Helium sub-cooling heat exchangers of the counter-flow type are used to minimize the vapor fraction produced in the final expansion of the 1.9 K distributed cooling loops used for cooling the superconducting magnets of the Large Hadron Collider (LHC). These components are of compact design, featuring low-pressure drop and handling very low pressure vapor at low temperature. Following a qualification phase of prototypes, a contract has been placed in European industry for the supply of 239 heat exchanger units. Different levels of extracted heat load require three different variants of heat exchangers. This paper will describe the manufacturing phase with emphasis on the main difficulties encountered to keep the production quality after a brief recall of the prototype phase. Finally, the acceptance tests performed at room temperature and at the nominal cryogenic condition at the factory and at CEA-Grenoble will be presented.

The cryogenic system for the Large Hadron Collider accelerator is presently in its final phase of installation and commissioning at nominal operating temperatures. The refrigeration capacity for the LHC will be produced using eight large cryogenic plants installed on five technical sites and distributed around the 26.7-km circumference ring located in a deep underground tunnel. The status of the cryogenic system commissioning is presented together with the experience gained in operating and commissioning it. ABSTRACTThe cryogenic system for the Large Hadron Collider accelerator is presently in its final phase of installation and commissioning at nominal operating temperatures. The refrigeration capacity for the LHC will be produced using eight large cryogenic plants installed on five technical sites and distributed around the 26.7-km circumference ring located in a deep underground tunnel. The status of the cryogenic system commissioning is presented together with the experience gained in operating and commissioning it.

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