Fabio Polonara - Academia.edu (original) (raw)

Papers by Fabio Polonara

E3S web of conferences, 2021

Due to the increasing spread of residential heating systems electrically powered, buildings show ... more Due to the increasing spread of residential heating systems electrically powered, buildings show a great potential in producing demand side management strategies addressing their thermal loads. Indeed, exploiting the intrinsic characteristics of the heating/cooling systems (i.e. the thermal inertia level), buildings could represent an interesting solution to reduce the electricity peak demand and to optimize the balance between demand and supply. The objective of this paper is to analyse the potential benefits that can be obtained if the electricity demand derived from the heating systems of a building cluster is managed with demand response strategies. A simulation-based analysis is presented in which a cluster of residential archetypal buildings are investigated. The buildings differ from each other for construction features and type of heating system (e.g. underfloor heating or with fan coil units). By supposing to be able to activate the energy flexibility of the single building with thermostatic load control, an optimized logic is implemented to produce programmatically an hourly electricity peak reduction. Results show how the involvement of buildings with different characteristics depends on the compromise that wants to be achieved in terms of minimization of both the rebound effects and the variation of the internal temperature setpoint.

International Journal of Productivity and Quality Management, 2016

Journal of Chemical & Engineering Data, May 15, 1999

Saturated pressure and P-V-T measurements were performed for 1,1,1,3,3,3-hexafluoropropane (R-236... more Saturated pressure and P-V-T measurements were performed for 1,1,1,3,3,3-hexafluoropropane (R-236fa) in a constant volume cell. The saturated pressure measurements covered a temperature range from 248 K up to 360 K and a corresponding pressure range from 34 kPa up to 1,472 kPa. The results were fitted to various empirical equations. The P-V-T measurements in the superheated vapor region were made

Experimental Thermal and Fluid Science, Dec 1, 2018

Abstract In the present work, the natural convection mechanism of air in a square cavity with act... more Abstract In the present work, the natural convection mechanism of air in a square cavity with active side and inferior walls has been investigated both experimentally and numerically. The experimental method developed by some of the authors has been tested against new boundary condition. In addition, the combined radiative-convective heat transfer method has been investigated. The position relative to the gravity vector and the temperature difference between hot and cold walls were analysed: four different inclination angles (ϑ = 0, ϑ = π/6, ϑ = π/3, ϑ = π/2) of the cavity and five different temperatures (104 ≤ Ra ≤ 105) of the hot walls were tested for a total of 20 different cases. The velocity fields and the effective temperature of the walls have been measured by, respectively, a Particle Image Velocimetry (PIV) system and a set of thermocouples. It has been assessed that both the average and maximum velocities increase with the increasing of the Rayleigh number and of the tilting angle. The velocity field is characterized by two vortices, with a symmetry axe passing from the cavity centre when ϑ = 0; by increasing the tilting angle the symmetry tends to disappear leading to the presence of only one vortex for ϑ = π/2. Numerical simulations with both pure convection and combined radiative-convective model have been performed. For the model validation, both the maximum and the average values of the velocity field on the cavity have been taken into account. The results are in good agreement with the experimental measurements. The addition of the radiance contribution does not influence the results.

Renewable Energy, May 1, 2019

The contemporary energy transition will be characterized by many sub-transitions in the next thre... more The contemporary energy transition will be characterized by many sub-transitions in the next three decades. Oil and gas will continue to play a very important role coupled with renewable energy sources in an energy mix scenario. In this context, the authors of the present work developed a project, named RELife (Renewable Energy for a new Life of offshore platforms), with the main goal of develop a model for the reuse of offshore Oil & Gas platforms at end-of-life stage for the production of renewable energy. In this paper, by considering two types of platforms (4-legged platform with 3 or 4 production wells), various technical scenarios are studied and investigated and for each scenario also the environmental and economic feasibility is evaluated. In addition, all the sub-models are compared with a standard decommissioning process. The evaluations are made for both the Adriatic Sea and the North Sea, two geographic areas with different availabilities of renewable resources. In order to assess also the economic and environmental feasibility, a Discount Cash Flow Analysis and a Life Cycle Assessment of all the scenarios have been conducted.

