Browsing by Author "Richard, Bradley"
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Item Development of a 3D Printed Loop Heat Pipe(49th International Conference on Environmental Systems, 2019-07-07) Richard, Bradley; Anderson, William; Crawmer, Joel; Augustine, Merryl; Chen, Chien-HuaAs the capabilities of CubeSats and SmallSats increase so do the heat rejection requirements. While loop heat pipes (LHPs) are capable of transporting heat across deployable radiators they are currently too expensive for most applications. The largest cost comes from the fabrication of the primary wick which requires multiple machining steps as well as a knife-edge seal. The focus of this work is the development of a 3D printed LHP evaporator using a direct metal laser sintering (DMLS) process to fabricate the primary wick. 3D printing LHP wicks offers several advantages. The overall cost can be significantly reduced by eliminating multiple machining steps, and the risk of failure can be reduced by eliminating the knife-edge seal. The challenge with 3D printing of LHPs us achieving a porous wick structure. A pore radius and permeability study was conducted for optimization of DMLS methods and parameters for fabricating both the primary and secondary wick. The primary wick and secondary wick were also fabricated as a single part to test the ability to connect areas of varying pore size. Experimental testing was completed on a complete LHP prototype with 3D printed primary wick fabricated using the optimized DMLS parameters. Life testing has been completed to demonstrate compatibility of the 3D printed stainless steel wicks with ammonia.Item Loop Heat Pipe Wick Fabrication via Additive Manufacturing(48th International Conference on Environmental Systems, 2018-07-08) Richard, Bradley; Anderson, William; Pellicone, DevinAs the capabilities of CubeSats and SmallSats increase so do the heat rejection requirements. While loop heat pipes (LHPs) are capable of transporting heat across deployable radiators they are currently too expensive for most applications. The largest cost comes from the fabrication of the primary wick which requires multiple machining steps as well as a knife-edge seal. The focus of this work is the development of a 3D printed LHP evaporator using a direct metal laser sintering (DMLS) process to fabricate the primary wick. 3D printing LHP wicks offers several advantages. The overall cost can be significantly reduced by eliminating multiple machining steps, and the risk of failure can be reduced by eliminating the knife-edge seal. The challenge with 3D printing of LHP primary wicks is that a very small pore radius is required to supply sufficient capillary pumping power. A pore radius and permeability study was conducted for optimization of DMLS methods and parameters for fabricating primary wicks. The result of this study is DMLS parameters for wicks with pore radii less than 10 µm. In addition, a DMLS parameter optimization study was performed for fabrication of the coarser secondary wick. Experimental testing is being completed on a complete LHP prototype with 3D printed primary wick fabricated using the optimized DMLS parameters. Modeling is being completed to optimize the design of the primary wick using geometries that are compatible with DMLS. Life testing has begun to demonstrate compatibility of the 3D printed stainless steel wick with ammonia.Item Loop Heat Pipe Wick Fabrication via Additive Manufacturing(47th International Conference on Environmental Systems, 2017-07-16) Richard, Bradley; Pellicone, Devin; Anderson, WilliamAs the capabilities of CubeSats and SmallSats increase so do the heat rejection requirements. While loop heat pipes (LHPs) are capable of transporting heat across deployable radiators they are currently too expensive for most applications. The largest cost comes from the fabrication of the primary wick which requires multiple machining steps as well as a knife-edge seal. In this work the feasibility of fabricating a loop heat pipe (LHP) primary wick using a direct metal laser sintering (DMLS) process was investigated. 3D printing a LHP wick offers several advantages. The overall cost can be significantly reduced by eliminating multiple machining steps and the risk of failure can be reduced by eliminating the knife-edge seal. The challenge with 3D printing of a LHP primary wick is that a very small pore radius is required to supply sufficient capillary pumping power. Most primary wicks have a pore radius of 1-2µm. A pore radius and permeability study was conducted using a range of DMLS methods and parameters to optimize for LHP primary wicks. The results of this study was a minimum pore radius of 6µm which provides a capillary pumping power of 11kPa. Based on this information CubeSats and SmallSats which have smaller heat loads and heat transport distances than traditional satellites can benefit from wicks made using a DMLS process. A 3D printed primary wick was designed and fabricated with a fully dense outer shell for direct welding to the compensation chamber and vapor line. A complete LHP prototype was built and tested to demonstrate the performance of the 3D printed wick. Life testing has begun to demonstrate compatibility of the 3D printed stainless steel wick with ammonia, and the long term structural integrity of the wick.