235 research outputs found
Solar-assisted district heating networks: Development and experimental validation of a novel simulation tool for the energy optimization
No full textDue to the growing interest in 4th and 5th generation district heating systems, characterized by lower working fluid temperatures compared to the past, poligenerative solar-assisted networks are experiencing increasing attention from the research community. In this framework, the adoption of large solar-based thermal systems will become more common for such applications. Therefore, optimising the design and operation of each solar field servicing a specific network will be crucial to improving its overall performance. In this context, the objective of the current research is to develop a method to maximise the performance of solar-assisted poligenerative district heating networks by optimising each associated solar system separately. To this end, a novel dynamic simulation tool for solar thermal field design and optimization has been developed and experimentally calibrated in the Simulink/Simscape environment. The tool is capable of investigating innovative control logics, and accurately assessing both the thermal and hydraulic behaviour of the systems. The latter is one of its novelty, as ignoring the hydronic behaviour of the system can lead to the adoption of flawed design or control logic. The resulting tool will enable accurate optimization of the design and management of each solar field servicing a given district heating network, thereby improving the efficiency of the system as a whole. In order to demonstrate the viability of the proposed method and the capabilities of the developed simulation tool, a proof-of-concept analysis is conducted on an existing solar thermal field serving the Geneva district heating network. Diverse control logics (including Rule-Based and Model Predictive Control) are evaluated for the selected case study. The performed analysis demonstrates that the proposed method has the potential to accomplish significant primary energy reductions (up to 10.3%) and CO2 emissions avoidance (up to 10.9 tCO2/year)
Building-façade integrated solar thermal collectors: Energy-economic performance and indoor comfort simulation model of a water based prototype for heating, cooling, and DHW production
No full textThis paper presents the design and the thermodynamic analysis of a new prototype of flat-plate solar thermal collector, suitable for building integration, using water as working fluid. The main novelty of the proposed solar thermal collector is the use of cheap materials and simple design solutions, taken into account with the aim to reduce the manufacturing and installation costs towards the improvement of the market penetration of this technology in the near-term future. The collector is suitable for domestic hot water production and for space heating and cooling, achieved through the use of adsorption chillers. A suitable dynamic simulation model for the system energy, comfort, economic, and environmental performance assessment is developed by taking into account both active and passive effects related to the building integration of the solar collector.
The developed simulation model, implemented in a suitable MatLab computer tool, is experimentally validated; the main results of the validation process are discussed in this paper. Moreover, in order to show the potential of the presented building integrated collector prototype and of the related simulation tool, a suitable case study is developed. It refers to a residential unit of a multi-floor building where the prototype collectors are integrated on the South façade. Simulations are carried out for 2 building envelope weights and 9 different weather zones. Interesting outcomes from the energy, economic, environmental, and comfort point of views are obtained
New ventilation design criteria for energy sustainability and indoor air quality in a post Covid-19 scenario
No full textThe Covid-19 outbreak raised great attention to the importance of indoor air quality in buildings. Even if the Covid-19 epidemic is nearing an end, all stakeholders agree that increasing outside air flow rates is beneficial for decreasing the likelihood of contagion, lowering the risk of future pandemics, and enhancing the general safety of the interior environment. Indeed, diverse concerns raised about whether the ventilation standards in place are still adequate. In this context, this research intends to assess the suitability of current ventilation standards in addressing the current pandemic scenario and to offer novel criteria and guidelines for the design and operation of HVAC systems, as well as useful guidance for the creation of future ventilation standards in a post-Covid-19 scenario. To that end, a comprehensive analysis of the ANSI/ASHRAE 62.1 is carried out, with an emphasis on its effectiveness in reducing the risk of infection. Furthermore, the efficacy of various ventil..
