Lead Performer: University of Virginia – Charlottesville, VA
March 24, 2021
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Lead Performer: University of Virginia – Charlottesville, VA
Partners:
-- Georgia Institute of Technology – Atlanta, GA
-- Tandem Repeat Technologies – Philadelphia, PA
DOE Total Funding: $1,500,000
Cost Share: $375,000
Project Term: April 1, 2020 – March 31, 2022
Funding Type: BENEFIT 2019 Funding Opportunity Announcement
Project Objective
Protein-based PCMs offer several revolutionary benefits, including room-temperature operation, an intrinsic safety profile, and switchable thermal conductivities that make possible new, more efficient heat-exchanger designs. Of interest to this program, the hydration-based storage capacity of the squid ring teeth (SRT) derived protein-based PCM allows for an incredibly unique thermal storage system design due to their unique abilities to rapidly switch their intrinsic thermal conductivities and energy storage densities based on hydration. Hydration of the SRT material at constant temperature causes an endothermic reaction, allowing the PCM to isothermally absorb heat from its surroundings, much like a traditional first-order phase transition. However, this hydration-based heat absorption can occur at any temperature between the hydrated glass transition temperature and the dry glass transition temperature. This allows for a novel system architecture that charges the PCM via dehydration at room temperature and discharges the PCM via hydration at the evaporator temperature. This way, the PCM can be stored at room temperature, whereas traditional PCMs must be stored below their freezing point. Upon successful completion, this project will present a formalized system architecture that best utilizes the SRT PCM behavior. As part of the design, we will identify the optimal method of hydrating and dehydrating the protein-based PCM, that will maximize the thermal conductivity switching ratio and energy storage density of the SRT derived protein-based PCM.
To enable the broad deployment of protein-based PCMs in heat exchangers for buildings, these materials must ultimately be manufactured at the megagram scale and at a cost that makes the exchangers market-competitive. The existing state of the art for manufacturing of protein-based PCMs is laboratory-scale batch production intended for academic research. In this project, we are building on that foundation to demonstrate kilogram-scale production of PCM, while maintaining purity to enable maximized thermal conductivity switching and thermal energy storage potential use in heat-exchanger prototyping. To achieve this improvement in scale, we are optimizing the PCM protein design, microbial production strain, feedstock, growth conditions, and purification parameters to increase the volumetric yield of the PCM and decrease the operational costs of production while maintaining the required standard of purity. In addition to producing PCM that can be used for later prototype construction, this effort will provide a manufacturing roadmap to inform future scale-up to pilot and commercial levels.
The novel operation of the SRT PCM thermal storage system will result in correspondingly unique thermodynamic and technoeconomic analysis results. Throughout the project, we will conduct thermodynamic analyses on the various system concepts, using the results to rank their individual merit. The results from the thermal analyses will relate material and system parameters (such as specific heat, glass transition temperatures, conductivity, and heat exchanger conductances) to the energy-savings capabilities of the various system designs. Not only will this inform the best potential SRT PCM thermal storage design, but it will also inform which parameters play the biggest role in system performance. Similarly, we are conducting technoeconomic analyses on the various system designs. Much like the thermal analysis results will inform key performance drivers, the technoeconomic results will inform which material and system properties can most improve the economics of the system. Throughout the course of the project, these results will be used internally for materials engineering feedback, leading to an optimized SRT PCM being produced by project completion.
Project Impact
Utilization of a novel, hydration-based protein PCM could lead to new thermal storage capabilities. By switching thermal conductivity, the PCM would require less insulation and could be easily integrated into the evaporator air handler unit of a building air conditioning system, thereby reducing the system cost. From an operational standpoint, the protein-based PCM will isothermally absorb heat when hydrated at any temperature above the hydrated glass transition (-20 deg C). This means that a single protein-based PCM can be used for thermal storage at multiple temperatures, allowing it to be used for both space heating and space cooling storage. This project represents a critical step on the path to commercialization of switchable protein-based PCM-based heat exchangers. Completion of the project objectives will demonstrate kilogram-scale production, measurements of thermal switching and storage capacity in this material, and modeling of heat-exchanger designs based on these data. Taken together, these achievements will provide convincing evidence that the technology warrants the greater investments necessary to fund the construction and testing of heat-exchanger prototypes as well as pilot-scale manufacturing of protein-based PCMs, notably the squid ring teeth derived proteins studied in this program.
Contacts
DOE Technology Manager: Sven Mumme, [email protected]
Lead Performer: Patrick Hopkins, University of Virginia