• Energy Research
• IT close
• DE close
• University of Bergamo close

The paper presents a three-dimensional (3-D), time-dependent Euler-Lagrange multiphase approach for high-fidelity numerical simulation of strongly swirling, turbulent, heavy dust-laden flows within large-sized cyclone separators, as components of the state-of-art suspension preheaters (SPH) of cement kilns. The case study evaluates the predictive performance of the coupled hybrid 3-D computational fluid dynamics–dense discrete phase model (CFD-DDPM) approach implemented into the commercial general purpose code ANSYS-Fluent R16.2, when applied to industrial cyclone collectors used to separate particles from gaseous streams. The gas (flue gases) flow is addressed numerically by using the traditional CFD methods to solve finite volume unsteady Reynolds-averaged Navier-Stokes (FV-URANS) equations. The multiphase turbulence is modeled by using an option of Reynolds stress model (RSM), namely dispersed turbulence model. The motion of the discrete (granular) phase is captured by DDPM methodology. The twin cyclones of SPH top-most stage have been analyzed extensively both for the overall pressure drop and global collection efficiency, and for the very complex multiphase flow patterns established inside this equipment. The numerical simulation results have been verified and partially validated against an available set of typical industrial measurements collected during a heat and mass balance (H&MB) of the cement kiln.

The main challenge for concrete industry - and in general for construction materials - is to serve the two major needs of human society, the protection of the environment, on one hand, and the requirements of buildings and infrastructures by the world?s growing population, on the other. In the past concrete industry has satisfied these needs well. However, for a variety of reasons, the situation has changed dramatically in the last years. First of all, the concrete industry is the largest consumer of natural resources. Secondly, Portland cement, the binder of modern concrete mixtures, is not as environmentally friendly. The world's cement production, in fact, contributes to the earth's atmosphere about 7% of the total CO2 emissions, CO2 being one of the primary greenhouse gas (GHG) responsible for global warming and climate change. As a consequence, concrete industry in the future has to face two antithetically needs. In other words, how the concrete industry can feed the growing population needs being - at the same time - sustainable? The answer to this question is represented by the ?3R-Green Strategy? widely discussed in the first chapter of this PhD thesis: Reduction in consumption of gross energy for construction materials production, Reduction in polluting emissions and Reduction in consuming not renewable natural resources. In particular, this thesis is focused on the alternative binders to Portland cement such as alkali-activated slag cements and calcium sulphoaluminate cement-based binders in order to manufacture sustainable mixtures for special applications such as repair mortars, lightweight reinforced plasters and concretes for slabs on ground. The experimental results show the feasibility of manufacturing both EN 1504-3 R3 class mortars and Portland-free concretes for jointless slabs on ground with calcium sulphoaluminate cement, supplementary cementitious materials (fly ash, ground granulated blast furnace slag) and hydrated lime instead of Portland cement. Moreover, alkali-activated mortars and concretes seem to be a reasonable alternative to natural hydraulic lime-based and/or traditional Portland cement-based mixtures for rehabilitation or restoration of ancient masonry buildings and existing concretes structures. Finally, a new sustainability index was developed taking into account the environmental impact, the performances and the durability of mixtures. In particular, in the environmental impact section, the natural raw materials consumption, the greenhouse gas emissions and the energy consumption have been considered. Furthermore, depending on the applications and the environments, design parameters and properties related to durability have been assigned to each mixture. less

A study of the production of prompt J/ψ mesons contained in jets in proton-proton collisions at s=8TeV is presented. The analysis is based on data corresponding to an integrated luminosity of 19.1 fb−1 collected with the CMS detector at the LHC. For events with at least one observed jet, the angular separation between the J/ψ meson and the jet is used to test whether the J/ψ meson is part of the jet. The analysis shows that most prompt J/ψ mesons having energy above 15 GeV and rapidity |y|<1 are contained in jets with pseudorapidity |ηjet|<1. The differential distributions of the probability to have a J/ψ meson contained in a jet as a function of jet energy for a fixed J/ψ energy fraction are compared to a theoretical model using the fragmenting jet function approach. The data agree best with fragmenting jet function calculations that use a long-distance matrix element parameter set in which prompt J/ψ mesons are predicted to be unpolarized. This technique demonstrates a new way to test predictions for prompt J/ψ production using nonrelativistic quantum chromodynamics. Physics Letters B, 804 ISSN:0370-2693 ISSN:0031-9163 ISSN:1873-2445