Liquid Nitrogen Subcooler ofr Calorimeters LN2 Supply

Sarychev, Michael

Fermi National Accelerator Laboratory

关键词: Copper;    Heat Transfer;    Dewars;    Pressure Drop;    Calorimeters;   

DOI  :  10.2172/1033662
RP-ID  :  FERMILAB-D0-EN-568
RP-ID  :  AC02-07CH11359
RP-ID  :  1033662

美国|英语

来源: UNT Digital Library

【 摘 要 】

This note provides calculations of heat load and coil sizing for a LN2 subcooler which will be installed in the liquid nitrogen line going from Dewar 42 to the. Liquid argon calorimeters. This subcooler must improve LN2 quality and facilitate LAr pressure regulation. The system is described in Engineering note 3740.510-EN-382. This note contains the calculations of heat loads/pressure drops of the liquid Nitrogen supply line going from the Dewar 42 to the liquid Argon calorimeters, and also the sizing of existing LN2 subcooler located in the V-tube. The note is used as a reference. The state of Nitrogen {at} point 6 - ECS entrance (according to 3740.510-EN-382) is used in the calculations. The quality of liquid x = 0.0066 with the use of existing 75 W LN2 subcooler. It has been determined that we need 29.3 W of additional subcooling in order to obtain. 100% liquid at this point with the mass flow of 25 g/s. Keeping in mind the possible error in heat transfer calculations, a 300W subcooler will be installed to replace the old 75 W subcooler. In order to achieve an acceptable conclusion, an assumption of a fully developed boundary layer was made. The hot fluid or the fluid condensing on the inside surface will determine the rate of heat transfer because A{sub o} = A{sub i} and h{sub o}A{sub o} >> h{sub i}A{sub i}. The conclusion drawn is to use a 1/2-inch copper tube wound approximately 8 times about a 9-inch diameter circle. The pressure drop in this coil will be 0.05 psi (0.0034 atm) and can be neglected.