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The paper provides results from a hardware-in-the-loop experimental campaign on the operation of an air-source heat pump (HP) for heating a reference dwelling in Pisa, Italy. The system performances suffer from typical oversizing of heat emission devices and high water-supply temperature, resulting in HP inefficiencies, frequent on-off cycles, and relevant thermal losses on the hydronic loop. An experimentally validated HP model under different supply temperatures and part-load conditions is used to simulate the installation of a thermal storage between heat generator and emitters, in both series and parallel arrangements. Results relative to a typical residential apartment show that the presence of the thermal storage in series configuration ensures smoother heat pump operation and energy performance improvement. The number of daily on-off cycles can be reduced from 40 to 10, also saving one-third of electric energy with the same building loads. Preliminary guidelines are proposed for correctly sizing the tank in relation to the HP capacity and the average daily heating load of the building. A storage volume of about 70 L for each kilowatt of nominal heating capacity is suggested.
Alessandro Franco; Carlo Bartoli; Paolo Conti; Daniele Testi. Optimal Operation of Low-Capacity Heat Pump Systems for Residential Buildings through Thermal Energy Storage. Sustainability 2021, 13, 7200 .
AMA StyleAlessandro Franco, Carlo Bartoli, Paolo Conti, Daniele Testi. Optimal Operation of Low-Capacity Heat Pump Systems for Residential Buildings through Thermal Energy Storage. Sustainability. 2021; 13 (13):7200.
Chicago/Turabian StyleAlessandro Franco; Carlo Bartoli; Paolo Conti; Daniele Testi. 2021. "Optimal Operation of Low-Capacity Heat Pump Systems for Residential Buildings through Thermal Energy Storage." Sustainability 13, no. 13: 7200.
This paper proposes an analytical method for the dynamic thermal simulation of energy piles with a short time resolution (e.g., tens of minutes) as an alternative to numerical approaches, which require relevant computational resources. The discussion is tailored to the implementation of analytical models in dynamic energy simulation software for buildings and HVAC systems. The main modeling challenges consist of accounting for the pile thermal capacity, pipes configuration, and time-varying inlet temperature and flow rate values. The heat transfer process occurs in three characteristic periods, each of them characterized by a 2D or 3D geometry of the heat transfer process. The first period concerns the evolution of the fluid temperature and heat transfer over the length of the pipes, the second period concerns the thermal diffusion within the heat capacity of the foundation, and the third period is driven by pile geometry and ground source characteristics. For short time resolution analyses, we proposed a general linear set of equations based on the e-NTU theory for heat exchangers, the infinite composite-medium line source solution, and the finite line source for the ground source. The proposed method is compared with a full transient 3D numerical simulation. The maximum deviation in terms of return temperature to the heat pump is 0.2 K. The general dimensionless form, the short time resolution, and the limited computational time make the method suitable for building simulation software and optimization codes for thermal analysis and energy pile design.
Walter Grassi; Paolo Conti; Eva Schito; Daniele Testi. A Fast Analytical Method for the Dynamic Energy Simulation of Energy Piles with Short Time Resolution. Journal of Heat Transfer 2021, 1 .
AMA StyleWalter Grassi, Paolo Conti, Eva Schito, Daniele Testi. A Fast Analytical Method for the Dynamic Energy Simulation of Energy Piles with Short Time Resolution. Journal of Heat Transfer. 2021; ():1.
Chicago/Turabian StyleWalter Grassi; Paolo Conti; Eva Schito; Daniele Testi. 2021. "A Fast Analytical Method for the Dynamic Energy Simulation of Energy Piles with Short Time Resolution." Journal of Heat Transfer , no. : 1.
The paper provides a methodology for the optimal control of heating, ventilation, and air conditioning (HVAC) systems used in public buildings, with the purpose of obtaining high comfort and safety standards along with energy efficiency. The combination of the two concurrent objectives of minimizing energy use and guaranteeing high standards of occupant comfort is obtained by means of multi-objective optimization, in which a comfort model is combined along with a dynamic energy model of the building. The use of dynamic setpoints for the HVAC and the inclusion of comfort indicators represent a step forward, compared to the current design and operation procedures suggested by technical standards. The utilization of the proposed methodology is tested with reference to a case study, represented by an academic building used by the University of Pisa for educational purposes, whose extensive and variable occupancy can help to emphasize the importance of comfort in the operation of HVAC systems in different climatic conditions and with different occupancy profiles. We show how this optimization brings interesting results in terms of energy-saving (up to 30%), obtaining an increased comfort level (of more than 25%) compared to the operating conditions suggested by technical standards.
Alessandro Franco; Carlo Bartoli; Paolo Conti; Lorenzo Miserocchi; Daniele Testi. Multi-Objective Optimization of HVAC Operation for Balancing Energy Use and Occupant Comfort in Educational Buildings. Energies 2021, 14, 2847 .
AMA StyleAlessandro Franco, Carlo Bartoli, Paolo Conti, Lorenzo Miserocchi, Daniele Testi. Multi-Objective Optimization of HVAC Operation for Balancing Energy Use and Occupant Comfort in Educational Buildings. Energies. 2021; 14 (10):2847.