The role of energy communities in electricity grid balancing: A flexible tool for smart grid power distribution optimization
No full textThe unpredictability of renewable energy systems can affect the stability of the electricity grid, causing voltage and frequency imbalances. In this work, a suitable methodology based on the peer-to-peer scheme applied to energy communities is developed and implemented in a simulation tool useful for investigating energy management strategies for decision-making aims. The developed model discretizes the energy community and its users into multiple control volumes, taking into account various technologies. It incorporates energy balances for individual users as well as the entire energy community, considering prosumers, consumers, energy storage systems, and electric vehicles. Moreover, the model enables the exploration of different solutions for grid frequency regulation and optimization of distributed energy resources. Additionally, the tool can predict electricity demand one day ahead, facilitating the organization of renewable energy availability and storage systems to minimize grid interactions and flatten electricity demand. The model incorporates different objective functions, including self-consumption, self-sufficiency, and grid-balancing factors, to evaluate the performance of energy communities. To show the capability of the developed model, it will be adopted to optimize the performance of an investigated community. As a result, an increase in renewable energy self-consumption from 59.4 to 83.9 MW h/year is achieved. Furthermore, the objective of grid balancing was achieved by guaranteeing a non-fluctuating load and providing 1.46 and 7.71 MW h/year for upward and downward grid frequency regulation. These findings illustrate the positive impact of energy dispatching management on the integration of renewable energy sources and the importance of further studying this topic to ensure grid stability
Optimising low-temperature district heating networks: A simulation-based approach with experimental verification
No full textFifth generation district heating and cooling systems are becoming increasingly popular due to their ability for working with low temperature of heat transfer fluids. Among the other benefits, this characteristic allows for a better exploitation of renewable energy sources. On the other hand, these networks require a fine design and precise management to exploit their full potential. Both these requirements can be met by using advanced simulation and optimisation tools. This research proposes a simulation tool purposely conceived for the design and the optimisation of fifth-generation district heating and cooling systems. This tool is capable of assessing the effects of each building-plant system on the whole district heating and cooling water loop, and to evaluate the effectiveness of diverse network morphology. These capabilities are due the level of detail of the mathematical modelling which takes into account the thermohydraulic characteristics of the network, each building thermo-physics properties, and the heat pump/chiller detailed operation. The described tool has been adopted to simulate an existing experimental network prototype (consisting of a central heat pump, behaving as thermal energy balancing station, and eight users), and the achieved results were compared to those experimentally obtained for validation aims. The capabilities of the validated tool have been demonstrated by investigating an innovative control logic (representing a further novelty of this research) for a “proof-of-concept” fifth-generation district heating and cooling network. In particular, by adopting a predictive control logic, the water loop temperature is dynamically optimised to minimise the entire network energy demand. The adopted control strategy has yielded significant primary energy savings, amounting to 10.3 MWh/year, with a rate of 6.5 % compared to the reference case characterised by a fixed network temperature. These results underscore the potential of the proposed method and demonstrate the effectiveness of the developed tool
Energy recovery through natural gas turboexpander and solar collectors: Modelling and thermoeconomic optimization
No full textThis paper presents a novel dynamic simulation model for the analysis of a hybrid turboexpander systemcoupled with innovative high-vacuum solar thermal collectors. The model is developed in MatLab and itis able to dynamically calculate the energy, exergy, environmental, and economic performances of theinvestigated system, by taking into account the hourlyfluctuation of thermodynamic and economicparameters (e.g. electricity cost, natural gas temperature, andflow rates, etc.). In addition, a computer-based Design of Experiment (DoE) approach was implemented for achieving the optimal design of theproposed system.A suitable case study is presented in order to show the capabilities of the developed simulation tool.Conventional and non-conventional decompression systems located in the weather zone of Messina(South-Italy) are investigated with the aim of assessing the optimal system configuration. By means ofthe computer-based DoE analysis, the optimal values of several design parameters (such as the numberof solar thermal collectors, the volume of the hot water storage tank, and the size of the water looppump) are calculated. Numerical results show significant primary energy savings (1.36 TWh/year) andavoided carbon dioxide emissions (348 tCO2/year). From the economic point of view, a feasible simplepay-back period of 4.51 years is achieved. The destroyed exergy of the system components are calculated,obtaining the highest value for the turbo-expander, equal to 12.0 TWh/year
