16 research outputs found
A test facility for distributed cogeneration: experiences on a microturbine and chiller based plant
No full textSystem description and test planning for a combined heat and Power Plant composed by a Micro gas Turbine and an Absorption Chiller / Heater
No full textSolution to the two-body Smoluchowski equation with shear flow for charge-stabilized colloids at low to moderate P\'eclet numbers
No full textWe developed an analytical theoretical method to determine the microscopical
structure of weakly to moderately sheared colloidal suspensions in dilute
conditions. The microstructure is described by the static structure factor,
obtained by solving the stationary two-body Smoluchowski advection-diffusion
equation. The singularly perturbed PDE problem is solved by performing an
angular averaging over the extensional and compressing sectors and by the
rigorous application of boundary-layer theory (intermediate asymptotics). This
allows us to expand the solution to a higher order in P\'eclet with respect to
previous methods. The scheme is independent of the type of interaction
potential. We apply it to the example of charge-stabilized colloidal particles
interacting via the repulsive Yukawa potential and study the distortion of the
structure factor. It is predicted that the distortion is larger at small
wavevectors and its dependence on is a simple power law. At increasing
, the main peak of the structure factor displays a broadening and shift
towards lower in the extensional sectors, which indicates shear-induced
spreading out of particle correlations and neighbor particles locally being
dragged away from the reference one. In the compressing sectors, instead, a
narrowing and shift towards high is predicted, reflecting shear-induced
ordering near contact and concomitant depletion in the medium-range. An overall
narrowing of the peak is also predicted for the structure factor averaged over
the whole solid angle. Calculations are also performed for hard spheres,
showing good overall agreement with experimental data. It is also shown that
the shear-induced structure factor distortion is orders of magnitude larger for
the Yukawa repulsion than for the hard spheres
Analisi e sperimentazione dell’interfacciamento di un impianto di cogenerazione con microturbine ad alta velocità di piccola potenza
No full textHomogenization of the turbulence inside autoclaves by using randomly localized velocity perturbations
No full textThis work analyzes the turbulent features inside the chamber of industrial size autoclaves typically used for thermal treatment of carbon fiber-based materials adopted in the aerospace industry. The state-of-the-art design of these machineries causes a highly anisotropic turbulent flow, which negatively influences the temperature distribution within the chamber, which ultimately leads to a non-optimal treatment of the materials. The aim of this work is, then, the proposal of an innovative design to homogenize the turbulence inside a 16 m3 industrial size autoclave. The design includes the addition of three contemporary localized velocity perturbations, randomly chosen from a set of six possible sources located at the walls of the chamber. The impact of these sources has been examined by LES simulations conducted on an hexahedral grid composed of 8 106 cells; They have been conducted by using the open-source software PLUTO 4.4.2 [1, 2]. The major target variables will be the mapping of the kinetic energy inside the system and the distribution of a tracer within the chamber.
A preliminary example of the positive impact of the perturbations is proposed in Figure 1, where contour plots of the kinetic energy on a transversal section of the autoclave have been proposed after 3.5 s of simulation: the addition of random velocity perturbations already decreases, even if still mildly, the internal anisotropy of the fluctuations of the system and it “spreads” turbulence in sections of the domain otherwise completely stagnant. Future research steps will be a complete control of the homogenization of the flow and temperature characteristics inside the chamber by optimizing the total number of perturbation sources, the fraction of them being randomly activated at the same time and the time interval between different perturbation configurations
Direct observation of heterogeneous formation of amyloid spherulites in real-time by super-resolution microscopy
No full textReal-time super-resolution microscopy analysis reveals the growth kinetics, morphology, and abundance of human insulin amyloid spherulites with different growth pathways.Protein misfolding in the form of fibrils or spherulites is involved in a spectrum of pathological abnormalities. Our current understanding of protein aggregation mechanisms has primarily relied on the use of spectrometric methods to determine the average growth rates and diffraction-limited microscopes with low temporal resolution to observe the large-scale morphologies of intermediates. We developed a REal-time kinetics via binding and Photobleaching LOcalization Microscopy (REPLOM) super-resolution method to directly observe and quantify the existence and abundance of diverse aggregate morphologies of human insulin, below the diffraction limit and extract their heterogeneous growth kinetics. Our results revealed that even the growth of microscopically identical aggregates, e.g., amyloid spherulites, may follow distinct pathways. Specifically, spherulites do not exclusively grow isotropically but, surprisingly, may also grow anisotropically, following similar pathways as reported for minerals and polymers. Combining our technique with machine learning approaches, we associated growth rates to specific morphological transitions and provided energy barriers and the energy landscape at the level of single aggregate morphology. Our unifying framework for the detection and analysis of spherulite growth can be extended to other self-assembled systems characterized by a high degree of heterogeneity, disentangling the broad spectrum of diverse morphologies at the single-molecule level.</p