Chicago/Turabian StyleAlessandro Franco; Carlo Bartoli; Paolo Conti; Lorenzo Miserocchi; Daniele Testi. 2021. "Multi-Objective Optimization of HVAC Operation for Balancing Energy Use and Occupant Comfort in Educational Buildings." Energies 14, no. 10: 2847.
Worldwide increasing awareness of energy sustainability issues has been the main driver in developing the concepts of (Nearly) Zero Energy Buildings, where the reduced energy consumptions are (nearly) fully covered by power locally generated by renewable sources. At the same time, recent advances in Internet of Things technologies are among the main enablers of Smart Homes and Buildings. The transition of conventional buildings into active environments that process, elaborate and react to online measured environmental quantities is being accelerated by the aspects related to COVID-19, most notably in terms of air exchange and the monitoring of the density of occupants. In this paper, we address the problem of maximizing the energy efficiency and comfort perceived by occupants, defined in terms of thermal comfort, visual comfort and air quality. The case study of the University of Pisa is considered as a practical example to show preliminary results of the aggregation of environmental data.
Giuseppe Anastasi; Carlo Bartoli; Paolo Conti; Emanuele Crisostomi; Alessandro Franco; Sergio Saponara; Daniele Testi; Dimitri Thomopulos; Carlo Vallati. Optimized Energy and Air Quality Management of Shared Smart Buildings in the COVID-19 Scenario. Energies 2021, 14, 2124 .
AMA StyleGiuseppe Anastasi, Carlo Bartoli, Paolo Conti, Emanuele Crisostomi, Alessandro Franco, Sergio Saponara, Daniele Testi, Dimitri Thomopulos, Carlo Vallati. Optimized Energy and Air Quality Management of Shared Smart Buildings in the COVID-19 Scenario. Energies. 2021; 14 (8):2124.
Chicago/Turabian StyleGiuseppe Anastasi; Carlo Bartoli; Paolo Conti; Emanuele Crisostomi; Alessandro Franco; Sergio Saponara; Daniele Testi; Dimitri Thomopulos; Carlo Vallati. 2021. "Optimized Energy and Air Quality Management of Shared Smart Buildings in the COVID-19 Scenario." Energies 14, no. 8: 2124.
The geothermal sector has a strength point with respect to other renewable energy sources: the availability of a wide range of both thermal and power applications depending on the source temperature. Several researches have been focused on the possibility to produce geothermal energy without brine extraction, by means of a deep borehole heat exchanger. This solution may be the key to increase the social acceptance, to reduce the environmental impact of geothermal projects, and to exploit unconventional geothermal systems, where the extraction of brine is technically complex. In this work, exergy efficiency has been used to investigate the best utilization strategy downstream of the deep borehole heat exchanger. Five configurations have been analyzed: a district heating plant, an absorption cooling plant, an organic Rankine cycle, a cascade system composed of district heat and absorption chiller, and a cascade system composed of the organic Rankine plant. District heating results in a promising and robust solution: it ensures high energy capacities per well depth and high exergy efficiency. Power production shows performances in line with typical geothermal binary plants, but the system capacity per well depth is low and the complexity increases both irreversibilities and sensibility to operative and source conditions.
Claudio Alimonti; Paolo Conti; Elena Soldo. Selecting the Optimal Use of the Geothermal Energy Produced with a Deep Borehole Heat Exchanger: Exergy Performance. Proceedings 2020, 58, 20 .
AMA StyleClaudio Alimonti, Paolo Conti, Elena Soldo. Selecting the Optimal Use of the Geothermal Energy Produced with a Deep Borehole Heat Exchanger: Exergy Performance. Proceedings. 2020; 58 (1):20.
Chicago/Turabian StyleClaudio Alimonti; Paolo Conti; Elena Soldo. 2020. "Selecting the Optimal Use of the Geothermal Energy Produced with a Deep Borehole Heat Exchanger: Exergy Performance." Proceedings 58, no. 1: 20.
Estimating and optimizing the dynamic performance of a heat pump system coupled to a building is a paramount yet complex task, especially under intermittent conditions. This paper presents the “hardware-in-the-loop” experimental campaign of an air-source heat pump serving a typical dwelling in Pisa (Italy). The experimental apparatus uses real pieces of equipment, together with a thermal load emulator controlled by a full energy dynamic simulation of the considered building. Real weather data are continuously collected and used to run the simulation. The experimental campaign was performed from November 2019 to February 2020, measuring the system performances under real climate and load dynamics. With a water set point equal to 40 °C, the average heat pump coefficient of performance was about 3, while the overall building-plant performance was around 2. The deviation between the two performance indexes can be ascribed to the continuous on-off signals given by the zone thermostat due to the oversized capacity of the heat emission system. The overall performance raised to 2.5 thanks to a smoother operation obtained with reduced supply temperature (35 °C) and fan coil speed. The paper demonstrates the relevance of a dynamic analysis of the building-HVAC system and the potential of the “hardware-in-the-loop” approach in assessing actual part-load heat pump performances with respect to the standard stationary methodology.
Paolo Conti; Carlo Bartoli; Alessandro Franco; Daniele Testi. Experimental Analysis of an Air Heat Pump for Heating Service Using a “Hardware-In-The-Loop” System. Energies 2020, 13, 4498 .
