applied sciences Article Evaluation of the Thermal Performance and Energy Efficiency of CRAC Equipment through Mathematical Modeling Using a New Index COP WEUED Alexandre F. Santos 1,2, Pedro D. Gaspar 1,3 and Heraldo J. L. de Souza 2,* 1 Department of Electromechanical Engineering, University of Beira Interior, 6201-001 Covilhã, Portugal; [email protected] (A.F.S.); [email protected] (P.D.G.) 2 FAPRO—Professional College, Curitiba 80230-040, Brazil 3 C-MAST—Centre for Mechanical and Aerospace Science and Technologies, 6201-001 Covilhã, Portugal * Correspondence: heraldo@escolaprofissional.com.br; Tel.: +55-41-999748928 Abstract: As the world data traffic increasingly grows, the need for computer room air conditioning (CRAC)-type equipment grows proportionally. The air conditioning equipment is responsible for approximately 38% of the energy consumption of data centers. The energy efficiency of these pieces of equipment is compared according to the Energy Standard ASHRAE 90.1-2019, using the index Net Sensible Coefficient Of Performance (NetSCOP). This method benefits fixed-speed compressor equipment with a constant inlet temperature air-cooled condenser (35 ◦C). A new method, COP WEUED (COP–world energy usage effectiveness design), is proposed based on the IPLV (integrated part load value) methodology. The IPLV is an index focused on partial thermal loads and outdoor Citation: Santos, A.F.; Gaspar, P.D.; temperature data variation for air intake in the condenser. It is based on the average temperatures of de Souza, H.J.L. Evaluation of the the USA’s 29 major cities. The new method is based on the 29 largest cities worldwide and with data- Thermal Performance and Energy center-specific indoor temperature conditions. For the same inverter compressor, efficiencies of 4.03 Efficiency of CRAC Equipment and 4.92 kW/kW were obtained, using ASHRAE 90.1-2019 and the proposed method, respectively. through Mathematical Modeling This difference of almost 20% between methods is justified because, during less than 5% of the annual Using a New Index COP WEUED. hours, the inlet air temperature in the condenser is close to the NetSCOP indication. Appl. Sci. 2021, 11, 5950. https://doi.org/10.3390/app11135950 Keywords: ASHRAE 90.1; data center; IPLV; Net Sensible COP; AHRI 1361 Academic Editors: Hassane Naji, María Isabel Lamas Galdo and Rodriguez J.D. 1. Introduction Received: 21 May 2021 The Cisco Annual Internet Report forecasts the global adoption of the Internet. The Accepted: 23 June 2021 proliferation of devices/connections and network performance, by the year 2023, will Published: 26 June 2021 be [1]: • 5.3 billion internet users (66% of the estimated population in 2023). Publisher’s Note: MDPI stays neutral • 3.6 global devices and connections per capita. with regard to jurisdictional claims in • Average global speed of fixed broadband of 110 Mbps. published maps and institutional affil- • In North America, 92% of the population will use the Internet. iations. In addition to the increasing number of users, there have been systems improvements, such as lower response time to search information, lower downtime (online for longer, without problems at critical moments), upgrade without interruption (in one click, man- agement of active and unlimited resources), resilience and self-repair (makes the data Copyright: © 2021 by the authors. pulverized automatically, and its update process is much simpler and optimized). Licensee MDPI, Basel, Switzerland. To sustain this growth in the global database and in user demand, the number of data This article is an open access article distributed under the terms and centers and their energy consumption have been increasing. In 2018, it was estimated that conditions of the Creative Commons data centers consumed 1% of all the global electricity generated. From 2010 to 2018, the Attribution (CC BY) license (https:// number of computers skyrocketed (Figure1)[2]. creativecommons.org/licenses/by/ 4.0/). Appl. Sci. 2021, 11, 5950. https://doi.org/10.3390/app11135950 https://www.mdpi.com/journal/applsci Appl. Sci. 2021, 11, x FOR PEER REVIEW 2 of 15 Appl. Sci. 2021, 11, x FOR PEER REVIEW 2 of 15 Appl. Sci. 2021, 11, 5950 2 of 14 Doubled demandDoubled demand 2018 2018 2010 2010 00 200 200 400 400 600 600 800 800 Global computerGlobal computer instances instances(millions) (millions) Figure 1. Growth of global data center instances [2]. Figure 1. GrowthFigure of1. 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