Thermodynamics Performance Engineer

We’re looking for a Sr. Thermodynamics Performance Engineer to own the dynamic and steady-state thermodynamic models of our direct-fired supercritical CO Brayton cycle. You’ll be the person who turns integrated system behavior into clear, actionable insight - running performance studies ahead of test campaigns, reconciling predictions against test data, and growing our modeling capability into a digital-twin-quality simulation platform that supports controls development, trip response, and eventual hardware-in-the-loop testing. You’ll work closely with our test, combustion, turbomachinery, recuperator, fluid systems, and controls engineers. This is the simulation backbone for a first-of-a-kind power system, and the work is foundational to how we operate, validate, and scale the technology., * Own the integrated cycle performance model - steady-state and dynamic - for our direct-fired sCO Brayton power loop, maintaining and advancing it through the hardware lifecycle

• Run performance prediction and sensitivity studies ahead of test campaigns; reconcile model output against test data to drive model refinement and surface component-level insights
• Own the architecture call on how our dynamic modeling stack should evolve over time - what platform, what fidelity, on what evidence
• Build property tables, turbomachinery map handling, heat exchanger transient models, and combustor representations appropriate to the cycle and fidelity required
• Collaborate with combustion, turbomachinery, and heat exchanger engineers to integrate component data into system-level models; collaborate with controls and software teams on closed-loop simulation and HIL planning
• Develop simulation infrastructure - scripted scenario runs, parameter sweeps, validation cases - that makes the model usable by engineers beyond yourself

• Bachelor’s degree in Chemical, Mechanical, Aerospace, Nuclear, or related Engineering field
• 6+ years of experience in cycle performance analysis, thermodynamic systems modeling, or dynamic process simulation
• Strong fundamentals in thermodynamics, fluid mechanics, and heat transfer, applied to integrated multi-component systems
• Demonstrated experience building dynamic simulation models of fluid/thermal systems in an industry-grade 1D system simulation platform - and a clear point of view on tool tradeoffs for closed-loop power cycle applications
• Working knowledge of integrated power loop equipment - heat exchanger sizing, compressor/pump curves, valve Cv, piping hydraulics - and how each shows up in dynamic response
• Programming proficiency: Python for data reduction and automation; one of MATLAB/Simulink, Modelica, or equivalent for modeling
• Strong ownership mentality and comfort driving rigorous analysis in a fast-paced startup environment, * Deep experience with industry dynamic simulation platforms (such as GT-SUITE, Modelica/Dymola, NPSS, Flownex, Simcenter Amesim, or equivalent) applied to turbomachinery, power cycles, or closed-loop thermal-fluid systems
• Background in nuclear thermal-hydraulics with fast-dynamic single-phase modeling experience (RELAP, TRACE, MARS, ATHLET, GAMMA, or equivalent), particularly applied to gas-cooled or sCO reactor concepts
• Working knowledge of real-fluid EOS handling (REFPROP, CoolProp, Span-Wagner) and turbomachinery map interpolation near critical conditions
• History of making and defending tool/methodology decisions in a constrained engineering environment
• Experience with supercritical CO , closed Brayton cycles, high-pressure systems (100+ bar), or other high-density working fluids
• Experience coupling plant models to control systems for HIL testing, controller validation, FMU export, or operator training simulators
• Hands-on plant startup, commissioning, or field troubleshooting on first-of-a-kind or developmental systems
• Background in rocketry, gas turbine, advanced reactors, or high-performance turbomachinery environments

• Pre-IPO stock options
• Medical, dental, and vision insurance (Arbor covers 90% for employees)
• Basic life insurance fully covered
• Health savings account (HSA) with matching
• Flexible savings account (FSA)
• Unlimited PTO
• 12+ company holidays, including Earth Day!
• 401(k)
• Commuter benefits
• Annual learning and development stipend
• And more!

Base Pay: $165,000 - $180,000 USD/year. The salary is subject to the applicant’s skills, qualifications, experience, and geographic location.