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Prof. Daniele Testi
University of Pisa - Department of Energy, Systems, Territory and Constructions Engineering

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Research Keywords & Expertise

0 Heat Pumps
0 combined heat and power (CHP)
0 heat transfer enhancement
0 Building energy performance
0 Integrated energy Systems

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Heat Pumps

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Journal article
Published: 28 June 2021 in Energies
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One of the main elements for increasing energy efficiency in large-scale buildings is identified in the correct management and control of the Heating Ventilation and Air Conditioning (HVAC) systems, particularly those with Heat Pumps (HPs). The present study aimed to evaluate the perspective of energy savings achievable with the implementation of an optimal control of the HVAC with HPs. The proposed measures involve the use of a variable air volume system, demand-controlled ventilation, an energy-aware control of the heat recovery equipment, and an improved control of the heat pump and chiller supply water temperature. The analysis has been applied to an academic building located in Pisa and is carried out by means of dynamic simulation. The achieved energy saving can approach values of more than 80% if compared with actual plants based on fossil fuel technologies. A major part of this energy saving is linked to the use of heat pumps as thermal generators as well as to the implementation of an energy efficient ventilation, emphasizing the importance of such straightforward measures in reducing the energy intensity of large-scale buildings.

ACS Style

Alessandro Franco; Lorenzo Miserocchi; Daniele Testi. Energy Intensity Reduction in Large-Scale Non-Residential Buildings by Dynamic Control of HVAC with Heat Pumps. Energies 2021, 14, 3878 .

AMA Style

Alessandro Franco, Lorenzo Miserocchi, Daniele Testi. Energy Intensity Reduction in Large-Scale Non-Residential Buildings by Dynamic Control of HVAC with Heat Pumps. Energies. 2021; 14 (13):3878.

Chicago/Turabian Style

Alessandro Franco; Lorenzo Miserocchi; Daniele Testi. 2021. "Energy Intensity Reduction in Large-Scale Non-Residential Buildings by Dynamic Control of HVAC with Heat Pumps." Energies 14, no. 13: 3878.

Journal article
Published: 27 June 2021 in Sustainability
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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.

ACS Style

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 Style

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 (13):7200.

Chicago/Turabian Style

Alessandro 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.

Journal article
Published: 23 June 2021 in Journal of Heat Transfer
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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.

ACS Style

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 Style

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.

Chicago/Turabian Style

Walter 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.

Journal article
Published: 14 May 2021 in Energies
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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.

ACS Style

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 Style

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 (10):2847.

Chicago/Turabian Style

Alessandro 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.

Journal article
Published: 10 April 2021 in Energies
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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.

ACS Style

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 Style

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 (8):2124.

Chicago/Turabian Style

Giuseppe 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.

Journal article
Published: 01 September 2020 in Energies
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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.

ACS Style

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 Style

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 (17):4498.

Chicago/Turabian Style

Paolo 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.

Journal article
Published: 20 March 2020 in Energy Conversion and Management
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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%).

ACS Style

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 Style

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.

Chicago/Turabian Style

Daniele 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.

Journal article
Published: 18 September 2019 in Energy Conversion and Management
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Polygeneration energy systems in building applications are widely recognized as an effective way to reduce primary energy consumption and greenhouse gas emissions, thanks to high energy efficiencies and optimal integration of different energy technologies and sources. In the present work, the integration of a reversible absorption heat pump and an internal combustion engine in a novel trigeneration system is proposed. The reversible absorption heat pump, which employs a water-ammonia mixture, is driven by the exhaust gas of the engine, and can produce heating and cooling, alternately. The proposed trigeneration system is presented, and the energy services provided under the heating and cooling operating modes are evaluated. A levelized cost of energy analysis is conducted to evaluate the economic viability of the proposed system. Next, a second-law analysis compares its overall exergy efficiency to those of conventional systems. Finally, the novel trigeneration system is implemented in a case study, namely a large office building located in Pisa, Italy. The integrated optimal sizing and operation are evaluated by using a genetic algorithm-based procedure. The findings show that the system integrating reversible absorption heat pump and cogeneration unit provides valuable economic and energy performance. The exergy efficiency of the system can reach 43%, and cost savings of around 5% and 10% are achieved compared to traditional cogeneration and separate-production system, respectively.

