237 research outputs found
Trinity in Separate \u27Secret\u27 Discussions With DIT
The separate discussions with DIT are looking at all possible forms of potential alliance such as joint degrees, shared services and even joint staff appointments
New Campus Will Create 4,500 Jobs in Construction.
UP TO 4,500 construction jobs will be created over 10 years in a planned new campus development, a report has revealed. A further 1,160 new posts are identified in a science and technology park, shops, offices, plus health and education facilities. The 73-acre site at Grangegorman is the planned new location of a campus for Dublin Institute of Technology which, at the moment, is spread around 40 centres in the city
The internal group space
In this article we describe dynamic structures and relationships that arise in the internal space of groups, a space which materializes from the unconscious internal world of each group member and within the group as a whole. We use keys and doors as metaphors to explicate our understanding of the internal dynamics. We give examples of how these metaphors can be used to understand the structure, the function and the relationships within the group. The possible connections of these ideas to other theoretical frameworks are discussed
CFD modelling of wind flow over complex and rough terrain
A model has been developed using the general-purpose Navier-Stokes solver CFX4 to
simulate Atmospheric Boundary Layer flow over complex terrain. This model has
been validated against the measured data from the Askervein Hill experiment, and has
been shown to perform well. The CFD model is also compared to the WAsP linear
model of wind flow over topography, and a significant improvement is noted for flow
over complex topography. Boundary conditions, gridding issues and sensitivity to
other solver parameters have all been investigated.
An advanced roughness model has been developed to simulate flow over forest
canopies, using a resistive body force within the canopy volume. The model is
validated against measured data for simple 2D cases, and for a complex 3D case over
real topography. The model is shown to give a more physically realistic profile for the
wind speed in and just above forest canopies than the standard roughness length
model used in most CFD simulations.
An automated methodology for setting up CFD simulations using the models
described has been developed. A custom pre-processing package to implement this
has been written, to enable the use of the CFD methodology in a commercial
environment
Evaluation of the Potential of Nanofluids Containing Different Ag Nanoparticle size Distributions for Enhanced Solar Energy Conversion in Hybrid Photovoltaic-Thermal (PVT) Applications
Hybridising photovoltaic and photothermal technologies into a single system that can simultaneously deliver heat and power represents one of the leading strategies for generating clean energy at more affordable prices. In a hybrid photovoltaic-thermal (PVT) system, the capability to modulate the thermal and electrical power output is significantly influenced by the spectral properties of the heat transfer fluid utilised. In this study, we report on one of the first experimental evaluations of the capability of a multimodal silver nanofluid containing various particle shapes and particle sizes to selectively modulate the solar energy for PVT applications. The diverse set of particle properties led up to a 50.4% enhancement in the solar energy absorbed by the nanofluid over the 300nm—550nm spectral region, where silicon is known to exhibit poor photovoltaic conversion performances. This improved substantially the absorption of solar energy, with an additional 18–129Wm−2 of thermal power being generated by the PVT system. Along with the advancements made in the thermal power output of the PVT system, a decrease of 4.7–36.6Wm−2 in the electrical power generated by the photovoltaic element was noted. Thus, for every∼11Wm−2 increase of thermal power achieved through the addition of the nanoparticles, a reduction of∼3Wm−2 in the ability to generate clean electricity was sustained by the PVT. Despite the energy trade-offs involved under the conditions of the nanofluid, the PVT system cumulatively harvested 405Wm−2 of solar energy, which amounts to a total conversion efficiency of 45%. Furthermore, the economics of the additional energy harvested through merging of the two systems was found to reach an enhancement of 77% under certain European conditions
A transfer matrix approach to aid in the design and optimization of hybrid advanced passive structures for enhancing photovoltaic efficiency
The addition of a luminescent down-shifting (LDS) layer directly onto a photovoltaic (PV) cell introduces additional loss mechanisms within the system. The combination of non-ideal photo-luminescent materials encapsulated within a limited range of viable host materials, with the increased reflection losses arising from the newly created interface represent losses which must be overcome for LDS to offer an enhancement to the underlying cells efficiency. Exploiting the interaction between the highly enhanced electric fields established close to a metal nanoparticles (MNP’s) surface is one route aimed at mitigating the poor optical properties of the luminophore-host combinations available. Alternative approaches, aimed at addressing the other loss mechanisms within such a system have gone relatively unexplored. Exploiting the non-ideal nature of the photo-luminescent materials available, offers a possibility of recycling the photons which previously did not undergo photoluminescence while also addressing the reflection losses through the inclusion of selectively reflecting optical structures. The hybrid device designs, incorporating single- and double layer- antireflection coatings composed of commonly available materials offer enhancements in the underlying PV cells performance of 8% - 30% depending upon the design criteria established. The transfer matrix approach adopted allowed the impact of individual design considerations on the reflection suppression capabilities of the structure, as well as their impact on the underlying cells efficiency to be readily determined
