Thermostatic Valves Containing Silicone-Oil Actuators

Flow-splitting and flow-mixing thermally actuated spool valves have been developed for controlling flows of a heat-transfer fluid in a temperature-regulation system aboard the Mars Science Laboratory (MSL) rover. Valves like these could also be useful in terrestrial temperature-regulation systems, including automobile air-conditioning systems and general refrigeration systems. These valves are required to provide smoother actuation over a wider temperature range than the flow-splitting, thermally actuated spool valves used in the Mars Explorer Rover (MER). Also, whereas the MER valves are unstable (tending to oscillate) in certain transition temperature ranges, these valves are required not to oscillate. The MER valves are actuated by thermal expansion of a wax against spring-loaded piston rods (as in common automotive thermostats). The MSL valves contain similar actuators that utilize thermal expansion of a silicone oil, because silicone-oil actuators were found to afford greater and more nearly linear displacements, needed for smoother actuation, over the required wider temperature range. The MSL valves also feature improved spool designs that reflect greater understanding of fluid dynamics, consideration of pressure drops in valves, and a requirement for balancing of pressures in different flow branches

Effect of Pre- and Post-Weld Heat Treatment on Metallurgical and Tensile Properties of Inconel 718 Alloy Butt Joints Welded using 4 kW Nd: YAG Laser

NRC publication: Ye

Effect of Joint Gap on Inconel 718 Alloy Quality Welded using 4 kW Continuous Wave Nd:YAG Laser Welding System

Peer reviewed: YesNRC publication: Ye