Improved cryogenic and cryoplant model

[jonmaddock]

By @mkovari on Nov 22, 2021, 16:18

The model for the cryogenic cooling power, and the electric power to provide this, is very old, and has a number of deficiencies.

The model is based on D.S. Slack, J.A. Kern, J.R., Miller, Cryogenic system design for a compact tokamak reactor, UCRL-98733, DE89 003176 (1989).

1. Heat conduction through gravity support is based on these assumptions:

Average thermal conductivity of stainless steel between 300 K and 4.5 K	10 W/(mK)
Stress in gravity support	67 MPa
Length of gravity support	1 m

2. Black body radiation load
   I don't know what this calculation is based on. In any case, it seems to take account solely the inward-facing (plasma-facing) area of the TF coil legs, neglecting the outward facing surface.

3. AC losses. This formula doesn’t seem to have anything to do with AC losses in the coils.

4. The code does not take account of high-temperature superconducting current leads, which will certainly be used.

5. The PF coils seem to have been omitted, both for radiation and for current leads.

6. We need to allow the TF and PF coils to be at different temperatures. (See also Allow tmpcry to be higher than 10 K #1462)

7. The hard-coded figure of 13% of the ideal Carnot efficiency is now being changed, but we need to make this relative efficiency as input, as in eff_tf_cryo needs to be an input but keeping the existing default values #1431.

8. See also Superconducting busbars #1253 (Superconducting busbars), Better conducted power to TF coil cold mass #1656 and other cryogenic issues.

Comments @cjwgriesel @jmorris-uk @jonmaddock @ajpearcey ?

[mkovari]

@clmould @jonmaddock

[cjwgriesel]

what about the performance and efficiencies of the heat exchangers. Pressure drops in the superconducting circuits?

[mkovari]

Electrical Loads and Power Systems for the DEMO Nuclear Fusion Project (2020)

EFDA_D_2RBD4J - Technical Report 2023 for WPDES Task DES-NFS.FLUID.CRYO-T001
Includes a brief description of how the cryogenic heat loads are calculated, with results and several references.

See also this folder: Cryo