216 research outputs found
Selected Topics from the World Renewable Energy Congress WREC 2014
No full textThis research concerns the design of an electrical machine that shall be implemented on a wave energy converter (WEC). Analysis of the available wave data and optimisation of the WEC were carried out so as to design the optimum system that will interact efficiently with the conditions of the selected location. The electrical model was designed for wave heights and periods that yielded the maximum power throughout the year. The initial finite element simulations were undertaken on the design of a 4-pole tubular permanent magnet (PM) linear synchronous machine. The performance of the system was optimised for a wave height and period of 3 meters and 6 seconds, respectively. The capacity of the linear generator was set at 15kVA and the dimensions of the WEC (floating point absorber) were determined accordingly through the application of a simplified model for predicting the coupled dynamic response of the absorber and the linear generator. It was necessary that the machine gives a reasonable performan+ce when operating under the slower and most common waves. Thus an 8-pole and a 16-pole tubular linear PM machine were also simulated and their performance was compared. Through this analysis the 16-pole design resulted in the best performance, especially at low speeds. Simulations were initially compared at fixed speed but were later simulated with variable speed conditions so as to represent more accurately the wave’s motion and monitor the power generator performance at variable loadings.peer-reviewe
Analytical modelling of integrated solar drying system
No full textThe drying of fruit and vegetables is a subject of great importance. Dried fruit and vegetables have gained commercial importance, and their growth on a commercial scale has become an important sector of the agricultural industry. However, food drying is one of the most energy intensive processes of the major industrial process and accounts for up to 15 % of all industrial energy usage. Due to increasingly high electricity prices and environmental concern, a dryer using traditional energy sources is not a feasible option anymore. Therefore, an alternative/renewable energy source is needed. In this regard, an integrated solar drying system that includes highly efficient double-pass counter flow v-groove solar collector, conical-shaped rock-bed thermal storage, auxiliary heater, the centrifugal fan and the drying chamber has been designed and constructed. Mathematical model for all the individual components as well as an integrated model combining all components of the drying system has been developed. Mathematical equations were solved using MATLAB program. This paper presents the analytical model and key finding of the simulation
Modelling conical rock-bed solar thermal storage tank
No full textAn important application of solar thermal storage is for power generation or process heating. Low-temperature thermal storage in a packed rock bed is considered the best option for thermal storage for solar drying applications. In this chapter, mathematical formulations for conical have been developed. The model equations are solved numerically for charging/discharging cycles utilizing MATLAB. Results were compared with rock-bed storage with standard straight tank. From the simulated results, the temperature distribution was found to be more uniform in the truncated conical rock-bed storage. Also, the pressure drop over a long period of time in the conical thermal storage was as low as 25 Pa. Hence, the amount of power required from a centrifugal fan would be significantly lower. The flow of air inside the tank is simulated in SolidWorks software. From flow simulation, 3D modelling of flow is obtained to capture the actual scenario inside the tank
Empowering Circular Economy Transition in the Building Sector: a Stakeholder-Centric approach in the Design Phase for Climate Change Mitigation
No full textWinery and oil-factory recovery and regeneration in Veglie: bioclimatic and sustainable principles
No full textEvaluation of the luminous environment in open-plan offices with skylights
No full textHigh Dynamic Range (HDR) imaging was used to collect luminance information at workstations in 2 open-plan office buildings in Queensland, Australia: one lit by skylights, vertical windows and electric light, and another by skylights and electric light. This paper compares illuminance and luminance data collected in these offices with occupant feedback to evaluate these open-plan environments based on available and emerging metrics for visual comfort and glare. This study highlights issues of daylighting quality and measurement specific to open plan spaces. The results demonstrate that overhead glare is a serious threat to user acceptance of skylights, and that electric and daylight integration and controls have a major impact on the perception of daylighting quality. With regards to measurement of visual comfort it was found that the Daylight Glare Probability (DGP) gave poor agreement with occupant reports of discomfort glare in open-plan spaces with skylights, and the CIE Glare Index (CGI) gave the best agreement. Horizontal and vertical illuminances gave no indication of visual comfort in these spaces
