Three-stage temperature control for synchrotron process cooling water

Stable process-cooling-water temperature is essential for limiting thermally induced disturbances in synchrotron radiation systems. We designed a dual-loop cooling system for an 88 kW load with a target inlet temperature of 42.00 ±0.05 ℃. The primary loop uses deionized water, whereas the secondary loop uses a 20% ethylene glycol–water solution for outdoor freeze protection. Bulk heat removal is provided by a plate heat exchanger, followed by 15 kW and 5 kW electric heaters for medium and fine temperature correction under proportional–integral–derivative control. A one-dimensional fluid model was subjected to repeated 0–88 kW thermal shocks with a 10 min cycle. The simulated load-inlet temperature remained within the specified control band, although the heat-exchanger outlet required approximately 10 min to recover after the final disturbance. The storage tank provided only limited passive attenuation because its 1.4 min nominal turnover time was substantially shorter than the disturbance period. These results indicate that the predicted stability arises primarily from coordinated three-stage regulation. Experimental commissioning and a traceable measurement-uncertainty budget are required before the ±0.05 ℃ performance can be considered validated.