembly and re-assembly of the High Speed Welding Station (HSWS) and move to the new Fabrication Lab. With this move, all fabrication equipment is located in the same room and efficiency has been improved by having all the process steps in the same room.Makai also developed and implemented a weld defect identification and repair system which has improved plate fabrication success rates from 50% to 77%. Makai will continue to improve the algorithm and repair techniques.TFHX Performance Makai developed additional pattern designs for seawater-ammonia testing, including varying the internal channel size across a plate and adding features to improve ammonia convection. Makai conducted seawater-ammonia performance tests on seven variations of the modular 4-port TFHX design. Makai also tested the new TFPX and TFAC designs.TFHX Characterization Makai’s characterization efforts were focused on better understanding the parameters that affect fatigue life. Makai identified a fabrication step that led to a 3X increase in fatigue life.Biofouling Makai established a baseline for biofouling performance of an untreated module in warm seawater and evaluated the efficacy of a commercially available biofouling mitigation device. Makai also designed, constructed, and started testing on the first manual cleaning prototype. Initial results indicate that the biofouling control methods have delayed the onset of biofouling-induced performance degradation, but have not successfully eliminated or mitigated performance impacts caused by biofouling.
DA - 2023/06//
PY - 2023
SP - 60
UR - https://www.hnei.hawaii.edu/publications/project-reports/aprises-18/
LA - English
KW - OTEC
KW - Lab Data
KW - Modeling
KW - Performance
KW - Fouling
ER -
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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 2022 – May 2023.

In this period, Makai’s efforts included introduction of new TFHX designs; implementation of weld defect identification and repair method; continued characterization of TFHX thermal and structural/mechanical performance, and initiation of biofouling mitigation methods.

TFHX Design 

Makai introduced two new designs, one intended for seawater application with a different form factor (TFPX) and a pass-through design intended for air cooling (TFAC). Makai also established operating ranges and sizes for the existing modular design.

TFHX Fabrication 

Makai completed the disassembly and re-assembly of the High Speed Welding Station (HSWS) and move to the new Fabrication Lab. With this move, all fabrication equipment is located in the same room and efficiency has been improved by having all the process steps in the same room.

Makai also developed and implemented a weld defect identification and repair system which has improved plate fabrication success rates from 50% to 77%. Makai will continue to improve the algorithm and repair techniques.

TFHX Performance 

Makai developed additional pattern designs for seawater-ammonia testing, including varying the internal channel size across a plate and adding features to improve ammonia convection. Makai conducted seawater-ammonia performance tests on seven variations of the modular 4-port TFHX design. Makai also tested the new TFPX and TFAC designs.

TFHX Characterization 

Makai’s characterization efforts were focused on better understanding the parameters that affect fatigue life. Makai identified a fabrication step that led to a 3X increase in fatigue life.

Biofouling 

Makai established a baseline for biofouling performance of an untreated module in warm seawater and evaluated the efficacy of a commercially available biofouling mitigation device. Makai also designed, constructed, and started testing on the first manual cleaning prototype. Initial results indicate that the biofouling control methods have delayed the onset of biofouling-induced performance degradation, but have not successfully eliminated or mitigated performance impacts caused by biofouling.