E3S web of conferences, 2020

The building sector represents one of the most energy-consuming worldwide and a great part of its... more The building sector represents one of the most energy-consuming worldwide and a great part of its consumption is accounted for residential demand for space heating and cooling. Although it is necessary to promote the buildings energy efficiency, energy flexibility is also of paramount importance to optimize the balance between demand and supply. In fact, an energy flexible building is defined as able to change, in a planned manner, the shape of its energy demand curve, electrical and thermal, while the comfort of the end-users is still guaranteed. Objective of this work is to exploit the energy demand management ability of different buildings composing a cluster, when their aggregated demand derived from electric heating systems (i.e. heat pumps) is subject to demand response (DR) strategies. Users with different occupancy profile are considered. By supposing to be able to activate the energy flexibility of the single building with thermostatic load control, different scenarios of cluster composition are evaluated in order to provide guidelines to implement optimal strategies for energy flexibility exploitation without drawback effects connected to the event.

Proceedings of Building Simulation 2019: 16th Conference of IBPSA, Jun 23, 2020

Due to its progressive aging, the need to plan a long-term renovation strategy for the European b... more Due to its progressive aging, the need to plan a long-term renovation strategy for the European building stock is increasingly urgent. Furthermore, the growing penetration of discontinuous and non-programmable renewable energy sources asks for an adaptable demand to the supply variability. Thus, the realization of new buildings which are both efficient and energy flexible can be a way to increase reliability and security of the current energy grid. Purpose of this work is to characterize the effect of different buildings renovation strategies on their energy flexibility performance obtained through electric heating energy demand management. The energy flexibility is quantified by means of a single indicator: the Flexibility Performance Indicator. As the Energy Performance Certificate, it is calculated with a standardized procedure. In this work, starting from a low energy performance reference building, the energy flexibility performance obtainable with different energy efficiency interventions is assessed. Eventually the extent of the requested investment combined with the potential electricity costs saving derived from it is evaluated.

Tecnica Italiana, Jul 30, 2021

Nowadays heat pumps (HPs) represent the main alternative to traditional heating systems for the t... more Nowadays heat pumps (HPs) represent the main alternative to traditional heating systems for the transition to nearly zero-energy buildings. Though HPs are a well-known technology, the estimation of their actual energy performance is still under discussion. Indeed, the proper choice of the HP design parameters (e.g. size, rated supply temperature) and the adopted control strategy can assume a paramount role to cover the mismatch between declared and actual performance of the system. Objective of this work is to analyze this mutual dependence in an operating system to provide guidelines for the design of a residential heating system with a HP. Through a dynamic energy simulation tool, a variableload air-to-water HP is used to cover the thermal demand of a residential building. The effect of the reciprocal influence of different design choices (e.g. rated heating capacity or design supply temperature) and control strategies (e.g. climatic regulation) is analyzed by simulating different scenarios. To complete the evaluation, the impact of a thermal energy storage is also assessed. The study allows to identify guidelines for the design of different system configurations and results seem to confirm the impact of the investigated parameters on the seasonal performance of the system.

Tecnica Italiana, Jul 30, 2021

Heat transfer research, 2021

Journal of Chemical & Engineering Data, Jan 30, 2019

Ninety-seven vapor-phase PvTx measurements are reported for six binary blends of cis-1,2,3,3,3-pe... more Ninety-seven vapor-phase PvTx measurements are reported for six binary blends of cis-1,2,3,3,3-pentafluoroprop-1-ene (R1225ye(Z)) and isobutane (R600a), and sixty-six vapor-phase PvTx measurements ...

Geothermics, Jul 1, 2016

This paper presents a case study of a vertical borehole ground-coupled heat pump (GCHP) system op... more This paper presents a case study of a vertical borehole ground-coupled heat pump (GCHP) system operating in Urbino (Central Italy), and includes an assessment of its seasonal performance and impact on the sedimentary heat reservoir from October 2010 to October 2014. The GCHP is installed in a commercial building and monitored by means of temperature and thermal energy data loggers. The temperature of the ground heat reservoir at various depths is also monitored down to a depth of 100 m, by means of temperature profiles measured along a borehole heat exchanger and in a monitoring well drilled ad hoc at a distance of 2.2 m. Almost three years of plant monitoring has confirmed the high efficiency of both the heating and cooling cycles of the ground-coupled heat pump system and has highlighted the high performance of the free-cooling mode during the summer. In addition, unbalanced exploitation of the sedimentary heat reservoir during winter and summer seasons has led to a general decreasing trend of ground temperature over the monitoring period. The temporary effects of an unusually heavy snowfall and groundwater circulation on ground temperature is also discussed.