AMA StylePaolo Conti, Carlo Bartoli, Alessandro Franco, Daniele Testi. Experimental Analysis of an Air Heat Pump for Heating Service Using a “Hardware-In-The-Loop” System. Energies. 2020; 13 (17):4498.
Chicago/Turabian StylePaolo Conti; Carlo Bartoli; Alessandro Franco; Daniele Testi. 2020. "Experimental Analysis of an Air Heat Pump for Heating Service Using a “Hardware-In-The-Loop” System." Energies 13, no. 17: 4498.
The paper deals with the multi-objective optimization of the HVAC control in museums. Scientific literature, technical standards and museums stakeholders mainly focus on the single-objective of artefacts conservation. However, a major attention should be paid at visitors’ comfort and energy consumption, without compromizing artwork integrity. In this work, we propose and apply a methodology to find the best control of the air-handling unit to concurrently optimize the three objectives. The proposed methodology is based on the achievement function method and finds the Pareto-optimal value of the HVAC control variables over the operational period. The priority given to each objective can be customized by changing the reference point of the achievement function. The method is applied to a museum in Italy hosting paper artworks during summer. Both exhibition room and HVAC system are simulated through an in-house dynamic model. The results show that all three objectives are improved with respect to typical fixed setpoint values (i.e., T = 23 °C and RH = 50%). Depending on the reference point, different profiles of indoor hygrothermal parameters are found; in any case, improvements of each of the objective functions indexes (equivalent lifetime multiplier for artwork preservation, predicted percentage of dissatisfied, and energy consumption) are obtained with respect to fixed setpoint strategy. The multi-objective optimization of museums with paper artworks in summer periods encourages low indoor temperatures. This would lead to slightly increased energy consumptions, which can be limited, by reducing the ventilation rate to 3–3.5 1/h instead of the typical 4–5 1/h.
Eva Schito; Paolo Conti; Luca Urbanucci; Daniele Testi. Multi-objective optimization of HVAC control in museum environment for artwork preservation, visitors’ thermal comfort and energy efficiency. Building and Environment 2020, 180, 107018 .
AMA StyleEva Schito, Paolo Conti, Luca Urbanucci, Daniele Testi. Multi-objective optimization of HVAC control in museum environment for artwork preservation, visitors’ thermal comfort and energy efficiency. Building and Environment. 2020; 180 ():107018.
Chicago/Turabian StyleEva Schito; Paolo Conti; Luca Urbanucci; Daniele Testi. 2020. "Multi-objective optimization of HVAC control in museum environment for artwork preservation, visitors’ thermal comfort and energy efficiency." Building and Environment 180, no. : 107018.
The performance of ground heat exchanger systems depends on the knowledge of the thermal parameters of the ground, such as thermal conductivity, capacity, and diffusivity. The knowledge of these parameters often requires quite accurate experimental analysis, known as a thermal response test (TRT). In this paper, after a general analysis of the various available types of TRT and a study of the theoretical basics of the method, we explore the perspective of the definition of a simplified routine method of analysis based on the combination of a particular version of TRT and the routine geotechnical tests for the characterization of soil stratigraphy and the ground characteristics. Geotechnical analyses are indeed mandatory before the construction of new buildings, even if limited to 30 m below the ground level or foundation base when piles are needed. The idea of developing TRT in connection with geotechnical test activity has the objective of promoting the widespread use of in situ experimental analysis and reducing TRT costs and time. The considerations presented in the present paper lead to reconsidering a particular variety of the TRT, in particular, the versions known as thermal response test while drilling (TRTWD) and TRT using heating cables (HC-TRT).
Alessandro Franco; Paolo Conti. Clearing a Path for Ground Heat Exchange Systems: A Review on Thermal Response Test (TRT) Methods and a Geotechnical Routine Test for Estimating Soil Thermal Properties. Energies 2020, 13, 2965 .
AMA StyleAlessandro Franco, Paolo Conti. Clearing a Path for Ground Heat Exchange Systems: A Review on Thermal Response Test (TRT) Methods and a Geotechnical Routine Test for Estimating Soil Thermal Properties. Energies. 2020; 13 (11):2965.
Chicago/Turabian StyleAlessandro Franco; Paolo Conti. 2020. "Clearing a Path for Ground Heat Exchange Systems: A Review on Thermal Response Test (TRT) Methods and a Geotechnical Routine Test for Estimating Soil Thermal Properties." Energies 13, no. 11: 2965.
Heat pumps represent a link between different energy vectors and their application in thermal and electrical grids can improve the overall operational flexibility of the system. In this work, the optimal integration of electrically driven heat pumps within a hybrid distributed energy system is investigated. A multi-objective stochastic optimization methodology is proposed to evaluate the integrated optimal sizing and operation of the energy systems under uncertainties in climate, space occupancy, energy loads, and fuel costs. A case study is considered, namely a University campus, and two different configurations, with and without heat pumps, are compared. Both configurations include a cogeneration system, photovoltaic and solar thermal panels, and a wind turbine. The results show how the integration of heat pumps can reduce the operational cost of the system, increase the renewables share, provide a more robust design of the system, and moderate the risk of the investment. Indeed, the configuration with heat pumps entails a 50% higher expected value of the energy savings, a 28% increase of the renewable energy production, and higher energy savings in the worst-case scenario (13% vs. 5%).
