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Principal Thermal Systems Engineer

Mechanical Engineering · Seattle, Washington

First Mode is a creative engineering company solving the toughest problems on and off the planet, with the goal of having an outsized impact on the world around us. We build the barely possible.  

From our state-of-the-art manufacturing and production facilities in Seattle and Perth, we design and deliver resilient, reliable solutions for the most demanding and constrained frontiers in existence. In the last year our engineers built a 2MW hydrogen fuel cell and battery powerplant to retrofit a three-story, 300-metric-ton-capacity diesel haul truck; designed the power source and refueling system for the world’s first endurance race vehicle to be powered by liquid hydrogen; and delivered spaceflight hardware headed 370 million kilometers from Earth to asteroid 16 Psyche. 

While each project is unique, we typically meld together robotics, automation, systems engineering, modeling and simulation, and advanced fabrication to create a new future across many industries. If you have exceptional talent and a vision for the future, we want to talk. 

As Principal Thermal Systems Engineer, you will lead the design and analysis of the thermal systems for the hydrogen-powered haul truck fleet powerplants.

Position Responsibilities

  • The architecture and design of vehicle and other thermal systems, including cooling and heating methods as well as general thermal system sizing (e.g., pumped fluid loops, convective systems, heat exchangers, refrigeration systems, etc.)
  • Own thermal component testing, qualification, model correlation, and system-level thermal requirements verification
  • Selection and specification of thermal system elements (e.g., fluid pumps, radiators, sensors, heat exchangers, resistive heaters, refrigeration cycles, etc.)
  • Develop thermal systems with associated structures, mechanisms, and instrumentation elements to solve customer challenges, and see these elements through build, test, integration, and operation
  • Perform trades within the mechanical and thermal systems to provide performance and system resource balance
  • Define thermal system and subsystem interface requirements for powerplant components which require thermal maintenance as a part of operational and non-operational constraints
  • Direct and mentor other thermal systems and mechanical systems engineers in the scope and development of their thermal systems work
  • Work with the Vehicle Systems Leads to determine the particular solutions for the thermal subsystem that provide the optimal solutions for the vehicle system-level performance
  • As subject matter expert, assist in technical review of other projects from time to time

Basic Qualifications

  • Experience in life-cycle development of thermal systems hardware within a complex system or product
  • 8+ years of industry experience

Preferred Qualifications

  • Experience designing thermal systems with interactions between mechanical, electrical and systems engineering teams
  • Hands-on experience applying a variety of thermal components including heat exchangers, compressors, fans, shielding, insulation, valves and pumps
  • Test evaluation experience including test planning, test fixture design/assembly, performing tests and analyzing data
  • Experience with CAD and an engineering documentation management software program
  • Experience with thermal analysis of steady state and transient environments
  • Experience in complex, fast-paced team design projects
  • Experience designing components for single and/or two-phase fluid applications
  • Experience identifying, selecting, and applying a variety of heat transfer fluids (air, hydrogen, water, refrigerants, etc.)
  • Proficiency in any of the following software: SolidWorks CAD tools, ANSYS, GT Suite, FEMAP, Thermal Desktop, MATLAB, LabVIEW, Python, or wiki documentation repositories
  • A knack for thinking about how the parts of a system work together
  • Ability to write and speak clearly about technical subject matter
  • Flexibility and responsiveness in a fast-paced, dynamic, small team environment

Additional Requirements

  • Occasional travel within the United States and internationally to represent First Mode to its customers, vendors, and partners and to coordinate with the FM Team in Australia


  • This position will be located at First Mode’s headquarters in Seattle, WA and will be required to work in office >60% of working hours


  • To conform to U.S. Government space technology export regulations, including the International Traffic in Arms Regulations (ITAR) you must be a U.S. citizen, lawful permanent resident of the U.S., protected individual as defined by 8 U.S.C. 1324b(a)(3), or eligible to obtain the required authorizations from the U.S. Department of State. Learn more about the ITAR here. 

Benefits & Perks

  • Competitive compensation and bonus structure
  • 100% employer-paid health insurance (medical, dental, vision)
  • Flexible PTO with 12 week supplementary paid parental leave
  • 401(k) retirement account with a discretionary employer match
  • Commuter benefits (parking and public transportation)
  • A culture that encourages professional growth with learning and development reimbursements
  • Open and collaborative workspaces with free office snacks and lunches
  • Hybrid work model


First Mode is an Equal Opportunity Employer; employment with First Mode is governed on the basis of merit, competence, and qualifications and will not be influenced in any manner by race, color, religion, gender, national origin/ethnicity, veteran status, disability status, age, sexual orientation, gender identity, marital status, mental or physical disability or any other legally protected status.