Experimental and Theoretical Evaluation of a Commercial Luminescent Dye for PVT Systems
Combining photovoltaic (PV) and photo-thermal (PT) energy collection strategies in a single system can enhance solar energy conversion efficiencies, leading to increased economic returns and wider adoption of renewable energy sources. This study focuses on incorporating a commercial luminescent organic dye (BASF Lumogen F Red 305) into ethylene glycol to explore its potential for PVT applications. The optical and electrical characteristics of the working fluid were evaluated at different temperatures under direct solar irradiance. Pristine ethylene glycol reduced the maximum PV cell temperature by 10 °C. The inclusion of luminescent dye at various concentrations further reduced the maximum temperature, with the lowest concentration achieving a 7 °C decrease compared to pristine ethylene glycol. The highest dye concentration (0.50 wt%) resulted in a significant temperature reduction of 12 °C. While electrical conversion efficiencies decreased with increasing dye concentration, all concentrations exhibited higher fill factors compared to the bare PV cell during the 100-min illumination period. A ray-tracing model was employed to analyze the behavior of the luminescent dye and quantify transmitted energy for electricity and thermal energy production. Different concentrations showed varying energy outputs, with lower concentrations favoring electrical energy and higher concentrations favoring thermal energy. Economic assessment revealed the viability of certain concentrations for specific countries, highlighting the trade-off between thermal and electrical energy generation. These findings provide valuable insights for PVT system applications in different geographical and economic contexts
Combined Experimental and Modeling Analysis for theDevelopment of Optical Materials Suitable to Enhance theImplementation of Plasmonic-Enhanced Luminescent Down-Shifting Solutions on Existing Silicon-Based Photovoltaic Devices
The development of highly efficient solar collectors requires modulating the light interactions with the semiconducting materials. Incorporating luminescent species and metal nanoparticles within a semitransparent polymeric material (e.g., polymethyl methacrylate (PMMA)) leads to the formation of a plasmon-enhanced luminescent down-shifting (PLDS) layer, which offers a retrofittable approach toward expanding the wavelength range over which the conversion process can effectively occur. Adding antireflection coatings (ARCs) further controls the spectral response. However, with each additional component comes additional loss pathways. In this study, the losses related to light interactions with the PMMA and the ARCs have been investigated theoretically using a transfer matrix method and experimentally validated. Two proposed architectures were considered, and the deviations between the optical response of each iteration helped to establish the design considerations. The proposed structure-enhanced (SE) designs generated a predicted enhancement of 37 to 62% for the collection performance of a pristine monocrystalline-silicon solar cell, as inferred through the short-circuit current density (Jsc). The results revealed the synergies among the SE-design components, demonstrating that the spectral response of the SEs, containing a thin polymer framework and an ARC, can be tuned to minimize the reflections, leading to the solar energy conversion enhancement
Development of poly-vinyl alcohol stabilized silver nanofluids for solar thermal applications
Nanofluids offer the potential to address the low thermal conductivities found in conventional heat transfer fluids, through their unique electrical, optical and thermal properties, but their implementation remains restricted due to absorption and stability limitations. Here, we characterize and exploit the distinctive plasmonic properties exhibited by polyvinyl-alcohol stabilized silver nanostructures by tuning their absorption and thermal properties through controlling the nanoparticle size, morphology and particle-size distribution configuration at the synthesis stage. The photo-thermal efficiency of different water-based silver nanofluids under a standard AM1.5G weighted solar spectrum were explored, the influence of each of these components on the resulting fluids performance within a direct absorption solar thermal collection system being considered. Nanofluids, containing an extensive ensemble of particle size-distributions (5 nm–110 nm in diameter) in addition to anisotropic particle morphologies (e.g. prisms, hexagons and other non-spherical geometries), exhibited a significant enhancement in the absorption and photo-thermal energy transfer. Enhancements of 5%–32% in the photo-thermal conversion efficiency were achieved, the enhancement being dependent upon the presence of multiple particle size-distributions and the particle concentration. The enhancement is influenced by the interactions occurring between the individual particle size-distributions but also by the collective behaviour of the particles ensemble. The critical particle diameter, above which the photo-thermal characteristics of the nanofluid become dominated by the larger sized particles present, was identified as 150 nm. The increased performance of these nanofluids, which adopt a more complex particle-size configuration, suggests that they can represent suitable candidates for solar-thermal applications
- …