ACS Style

Luca Urbanucci; Daniele Testi. Integration of reversible absorption heat pumps in cogeneration systems: Exergy and economic assessment. Energy Conversion and Management 2019, 200, 112062 .

AMA Style

Luca Urbanucci, Daniele Testi. Integration of reversible absorption heat pumps in cogeneration systems: Exergy and economic assessment. Energy Conversion and Management. 2019; 200 ():112062.

Chicago/Turabian Style

Luca Urbanucci; Daniele Testi. 2019. "Integration of reversible absorption heat pumps in cogeneration systems: Exergy and economic assessment." Energy Conversion and Management 200, no. : 112062.

Journal article
Published: 06 August 2019 in Energies
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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.

ACS Style

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 Style

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 (15):3026.

Chicago/Turabian Style

Paolo 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.

Journal article
Published: 05 August 2019 in Applied Sciences
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District heating and cooling networks based on trigeneration systems and renewable energy technologies are widely acknowledged as an energy efficient and environmentally benign solution. These energy systems generally include back-up units, namely fossil-fuel boilers and electric chillers, to enhance system flexibility and cover peak energy demand. On the other hand, 4th generation district heating networks are characterized by low-temperature water distribution to improve energy and exergy efficiencies. Moreover, reversible heat pumps are a versatile technology, capable of providing both heating and cooling, alternately. In this paper, the integration of reversible heat pumps as single back-up units in hybrid renewable trigeneration systems serving low-energy micro-district heating and cooling networks is investigated. A detailed modeling of the system is provided, considering part-load and ambient condition effects on the performance of the units. Size and annual operation of the proposed system are optimized in a case study, namely a large office building located in Pisa (Italy), by means of a genetic algorithm-based procedure. A comparison with the conventional trigeneration system is performed in terms of economic and environmental perspectives. Results show that the integration of reversible heat pumps is an economically viable solution capable of reducing by 7% the equivalent annual cost, increasing the installed power of renewables up to 23%, and lowering by 11% carbon dioxide emissions, compared to the energy system with conventional back-up units.

ACS Style

Luca Urbanucci; Daniele Testi; Joan Carles Bruno. Integration of Reversible Heat Pumps in Trigeneration Systems for Low-Temperature Renewable District Heating and Cooling Microgrids. Applied Sciences 2019, 9, 3194 .

AMA Style

Luca Urbanucci, Daniele Testi, Joan Carles Bruno. Integration of Reversible Heat Pumps in Trigeneration Systems for Low-Temperature Renewable District Heating and Cooling Microgrids. Applied Sciences. 2019; 9 (15):3194.

Chicago/Turabian Style

Luca Urbanucci; Daniele Testi; Joan Carles Bruno. 2019. "Integration of Reversible Heat Pumps in Trigeneration Systems for Low-Temperature Renewable District Heating and Cooling Microgrids." Applied Sciences 9, no. 15: 3194.

Journal article
Published: 27 June 2019 in Sustainable Cities and Society
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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.

ACS Style

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 Style

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.

Chicago/Turabian Style

Francesco 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.

Journal article
Published: 25 April 2019 in Energies
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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.

ACS Style

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 Style

Paolo 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 Style

Paolo 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.

Data article
Published: 15 March 2019 in Data in Brief
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The correct preservation of old and rare books in libraries needs suitable values of temperature and relative humidity. This paper shows the hygrothermal data acquired in a historic library, the Baroque Library, of the University of Coimbra, Portugal, where several old and rare books are stored. The data were acquired during a 6-month monitoring campaign. In particular, in this paper the spatial and temporal variations of these two parameters are analysed. The data presented in the article are related to the research article entitled “A procedure for identifying chemical and biological risks for books in historic libraries based on microclimate analysis” [1].

ACS Style

Eva Schito; Luisa Dias Pereira; Daniele Testi; Manuel Carlos Gameiro da Silva. Data of temperature and relative humidity in a historic library in Portugal. Data in Brief 2019, 24, 103788 .

AMA Style

Eva Schito, Luisa Dias Pereira, Daniele Testi, Manuel Carlos Gameiro da Silva. Data of temperature and relative humidity in a historic library in Portugal. Data in Brief. 2019; 24 ():103788.

