Chang, J.-C. Chang, Y.C. Hsiao, F.Z. Kao, S.P. Li, H.C. Liao, W.R. Liu, C.Y. JACoW Publishing Geneva, Switzerland 978-3-95450-188-5 10.18429/JACoW-MEDSI2016-TUPE02 English 156-158 TUPE02 ion simulation experiment SRF cryogenics Contribution to a conference proceedings 2017 2017-06 https://doi.org/10.18429/JACoW-MEDSI2016-TUPE02 http://jacow.org/medsi2016/papers/tupe02.pdf National Synchrotron Radiation Research Center in Taiwan (NSRRC) had set up three cryogenic systems to provide liquid helium to superconducting radio-frequency (SRF) cavities, insertion devices, and highly brilliant hard X-ray. The first one could produce liquid helium 134 LPH, with maximum cooling capacity of 469 W at 4.5 K. The second one could produce liquid helium 138 LPH, with maximum cooling capacity of 475 W at 4.5 K. The third one could produce liquid helium 239 LPH, with maximum cooling capacity of 890 W at 4.5 K. However, large liquid helium discharge in a closed space will cause personnel danger of lack of oxygen. We performed Computational Fluid Dynamic (CFD) simulation to analyse helium discharge through a SRF cavity in the Taiwan Light Source (TPS) tunnel. We simulated cases of helium discharge flow rates from 0.1 kg/s to 4.2 kg/s with and without fresh air supplied from the air conditioning system. We also set up both physical and numerical models within a space of 2.4m in length, 1.2m in width and 0.8m in height with nitrogen discharge inside to validate the CFD simulation.