Mechanical Engineer, Thermofluids

Fluidstack • Austin, TX

1d • $210,000 - $260,000 • Hybrid

About The Position

Fluidstack is hiring a Mechanical Engineer for its Thermofluids R&D Team, which is developing cooling and thermal systems to support the company’s planned deployment of tens of gigawatts of AI compute. The role spans thermodynamic cycle modeling, heat exchanger design, high-pressure fluid systems, and test-stand validation. The engineer will help define machine architectures and design systems intended for deployment at large scale, from initial models through production-oriented engineering.

Requirements

• 10+ years of experience in thermofluids engineering, including thermodynamic cycle modeling, heat exchanger design, and high-pressure fluid system design.
• Experience building a thermodynamic cycle model from fluid properties and defending its assumptions under scrutiny.
• Experience sizing real heat exchangers using published correlations and identifying when a correlation does not fit the geometry being analyzed.
• Experience calibrating a model against machine datasheets or test data and honestly reporting discrepancies.
• Experience writing analysis that changes design decisions in a clear, actionable form.
• Experience sizing a relief path and signing off that the system is protected.
• Comfort with regular travel; expect 25% or more depending on business needs.

Nice To Haves

• Experience with vapor-compression and transcritical cycles, including chillers, heat pumps, or refrigeration.
• Experience with propulsion and cryogenic fluid systems, including feed systems, regenerative cooling, or two-phase transport.
• Experience with piping and relief design for high-pressure fluid systems.
• Experience with real-gas properties and two-phase heat-transfer correlations, such as CoolProp, REFPROP, Cavallini, Gnielinski, or Wang.
• Experience with data center thermal architecture, including CDUs, dry coolers, or direct-to-chip systems.

Responsibilities

• Own the cycle model that defines the working fluid and the pressures, temperatures, and flows used to design compressors, turbines, and heat exchangers.
• Design large heat exchangers, including systems with surface areas reaching millions of square meters.
• Design fluid systems around the machine, including piping, valves, headers, relief, and isolation, within the cycle’s pressure-drop budget and operating pressures.
• Analyze design trades such as air-side temperature rise, face velocity, and subcooling, deriving operating points from coupled exchanger ratings.
• Compare cycle predictions with test-stand measurements, reconcile predicted and measured COP, and identify where models were incorrect.
• Produce analysis that informs design decisions and can be understood and acted upon by people who did not run the code.
• Size relief paths and sign off that systems are protected.

What This Job Offers

• Job Type: Full-time
• Career Level: Senior
• Education Level: No Education Listed