Search results for "Efficient"
showing 10 items of 1603 documents
A model for predicting the potential diffusion of solar energy systems in complex urban environments
2011
Abstract The necessity to reduce greenhouse gases emission produced by energy building consumptions and to cut the energy bill (mainly due to the use of fossil sources) leads to the employment of renewable energy sources in new planned scenarios. In particular, more and more often municipal energy and environmental plans pay great attention to the possibilities of employment of the solar technologies at urban scale. Solar thermal and photovoltaic (PV) systems are, by far, the most suitable tools to be utilized in urban areas. Obviously, the proper adoption of such systems in buildings does call for the availability of calculation methods suitable to provide the actual level of exploitation …
The interaction between intermittent renewable energy and the electricity, heating and transport sectors
2012
In a global perspective, it is essential that the world transfers from fossil fuels to renewable energy sources in order to minimise climate change effects. As a part of such transition energy savings are also important, as they can decrease production costs effectively. The nature of such a change is that it has to be implemented on a local level. Energy saving technologies are placed with the demand decrease and renewable energy is typically distributed where the resources are. In some parts of the world, energy savings have resulted in a stabilisation of the energy demands, however in the world as such, demands are still increasing in buildings, transport and industry. Although the deman…
Colours and building thermal balance: the impact of coating colour on energy loads
2013
Turbulent heat transfer in spacer-filled channels: Experimental and computational study and selection of turbulence models
2019
Abstract Heat transfer in spacer-filled channels of the kind used in Membrane Distillation was studied in the Reynolds number range 100–2000, encompassing both steady laminar and early-turbulent flow conditions. Experimental data, including distributions of the local heat transfer coefficient h, were obtained by Liquid Crystal Thermography and Digital Image Processing. Alternative turbulence models, both of first order (k-e, RNG k-e, k-ω, BSL k-ω, SST k-ω) and of second order (LRR RS, SSG RS, ω RS, BSL RS), were tested for their ability to predict measured distributions and mean values of h. The best agreement with the experimental results was provided by first-order ω-based models able to …
CFD Investigation of Spacer-Filled Channels for Membrane Distillation
2019
The membrane distillation (MD) process for water desalination is affected by temperature polarization, which reduces the driving force and the efficiency of the process. To counteract this phenomenon, spacer-filled channels are used, which enhance mixing and heat transfer but also cause higher pressure drops. Therefore, in the design of MD modules, the choice of the spacer is crucial for process efficiency. In the present work, different overlapped spacers are investigated by computational fluid dynamics (CFD) and results are compared with experiments carried out with thermochromic liquid crystals (TLC). Results are reported for different flow attack angles and for Reynolds numbers (Re) ran…
Experimental and computational investigation of heat transfer in channels filled by woven spacers
2017
Abstract Models of woven-type spacer-filled channels were investigated by Computational Fluid Dynamics (CFD) and parallel experiments in order to characterize the performance of Membrane Distillation (MD) modules. The case of overlapped spacers was analysed in a companion paper. Experiments were based on a non-intrusive technique using Thermochromic Liquid Crystals (TLC) and digital image processing, and provided the distribution of the local convective heat transfer coefficient on a thermally active wall. CFD simulations ranged from steady-state conditions to unsteady and early turbulent flow, covering a Reynolds number interval of great practical interest in real MD applications. A specif…
Investigation of heat transfer in spacer-filled channels by experiments and direct numerical simulations
2016
Abstract The analysis of flow fields and heat or mass transfer phenomena is of great importance in the optimum design of spacer-filled channel geometries for a variety of membrane-based processes. In the present work, models of spacer-filled channels often adopted in Membrane Distillation are simultaneously investigated by experiments and Computational Fluid Dynamics (CFD). Experiments rely on a non-intrusive technique, based on the use of Thermochromic Liquid Crystals (TLC) and digital image processing, and provide the local distribution of the convective heat transfer coefficient on a thermally active wall. CFD relies on steady-state (laminar flow) simulations in the lower end of the Reyn…
Bipolar membrane reverse electrodialysis for the sustainable recovery of energy from pH gradients of industrial wastewater: Performance prediction by…
2021
Abstract The theoretical energy density extractable from acidic and alkaline solutions is higher than 20 kWh m−3 of single solution when mixing 1 M concentrated streams. Therefore, acidic and alkaline industrial wastewater have a huge potential for the recovery of energy. To this purpose, bipolar membrane reverse electrodialysis (BMRED) is an interesting, yet poorly studied technology for the conversion of the mixing entropy of solutions at different pH into electricity. Although it shows promising performance, only few works have been presented in the literature so far, and no comprehensive models have been developed yet. This work presents a mathematical multi-scale model based on a semi-…
Architetture e logiche di controllo ottimale di microreti per la razionalizzazione energetica Report 2 Applicazioni in reti di distribuzione
2011
Il presente Rapporto descrive, le attività svolte dal personale del DIEET dell’Università degli Studi Palermo nell’ambito della seconda fase delle attività di ricerca dal titolo: “ARCHITETTURE E LOGICHE DI CONTROLLO OTTIMALE DI MICRORETI PER LA RAZIONALIZZAZIONE ENERGETICA’”, oggetto dell’Accordo di Collaborazione tra ENEA e DIEET sottoscritto in data 24 febbraio 2011. Il presente Rapporto riporta le implementazioni della logica di controllo con una particolare attenzione al software che sovrintende alla gestione energeticamente efficiente dei sistemi individuati. Le implementazioni sono sviluppate in un ambiente di programmazione ad oggetti con una grafica di interfaccia che consente di se…
Sensor9k : A testbed for designing and experimenting with WSN-based ambient intelligence applications
2012
Ambient Intelligence systems are typically characterized by the use of pervasive equipment for monitoring and modifying the environment according to users' needs, and to globally defined constraints. Our work describes the implementation of a testbed providing the hardware and software tools for the development and management of AmI applications based on wireless sensor and actuator networks, whose main goal is energy saving for global sustainability. A sample application is presented that addresses temperature control in a work environment, through a multi-objective fuzzy controller taking into account users' preferences and energy consumption.