International Journal of Thermophysics, Oct 17, 2007

A recently built experimental set-up was employed for the estimation of the SLE of following bina... more A recently built experimental set-up was employed for the estimation of the SLE of following binary systems: R744 + R744A, R744 + R32, R744A + R32, R744 + R125, R744A + R125, R744 + R134a, R744A + R134a, R744 + R143a, R744A + R143a, R744 + R152a, R744A + R152a, R744 + R23, and R744A + R23. The measurements were performed down to temperatures of about 115 K. The triple points of the pure fluids contained in the mixture were measured to check the reliability of the apparatus, revealing a generally good consistency with the literature. The results obtained for the mixtures were interpreted by means of the Schroder equation. In addition, because a constant cooling rate was not guaranteed by our experimental method, the results of the temperature data acquisitions were corrected using the Rossini method.

Journal of physics, Nov 1, 2017

Nowadays the thermal energy demand in the industrial sector is usually satisfied by means of fire... more Nowadays the thermal energy demand in the industrial sector is usually satisfied by means of fire tube boilers while electricity is supplied from the grid. Alternatively cogeneration units could be adopted for thermal and electrical energy self-production, whilst installing boilers only as back-up units. However, even when cogeneration is profitable, it is not widespread because industries are usually unwilling to accept cogeneration plants for reliability and high investment costs issues. In this work a system aimed at overcoming the above mentioned market difficulties is proposed. It consists of an innovative coupling of a combined heat and power unit with a modified fire tube boiler. In particular, a CFD analysis was carried out by the authors in order to address the most critical aspects related with the coupling of the two systems. More precisely, the following aspects were evaluated in detail: (i) pressure losses of the exhausts going from the prime mover to the boiler due to the sudden cross-section area variations; (ii) thermal power recoverable from the exhausts in the tubes of the boiler; (iii) dependence of the system on the final users' specification.

E3S web of conferences, 2021

Due to the increasing spread of residential heating systems electrically powered, buildings show ... more Due to the increasing spread of residential heating systems electrically powered, buildings show a great potential in producing demand side management strategies addressing their thermal loads. Indeed, exploiting the intrinsic characteristics of the heating/cooling systems (i.e. the thermal inertia level), buildings could represent an interesting solution to reduce the electricity peak demand and to optimize the balance between demand and supply. The objective of this paper is to analyse the potential benefits that can be obtained if the electricity demand derived from the heating systems of a building cluster is managed with demand response strategies. A simulation-based analysis is presented in which a cluster of residential archetypal buildings are investigated. The buildings differ from each other for construction features and type of heating system (e.g. underfloor heating or with fan coil units). By supposing to be able to activate the energy flexibility of the single building with thermostatic load control, an optimized logic is implemented to produce programmatically an hourly electricity peak reduction. Results show how the involvement of buildings with different characteristics depends on the compromise that wants to be achieved in terms of minimization of both the rebound effects and the variation of the internal temperature setpoint.

International Journal of Productivity and Quality Management, 2016

Journal of Chemical & Engineering Data, May 15, 1999

Saturated pressure and P-V-T measurements were performed for 1,1,1,3,3,3-hexafluoropropane (R-236... more Saturated pressure and P-V-T measurements were performed for 1,1,1,3,3,3-hexafluoropropane (R-236fa) in a constant volume cell. The saturated pressure measurements covered a temperature range from 248 K up to 360 K and a corresponding pressure range from 34 kPa up to 1,472 kPa. The results were fitted to various empirical equations. The P-V-T measurements in the superheated vapor region were made