Daniele Testi; Luca Urbanucci; Chiara Giola; Eva Schito; Paolo Conti. Stochastic optimal integration of decentralized heat pumps in a smart thermal and electric micro-grid. Energy Conversion and Management 2020, 210, 112734 .
AMA StyleDaniele Testi, Luca Urbanucci, Chiara Giola, Eva Schito, Paolo Conti. Stochastic optimal integration of decentralized heat pumps in a smart thermal and electric micro-grid. Energy Conversion and Management. 2020; 210 ():112734.
Chicago/Turabian StyleDaniele Testi; Luca Urbanucci; Chiara Giola; Eva Schito; Paolo Conti. 2020. "Stochastic optimal integration of decentralized heat pumps in a smart thermal and electric micro-grid." Energy Conversion and Management 210, no. : 112734.
The paper presents a comprehensive energy and exergy analysis of a possible geothermal power plant located in the geothermal district of Campi Flegrei (Italy), made of a coaxial WellBore Heat eXchanger coupled to an Organic Rankine Cycle. We have accounted for all system components: the ground source, the WellBore Heat eXchanger, the Organic Rankine Cycle cycle, and cooling system. The energy and exergy performance indexes of each subsystems and overall system have been evaluated, thus calculating the net power, the First-Law efficiency, the Second-Law efficiency, the irreversibilities. The results indicate a good potential of the WellBore Heat eXchanger – Organic Rankine Cycle technology in the area, as the estimated performances have similar values to those of classical binary geothermal power plants: a First-Law efficiency of 11.67% and a Second-Law efficiency of about 43.80%. The overall system performances decrease respectively to 10.62% due to the fans energy requirements in the cooling tower and to 23.15% due to the large exergy destruction occurring in the WellBore Heat eXchanger. A deep exergy analysis of the WellBore Heat eXchanger has highlighted that the overall irreversibility is strongly affected by the insulation performance between the two coaxial pipes and by the temperature deviation between the ground and the fluid. The latter one is mainly due to the continuous heat extraction from the geothermal source, therefore proposed improvement strategies consist of both the increasing of thermal resistance of the material insulating the upward pipe and the reduction of the equivalent thermal radius of the well optimizing the heat extraction profiles over the plant lifetime.
Alimonti C; Conti P; Soldo E. A comprehensive exergy evaluation of a deep borehole heat exchanger coupled with a ORC plant: the case study of Campi Flegrei. Energy 2019, 189, 116100 .
AMA StyleAlimonti C, Conti P, Soldo E. A comprehensive exergy evaluation of a deep borehole heat exchanger coupled with a ORC plant: the case study of Campi Flegrei. Energy. 2019; 189 ():116100.
Chicago/Turabian StyleAlimonti C; Conti P; Soldo E. 2019. "A comprehensive exergy evaluation of a deep borehole heat exchanger coupled with a ORC plant: the case study of Campi Flegrei." Energy 189, no. : 116100.
This work presents an optimization strategy and the cost-optimal design of an off-grid building served by an energy system involving solar technologies, thermal and electrochemical storages. Independently from the multi-objective method (e.g., utility function) and algorithm used (e.g., genetic algorithms), the optimization of this kind of systems is typically characterized by a high-dimensional variables space, computational effort and results uncertainty (e.g., local minimum solutions). Instead of focusing on advanced optimization tools to handle the design problem, the dimension of the full problem has been reduced, only considering the design variables with a high “effect” on the objective functions. An off-grid accommodation building is presented as test case: the original six-variable design problem consisting of about 300,000 possible configurations is reduced to a two-variable problem, after the analysis of 870 Monte Carlo simulations. The new problem includes only 220 possible design alternatives with a clear benefit for the multi-objective optimization algorithm. The energy-economy Pareto frontiers obtained by the original and the reduced problems overlap, showing the validity of the proposed methodology. The No-RES (no renewable energy sources) primary energy consumption can be reduced up to almost 0 kWh/(m2yr) and the net present value (NPV) after 20 years can reach 70 k€ depending on the number of photovoltaic panels and electrochemical storage size. The reduction of the problem also allows for a plain analysis of the results and the drawing of handy decision charts to help the investor/designer in finding the best design according to the specific investment availability and target performances. The configurations on the Pareto frontier are characterized by a notable electrical overproduction and a ratio between the two main design variables that goes from 4 to 8 h. A sensitivity analysis to the unitary price of the electrochemical storage reveals the robustness of the sizing criterion.
Paolo Conti; Giovanni Lutzemberger; Eva Schito; Davide Poli; Daniele Testi. Multi-Objective Optimization of Off-Grid Hybrid Renewable Energy Systems in Buildings with Prior Design-Variable Screening. Energies 2019, 12, 3026 .
AMA StylePaolo Conti, Giovanni Lutzemberger, Eva Schito, Davide Poli, Daniele Testi. Multi-Objective Optimization of Off-Grid Hybrid Renewable Energy Systems in Buildings with Prior Design-Variable Screening. Energies. 2019; 12 (15):3026.
