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The Role of Thermal Storage in Distributed Air-Conditioning Plants: Energy and Environmental Analysis
Get PDFEnergy efficiency is becoming a crucial target in the construction of a decarbonized society to guarantee sustainable development and tackle climate change issues. The building sector is one of the major players being responsible for a huge amount of primary energy, mostly related to heating and cooling services. Aside from intervening on the building envelope, intending to reduce energy demand, it is of fundamental importance to consider appropriate air-conditioning systems that can easily integrate renewable sources and rationalize energy use. Heat pumps are an appealing solution because of the renewable energy available in the external sources and because of the possibility to drive them with PV systems. Solar assisted heat pumps have therefore become a promising solution for energy efficiency in buildings, allowing lower primary energy demands and generating lower CO2 emissions. The ulterior integration of thermal storage in the systems allows for a further improvement of energy efficiency. This paper investigates the achievable energy savings after interventions of energy efficiency on a building aggregate composed of four buildings. In particular, two different scenarios of improvement of the HVAC system substituting the existing plant with PV-assisted heat pumps are considered. The performances obtained with the use of single-heat pumps and a centralized one with thermal storage are investigated employing dynamic simulations conducted in the TRNSYS environment
Considerations about Maximum Temperature of Toroidal Transformers in Steady-State Conditions
Get PDF In this paper, a novel method based on a thermal mathematical model which includes the main geometrical, physical and thermal parameters of the toroidal transformer has been developed in order to obtain the maximum temperature inside the transformer during steady-state operating conditions. The influence of electric current and ambient temperature on the maximum temperature has been investigated. To validate the proposed method, some experimental tests have been done. The analyzed transformer had a rated power of 2kVA and the rated primary voltage of 230V. There is a good correlation between experimental and theoretical results with a maximum difference of 3°C
Contribution of Low Enthalpy Geothermal Energy in the Retrofit of a Single-Family House: A Comparison between Two Technologies
Get PDF In recent years, the European Union has developed a sustainable, competitive, safe, and “decarbonised” energy approach. To achieve this objective, especially in highly urbanized contexts, there is a need to drastically improve the energy behavior of buildings and related energy systems. For this purpose, the aim of this paper is to analyse two very promising technologies that exploit the geothermal energy of the ground: the Earth-to-Air Heat eXchanger (EAHX) and the Ground Source Heat Pump (GSHP). These two systems are used as an energy retrofit strategy for the air conditioning system in an existing single-family house, located in Naples (south Italy). The building and the related systems are dynamically simulated using the DesignBuilder software. The results show energy savings of these two systems (compared to a traditional solution with an air-to-water heat pump) between 13% and 28%, with a total yearly primary energy consumption of about 80 kWh/m2 for the case with EAHX and around 67 kWh/m2 for the case with GSHP
Particle Size and Particle Size Distribution of Emulsion Polymers: A Review of Modeling Studies
Get PDFThe aim of this work is to provide a literature review in the area of modeling of particle size and particle size distribution of emulsion polymers. Modeling studies of emulsion polymerization are of great interest due to the industrial importance of latexes produced. There are two broad strategies adopted to model particle size distribution: 1) Lumped model in which average particle size assuming the monodispersed distribution is modelled. 2) Distributed model or population balance model in which full particle size distribution is modelled. Lumped model serves as a learning model and a stepping stone to develop a population balance model
Multi-Point Geostatistical Sedimentary Facies Modeling Based on Three-Dimensional Training Images
Get PDFAs an important modeling parameter in multi-point geostatistics, training images determine the modeling effect to a great extent. It is necessary to evaluate and optimize the applicability of candidate training images before modeling by multi-point geostatistics. Conventional two-dimensional training images can’t describe the overlapping relation of sedimentary facies in space, and there is a deficiency in describing the event relation of single data. This paper puts forward a new training image optimization method. The basic idea is to arrange and analyze sand bodies filled with sedimentary sand bodies in point dams and river channels in different periods. The method of obtaining three-dimensional training images is to use sand thickness maps and sedimentary facies maps for spatial constraints. The simulation test shows that compared with the sedimentary facies model obtained from two-dimensional training images, the sedimentary facies model obtained from three-dimensional training images through multi-point geostatistics has high compatibility and is more in line with geological understanding. On the basis of fully understanding the development characteristics of the sedimentary system and quantitative geometry of sedimentary body in the study area, sedimentary microfacies models based on sequential indicator simulation method and target simulation method are established, respectively. By comparing and analyzing the sedimentary microfacies models established by three different methods, the results show that the multi-point geostatistics can stably present the planar distribution characteristics and overlapping spatial relationship of sedimentary microfacies and reproduce the complex spatial structure and geometric shape of fluvial facies. The model established by this method is more in line with the geological sedimentary model
