Thermal Fluid-Dynamic Study for the thermal control of the new ALICE Central Detectors

The Inner Tracking System Detector of the ALICE Experiment at CERN laboratory will be replaced in 2020 with a new Detector. It will have to provide, among others, higher spatial resolution, higher tracking precision and faster data read-out. These goals will be attained thanks to new pixel sensors chips and new electronic components, which will have a high impact in terms of dissipated heat. Therefore, one of the critical aspects for the success of the Upgrade project is the design of the Detector cooling system. This thesis work has been developed at CERN in Geneva in close contact with the group responsible for the Mechanics and Cooling of the Detector. The aim of the thermal fluid dynamic study devised is to deliver to the group a reliable and accurate description of the air flow inside the New Inner Tracking System Detector. After a first part of problem definition and design study, a Computational Fluid Dynamic (CFD) analysis has been developed with the ANSYS Fluent software. The CFD model built in this work is a useful tool to predict the air temperature distribution and the air velocity inside the Detector in different operating conditions. This model allowed to explore various scenarios and optimize the in-detector cooling system design process. Furthermore, the optimization of the mass flow rate has provided important information and details about air cooling pipes number and diameter. In this sense, the ultimate purpose of the thesis is to support decisions about the design of the entire ALICE-Upgrade air circulation system.