Chicago/Turabian StylePaolo Conti; Giovanni Lutzemberger; Eva Schito; Davide Poli; Daniele Testi. 2019. "Multi-Objective Optimization of Off-Grid Hybrid Renewable Energy Systems in Buildings with Prior Design-Variable Screening." Energies 12, no. 15: 3026.
Mattia De Rosa; Paolo Conti; Yasser Mahmoudi; Vincenzo Bianco. Advanced Solar Technologies in Buildings. International Journal of Photoenergy 2019, 2019, 1 -2.
AMA StyleMattia De Rosa, Paolo Conti, Yasser Mahmoudi, Vincenzo Bianco. Advanced Solar Technologies in Buildings. International Journal of Photoenergy. 2019; 2019 ():1-2.
Chicago/Turabian StyleMattia De Rosa; Paolo Conti; Yasser Mahmoudi; Vincenzo Bianco. 2019. "Advanced Solar Technologies in Buildings." International Journal of Photoenergy 2019, no. : 1-2.
The present paper assesses the capability of a cost-optimal control strategy to activate demand response actions in a building equipped with an air-source heat pump coupled with a water thermal storage system. Commencing with a reference scenario where no demand response actions are considered, the electricity consumption pattern and the operational cost are evaluated. Several demand response scenarios are next considered by adapting consumption patterns by reduction of baseline heat pump power consumption. The difference between the operational cost evaluated under a specific demand response program and the benchmark cost are used to assess the marginal cost that should be considered to provide incentives to promote user participation in demand response programs. The results illustrate the effectiveness of thermal energy storage for reducing the total system operational cost and its seasonal primary energy consumption, both with and without demand response actions. The application of the proposed methodology over the whole heating season, allows performance maps to be created that can be used either by the grid-operator or end-user to identify the best demand response action to be implemented on any particular day. These maps represent useful decision tools to assess and optimise the flexibility potential while meeting end-user needs.
Francesco D’Ettorre; Mattia De Rosa; Paolo Conti; Daniele Testi; Donal Finn. Mapping the energy flexibility potential of single buildings equipped with optimally-controlled heat pump, gas boilers and thermal storage. Sustainable Cities and Society 2019, 50, 1 .
AMA StyleFrancesco D’Ettorre, Mattia De Rosa, Paolo Conti, Daniele Testi, Donal Finn. Mapping the energy flexibility potential of single buildings equipped with optimally-controlled heat pump, gas boilers and thermal storage. Sustainable Cities and Society. 2019; 50 ():1.
Chicago/Turabian StyleFrancesco D’Ettorre; Mattia De Rosa; Paolo Conti; Daniele Testi; Donal Finn. 2019. "Mapping the energy flexibility potential of single buildings equipped with optimally-controlled heat pump, gas boilers and thermal storage." Sustainable Cities and Society 50, no. : 1.
This paper analyzes the use of hybrid photovoltaic/thermal (PVT) collectors in nearly zero-energy buildings (NZEBs). We present a design methodology based on the dynamic simulation of the whole energy system, which includes the building energy demand, a reversible heat pump as generator, the thermal storage, the power exchange with the grid, and both thermal and electrical energy production by solar collectors. An exhaustive search of the best equipment sizing and design is performed to minimize both the total costs and the non-renewable primary energy consumption over the system lifetime. The results show that photovoltaic/thermal technology reduces the non-renewable primary energy consumption below the nearly zero-energy threshold value, assumed as 15 kWh/(m2·yr), also reducing the total costs with respect to a non-solar solution (up to 8%). As expected, several possible optimal designs exist, with an opposite trend between energy savings and total costs. In all these optimal configurations, we figure out that photovoltaic/thermal technology favors the production of electrical energy with respect to the thermal one, which mainly occurs during the summer to meet the domestic hot water requirements and lower the temperature of the collectors. Finally, we show that, for a given solar area, photovoltaic/thermal technology leads to a higher reduction of the non-renewable primary energy and to a higher production of solar thermal energy with respect to a traditional separate production employing photovoltaic (PV) modules and solar thermal (ST) collectors.
Paolo Conti; Eva Schito; Daniele Testi. Cost-Benefit Analysis of Hybrid Photovoltaic/Thermal Collectors in a Nearly Zero-Energy Building. Energies 2019, 12, 1582 .
AMA StylePaolo Conti, Eva Schito, Daniele Testi. Cost-Benefit Analysis of Hybrid Photovoltaic/Thermal Collectors in a Nearly Zero-Energy Building. Energies. 2019; 12 (8):1582.
Chicago/Turabian StylePaolo Conti; Eva Schito; Daniele Testi. 2019. "Cost-Benefit Analysis of Hybrid Photovoltaic/Thermal Collectors in a Nearly Zero-Energy Building." Energies 12, no. 8: 1582.
