Browsing by Keyword "Energy analysis"

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    A simulation-based assessment of humidity treatment in data centre cooling systems with air-side economisers
    (2018) Rachman, Arinda Puspita; Zavřel, Vojtěch; Torrens-Galdiz, J. Ignacio; Hensen, J. L.M.; Tecnalia Research & Innovation
    The increasing digitalisation of data is resulting in the need for ever greater computational capacity, which in turn leads to the increasing energy consumption in data centres. A large percentage of this energy use arises from the need to mechanically remove an enormous amount of heat from the data centre environment. In fact, in current practice, the mechanical infrastructure (especially cooling systems) of the data centre accounts for up to half of the overall energy consumption. To reduce the energy consumption of the mechanical infrastructure, several economisation methods are commonly implemented in cooling systems, one of which is the application of a direct air-side economiser addressed in the current research. The use of an air-side economiser has been shown to lead to major savings of the cooling electricity demand, and, as such, it has been widely used as a necessary addition to conventional cooling systems. This study analyses the energy breakdown of data centre cooling systems that include an air-side economiser in order to determine which components within the system are responsible for the major energy consumption. This study investigates, via a computational simulation, the impact of the use of a conventional cooling system and a system with an air-side economiser on total energy demand in three locations representing different climate regions in Europe. The study is especially focused on the energy demand related to the humidity treatment in the data rooms, since the effect is rarely considered in the overall DC energy balance. The results demonstrate, as expected, that the air-side economiser can yield major savings of around 62.5% to 78.7%, depending on the given climate regions. However, the key result of this study is that the humidity treatment necessary for the direct air-side economiser system may consume up to 34.8% of the total energy demand of the cooling system with the air-side economiser. © 2018, Society of Environmental Engineering.
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    Techno-economic assessment of different routes for olefins production through the oxidative coupling of methane (OCM): Advances in benchmark technologies: Advances in benchmark technologies
    (2017-12-15) Spallina, Vincenzo; Velarde, Ildefonso Campos; Medrano Jimenez, José Antonio; Godini, Hamid Reza; Gallucci, Fausto; Van Sint Annaland, Martin; Tecnalia Research & Innovation
    his paper addresses the techno-economic assessment of two technologies for olefins production from naphtha and natural gas. The first technology is based on conventional naphtha steam cracking for the production of ethylene, propylene and BTX at polymer grade. The unused products are recovered in a boiler to produce electricity for the plant. The plant has been designed to produce 1 MTPY of ethylene. In the second case, ethylene is produced from natural gas through the oxidative coupling of methane (OCM) in which natural gas is fed to the OCM reactor together with oxygen from a cryogenic air separation unit (ASU). The overall reactions are kinetically controlled and the system is designed to work at about 750–850 °C and close to 10 bar. Since the overall reaction system is exothermic, different layouts for the reactor temperature control are evaluated. For the naphtha steam cracking plant, the energy analysis shows an overall conversion efficiency of 67% (with a naphtha-to-olefins conversion of 65.7%) due to the production of different products (including electricity), with a carbon conversion rate of 70%. The main equipment costs associated with naphtha steam cracking are represented by the cracker (about 30%), but the cost of ethylene depends almost entirely on the cost associated with the fuel feedstock. In case of the OCM plant, the overall energy conversion efficiency drops to maximally 30%. In the studied plant design, CO2 capture from the syngas is also considered (downstream of the OCM reactor) and therefore the final carbon/capture efficiency is above 20%. The cost of ethylene from OCM is higher than with the naphtha steam cracking plant and the CAPEX affects the final cost of ethylene significantly, as well as the large amount of electricity required.