Bachelor's degree in Chemical, Mechanical, Aerospace, Nuclear, or related Engineering field
6+ years of experience in cycle performance analysis or thermodynamic systems modeling
Strong fundamentals in thermodynamics, fluid mechanics, and heat transfer
Demonstrated experience with dynamic simulation models in 1D system simulation platforms
Working knowledge of integrated power loop equipment and its dynamic response
Proficiency in Python and MATLAB/Simulink or equivalent modeling software
Strong ownership mentality in a fast-paced startup environment
Responsibilities
Own the integrated cycle performance model for our direct-fired sCO? Brayton power loop
Run performance prediction and sensitivity studies ahead of test campaigns
Own the evolution architecture of our dynamic modeling stack
Build property tables and transient models appropriate for the cycle
Collaborate with engineers across various teams to integrate data into system-level models
Develop simulation infrastructure for parameter sweeps and validation cases
Benefits
Pre-IPO stock options
Medical, dental, and vision insurance with 90% coverage 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
Full Job Description
Role Overview
We're looking for a Sr. Thermodynamics Performance Engineer to own the dynamic and steady-state thermodynamic models of our direct-fired supercritical CO₂ 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. Responsibilities
Own the integrated cycle performance model - steady-state and dynamic - for our direct-fired sCO₂ 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
Requirements
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
Preferred Qualifications
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 sCO₂ 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 CO₂, 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
Compensation & Benefits
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.