Micro-district heating networks based on cogeneration plants and renewable energy technologies are considered efficient, viable and environmentally-friendly solutions to realizing smart multi-energy microgrids. Nonetheless, the energy production from renewable sources is intermittent and stochastic, and cogeneration units are characterized by fixed power-to-heat ratios, which are incompatible with fluctuating thermal and electric demands. These drawbacks can be partially overcome by smart operational controls that are capable of maximizing the energy system performance. Moreover, electrically driven heat pumps may add flexibility to the system, by shifting thermal loads into electric loads. In this paper, a novel configuration for smart multi-energy microgrids, which combines centralized and distributed energy units is proposed. A centralized cogeneration system, consisting of an internal combustion engine is connected to a micro-district heating network. Distributed electric heat pumps assist the thermal production at the building level, giving operational flexibility to the system and supporting the integration of renewable energy technologies, i.e., wind turbines, photovoltaic panels, and solar thermal collectors. The proposed configuration was tested in a hypothetical case study, namely, a University Campus located in Trieste, Italy. The system operation is based on a cost-optimal control strategy and the effect of the size of the cogeneration unit and heat pumps was investigated. A comparison with a conventional configuration, without distributed heat pumps, was also performed. The results show that the proposed configuration outperformed the conventional one, leading to a total-cost saving of around 8%, a carbon emission reduction of 11%, and a primary energy saving of 8%.
Daniele Testi; Paolo Conti; Eva Schito; Luca Urbanucci; Francesco D’Ettorre. Synthesis and Optimal Operation of Smart Microgrids Serving a Cluster of Buildings on a Campus with Centralized and Distributed Hybrid Renewable Energy Units. Energies 2019, 12, 745 .
AMA StyleDaniele Testi, Paolo Conti, Eva Schito, Luca Urbanucci, Francesco D’Ettorre. Synthesis and Optimal Operation of Smart Microgrids Serving a Cluster of Buildings on a Campus with Centralized and Distributed Hybrid Renewable Energy Units. Energies. 2019; 12 (4):745.
Chicago/Turabian StyleDaniele Testi; Paolo Conti; Eva Schito; Luca Urbanucci; Francesco D’Ettorre. 2019. "Synthesis and Optimal Operation of Smart Microgrids Serving a Cluster of Buildings on a Campus with Centralized and Distributed Hybrid Renewable Energy Units." Energies 12, no. 4: 745.
Daniel Aelenei; Laura Aelenei; Rafaela A. Agathokleous; Francesco Asdrubali; Constantinos A. Balaras; Giorgio Baldinelli; Ilaria Ballarini; Umberto Berardi; Paolo Bertoldi; Francesco Bianchi; Fabio Bisegna; Chiara Burattini; Luisa F. Cabeza; Beatrice Castellani; Carlo Cecere; Maurizio Cellura; Heejin Cho; Helena Coch; Paolo Conti; Vincenzo Corrado; Edoardo Currà; Francesco D’Alessandro; Elena G. Dascalaki; Livio De Santoli; Umberto Desideri; Chuanshuai Dong; Luca Evangelisti; Enrico Fabrizio; Prudence Ferreira; Faidra Filippidou; Chiara Foglietta; David Gattie; Paola Gori; Walter Grassi; Claudia Guattari; Franco Gugliermetti; Patxi Hernandez; Pei Huang; Gongsheng Huang; Soteris A. Kalogirou; Katrin Klingenberg; Thomas M. Lawrence; Eleanor S. Lee; Peike Li; Sonia Longo; Roel Loonen; Lin Lu; Pedro J. Mago; Dario Masucci; Benedetta Mattoni; Michele Morganti; Elena Morini; Mojtaba Navvab; Xabat Oregi; Cosimo Palazzo; Stefano Panzieri; Marco Perino; Anna L. Pisello; Andrea Presciutti; Bale V. Reddy; Marc A. Rosen; Federico Rossi; Federica Rosso; Antonella Rotili; Agnese Salvati; Mattheos Santamouris; Samuele Schiavoni; Eva Schito; Valentina Serra; Ashlynn S. Stillwell; Daniele Testi; RuZhu Wang; Graham S. Wright; Hongxing Yang; Xiaoqiang Zhai; Tiantian Zhang. Contributors. Handbook of Energy Efficiency in Buildings 2019, 1 .
AMA StyleDaniel Aelenei, Laura Aelenei, Rafaela A. Agathokleous, Francesco Asdrubali, Constantinos A. Balaras, Giorgio Baldinelli, Ilaria Ballarini, Umberto Berardi, Paolo Bertoldi, Francesco Bianchi, Fabio Bisegna, Chiara Burattini, Luisa F. Cabeza, Beatrice Castellani, Carlo Cecere, Maurizio Cellura, Heejin Cho, Helena Coch, Paolo Conti, Vincenzo Corrado, Edoardo Currà, Francesco D’Alessandro, Elena G. Dascalaki, Livio De Santoli, Umberto Desideri, Chuanshuai Dong, Luca Evangelisti, Enrico Fabrizio, Prudence Ferreira, Faidra Filippidou, Chiara Foglietta, David Gattie, Paola Gori, Walter Grassi, Claudia Guattari, Franco Gugliermetti, Patxi Hernandez, Pei Huang, Gongsheng Huang, Soteris A. Kalogirou, Katrin Klingenberg, Thomas M. Lawrence, Eleanor S. Lee, Peike Li, Sonia Longo, Roel Loonen, Lin Lu, Pedro J. Mago, Dario Masucci, Benedetta Mattoni, Michele Morganti, Elena Morini, Mojtaba Navvab, Xabat Oregi, Cosimo Palazzo, Stefano Panzieri, Marco Perino, Anna L. Pisello, Andrea Presciutti, Bale V. Reddy, Marc A. Rosen, Federico Rossi, Federica Rosso, Antonella Rotili, Agnese Salvati, Mattheos Santamouris, Samuele Schiavoni, Eva Schito, Valentina Serra, Ashlynn S. Stillwell, Daniele Testi, RuZhu Wang, Graham S. Wright, Hongxing Yang, Xiaoqiang Zhai, Tiantian Zhang. Contributors. Handbook of Energy Efficiency in Buildings. 2019; ():1.
