Case Study: Development of a Liquid Nitrogen Distribution & Multi‑Channel Cooling System
Project Overview
Tokamak Energy Ltd required an advanced cryogenic cooling system to support their nuclear fusion research, where plasma temperatures approached 100 million °C. Their earlier deionised/chilled‑water system could no longer meet performance demands as experiments reached more extreme temperatures.
GRE was contracted to produce a cryogenic cooling concept and transform it into a fully engineered, safe, and reliable system capable of supporting the next phase of ST40 fusion reactor trials.
General Project Challenges
The system needed to comply with a multitude of requirements, including:
- Delivering high‑performance cryogenic cooling
- Fitting within tight spatial constraints
- Operating safely near high electrical currents
- Supplying and controlling 24 individual cooling channels inside the Tokamak
- Transporting liquid nitrogen across 60 metres without premature boil‑off
- Withstanding temperature swings from +20°C to –200°C
GRE’s Approach & Solutions
- Extensive Materials Research
Working alongside cryogenic specialists Monroe Brothers, GRE conducted comprehensive material analysis, selecting components that maintained vacuum integrity and could operate safely at cryogenic temperatures.
- Cryostat Design & Precision Temperature Control
GRE designed and built:
- A vacuum‑insulated cryostat
- Electronically actuated cryogenic control valves
- A custom control system capable of adjusting liquid nitrogen injection in real time
- A variable gas–liquid mixing mechanism to stabilise temperatures
This system allowed nitrogen to enter the reactor at precisely controlled temperatures, even as experimental conditions fluctuated.
- Safe Liquid‑to‑Gas Phase Management
To prevent the dangerous expansion of liquid nitrogen in the client’s extraction system, GRE engineered a warming bath/vapouriser that:
- Heated the nitrogen mixture in a controlled manner
- Ensured full phase transition before exhaust
- Protected equipment and personnel from rapid expansion hazards
- Bespoke Structural Engineering
GRE designed and manufactured:
- Two 7‑metre‑long, multi-channel vacuum‑insulated transfer lines
- Specialised 10‑way vacuum‑tight connections
- Custom low‑heat‑transfer joints
- Multiple sealed expansion joints
- Bespoke transport, lifting, and installation fixtures
These enabled reliable, controlled distribution to all 24 cooling channels.
- Novel Design Concepts
With no template to follow, GRE developed:
-
- Iterative prototyping cycles
- A complex heated water bath incorporating multiple gas‑filled coils
- Custom measurement and control systems for each coil
- Computer analysed, empirically validated assembly methods
Every part of the system was created through a balance of analytical modelling and practical experimentation.
-
- Comprehensive Testing & Verification
GRE created a full testing and verification strategy that included:
- Theoretical analysis
- Factory dry‑runs
- Cryogenic testing
- Installation and commissioning procedures
- A complete, repeatable documentation suite
This ensured that performance, safety, and reliability were fully validated.
Outcome
GRE successfully delivered a highly engineered, innovative, and reliable cryogenic cooling system that:
- Provided precise temperature control for Tokamak Energy’s reactor
- Safely managed liquid nitrogen distribution and gas‑phase transition
- Operated effectively in a demanding thermal and electrical environment
- Could be reproduced thanks to robust design, testing, and documentation processes
This project demonstrated GRE’s capability to push the boundaries of cryogenic engineering, advanced manufacturing, and complex system design.