Effectiveness of Occupant Behavioral Ventilation Strategies on Indoor Thermal Comfort in Hot Arid Climate
No full textThis paper discusses the effectiveness of occupant behavioral strategies of open and close windows on indoor thermal comfort in residential buildings in the hot arid climate of Cairo, Egypt. Based behavioral survey scenarios were deduced from a questionnaire analysis in both winter and summer seasons. The behavioral scenarios were compared to the base case and were categorized into two main groups. The first group includes the based behavioral survey scenarios that were deduced from the questionnaire analysis, and the second group includes the scenarios that were suggested to improve thermal comfort if applied in the summer season. Each scenario was applied to the case study and then was simulated through the IESVE simulation software program. The effect of each scenario was investigated in winter (represented by the months that need zero cooling demand), summer (represented by the months that need zero heating demand), and spring and autumn months (represented by the months where both cooling and heating are needed)
CREATION OF A METHODOLOGY AND A DIGITAL TECHNOLOGICAL PLATFORM AIMED TO ENERGY EFFICIENCY IN THE HISTORICAL HERITAGE AND DIFFUSED BUILDING
No full textThis research intersects the thematic area of performance improvement in historic buildings and the theme of Digital Cultural Heritage, trying to combine the growing interdisciplinary focus on energy efficiency applied to historic buildings, with the innovative digital technologies of the use of energy in architecture.
The research broadens the gaze on the improvement of comfort conditions in the architectural heritage of historical aggregation, in which the real connective tissue is made up of poor buildings, an expression of the traditional constructive knowledge of the place.
To obtain an improvement in performance, a methodological path is necessary from the evaluation process to the intervention, the result of which can be translated into a "multi-user platform" based on the reading of energy data and oriented towards the perspective of improvement strategies.
The research aims to identify a simplified model that allows the estimation of the energy losses of the buildings examined, with the aim of monitoring current consumption and quantifying the energy saved through suggested improvement measures that can also be quantified with an evaluation. summary of intervention costs. The informative dataset of this evaluation process flows into an easy-to-consult platform with 3D visualization for local administrations, to implement effective energy governance and more careful and aware planning of the territory
Low-Cost Procedure for Evaluating the Thermal Resistance of Building Materials
No full textThe use of unconventional building materials locally produced through an artisan process, as well as the upcycling of materials and components, is severely limited by the lack of technical information and product specifications enabling their use in building design and construction. In many cases, nonstructural building elements with relevant insulating properties cannot be employed due to missing information on their thermal properties. On the other hand, standard certification procedures are so complex, expensive, and time-consuming to be fully out of reach for do-it-yourself (DIY) builders.To address this problem, a simplified, low-cost test procedure was developed at Politecnico di Milano to be used by students, as well as for a first thermal performance evaluation of building materials in research projects, where accuracy is not strictly regulated. A cube test box with a side of 600 mm was built using a certified insulating material, with known third-party product specifications (extruded polystyrene insulation—XPS), leaving an open side for accommodating the sample to be tested. An incandescent lamp was placed inside the box to heat its interior up to a stable temperature, while an infrared optical pyrometer was used to measure the external surface temperature of the testing sample.Assuming a direct relationship between temperature difference and variation of thermal conductivity, it was possible to estimate the R-value of the sample material with a precision higher than 94%. Certified materials with known thermal conductivity were also measured using the same procedure, in order to validate the proposed simplified testing method.The testing equipment, which is extremely cheap and easy to build, proved effective to perform a preliminary assessment of thermal properties of building material samples, achieving results with acceptable accuracy for initial research stages. This simplified testing method could also be easily employed in developing countries as an aid for DIY construction practice—when thermal property specifications of local building materials may not be available
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