Design of the water-cooling system and analysis of the heat dissipation characteristics of the barrel electromagnetic calorimeter in China's new generation electron-positron collider

Heat from front-end electronics can compromise the temperature stability of cesium iodide (CsI) crystals in the confined, curved barrel region of the Super Tau-Charm Facility (STCF) electromagnetic calorimeter. A composite water-cooling scheme combining dual counter-flow cooling and heat-source isolation was proposed to enhance electronics heat removal while limiting heat leakage toward the crystals. A three-dimensional steady-state conjugate heat transfer model comprising 51 detector units was established. The heat-source representation and solid-domain heat-conduction model were assessed against a single-unit heat-generation experiment, with pointwise temperature differences of 0.06–0.77 °C. Increasing the per-tube cooling-water flow rate increased the relative Nu – f performance index, but provided diminishing improvements in crystal-temperature control while increasing hydraulic power demand. Reducing the inlet-water temperature from 20 °C to 18 °C decreased the maximum temperature at the large ends of the crystals from 21.26 °C to 19.32 °C, while causing only minor changes in the spatial temperature distribution of the crystal array and the longitudinal temperature gradient. Reducing the thermal conductivity of the insulation layer suppressed heat transfer from the electronics to the crystal region, but further improvement was limited by the local thermal bridge at the signal-cable routing opening. Considering crystal-temperature control, temperature uniformity, pressure drop, and condensation risk, a per-tube flow rate of 160 L·h −1 , an inlet-water temperature of 19 °C, and an insulation-layer thermal conductivity of 0.02–0.20 W·m −1 ·K −1 are recommended. The results guide the selection of coolant operating conditions and identify the signal-cable routing opening as a priority for further insulation improvement in the STCF barrel EMC.