Abstract
Despite the promise of abundant renewable energy resources in the world, the poultry sector is still dominated by traditional energy sources. In this study, results of a field trial of an ...innovative and cost-effective HVAC system design applied to a poultry house have been presented. This system comprises of two integrated novel components; a polyethylene heat exchanger (PHE) based a photovoltaic thermal (PVt) array and an efficient and innovative ground pipe array coupled to a heat pump driven HVAC system. The analysis included the daily PV electrical output and heat pump performance. The results of the experimental study reveal that 3733 kWh and 2432 kWh heat energy have been supplied in the 7-week growth cycle of chickens condition, respectively. The COP of the HP has been calculated for the winter period and observed between 2.3 and 2.43. The PV system was able to generate 1876 kWh electrical energy with potential to meet HP’s energy needs in the most energy needing period.
The design and response of ground source heat pumps coupled to vertical closed loop arrays in UK domestic applications are investigated in this article. Two typical UK house types are selected as the ...vehicle for the study and a detailed dynamic thermal modelling method is used to arrive at time-series heating demands for the two houses. A new empirical heat pump model is derived using experimental data taking into account the deteriorating performance of the heat pump during periods of light load. The heat pump model is incorporated into an existing numerical ground model and completed with a classical effectiveness type heat exchange model of the closed loop array. The model is used to analyse array sizing and performance over an extended time period, as well as sensitivity of the design to soil conductivity and borehole heat exchanger resistance and sensitivity to over-sizing and part-load behavior of the heat pump. Results show that the UK's standard for ground source design (the Microgeneration Certification Scheme) may lead to under-estimated array sizes and that heating system over-sizing and deleterious part-load heat pump performance can add up to 20% to the electrical consumption of these systems.
This paper presents a novel two‐dimensional (2‐D) defected ground array (DGA) for planar circuits, which has horizontal and vertical periodicities of defect structure. The defected unit cell of DGA ...is composed of a Sierpinski carpet structure to improve the effective inductance. Measurements show that the proposed DGA provides steeper cutoff characteristics, lower cutoff frequency, and higher slow‐wave factors than the conventional periodic defected ground structure in the same occupied surface.
A recently published article in Science A. Cho, Science, 318(5852), 896 (2007) by the Pierre Auger Laboratory has helped pinpoint the source of ultrahigh energy cosmic rays, which are the most ...energetic particles known in the universe. The sources found indicate support for the "active galactic nuclei" theory, which is that the ultrahigh energy cosmic rays come from supermassive black holes found at the centers of galaxies. The Pierre Auger Observatory (website: AUGER EXPERIMENT, www.auger.org) records the extensive air showers through an array of 1600 particle detectors placed 1.5 km apart in a grid spread across 3000 km.sup.2. The window of TeV gamma-ray astrophysics was opened less than 2 decades ago, when the Crab Nebula was detected for the first time. After several years of development, the technique used by imaging atmospheric Cherenkov telescopes such as HESS and MAGIC is now allowing to conduct sensitive observations in the TeV regime. Water Cherenkov instruments such as Milagro are also providing results. Different types of extragalactic and galactic sources have been detected, showing a variety of interesting phenomena that are boosting theory in very high energy gamma-ray astrophysics. Here I review basic cosmic rays, the detection methods, and then present a simulation study of the gamma-ray astronomy at PeV energies--phase 3 (GRAPES3) experiment. GRAPES-3 is a scintillator detector array equipped with a muon detector tracker at Ooty, India. The capabilities of the array can be enhanced by changing the detector separation, etc. This can reduce the energy threshold (Eth), improve the angular resolution of the array, and hence improve the significance that the array can get from a gamma-ray source. This makes the array suitable to be used for gamma-ray source detection and studies. In the present article a study of the effect of reduction in detector separation, on the performance of the array, using simulation techniques has been presented. Simulation shows that reducing the detector separation by a factor of 2 results in a factor of 2 reduction in Eth. It also gives direction of study for further improvement in the angular resolution and significance, specifically from a Crab Nebula-like spectrum. DOI: 10.4006/1.3287950 Key words: TeV Gamma-Ray Astronomy; Cascade Showers; Hadronic Showers; Cosmic Rays; High Energy Physics; Cherenkov Detectors; Fluorescence; Ground Arrays; Electromagnetic Showers; Angular Resolution; Trigger Efficiency. Un article recemment publie dans Science par le Laboratoire Pierre Auger a aide a cerner la source de rayons cosmiques d'energie extremement haute, qui sont les particules les plus energetiques connus dans l'univers. Les sources trouvees semblent soutenir la theorie des "noyaux galactiques actifs," qui dit que les rayons cosmiques d'extremement haute energie proviennent de trous noirs extremement massifs trouves au center des galaxies. L'Observatoire Pierre Auger enregistre les gerbes atmospheriques etendues grace a un vaste eventail de 1600 detecteurs de particules places 1,5 km a part dans un reseau occupant 3000 kilometres carres. La fenetre d''astrophysique des rayons gamma TeV a ete ouverte moins de deux decennies auparavant, lorsque la nebuleuse du Crabe a ete detecte pour la premiere fois. Apres plusieurs annees de developpement, la technique d'imagerie utilizee par les telescopes Cherenkov atmospheriques, comme HESS, MAGIC, permet maintenant d'effectuer des observations sensibles dans le regime de TeV. Les instruments Cherenkov a eau comme Milagro fournissent des resultats egalement. Des types differents de sources extragalactiques et galactiques ont ete detectes, qui montrent une variete de phenomenes interessants renforcant la theorie des rayons gamma de tres haute energie (VHE). Ici, j'examine les rayons cosmiques de base, leurs methodes de detection et puis je presente une etude de simulation de l'experience de GRAPES 3. GRAPES-3 est un ensemble de detecteurs scintillateurs equipes de systeme di depistage de muon a Ooty, Inde. Les capacites du reseau peuvent etre ameliorees en changeant la separation des detecteurs etc. Ca peut reduire le seuil d'energie (Eth), ameliorer la resolution angulaire de la matrice et, pourtant, accroitre l'importance que le tableau peut obtenir a partir d'une source de rayons gamma. Ce qui rend le tableau apte a etre utilize pour la detection de sources de rayons gamma et de leur etude. Dans cet article, une etude de l'effet de la reduction de la separation des detecteurs sur la performance de la matrice, en utilizant des techniques de simulation, est presentee. La simulation montre que la reduction de la separation des detecteurs par un facteur de 2 reduits (Eth) par un facteur de 2. Il donne egalement une orientation d'etude pour une plus grande amelioration de la resolution angulaire et son importance, specialement a partir d'un spectre du type de Crabe.
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