Advanced Ceramic Binder Jetting Heat Exchangers

In a recent article published in the journal Additive manufacturingresearchers discussed the utility of ceramic heat exchangers fabricated by binder jetting additive manufacturing for concentrating solar energy applications with thermal energy storage in molten chlorides.

Study: Binder jetting additive manufacturing of ceramic heat exchangers for concentrated solar power applications with thermal energy storage in molten chlorides. Image Credit: shmai/Shutterstock.com

Background

The ability to distribute power on demand using thermal energy storage (TES) and a conventional heat engine sets Concentrating Solar Power (CSP) apart from other renewable energy sources. However, in order to achieve a competitive levelized cost of energy (LCOE), the costs of the CSP system must be reduced.

A recent study of several triply periodic minimum surfaces (TPMS) and periodic nodal surfaces as heat exchangers revealed that the Schwarz-D TPMS surface has outstanding heat transfer performance. Group IV-VI transition metal carbides, borides and composites are the most common ultra-high temperature ceramic (UHTC) materials. Before the introduction of additive manufacturing, TPMS devices were difficult to build.

Binder jetting additive manufacturing, unlike previous methods of fabricating ceramic TPMS structures, is emerging as a promising and scalable ceramic forming approach. Binder jetting has been used to create UHTC heat exchanger plates in combination with reactive infiltration, but it has not yet been used to fabricate UHTC TPMS structures which are sintered at high relative densities . Lessons learned from sintering nanomaterials show that low green densities from forming procedures are not always a problem and that achieving good uniformity is more important.

About the study

In this study, the authors demonstrated the feasibility of binder jetting additive manufacturing of a UHTC-TPMS structure by sintering and printing a null candidate. Components with a relative density of at least 92% theoretical, which were also part of the TPMS, were created.

The target density denoted the transition from the intermediate stage to the final stage of sintering, which was necessary for the sintering of the complex shapes close to the mesh at full density using the sinter-HIP technology and for the inhibition gas permeability. The purpose of the TPMS part demonstration was to see if the printing and sintering parameters derived from the test coupons applied to the complex geometries that would be used in the design of heat exchangers.

The team printed 9 cm3 cubic and sintered TPMS parts without deforming or breaking them. Advances in design topology, materials, and manufacturing to achieve best-in-class performance in molten chloride salts in a CSP heat exchanger have been proposed.

Researchers discussed the use of binder jetting additive manufacturing combined with sintering to build ZrB2-MoSi2 based UHTC-TPMS cells with particle sizes. Since ZrB2-MoSi2 has favorable processing characteristics and qualities, it was intentionally chosen as a null candidate to demonstrate the viability of UHTC-TPMS heat exchanger until the optimal UHTC material for the application can be determined.

Comments

The prepared structure had a length of 1.25 cm and a wall thickness of 1.5 mm as the final unit size. The measured densities were 5.62 to 5.80 g/cm3, i.e. 92 to 95% of the theoretical densities. Two of the three samples had a higher density, 5.90-5.94 g/cm3while one sample had a lower density of 5.65 g/cm3. Sintering of three samples at 2000 ºC for 18 hours gave densities ranging from 5.65 to 5.94 g/cm3, which were 93 to 98% of the theoretical value, while an increase in time between 1900 ºC and 18 hours gave a sample with a density of 5.66 g/cm3. The majority of particles were in the 1-5 μm range, with no particles larger than 7 μm.

Based on the Schwarz-D TPMS, ZrB2-MoSi2 composite components were sintered with an isotropic shrinkage of up to 60% by volume, resulting in theoretical densities of 92-96%. Compared to tube or plate based systems, a TPMS based heat exchanger offered the potential to increase power density. Using the achieved scaffold dimensions, a Schwarz-D TPMS based UHTC heat exchanger with molten salt and supercritical carbon dioxide working fluids could achieve a power density of up to 50 MW/m3.

conclusion

In conclusion, this study demonstrated that binder jetting additive manufacturing can be used to print and sinter UHTC-TPMS structures. To effectively limit the distortion, it was discovered that a spatial confinement strategy was needed. He was able to use traditional powdered raw materials with a d50 of around 2-3 m, which are the same sizes used in conventional UHTC processing. These materials were sintered to relative densities of 92-98% theoretical, high enough to prevent heat exchanger fluids from passing through the walls, separating the two domains and allowing hot isostatic pressing if a higher density is required.

The authors proposed to combine developments in the design, materials and production of CSP heat exchangers in light of these promising results. They mentioned that the largest binder jet printer on the market for printing ceramics has the potential to print a one-piece heat exchanger with a nominal capacity of up to 3 MW depending on this power density .

More AZoM: Consideration of the behavior of doped SrTiO3 ceramics

Source

Kelly, JP, Finkenauer, LR, Roy, P., et al. Binder jetting additive manufacturing of ceramic heat exchangers for concentrated solar power applications with thermal energy storage in molten chlorides. Additive manufacturing 102937 (2022).

https://www.sciencedirect.com/science/article/abs/pii/S2214860422003335

Disclaimer: The views expressed here are those of the author expressed privately and do not necessarily represent the views of AZoM.com Limited T/A AZoNetwork, the owner and operator of this website. This disclaimer forms part of the terms of use of this website.

Comments are closed.