Chicago/Turabian Style

Eva Schito; Luisa Dias Pereira; Daniele Testi; Manuel Carlos Gameiro da Silva. 2019. "Data of temperature and relative humidity in a historic library in Portugal." Data in Brief 24, no. : 103788.

Journal article
Published: 13 March 2019 in International Communications in Heat and Mass Transfer
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After shortly highlighting the main features of the classical hydrodynamic theory of pool boiling critical heat flux (CHF), the present paper describes a new approach to predict CHF in the presence of a submerged liquid jet impinging onto the heating surface in saturated conditions at both atmospheric and sub-atmospheric pressure. This approach, based on the instability of liquid-vapor interfaces, has proved to be able of fitting CHF data for submerged jets as well as for electrohydrodynamic (ionic) jets. The main dimensionless parameters governing the phenomenon have been disclosed, namely the Bond number and an equivalent Froude number. Two distinct fluid-dynamic regimes have been identified, herein named velocity-prevailing and gravity-prevailing, depending on the equivalent Froude number values and the subsequent effect of vapor buoyancy on liquid-solid contacts. The developed correlations providing CHF for both regimes have coefficients of determination higher than 0.9 with respect to the available experimental data. Further development may involve the identification of dimensionless parameters and specific correlations for CHF under free-surface jets.

ACS Style

Walter Grassi; Daniele Testi. A new hydrodynamic approach for jet impingement boiling CHF. International Communications in Heat and Mass Transfer 2019, 104, 83 -88.

AMA Style

Walter Grassi, Daniele Testi. A new hydrodynamic approach for jet impingement boiling CHF. International Communications in Heat and Mass Transfer. 2019; 104 ():83-88.

Chicago/Turabian Style

Walter Grassi; Daniele Testi. 2019. "A new hydrodynamic approach for jet impingement boiling CHF." International Communications in Heat and Mass Transfer 104, no. : 83-88.

Journal article
Published: 06 March 2019 in Energies
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Cogeneration systems are widely acknowledged as a viable solution to reduce energy consumption and costs, and CO2 emissions. Nonetheless, their performance is highly dependent on their capacity and operational strategy, and optimization methods are required to fully exploit their potential. Among the available technical possibilities to maximize their performance, the integration of thermal energy storage is recognized as one of the most effective solutions. The introduction of a storage device further complicates the identification of the optimal equipment capacity and operation. This work presents a cutting-edge methodology for the optimal design and operation of cogeneration systems with thermal energy storage. A two-level algorithm is proposed to reap the benefits of the mixed integer linear programming formulation for the optimal operation problem, while overcoming its main drawbacks by means of a genetic algorithm at the design level. Part-load effects on nominal efficiency, variation of the unitary cost of the components in relation to their size, and the effect of the storage volume on its thermal losses are considered. Moreover, a novel formulation of the optimization problem is proposed to better characterize the heat losses and operation of the thermal energy storage. A rolling-horizon technique is implemented to reduce the computational time required for the optimization, without affecting the quality of the results. Furthermore, the proposed methodology is adopted to design a cogeneration system for a secondary school in San Francisco, California, which is optimized in terms of the equivalent annual cost. The results show that the optimally sized cogeneration unit directly meets around 70% of both the electric and thermal demands, while the thermal energy storage additionally covers 16% of the heat demands.

ACS Style

Luca Urbanucci; Francesco D’Ettorre; Daniele Testi. A Comprehensive Methodology for the Integrated Optimal Sizing and Operation of Cogeneration Systems with Thermal Energy Storage. Energies 2019, 12, 875 .

AMA Style

Luca Urbanucci, Francesco D’Ettorre, Daniele Testi. A Comprehensive Methodology for the Integrated Optimal Sizing and Operation of Cogeneration Systems with Thermal Energy Storage. Energies. 2019; 12 (5):875.

Chicago/Turabian Style

Luca Urbanucci; Francesco D’Ettorre; Daniele Testi. 2019. "A Comprehensive Methodology for the Integrated Optimal Sizing and Operation of Cogeneration Systems with Thermal Energy Storage." Energies 12, no. 5: 875.

Journal article
Published: 23 February 2019 in Energies
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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%.

ACS Style

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 Style

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 (4):745.

Chicago/Turabian Style

Daniele 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.

