Theoretical and experimental analysis of a direct expansion unit prototype using CO₂ and a CO₂–DME mixture for Data Center applications

A Data Center is a highly energy-demanding infrastructure, as significant amounts of electrical power are required not only for data storage and processing but also for the cooling of its components. For this reason, improving its energy efficiency is essential to promote energy savings and reduce greenhouse gas emissions. This thesis investigates a refrigeration cycle, for the cooling of a Data Center, that can use carbon dioxide (CO₂) or a CO₂–dimethylether (DME) mixture as working fluids. The main objective is to evaluate whether the proposed mixture can combine the environmental advantages of CO₂, characterized by a Global Warming Potential (GWP) of 1, with the favourable thermodynamic properties of dimethylether, without resulting in a flammable class under current safety standards. The first part of the work presents a mathematical model developed to simulate and analyse the cycle from a theoretical perspective. The second part focuses on experimental analysis and compares the performance of the cycle using pure CO₂ with the mathematical model. The third part of the work focuses on the comparison of the performance of the model’s cycle using pure CO₂ and the model’s cycle using the CO₂– DME mixture. The comparison aims to identify the potential advantages and drawbacks of integrating the mixture, particularly in terms of efficiency, safety, and applicability in data center cooling systems.