Chicago/Turabian StyleDaniel Aelenei; Laura Aelenei; Rafaela A. Agathokleous; Francesco Asdrubali; Constantinos A. Balaras; Giorgio Baldinelli; Ilaria Ballarini; Umberto Berardi; Paolo Bertoldi; Francesco Bianchi; Fabio Bisegna; Chiara Burattini; Luisa F. Cabeza; Beatrice Castellani; Carlo Cecere; Maurizio Cellura; Heejin Cho; Helena Coch; Paolo Conti; Vincenzo Corrado; Edoardo Currà; Francesco D’Alessandro; Elena G. Dascalaki; Livio De Santoli; Umberto Desideri; Chuanshuai Dong; Luca Evangelisti; Enrico Fabrizio; Prudence Ferreira; Faidra Filippidou; Chiara Foglietta; David Gattie; Paola Gori; Walter Grassi; Claudia Guattari; Franco Gugliermetti; Patxi Hernandez; Pei Huang; Gongsheng Huang; Soteris A. Kalogirou; Katrin Klingenberg; Thomas M. Lawrence; Eleanor S. Lee; Peike Li; Sonia Longo; Roel Loonen; Lin Lu; Pedro J. Mago; Dario Masucci; Benedetta Mattoni; Michele Morganti; Elena Morini; Mojtaba Navvab; Xabat Oregi; Cosimo Palazzo; Stefano Panzieri; Marco Perino; Anna L. Pisello; Andrea Presciutti; Bale V. Reddy; Marc A. Rosen; Federico Rossi; Federica Rosso; Antonella Rotili; Agnese Salvati; Mattheos Santamouris; Samuele Schiavoni; Eva Schito; Valentina Serra; Ashlynn S. Stillwell; Daniele Testi; RuZhu Wang; Graham S. Wright; Hongxing Yang; Xiaoqiang Zhai; Tiantian Zhang. 2019. "Contributors." Handbook of Energy Efficiency in Buildings , no. : 1.
The present paper analyses the cost-optimal sizing and hourly control strategy of a hybrid heat pump system for heating application, composed by an electrically-driven air source heat pump and a gas boiler. These hybrid systems represent a promising solution for the energy retrofit of existing buildings and new installations, being able to increase the efficiency of monovalent systems, especially at low external temperatures. The use of thermal storage can furtherly minimize both the operating cost and the primary energy consumption, shifting the operation of the heat pump to the most profitable periods. In this work, the optimal control problem has been investigated by means of mixed-integer linear programming, considering an ideal forecast of external temperature and thermal load on given horizon periods (i.e. model predictive control). Achievable cost savings with respect to a traditional rule-based control strategy with no storage are presented as a function of both prediction horizon and storage capacity in a dimensionless form. A relation between prediction horizon length and optimal storage capacity is shown. An example of application of the method is illustrated, showing cost savings up to 8%. A sensitivity analysis on the storage tank losses, climatic conditions, generators efficiency, and energy prices is also presented, showing the cost saving potential in all these different conditions.
Francesco D'Ettorre; Paolo Conti; Eva Schito; Daniele Testi. Model predictive control of a hybrid heat pump system and impact of the prediction horizon on cost-saving potential and optimal storage capacity. Applied Thermal Engineering 2018, 148, 524 -535.
AMA StyleFrancesco D'Ettorre, Paolo Conti, Eva Schito, Daniele Testi. Model predictive control of a hybrid heat pump system and impact of the prediction horizon on cost-saving potential and optimal storage capacity. Applied Thermal Engineering. 2018; 148 ():524-535.
Chicago/Turabian StyleFrancesco D'Ettorre; Paolo Conti; Eva Schito; Daniele Testi. 2018. "Model predictive control of a hybrid heat pump system and impact of the prediction horizon on cost-saving potential and optimal storage capacity." Applied Thermal Engineering 148, no. : 524-535.
