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Abstract The international efforts for improving energy efficiency in buildings and reducing their environmental impact also constitute a challenge for working against the risk of energy poverty. The work aims to test a methodology for optimizing the operational costs of the different flats of a multi-family building for social housing. The method combines the use of TRNSYS building energy simulation program with GenOpt Generic Optimization program in a so-called simulation-based optimization method. A typical floor of a real case study building was modeled and the energy costs for heating and cooling due to the variation of design variables related to the building envelope was studied. The optimization led to reduce the total operational costs of the flats by the range 17%-23%. The different share of heating, cooling, ventilation and DHW in the total operational costs was studied and resulted differences in energy rating and costs between flats were analyzed.

AbstractThe paper presents the design and prototyping of a gas generator system for turbocharger experimental testing capable of delivering a wide range of flow rates with adequate thermodynamic characteristics. The system feeds the turbocharger test section with an hot gas stream of prescribed mean and time varying pressure and temperature in order to fully span the operating domain of the device with controlled accuracy. Compared with the more conventional gas combustor system, it allows for a safer rig operation ensured by the structural robustness of a four stroke diesel engine and an easier turbine inlet flow control. The latter is achieved by means of an external supercharging station and a modern ICE electronic control unit so that mass flow rate, pressure and temperature values can be set independently.The steady compressor and turbine performance maps can be obtained operating the rig according to a conventional procedure, i.e. collecting a set of flow rate pressure ratio data points (mg, π) for given hot gas properties. Alternatively using more advanced operating modes unsteady testing is possible to reproduce the complexities characterizing the driving cycles required by the latest European regulations.

AbstractOne of the problems with solar flat plate collectors for domestic water heating is that they produce more energy in the summer months, when the domestic hot water needs are lower than in winter months. This causes a significant difference between supply and demand and thus overheating during the summer. A method to avoid this problem is to design solar collector fields that offer a 100% of the water needs in the summer, but a small percentage during the winter, which is certainly not ideal.In this work, ray tracing is used to design a solar thermal collector that offers a more uniform production during the year. A novel geometry is chosen where the collector is split in two parts, a curved absorber and a mini parabolic concentrator. The concentrator is designed to concentrate the radiation during the midday hours of winter days and to not doing it in the midday hours of summer days. This increases the energy produced in winter and prevents the installation from overheating.In order to study the hours when this geometry will concentrate the solar radiation, ray tracing is used. As the solar collector has a design that allows the collector to be easily integrated into a facade, the simulations in the most useful architectural integration positions are simulated, those are horizontal positions, but vertical positions or any other position are suitable if the collector is installed on a roof.For each position, the amount of hours where the whole collector is working and the total radiation captured are calculated and compared with the solar radiation captured by an equivalent flat surface, which would corresponds to conventional flat plate collectors.Simulation results shows how for a concentrator designed to work properly in the 5 midday hours during the winter solstice it will not work during the 5 midday hours during the summer solstice, avoiding overheating.

AbstractLatent Heat Storage is used to balance temporary temperature alternations and storage of energy in several practical application areas. Numerical modelling and analysis of Latent Heat Storage is essential step in designing it for particular application. The present study explores numerically and experimentally the process of melting and solidification of a Phase Change Material in vertical concentric cylindrical unit. Two different cases are considered for analysis; first is without considering gravity and buoyancy effect and second is with considering its effect on PCM. In this analysis melting and solidification time, variation of mushy zone, solid- liquid interface have been studied for both the cases. Commercially available paraffin wax is used as a phase change material. Numerical results have a good agreement with the experimental results. The obtained results can be helpful to study the heat transfer process and designing of Latent Heat base Thermal Energy Storages.

AbstractIn this paper, a dataset of 92,906 dwellings was analysed adopting data mining techniques for the classification of heating and domestic hot water primary energy demand and for the evaluation of the most influencing factors. The sample was classified in three energy demand categorical variables (Low, Medium, High) considering different geometrical and physical attributes. The output of the model made it possible to set reference threshold values among the physical variables. Moreover, high energy demand dwellings were analysed in depth using a k-means algorithm in order to evaluate the design variables which need to be considered in a refurbishment process.

AbstractFollowing the most recent European Directives on Energy Performance of Buildings and Energy Efficiency, new solutions for DHW production, space heating and cooling have to be developed and applied to reduce the primary energy consumption of residential buildings.Due to the complexity of installation and control, H&C hybrid systems exploiting a mix of conventional fuels and RES are not yet widespread although they can bring important savings to the yearly building energy consumptions.This work summarizes the parametric analysis used as part of the design process of a hybrid system for the retrofit of a multifamily house located in Madrid, and shows how heating, cooling and DHW demands of multifamily houses can be covered by a heat pump plus solar systems, integrating a high share of RES. The design of the system has taken into account energy savings, economics and architectural aspects.

AbstractThe Fluid Catalytic Cracking (FCC) process may represent as much as 30% of the total CO2 emissions from a refinery. Oxy-combustion technology is a promising option to reduce these emissions and as part of the CO2 Capture Project-Phase 3 (CCP3), Petrobras has retrofitted its large pilot scale FCC unit to demonstrate the technical viability of operating the unit in oxy-combustion conditions. The startup of the unit has shown that the transition from air to oxy is fast, however there must be a close monitoring of the excess O2 in the flue gas as it may reach low levels, taking the unit to a partial burn mode. Two extreme conditions were tested and these were called the same heat balance condition and secondly the same flow rate condition. For the same heat balance, the O2 content in the recycled gas mixture is higher and there is minimum impact on unit operational conditions and product yields. For the same flow rate, a higher overall feed conversion is observed due to a larger catalyst circulation. The oxy-combustion operation in this last condition allowed an increase of feed processing with very low changes in product slate. In all oxy tests, the CO2 content in the flue gas showed values close to 95%vol. Overall, the tests have demonstrated that it is technically viable to operate an FCC unit in the oxy-combustion mode.