Thermal Design Engineer II / Senior Thermal Design Engineer

Nitricity • San Francisco, CA

1d

About The Position

Nitricity is a startup developing technology to produce fertilizer using air, water, and renewable electricity. Its process uses plasma to convert air into fixed nitrogen, producing high-temperature gas streams that must be cooled while preserving nitric oxide and recovering high-grade heat.

The Thermal Design Engineer will join the core product engineering team developing megawatt-scale chemical production facilities and lead computational fluid dynamics work for high-temperature, chemically reacting air. The role builds CFD models coupling fluid flow, heat transfer, and chemical kinetics to inform reactor, quench-system, and heat-recovery-equipment design. The engineer will work with chemical, mechanical, and electrical engineers and the test team to validate models against laboratory and pilot data. This position reports to Nitricity’s Chief Science Officer.

Requirements

• BS in Mechanical, Chemical, or Aerospace Engineering or a related field with at least 2 years of relevant experience, or an MS, with a focus on fluid mechanics, heat transfer, combustion, or reacting flows.
• Hands-on experience running reacting-flow CFD simulations of high-temperature gas flows using a commercial or open-source package such as ANSYS Fluent, STAR-CCM+, CONVERGE, OpenFOAM, or similar.
• Strong grounding in turbulence modeling, turbulence-chemistry interaction, radiation, and heat transfer.
• Working knowledge of chemical kinetics and experience coupling finite-rate chemistry to flow simulations using tools such as Cantera, CHEMKIN, or equivalent.
• Proficiency with 3D CAD such as SolidWorks, Onshape, or similar, including parts, assemblies, engineering drawings, and preparing geometry and meshes for simulation.
• Working knowledge of GD&T, materials selection, and design for manufacturing for high-temperature components.
• Experience validating simulations against experimental data and clearly communicating uncertainty.
• Scripting skills in Python or similar for pre- and post-processing, automation, and parametric studies.
• Ability to work well in focused, multidisciplinary teams and thrive in a fast-moving startup environment.
• Enthusiasm for high-impact hard-tech solutions.

Nice To Haves

• Proficiency with ANSYS simulation tools, including Fluent, CFX, Chemkin-Pro, and/or Mechanical.
• Experience with AI-enabled modeling and simulation workflows, such as machine-learning surrogate models, reduced-order models, AI-assisted design optimization, or automated parametric studies.
• Experience with high-temperature air chemistry, NOx formation and destruction (including Zeldovich and related mechanisms), plasma-assisted chemistry, or non-equilibrium flows.
• Experience with rapid quench, gas-phase reactor design, or hypersonic and arc-heated flows.
• Experience with mechanism reduction, chemical reactor network modeling, or 0D/1D reactor models alongside full CFD.
• Background designing heat exchangers or heat-recovery equipment for industrial processes.
• Familiarity with HPC environments and cloud-based simulation workflows.

Responsibilities

• Build, run, and validate CFD models of high-temperature air flows exiting plasma reactors, including turbulent reacting flow, quenching, and heat transfer.
• Couple detailed and reduced chemical kinetic mechanisms for N2/O2/NOx chemistry to flow solvers to predict NO formation, NO decomposition during cooling, and fixation yield.
• Use simulation results to guide the design of reactors, quench sections, and heat-recovery equipment that capture high-grade heat while preserving product.
• Develop and reduce kinetic mechanisms as needed, and conduct sensitivity and reaction-pathway analyses to identify steps controlling yield and energy efficiency.
• Partner with the experimental team to plan diagnostics and test campaigns measuring temperature, species, and pressure to validate and calibrate models.
• Conduct conjugate heat transfer, thermal stress, and materials-temperature assessments for components exposed to high-temperature, oxidizing gas.
• Translate CFD and kinetics results into design recommendations, technical specifications, and clear documentation for engineering and leadership.
• Establish simulation best practices, including meshing standards, solver settings, verification and validation workflows, and model version control.
• Work with outside engineering firms and software vendors, and help scale models from laboratory and pilot systems to megawatt-scale commercial plants.

Benefits

• Three weeks of paid vacation (accruing).
• Medical and dental insurance.
• 401(k) plan with matching.
• Parental leave.
• Commuter benefits. Benefits are subject to change and may require employment in California to be eligible.

What This Job Offers

• Job Type: Full-time
• Career Level: Mid Level