Journal article
Published: 23 January 2019 in Applied Energy
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Polygeneration energy systems are proven to be a reliable, competitive and efficient solution for energy production. The recovery of otherwise wasted energy is the primary reason for the high efficiency of polygeneration systems. In this paper, the integration of a high-temperature heat pump within a trigeneration system is investigated. The heat pump uses the low-temperature heat from the condenser of the absorption chiller as heat source to produce hot water. A numerical model of the heat pump cycle is developed to evaluate the technical viability of current heat pump technology for this application and assess the performance of different working fluids. An exergy analysis is performed to show the advantages of the novel trigeneration system with respect to traditional systems for energy production. Moreover, a levelized cost of electricity method is applied to the proposed energy system to show its generic economic feasibility. Finally, actual energy demand data from an Italian pharmaceutical factory are considered to evaluate the economic savings obtainable with the integrated system, implemented in a case study. A two-level algorithm is proposed for the economic optimization of the investment. The synthesis/design problem is addressed by a genetic algorithm and the optimal operation problem is solved by a linear programming method. Results show that the integration of a high-temperature heat pump within a trigeneration system provides flexibility to cover variable energy demands and achieve valuable economic and energy performances, with global cost savings of around 40% with respect to separate production and around 10% with respect to traditional cogeneration and trigeneration systems.

ACS Style

Luca Urbanucci; Joan Carles Bruno; Daniele Testi. Thermodynamic and economic analysis of the integration of high-temperature heat pumps in trigeneration systems. Applied Energy 2019, 238, 516 -533.

AMA Style

Luca Urbanucci, Joan Carles Bruno, Daniele Testi. Thermodynamic and economic analysis of the integration of high-temperature heat pumps in trigeneration systems. Applied Energy. 2019; 238 ():516-533.

Chicago/Turabian Style

Luca Urbanucci; Joan Carles Bruno; Daniele Testi. 2019. "Thermodynamic and economic analysis of the integration of high-temperature heat pumps in trigeneration systems." Applied Energy 238, no. : 516-533.

Book chapter
Published: 01 January 2019 in Handbook of Energy Efficiency in Buildings
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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 Style

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.

Chicago/Turabian Style

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. 2019. "Contributors." Handbook of Energy Efficiency in Buildings , no. : 1.

Journal article
Published: 23 November 2018 in Journal of Cultural Heritage
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The study presents a new procedure for identifying possible risks for books kept in historic libraries. It is addressed to all those historic libraries where large collections of old and rare books are stored and preserved. These libraries were rarely used by people, but, nowadays, many of them have become touristic attractions. Consequently, their indoor microclimate may have changed, possibly leading to risks for books conservation. The proposed methodology is based on an intensive monitoring campaign, followed by an in-depth data analysis. Handy indices are also proposed to guide the researchers in the identification of possible risks. Problems related to too-high daily or spatial hygrothermal variations or problems related to specific risks (e.g., biological or chemical risks) can be identified. If a problem is observed, the identification of the most suitable solutions is more straightforward. The application of the proposed procedure to a real case study (the Baroque Library of the University of Coimbra, Portugal) has highlighted its handiness. A 6-month monitoring campaign and its consequent data analysis has pointed out potentially risky situations. Thus, measures should be taken to avoid books damage. Primarily, local actions are suggested.

ACS Style

Eva Schito; Luisa Dias Pereira; Daniele Testi; Manuel Gameiro da Silva. A procedure for identifying chemical and biological risks for books in historic libraries based on microclimate analysis. Journal of Cultural Heritage 2018, 37, 155 -165.

AMA Style

Eva Schito, Luisa Dias Pereira, Daniele Testi, Manuel Gameiro da Silva. A procedure for identifying chemical and biological risks for books in historic libraries based on microclimate analysis. Journal of Cultural Heritage. 2018; 37 ():155-165.

Chicago/Turabian Style

Eva Schito; Luisa Dias Pereira; Daniele Testi; Manuel Gameiro da Silva. 2018. "A procedure for identifying chemical and biological risks for books in historic libraries based on microclimate analysis." Journal of Cultural Heritage 37, no. : 155-165.

Journal article
Published: 19 November 2018 in Applied Thermal Engineering
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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.

ACS Style

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 Style

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.

Chicago/Turabian Style

Francesco 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.