Thermal Engineer

Thermal Engineer LocationSan Francisco, CAEmployment TypeFull timeLocation TypeOn-siteDepartmentDirect-to-ChipOrbital is an AI-first industrial company building hardware from the atoms up. Our goal is to lead an industrial renaissance to advance critical technologies and secure our planet for generations to come.We’re starting with critical hardware for AI data centers to make them more performant and sustainable. Every Orbital product is invented with our AI platform — uniting AI-automated hardware engineering with AI-designed material science to achieve breakthrough real-world performance.We have an ambitious mission and need excellent people in all our teams - AI research, operations, advanced materials, mechanical engineering, chemical engineering and manufacturing.Working at Orbital means working in tightly integrated, vertically integrated teams. We’re looking for people who have a love of physical technology, curiosity in AI and a desire to learn.Role OverviewOrbital is seeking a highly skilled and innovative Thermal Engineer to develop next-generation cooling technologies for high-density data center applications. The role spans the full development cycle: from modeling and simulations to cold plate design, condenser optimization, physical prototyping, flow loop construction, and system-level testing. You will work directly with novel refrigerators and proprietary AI toolsets to push the boundaries of speed and efficiency in data center cooling.  Key ResponsibilitiesThis is a key role within Orbital’s cooling technology portfolio from design to deployment. As a subject matter expert, you’ll need equal comfort at the whiteboard and the bench. You will design, build and operate two-phase test loops, analyse performance data and rapidly iterate towards solutions that can scale from prototype to product.Physical Prototyping and TestingEvaluate candidate refrigerants based on thermodynamic properties, saturation temperature, safety classification, material compatibility, and regulatory requirements for integration into two-phase cooling designs.Design and optimize evaporator cold plates including channel geometry selection, inlet restriction sizing and exit vapor quality targetingEvaluate and develop enhanced boiling surfaces to improve nucleation site density and increase critical heat flux marginsConstruct thermal test vehicles to evaluate cold plate performance under control and representative heat flux conditionsOperate two-phase test loops to characterize flow, generate boiling curves and CHF data.Translate experimental findings into design rules and validated simulation inputs Modeling and SImulationsPerform system-level thermodynamic analyses: pressure-enthalpy cycle mapping, charge optimization, subcooling control, and component sizing for two-phase flowUse or direct CFD or other modeling tools to evaluate cold plate designs, flow distribution in manifolds and thermal stresses in assemblies.Build or contribute to system-level models for cycle analysis, parametric studies and impact of fluid properties on total performance.MiscellaneousSupport Obrital’s proprietary fluid development efforts by contributing to compatibility testing, accelerated aging studies, and performance characterization.Specify materials, bonding processes, and manufacturing methods for prototype and production cold plate units.As the team continues to grow, this role will be responsible for the direction of intermediate engineers, designers, and researchers contributing to two-phase developmentProduce technical reports, test plans, and design specifications for internal and external stakeholders.  What We’re Looking ForDegree in mechanical engineering, chemical engineering or a closely related discipline with 5+ years of experience.Demonstrated experience in single or two-phase heat transfer, boiling phenomena or refrigeration system designProficiency in conducting thermodynamic analysis to optimize cooling system performance, energy efficiency...