Performance Analysis of Hybrid Cooling Systems Using Artificial Neural Network
Get PDF In the present study, an artificial neural network (ANN) model for a solid desiccant – vapor compression hybrid air-conditioning system is developed to predict the cooling capacity, power input and coefficient of performance (COP) of the system. This paper also describes the experimental test set up for collecting the required experimental test data. The experimental measurements are taken at steady-state conditions while varying the input parameters like air stream flow rates and regeneration temperature. Most of the experimental test data (80%) were used for training the ANN model while the remaining (20%) were used for the testing of the ANN model. Experimental data were collected during the cooling period of March to September. The outputs predicted from the ANN model have a high coefficient of correlation (R>0.988) in predicting the system performance. The results show that the ANN model can be applied successfully and can provide high accuracy and reliability for predicting the performance of the hybrid desiccant cooling systems
Innovative Energy Technologies for Powering Buildings
Get PDFThis paper makes a technical analysis of the methods that can be used to provide Energy to Residential Buildings. The paper firstly describes the legislative framework for increasing the efficiency in the building sector and building certification. The key for improving the energy efficiency of buildings is ‘Nearly Zero-Energy Buildings(nZEB)‘. The main research in nZEB is described in section three and the technologies for increasing the energy performance of buildings, in summary, are presented in section four. A case study of the integration of renewable sources in the energy supply of residential buildings describes the calculation methodology of required energy, the specific consumption, and energy performance of building after inclusion of renewable energy for powering the building. The results of this analysis show that the energy uses in nZEB buildings are influenced by the building location, their architecture, energy system design, and level of renewable energy production
Evaluations on Compressibility Factor Calculation Methods for High-Pressure H2S-Containing Natural Gases
Get PDFThe compressibility factor is an essential parameter for natural gas exploitation and processing. The method based on the equation of state (EoS) represents the most popular method for compressibility factor calculations. In this paper, the accuracy of compressibility factor calculations for two traditional cubic-EoSs (Soave-Redlich-Kwong (SRK) EoS, the Peng–Robinson(PR) EoS), the Benedict–Webb–Rubin-Starling (BWRs) EoS, and the Cubic-Plus-Association (CPA) EoS are evaluated based on experimental data for high-pressure H2S-containing natural gases. A total of 234 sets of experimental compressibility factors are applied to validate the above four EoSs, which cover pressures from 70MPa to 131MPa. Results show that for the high-pressure and low H2S content natural gas (35MPa≤P<70MPa, H2S<0.3%), the BWRS EoS yields the best results among the above four EoSs. The average relative deviation (ARD) between the experimental results and the calculated values is 1.07%. For high-pressure and high H2S content natural gas (35MPa≤P<70MPa, H2S≥0.3%), the CPA EoS yields the best results with an ARD of 1.01%. For ultra-high-pressure natural gas (P≥70MPa) without H2S, the BWRS EoS gives the best results with an ARD of 0.32% and the maximum relative deviation is 1.50%
Research on the Development Features of the Shengquan Minefield Fault Structure in Shandong Province
Get PDFIn order to figure out the complexity of Shengquan Minefield fault structure, the required sample data was reorganized and collected in accordance with the field measurement data and the geological information of the 15th coal layer of the minefield. Firstly, according to the exposure condition of the drilling hole, the rose diagram of the fault direction was drawn after specifically collecting the nature, direction, and height gap and realize the visualization of the fault field measurement data, so the complexity of sectional structure can be initially analyzed. Secondly, the similarity dimension model was built through the box-type covering method in order to count the grid number of the fault trace under each sideline, and then the result was applied to the logarithmic coordinate system. By using the least square method, the slope of the bridging curve and, moreover, the fractal dimension value were achieved. Finally, Sufer was applied to draw the contour map of the fractal dimension value. The research result indicates that, through a series of quantitative analyses, this field can be divided into a simple tectonic area, mid-complex tectonic area, and complex tectonic area.
 
Better Natural Ventilation Design for Single Sided Apartments Utilising Computational Fluid Dynamics
Get PDF Wind-driven natural cross ventilation to many single-aspect apartments can be achieved via building indentations and façade articulation. The ventilation rate of these apartments will rely on pressures differences between openings caused by approaching wind pressure, local wind climate and interaction with the surrounding built environment and external pressure gradients on the building indentations or any other facades articulation and their potential driving force on natural ventilation. Detailed simulation methods are therefore required to consider all above mentioned parameters and provide internal and external airflow information to the design team to allow for design modifications or refinement where required to provide robust natural cross ventilation for such apartments. This study assesses the above parameters for a proposed development, designed with recesses and slots to enhance natural cross ventilation in single-sided apartments, and presents a reliable procedure to advise on compliance with national and/or international design guidelines utilising an advanced combined outdoor-indoor Computational Fluid Flow (CFD) analysis integrated with localized weather data for the project site