Thermofluids Engineer - Data-Center Thermal Systems

FluidStack; Austin (TX); On-site; USD 120,000 - 150,000; Full time

Job summary

Fluidstack in Austin, Texas, is building a Thermofluids R&D team to push groundbreaking data-center cooling through advanced cycle design and machine architectures.

As a senior engineer you will own cycle models, design heat exchangers, and reconcile predictions with test data, influencing next-gen energy-efficient compute at scale.

The role demands rigorous analysis, hands-on modeling, and collaboration with cross-functional teams in a fast-paced environment.

Qualifications

• You’ve built a thermodynamic cycle model from fluid properties up and defended its assumptions to someone actively trying to break it.
• You’ve sized real heat exchangers against published correlations, and you’ve caught a case where the correlation belonged to a different geometry than the one in front of you.
• You’ve calibrated a model against a machine datasheet or test data and reported the gap honestly rather than tuning until it disappeared.
• You’ve written the analysis that changed a design decision, in a form that people who never ran the code could read and act on.
• You’ve sized a relief path and been the one who signed off that the system was protected.
• You’ve held a result open when it was still open, instead of closing it early to be helpful.
• Bonus: Vapor-compression and transcritical cycles (chillers, heat pumps, refrigeration). Propulsion and cryogenic fluid systems (feed systems, regenerative cooling, two-phase transport). Piping and relief design for high-pressure fluid systems. Real-gas properties and two-phase heat-transfer correlations (CoolProp, REFPROP, Cavallini, Gnielinski, Wang). Data center thermal architecture (CDUs, dry coolers, direct-to-chip).

Responsibilities

• Define what the machine has to be, owning the cycle model that sets the working fluid and the pressures, temperatures and flows the compressor, turbine and exchangers are designed against.
• Design heat exchangers with surface areas running into millions of square meters, among the largest single drivers of a data center’s physical footprint.
• Design the fluid system around the machine: piping, valves, headers, relief and isolation, sized against the pressure-drop budget the cycle can afford and the pressures the fluid actually runs at.
• Run the trades that decide the machine: air-side temperature rise, face velocity and subcooling. Derive the operating points from coupled exchanger ratings rather than asserted approach temperatures, so infeasible designs get caught in the model instead of in hardware.
• Take the cycle predictions onto the test stand and reconcile them against measured COP, then say plainly where the model was wrong.

Skills

Thermodynamic modeling

Heat exchanger design

Heat transfer correlations

Model calibration

Data analysis

CoolProp

REFPROP

Gnielinski

Cavallini

Tools

CoolProp

REFPROP

Gnielinski

Cavallini

Job description

Fluidstack in Austin, Texas, is building a Thermofluids R&D team to push groundbreaking data-center cooling through advanced cycle design and machine architectures.

As a senior engineer you will own cycle models, design heat exchangers, and reconcile predictions with test data, influencing next-gen energy-efficient compute at scale.

The role demands rigorous analysis, hands-on modeling, and collaboration with cross-functional teams in a fast-paced environment.