FRESCA 2 LiquidLiquid Heat Exchanger calculations J Polinski

FRESCA 2 Liquid-Liquid Heat Exchanger calculations J. Polinski FRESCA 2 Final Design Review, 21. 03. 2018 CERN, CH

IC heat exchanger design

IC L-L HX calculation assumptions • The inner cryostat insert shall be cooled-down from 4. 22 K to 1. 9 K in 1 hour • The He. IIp volume of the IC is 56. 76 dm 3 • The insert mass in He. IIp is of 25 kg, but its heat capacity is negligible • The heat exchanger consists of 36 tubes made of RRR=30 Cu with ID 12 mm, OD 15 mm and 358 mm in length each • Total area of the L-L HX is 0. 547 m 2 • Total volume of the He. IIs in the tubes and in half of the heat exchanger manifold is of about 4. 53 dm 3

Calculation assumptions – heat transfer coefficients • He. IIp bath – If THe. IIp>Tl – natural convection between the liquid and Cu pipes – If THe. IIp<Tl – Kapitza conductance between the liquid and Cu pipes

Calculation assumptions – heat transfer coefficients • He. IIs bath – If THe. IIs>Tl – boiling convection between the liquid and Cu pipes – If THe. IIs<Tl – Kapitza conductance between the liquid and Cu pipes

Warm compressor pumping speed • • Input data: 1 g/s @ 1. 8 K Saturation He. IIs pressure @ 1. 8 K – 16. 4 mbar He. IIs vapour density @ 1. 8 K – 0. 4546 kg/s WC pumping speed @ 300 K – 1370 m 3/h

IC L-L HX calculation results THe. IIp<1. 9 K in 55 min DT in steady state for Qlplate= 20 W = 14 m. K Time, min

OC L-L HX calculations • The OC L-L heat exchanger consists of 24 tubes made of RRR=30 Cu with ID 27 mm, OD 30 mm and 686 mm in length each • Total area of the L-L HX is 1. 642 m 2 • For Qlplate= 20 W and 3 time larger heat transfer area than IC L-L HX, expected DT in OC L-L HX is ≈ 4. 66 m. K

OC L-L HX calculation results THe. IIp<1. 9 K in 707 min

OC L-L HX calculation results No filler material