Photovoltaic thermal collectors: Experimental analysis and simulation model of an innovative low-cost water-based prototype
No full textThis paper presents an innovative water photovoltaic thermal collector prototype. One of the main novelties of such system is its economic affordability, obtained through low-cost materials. The collector, constructed and experimentally tested at the University of Patras (Greece), is composed of a polycrystalline photovoltaic module coupled to eleven plastic pipes for water heating, located under the PV panel in an aluminium box. The prototype, suitable for building architectonical integration, can provide domestic hot water and electricity to the building. In order to assess the energy, economic and environmental performance of the system under different weather conditions and for diverse building uses, a suitable dynamic simulation model was developed and validated vs. experimental data. To investigate the convenience of the presented prototype and the potentiality of the developed software, a suitable case study is presented. In particular, the photovoltaic thermal collector is coupled to a stratified hot water storage tank for supplying domestic hot water to a single-family house located in three different European weather zones: Freiburg, Naples and Almeria. The system layout optimization was also performed through an energy and economic sensitivity analysis to some design and operating parameters. Useful design criteria and interesting energy and economic results were obtained
Solar heating and cooling systems for residential applications: a comparison among different system layouts and technologies
No full textA purposely developed dynamic simulation model for different Solar Heating and Cooling (SHC) systems including adsorption and absorption chillers driven by Evacuated Tube solar Collectors (ETC) and Concentrating PhotoVoltaic/Thermal (CPVT) collectors is presented. The modelled system layouts are capable to simultaneously produce electricity, space heating/cooling and domestic hot water. A case study focused on a representative cluster of two buildings, including office and residential spaces, located in cold and temperate European climate zones, is developed. A comprehensive parametric analysis is carried out in order to find out the design and operating conditions for the optimal energy performance of systems
Building to vehicle to building concept toward a novel zero energy paradigm: Modelling and case studies
No full textThis paper proposes and analyses a novel energy management system for buildings connected in a micro-grid, by considering electric vehicles as active components of such energy scheme. Renewable energy sources, PV, energy storage systems and bidirectional electricity exchange with the buildings and the grid are taken into account. The considered energy scheme, Building to Vehicle to Building, is analysed by including both buildings and mobility consumptions in the energy balance. Three different management system scenarios, designed to analyse the role of electric vehicles as electricity vector among buildings integrating PV panels and electrical storages, are analysed through a case study analysis. To this aim, a dynamic simulation model, implemented in MatLab, is suitably developed for the assessment of the energy demands and loads of the building, as a function of the considered electric vehicles energy use patterns. Simulation results show that the proposed energy management systems improves the building grid reliance and the grid electricity consumption is remarkably reduced up to 45% and 77% depending on the proposed scenarios. Their energy exchange options also enhanced the energy-matching indexes. The economic analysis highlights the economic viability of the system, as well as the need of suitable funding policies to support the development of such micro-grid systems
Enhancing trains envelope – heating, ventilation, and air conditioning systems: A new dynamic simulation approach for energy, economic, environmental impact and thermal comfort analyses
No full textNowadays, due also to high hygrothermal comfort requirements, the energy consumption for heating/cooling of modern trains can reach 30% of the related overall electricity demand. Energy-saving of train Heating, Ventilation and Air Conditioning systems can be suitably assessed through dynamic simulation approaches. Specifically, the weather solicitation has to be dynamically accounted for by considering the actual moving train location and orientation. Through such methodology different innovative actions for energy efficiency, environmental impact reduction and comfort enhancement can be analysed by also assessing their economic feasibility. In this paper, a novel simulation tool for the complete performance analysis of trains was developed in TRNSYS environment. To show the capabilities of the considered approach, a novel case study referred to an existing medium-distance train operating in South Italy is presented. Heating/cooling loads and demands, and the related electricity requirements, are dynamically assessed for the standard and revamped train. Several energy saving actions are considered for the coupling between the envelope and the Heating, Ventilation and Air Conditioning systems enhancement. The obtained results return significant benefits in terms of energy saving, avoided CO2 emissions and comfort. Paybacks depend on operating conditions. Useful design and operating criteria for trains manufacturers and users are provided
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