Senior Thermofluids Engineer - Heat Exchanger Design & CFD

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. About Us We are a venture-backed energy technology company building compact, factory-built power generation equipment for fast-growing electricity demand, including data centers. Our system pairs advanced turbomachinery with high-performance heat transfer hardware to deliver more power in a smaller footprint than conventional plants. We recently moved into a larger facility in El Segundo and are scaling the engineering team around our first full-scale units. 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 Compensation Details $170,000 - $230,000 + equity #J-18808-Ljbffr Approach Venture LLC