Process Modelling and Dynamic Simulation of CO₂ Cooling Systems based on Two-Phase Pumped Loops

Abstract

The Large Hadron Collider is scheduled for upgrade during the middle of this decade, and with it will be upgraded most of the Silicon detectors used in the four experiments of the collider. The upgraded detectors will require a more advanced cooling system that will need to be larger and operate colder than ever before. This thesis describes activities related to the modelling and simulation of the two-phased pumped-loop cooling systems that will cool these Silicon detectors. The development of the tool is described, with details on modelling fluid properties, two-phase flow and some numerical techniques used to facilitate the solver’s operation. The experimental setup that was refurbished and upgraded is also described. The setup was used to collect transient data to validate the performance of the tool. The application of the tool is discussed next. The tool was initially validated by simulating a residential heat pump unit. Simulation results were compared against experimental data as well as against another established simulation tool. Residential heat pumps are well-understood two-phase systems which exhibit transients of similar complexity to pumped loop systems. The comparison is, thus, informative. The tool was then used to validate the performance of a laboratory prototype of a pumped loop cooling system representative of the full-scale Silicon detector cooling systems. Startup and step change transients were compared and the tool captured the experimental trends well. The tool is now being used to design a prototype cooling system that will serve as a proof-of-concept for the future detector cooling systems to be deployed on the LHC. The tool is used to study plant behaviour in different dynamic scenarios such as startup, temperature set-point change and detector load change. The full control system to be used for the plant was implemented in the tool and control strategies were iterated. The simulation results are in line with expected behaviour, indicating a readiness of the tool to be used for tasks such as controller parameter tuning, virtual commissioning and operator training.

Date of Award	1 Aug 2020
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Hector Iacovides (Supervisor) & Andrea Cioncolini (Supervisor)