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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.
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.
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.
We present an experimental investigation of the effect of ultrasound application to increase the heat-transfer coefficient for natural convection of a dielectric fluid. An experimental analysis is carried out to estimate the increase of the convective heat-transfer coefficient between an electronic board and a refrigerant fluid, the Fluorinert Electronic Fluid FC-72. For this purpose, an experimental apparatus composed of an electronic board, its electronic control circuit, and data acquisition systems have been designed and implemented. The data collected appear to confirm in some situations of practical interest the enhancement effect of the convective heat-transfer coefficient in connection with the use of ultrasound. The most favorable condition was observed with the fluid in quite low subcooled conditions.
Carlo Bartoli; Alessandro Franco; Massimo Macucci. Ultrasounds Used as Promoters of Heat-Transfer Enhancement of Natural Convection in Dielectric Fluids for the Thermal Control of Electronic Equipment. Acoustics 2020, 2, 279 -292.
AMA StyleCarlo Bartoli, Alessandro Franco, Massimo Macucci. Ultrasounds Used as Promoters of Heat-Transfer Enhancement of Natural Convection in Dielectric Fluids for the Thermal Control of Electronic Equipment. Acoustics. 2020; 2 (2):279-292.
Chicago/Turabian StyleCarlo Bartoli; Alessandro Franco; Massimo Macucci. 2020. "Ultrasounds Used as Promoters of Heat-Transfer Enhancement of Natural Convection in Dielectric Fluids for the Thermal Control of Electronic Equipment." Acoustics 2, no. 2: 279-292.
The aim of this paper is to expose the main involved physical phenomena underlying the alteration of convective heat transfer in a heat exchanger subjected to imposed vibrations. This technique seems to have interesting features and industrial applications, such as for efficiency increases, heat transfer rate control and cleanliness action. However, a clear description and comprehension of how vibrations may alter the convective heat transfer coefficient in a heat exchanger has still not been reached due to the complexity of the involved physical mechanisms. For this reason, after a presentation and a schematization of the analyzed thermodynamic system, the fundamental alterations of the thermo-fluid dynamics fields are described. Then, the main involved physical phenomena are exposed for the three cases of gaseous, monophasic liquid and boiling liquid mediums. Finally, on the basis of the characteristics of these described phenomena, some considerations and indications of general validity are presented.
Alessandro Franco; Carlo Bartoli. Heat Transfer Enhancement due to Acoustic Fields: A Methodological Analysis. Acoustics 2019, 1, 281 -294.
AMA StyleAlessandro Franco, Carlo Bartoli. Heat Transfer Enhancement due to Acoustic Fields: A Methodological Analysis. Acoustics. 2019; 1 (1):281-294.
Chicago/Turabian StyleAlessandro Franco; Carlo Bartoli. 2019. "Heat Transfer Enhancement due to Acoustic Fields: A Methodological Analysis." Acoustics 1, no. 1: 281-294.