Experimental Thermal and Fluid Science, Dec 1, 2018

Abstract In the present work, the natural convection mechanism of air in a square cavity with act... more Abstract In the present work, the natural convection mechanism of air in a square cavity with active side and inferior walls has been investigated both experimentally and numerically. The experimental method developed by some of the authors has been tested against new boundary condition. In addition, the combined radiative-convective heat transfer method has been investigated. The position relative to the gravity vector and the temperature difference between hot and cold walls were analysed: four different inclination angles (ϑ = 0, ϑ = π/6, ϑ = π/3, ϑ = π/2) of the cavity and five different temperatures (104 ≤ Ra ≤ 105) of the hot walls were tested for a total of 20 different cases. The velocity fields and the effective temperature of the walls have been measured by, respectively, a Particle Image Velocimetry (PIV) system and a set of thermocouples. It has been assessed that both the average and maximum velocities increase with the increasing of the Rayleigh number and of the tilting angle. The velocity field is characterized by two vortices, with a symmetry axe passing from the cavity centre when ϑ = 0; by increasing the tilting angle the symmetry tends to disappear leading to the presence of only one vortex for ϑ = π/2. Numerical simulations with both pure convection and combined radiative-convective model have been performed. For the model validation, both the maximum and the average values of the velocity field on the cavity have been taken into account. The results are in good agreement with the experimental measurements. The addition of the radiance contribution does not influence the results.

Renewable Energy, May 1, 2019

The contemporary energy transition will be characterized by many sub-transitions in the next thre... more The contemporary energy transition will be characterized by many sub-transitions in the next three decades. Oil and gas will continue to play a very important role coupled with renewable energy sources in an energy mix scenario. In this context, the authors of the present work developed a project, named RELife (Renewable Energy for a new Life of offshore platforms), with the main goal of develop a model for the reuse of offshore Oil & Gas platforms at end-of-life stage for the production of renewable energy. In this paper, by considering two types of platforms (4-legged platform with 3 or 4 production wells), various technical scenarios are studied and investigated and for each scenario also the environmental and economic feasibility is evaluated. In addition, all the sub-models are compared with a standard decommissioning process. The evaluations are made for both the Adriatic Sea and the North Sea, two geographic areas with different availabilities of renewable resources. In order to assess also the economic and environmental feasibility, a Discount Cash Flow Analysis and a Life Cycle Assessment of all the scenarios have been conducted.

E3S web of conferences, 2020

The building sector represents one of the most energy-consuming worldwide and a great part of its... more The building sector represents one of the most energy-consuming worldwide and a great part of its consumption is accounted for residential demand for space heating and cooling. Although it is necessary to promote the buildings energy efficiency, energy flexibility is also of paramount importance to optimize the balance between demand and supply. In fact, an energy flexible building is defined as able to change, in a planned manner, the shape of its energy demand curve, electrical and thermal, while the comfort of the end-users is still guaranteed. Objective of this work is to exploit the energy demand management ability of different buildings composing a cluster, when their aggregated demand derived from electric heating systems (i.e. heat pumps) is subject to demand response (DR) strategies. Users with different occupancy profile are considered. By supposing to be able to activate the energy flexibility of the single building with thermostatic load control, different scenarios of cluster composition are evaluated in order to provide guidelines to implement optimal strategies for energy flexibility exploitation without drawback effects connected to the event.

Proceedings of Building Simulation 2019: 16th Conference of IBPSA, Jun 23, 2020

Due to its progressive aging, the need to plan a long-term renovation strategy for the European b... more Due to its progressive aging, the need to plan a long-term renovation strategy for the European building stock is increasingly urgent. Furthermore, the growing penetration of discontinuous and non-programmable renewable energy sources asks for an adaptable demand to the supply variability. Thus, the realization of new buildings which are both efficient and energy flexible can be a way to increase reliability and security of the current energy grid. Purpose of this work is to characterize the effect of different buildings renovation strategies on their energy flexibility performance obtained through electric heating energy demand management. The energy flexibility is quantified by means of a single indicator: the Flexibility Performance Indicator. As the Energy Performance Certificate, it is calculated with a standardized procedure. In this work, starting from a low energy performance reference building, the energy flexibility performance obtainable with different energy efficiency interventions is assessed. Eventually the extent of the requested investment combined with the potential electricity costs saving derived from it is evaluated.

