Experimental studies on process parameters during loss of insulation vacuum in a cryoline

Vacuum insulated cryolines serve as an efficient medium to transport cryogens. Insulation vacuum of these cryolines can degrade under various accidental scenarios. One such case is due to a major leak of ambient air inside the Outer Vacuum Jacket (OVJ) which cannot be compensated by vacuum pump. For an accurate estimation of the rate of pressurization in process pipe, precise heat transfer coefficients and heat fluxes are necessary. Hence, a small experiment on the representative cryoline of 0.5m OVJ diameter and 4m length has been performed. The Loss of Insulation Vacuum (LIV) is simulated by externally injecting dry nitrogen inside evacuated OVJ while process pipes are in cold condition. The present work indicates the assumptions, details of test scheme and the estimated convective heat transfer values based on mass and energy balance.