Thermal Engineer

Orbital•San Francisco, CA

About The Position

Orbital 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.

Requirements

Degree 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 design.
Proficiency in conducting thermodynamic analysis to optimize cooling system performance, energy efficiency and heat transfer.
Hands-on prototyping and lab experience: ability to design test fixtures, build flow loops, select and install instrumentation, and run experiments independently.
Experience with or strong aptitude for CAD for test fixture design.
Ability to interpret experimental data and translate findings into design improvements.
Continuous improvement mindset.

Nice To Haves

Background in chemistry, materials science, or chemical engineering as it relates to refrigerant behavior, surface treatments, or coating processes is a strong plus.
Experience with relevant simulation software (e.g. CFD, FEA) for thermal and fluid dynamics an asset.
Familiarity or experience with cold plate manufacturing processes (CNC machining, brazing, sintering, skiving) is an asset.

Responsibilities

Design, build and operate two-phase test loops, analyse performance data and rapidly iterate towards solutions that can scale from prototype to product.
Evaluate 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 targeting.
Evaluate and develop enhanced boiling surfaces to improve nucleation site density and increase critical heat flux margins.
Construct thermal test vehicles to evaluate cold plate performance under control and representative heat flux conditions.
Operate two-phase test loops to characterize flow, generate boiling curves and CHF data.
Translate experimental findings into design rules and validated simulation inputs.
Perform system-level thermodynamic analyses: pressure-enthalpy cycle mapping, charge optimization, subcooling control, and component sizing for two-phase flow.
Use 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.
Support Orbital’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 development.
Produce technical reports, test plans, and design specifications for internal and external stakeholders.