Bachelor's degree in mechanical or aerospace engineering or related field
5+ years of hands-on experience with thermal-fluid hardware
Experience in early-stage hardware startups or engineering consultancies, managing projects independently
Extensive 3D CFD experience on internal flows, including conjugate heat transfer
Strong CAD skills with a history of creating detailed mechanical models
Direct experience in designing and sizing heat exchangers
Proficiency in 1D thermal-hydraulic modeling
Responsibilities
Own the thermal and hydraulic design of heat exchanger systems
Size heat exchangers using effectiveness-NTU methods and pressure-drop budgets
Create and revise detailed CAD models of thermal components
Run 3D CFD simulations on internal flows and heat transfer
Utilize CFD results to inform design changes
Build and maintain 1D network models for performance predictions
Collaborate with engineers across disciplines on design requirements
Lead technical interactions with heat exchanger vendors and fabricators
Support testing and correlate models with experimental data
Benefits
Own a subsystem that impacts the efficiency and cost of the power unit
Engage in hands-on design and testing rather than pure analysis
Rapid design-to-test cycle, with results available in weeks
Work closely with founders and a small, experienced team
Opportunity for early equity ownership in a growing company
Comprehensive medical, dental, and vision coverage
Access to a fully stocked kitchen with snacks and meals
Full Job Description
Senior Thermofluids Engineer - Design and simulate the heat-transfer core of a new class of power hardware
El Segundo, CA | On-site
Opportunity Summary
We are looking for a hands-on thermofluids engineer who is equally comfortable building geometry in CAD and running internal-flow CFD on it. You will be the technical owner of the heat exchangers inside a megawatt-scale power unit, from first sizing calculations through detailed design, supplier builds, and test. This role suits someone who has done this work at an early-stage hardware company or a technical engineering consultancy, where you owned the problem end to end and could not hand the CAD or the simulation off to someone else.
The team is small and moving fast. Hardware is already on the floor and testing is underway, so your designs will be cut, welded, and run on a short cycle, and the results will feed straight back into your next iteration.
Job Duties
Own the thermal and hydraulic design of the recuperator, primary heater, and air-cooled heat rejection hardware
Size heat exchangers using effectiveness-NTU methods, pressure-drop budgets, and channel and core geometry trades
Create and revise detailed CAD of cores, headers, manifolds, and flow passages yourself
Run 3D CFD on internal flows, including conjugate heat transfer, flow maldistribution, and header and manifold losses
Use CFD results to drive geometry changes directly, closing the loop between analysis and design
Build and maintain 1D network models to predict performance at design point, part load, and off-design conditions
Balance thermal performance against pressure drop, structural limits, packaging, cost, and manufacturability
Partner with cycle, structures, turbomachinery, and manufacturing engineers on interfaces and requirements
Lead technical work with heat exchanger vendors and fabricators from design review through inspection and acceptance
Support build, instrumentation, and testing, then correlate models against test data
Qualifications
Bachelor's degree or higher in mechanical or aerospace engineering, or a closely related field
5+ years of hands-on engineering on thermal-fluid hardware
Experience at an early-stage hardware startup or an engineering consultancy, owning technical problems end to end with limited support
Deep, hands-on 3D CFD experience on internal flows such as channels, manifolds, headers, and piping, including conjugate heat transfer (external aerodynamics experience alone is not a fit)
Strong CAD skills, with a track record of building and modifying your own detailed mechanical models
Direct experience designing and sizing heat exchangers, including effectiveness, pressure drop, and flow distribution
Proficiency with 1D or network thermal-hydraulic modeling
Have taken at least one thermal-fluid design from concept through fabrication and test
Clear communicator who can walk through technical work in depth and defend design decisions
Preferred Experience
Supercritical CO₂ or other high-pressure, high-temperature, or near-critical working fluids
Compact, high-effectiveness heat exchangers such as printed-circuit, microchannel, or plate-fin designs
nTop or other implicit and field-driven design or topology optimization tools
Additively manufactured heat exchangers or complex internal flow geometry
Air-cooled or dry-cooling heat rejection systems
Combustion-side heat transfer, including fired heater design
Pressure-boundary mechanical design and familiarity with ASME BPVC
Commercial CFD tools such as STAR-CCM+, Ansys Fluent, or CFX
Correlating thermal and hydraulic models against test data
Why Join Us
Own a subsystem that directly sets the efficiency, size, and cost of the entire power unit
Do the CAD, the CFD, and the hardware rather than sitting in a pure analysis seat
See your designs built and tested in weeks, not years
Work alongside the founders and a small team of experienced turbomachinery and power hardware engineers
Early, meaningful equity ownership in a company in a high-growth phase
Medical, dental, and vision coverage
Fully stocked kitchen with coffee, snacks, and meals