The heat transfer process in energy piles is strongly affected by the heat capacity of such foundation elements. This phenomenon is more pronounced for energy piles compared to borehole heat exchangers, because of the lower slenderness of the former compared to the latter, and involves axial thermal gradients. In literature, capacity effects of energy piles and their transient thermal performance have not been analysed in depth. Looking at such challenge, this paper investigates the dynamic thermal performance of energy piles at short-to-medium time scales. The work analyses the results of almost thirty 3D finite element simulations of an energy pile equipped with 3-U ducts by varying: (i) the velocity of the fluid circulating in the ducts, (ii) the slenderness ratio of the pile, (iii) the radial position of the ducts, and (iv) the boundary condition characterizing the uppermost surface of the model. Simulation results are analysed to identify for which times, geometries, and operative conditions the energy pile can be modelled with a 2D geometry, instead of a full 3D geometry. Our analysis highlights a limited relevance of the axial effects during the transient period in any tested configuration. These results are functional to the application of simplified analytical models and design criteria for energy piles.
Paolo Conti; Eva Schito; Daniele Testi. Thermal Characterization of Energy Pile Dynamics. Proceedings of the 28th International Symposium on Mine Planning and Equipment Selection - MPES 2019 2018, 123 -131.
AMA StylePaolo Conti, Eva Schito, Daniele Testi. Thermal Characterization of Energy Pile Dynamics. Proceedings of the 28th International Symposium on Mine Planning and Equipment Selection - MPES 2019. 2018; ():123-131.
Chicago/Turabian StylePaolo Conti; Eva Schito; Daniele Testi. 2018. "Thermal Characterization of Energy Pile Dynamics." Proceedings of the 28th International Symposium on Mine Planning and Equipment Selection - MPES 2019 , no. : 123-131.
The ongoing decarbonisation process of the current energy system, driven by the EU directives, requires that more renewable energy sources are integrated in the global energy mix, as well as policies promoting investments in new low-carbon technologies, energy efficiency and grid infrastructure. The technical integration of renewable energy sources into the existing power system is not straightforward, due to the intrinsic aleatory characteristics of renewable production, which make the power grid balance harder. To handle this issue, beside the traditional supply-side management, grid flexibility can also be provided by enabling the active participation of the demand-side in power system operational procedures, by means of the so-called demand-side management (DSM). The present paper is aimed at assessing the ability of a cost-optimal control strategy, based on model predictive control, to activate demand-response (DR) actions in a residential building equipped with a hybrid heat pump generator coupled with a water thermal storage. Hourly electricity prices are considered as external signals from the grid driving the demand response actions. It is shown that the thermal energy storage turns out to be an effective way to improve the controller performances and make the system more flexible and able to provide services to the power grid. A daily cost-saving up to 35% and 15% have been highlighted with a 1 m3 0.5.m3 tanks, respectively. Finally, the achievable flexibility is shown to be strictly dependent on the storage capacity and operations, which in turn are affected by the generators sizing.
F. D’Ettorre; M. De Rosa; P. Conti; Eva Schito; D. Testi; D.P. Finn. Economic assessment of flexibility offered by an optimally controlled hybrid heat pump generator: a case study for residential building. Energy Procedia 2018, 148, 1222 -1229.
AMA StyleF. D’Ettorre, M. De Rosa, P. Conti, Eva Schito, D. Testi, D.P. Finn. Economic assessment of flexibility offered by an optimally controlled hybrid heat pump generator: a case study for residential building. Energy Procedia. 2018; 148 ():1222-1229.
Chicago/Turabian StyleF. D’Ettorre; M. De Rosa; P. Conti; Eva Schito; D. Testi; D.P. Finn. 2018. "Economic assessment of flexibility offered by an optimally controlled hybrid heat pump generator: a case study for residential building." Energy Procedia 148, no. : 1222-1229.
This paper proposes a dynamic analytical method to simulate the thermal performances of truncated cone helix ground heat exchangers (i.e., the so-called “energy baskets”). These ground-coupled devices are attractive solutions to reduce the initial cost of ground-coupled heat pump systems, as they require lower cost to be drilled and installed with respect to traditional boreholes. However, both design methodologies and performance assessment models are still not well developed, producing substantial uncertainties on final operative performances. This work presents a plain evaluation method based on the heat exchangers theory and the analytical solution of the truncated cone helix heat source in a semi-infinite medium. It can be advantageously used to simulate the thermal performance of truncated cone helix ground heat exchangers as a function of helix geometries and operative conditions evolution (e.g., inlet temperature, fluid flow rate, ground temperature…). Specifically, in this paper, we perform a sensitivity analysis of the thermal performances of a case study by varying the main geometrical parameters. Besides, we compare the heat transfer of the reference configuration with an equivalent cylindrical arrangment. The truncated coil configuration is more effective than cylindrical one as the cone aperture reduces the short-circuits between helix pitch and the equivalent thermal resistance with the ground surface. However, obtained results are notably affected by the assumption of an isothermal surface temperature, which leads to a shallow/plain helix/spiral as the best configuration: different conclusions are expected when a time dependent or adiabatic boundary condition will be accounted in the model.
Paolo Conti. An analytical method to simulate the dynamic performances of truncated cone helix ground heat exchangers. Energy Procedia 2018, 148, 1214 -1221.
AMA StylePaolo Conti. An analytical method to simulate the dynamic performances of truncated cone helix ground heat exchangers. Energy Procedia. 2018; 148 ():1214-1221.
Chicago/Turabian StylePaolo Conti. 2018. "An analytical method to simulate the dynamic performances of truncated cone helix ground heat exchangers." Energy Procedia 148, no. : 1214-1221.