Tecnica Italiana, Jul 30, 2021

Nowadays heat pumps (HPs) represent the main alternative to traditional heating systems for the t... more Nowadays heat pumps (HPs) represent the main alternative to traditional heating systems for the transition to nearly zero-energy buildings. Though HPs are a well-known technology, the estimation of their actual energy performance is still under discussion. Indeed, the proper choice of the HP design parameters (e.g. size, rated supply temperature) and the adopted control strategy can assume a paramount role to cover the mismatch between declared and actual performance of the system. Objective of this work is to analyze this mutual dependence in an operating system to provide guidelines for the design of a residential heating system with a HP. Through a dynamic energy simulation tool, a variableload air-to-water HP is used to cover the thermal demand of a residential building. The effect of the reciprocal influence of different design choices (e.g. rated heating capacity or design supply temperature) and control strategies (e.g. climatic regulation) is analyzed by simulating different scenarios. To complete the evaluation, the impact of a thermal energy storage is also assessed. The study allows to identify guidelines for the design of different system configurations and results seem to confirm the impact of the investigated parameters on the seasonal performance of the system.

Tecnica Italiana, Jul 30, 2021

Heat transfer research, 2021

Journal of Chemical & Engineering Data, Jan 30, 2019

Ninety-seven vapor-phase PvTx measurements are reported for six binary blends of cis-1,2,3,3,3-pe... more Ninety-seven vapor-phase PvTx measurements are reported for six binary blends of cis-1,2,3,3,3-pentafluoroprop-1-ene (R1225ye(Z)) and isobutane (R600a), and sixty-six vapor-phase PvTx measurements ...

Geothermics, Jul 1, 2016

This paper presents a case study of a vertical borehole ground-coupled heat pump (GCHP) system op... more This paper presents a case study of a vertical borehole ground-coupled heat pump (GCHP) system operating in Urbino (Central Italy), and includes an assessment of its seasonal performance and impact on the sedimentary heat reservoir from October 2010 to October 2014. The GCHP is installed in a commercial building and monitored by means of temperature and thermal energy data loggers. The temperature of the ground heat reservoir at various depths is also monitored down to a depth of 100 m, by means of temperature profiles measured along a borehole heat exchanger and in a monitoring well drilled ad hoc at a distance of 2.2 m. Almost three years of plant monitoring has confirmed the high efficiency of both the heating and cooling cycles of the ground-coupled heat pump system and has highlighted the high performance of the free-cooling mode during the summer. In addition, unbalanced exploitation of the sedimentary heat reservoir during winter and summer seasons has led to a general decreasing trend of ground temperature over the monitoring period. The temporary effects of an unusually heavy snowfall and groundwater circulation on ground temperature is also discussed.

International Journal of Thermophysics, Oct 17, 2007

A recently built experimental set-up was employed for the estimation of the SLE of following bina... more A recently built experimental set-up was employed for the estimation of the SLE of following binary systems: R744 + R744A, R744 + R32, R744A + R32, R744 + R125, R744A + R125, R744 + R134a, R744A + R134a, R744 + R143a, R744A + R143a, R744 + R152a, R744A + R152a, R744 + R23, and R744A + R23. The measurements were performed down to temperatures of about 115 K. The triple points of the pure fluids contained in the mixture were measured to check the reliability of the apparatus, revealing a generally good consistency with the literature. The results obtained for the mixtures were interpreted by means of the Schroder equation. In addition, because a constant cooling rate was not guaranteed by our experimental method, the results of the temperature data acquisitions were corrected using the Rossini method.

Journal of physics, Nov 1, 2017

Nowadays the thermal energy demand in the industrial sector is usually satisfied by means of fire... more Nowadays the thermal energy demand in the industrial sector is usually satisfied by means of fire tube boilers while electricity is supplied from the grid. Alternatively cogeneration units could be adopted for thermal and electrical energy self-production, whilst installing boilers only as back-up units. However, even when cogeneration is profitable, it is not widespread because industries are usually unwilling to accept cogeneration plants for reliability and high investment costs issues. In this work a system aimed at overcoming the above mentioned market difficulties is proposed. It consists of an innovative coupling of a combined heat and power unit with a modified fire tube boiler. In particular, a CFD analysis was carried out by the authors in order to address the most critical aspects related with the coupling of the two systems. More precisely, the following aspects were evaluated in detail: (i) pressure losses of the exhausts going from the prime mover to the boiler due to the sudden cross-section area variations; (ii) thermal power recoverable from the exhausts in the tubes of the boiler; (iii) dependence of the system on the final users' specification.