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64
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Introduction
Current institution
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April 2021 - present
February 2017 - January 2021
Education
November 2013 - October 2016
October 2011 - October 2013
September 2008 - July 2011
Publications
Publications (64)
Efficiency of energy systems can be improved in different ways. One of these consists in adopting heat transfer fluids with better thermo-physical properties, e.g. thermal conductivity and dynamic viscosity, which can improve convective heat transfer coefficient. Being mixtures of high-conductive nanoparticles and common base fluids, nanofluids hav...
Thanks to their excellent heat transfer coefficient, nanofluids can be considered as ideal heat transfer fluids for a large number of relevant engineering and scientific applications. Precise assessments of their thermophysical properties are thus essential for reliable calculations. In this work, a new semi-empirical scaled correlation based on 8...
To solve the series of heat balances that EN ISO 52016-1 uses to simulate the dynamic hourly energy requirements of a building, detailed climatic data are required as input. Differently from air temperatures, relative humidity and wind speed, which are easily measurable and available in databases, the direct and diffuse solar irradiances incident o...
The increasing use of renewable energy sources has highlighted the importance of energy storages, and in particular of latent heat thermal energy storages (LHTESs). Among the phase change materials (PCMs) that can be used in such systems, sugar alcohols (SAs) are considered potential substances that may lead to interesting applications in the LHTES...
Five funnel solar cookers have been tested to investigate the influence of the aperture area on their performance. The largest cooker had an aperture area of 0.5 m² and it was tested side by side with two other two smaller cookers. Each cooker was tested with the same amount of glycerine.
The linear performance curves relating the efficiency with t...
In the present work, an improvement of protocol widely used for reporting the thermal behaviour of solar cookers is communicated to the scientific community. The linear regression used to represent the standardised cooking power is based on the well-known Hottel-Whillier-Bliss equation written in dimensionless format. The authors’ new formulation p...
Performance parameters of solar cookers have conventionally been determined by assuming a linear trend between the cooker power and the difference between load temperature and ambient air temperature. This approach may not be convenient for some solar cooker designs. In the present work, the suitability of a non-linear regression derived from fitti...
Sugar alcohols have interesting thermodynamic properties that make them good options as heat storage materials (HSMs) to be used in solar cookers. Among sugar alcohols, xylitol is affected by severe supercooling that can significantly alter its usefulness in thermal energy storage (TES) systems. To overcome the supercooling issue, in this work the...
The comparison between I-V (current-voltage) curves measured on site and I-V curves declared by the manufacturer allows to detect decrease of performance and control the degradation of photovoltaic modules and strings. On site, I-V curves are usually obtained under operating conditions (OPCs), i.e. at variable solar radiation and module temperature...
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) a...
A way to improve the performance of heat pumps lies in the possibility of adhering to Demand Response (DR) programs. DR consists of changes in electricity use of end users in response to changes in the electricity price over time. Taking advantage of the energy flexibility given by the end-use system, such as a building, it is possible to collect m...
Solar radiation can be considered as one of the most suitable energy source to be used for cooking food. It is therefore important to promote advancement in solar cooking systems, in particular as concerns their efficiency and cooking times. In this work, we designed, realized and tested a novel low-cost solar cooker that uses a high-performance li...
District cooling systems (DCSs) belonging to multi-energy systems can be managed by model predictive controls (MPCs) designed to reduce the amount of electrical energy collected from the grid for backup cooling systems when there is a temporal mismatch between energy demand and availability. In this paper, a DCS recovering cold thermal energy from...
The integration of multi-energy systems to meet the energy demand of buildings represents one of the most promising solutions for improving the energy performance of the sector. The energy flexibility provided by the building is paramount to allowing optimal management of the different available resources. The objective of this work is to highlight...
During their lifetime, photovoltaic (PV) plants are subject to a normal degradation of their components, and they are consequently characterized by decrease of the expected production. In order to prevent and evaluate failures and loss of production, specific tests can be carried out on the PV modules. Non-destructive methods, such as visual inspec...
The implementation of model predictive controls (MPCs) in buildings represents an important opportunity to reduce energy consumption and to apply demand side management strategies. In order to be effective, the MPC should be provided with an accurate model that is able to forecast the actual building energy demand. To this aim, in this paper, a dat...
Solar radiation is a variable energy source and the mismatch between the availability of such source and the domestic energy demand is a paramount challenge to deal with. For this reason, in this work a 4.08 concentration ratio portable solar box cooker coupled with a thermal energy storage (TES) based on a phase change material (PCM) was character...
This paper presents a literature survey of the experimental thermal conductivity data for environmentally friendly refrigerants, namely HydroFluoroOlefins (HFOs) and HydroChloroFluoroOlefins (HCFOs), in the liquid phase. A total of 2073 experimental data for six alternative refrigerants, i.e. R1233zd(E), R1234yf, R1234ze(E), R1234ze(Z), R1224yd(Z),...
Accounting for about 17% of the overall electricity consumption worldwide, the refrigeration sector requires improvements in energy reduction and management. Demand side management (DSM) could be adopted to improve the overall system energy efficiency. In this work, a CO2 commercial refrigeration system coupled with different cold thermal energy st...
This paper provides 217 PvTz points for the binary systems of difluoromethane (R32) and 2,3,3,3-tetrafluoroprop-1-ene (R1234yf) both in the two-phase and superheated vapor regions. The R32 + R1234yf data were measured along eleven isochores (0.029794, 0.029936, 0.030724, 0.032113, 0.061323, 0.063915, 0.102150, 0.111536, 0.116592, 0.144796, 0.280627...
District cooling systems (DCSs) are networks able to distribute thermal energy, usually as chilled water, from a central source to industrial, commercial, and residential consumers, to be used for space cooling/dehumidification. As cooling demand will increase significantly in the next decades, DCSs can be seen as efficient solutions to improve sus...
In this paper, the solid–liquid equilibrium of the binary system containing difluoromethane (R32) and trans-1,3,3,3-tetrafluoropropene (R1234ze(E)) was experimentally evaluated. An experimental setup was used to measure 20 different compositions of the binary system in the temperature range from 168.2 K to 132.00 K. The studied binary system showed...
The Boyle temperature represents the temperature at which a real gas behaves more like an ideal gas. It is an useful thermodynamic parameter but it is difficult to measure experimentally. Thus, in this work we provide the Boyle temperatures of 16 pure gases, namely: argon, carbon dioxide, carbon monoxide, deuterium, helium-3, helium-4, hydrogen, kr...
Supermarkets are intensive energy consumers because of a high electricity demand, mainly due to refrigeration utilities. Thus, in this work a supermarket integrated HVAC, refrigeration and water loop heat pump (WLHP) system was analyzed according to a demand side management approach, adopting a demand response strategy coupled with real-time pricin...
Demand side management (DSM) strategies can be used to reduce customers' demand at peak times, change the timing of end-use consumption from high to low-cost periods and increase consumption during off-peak periods. They can be implemented by using the energy flexibility available in the final users' applications, energy storages or control systems...
Demand side management (DSM) strategies can be used to reduce customers' demand at peak times, change the timing of end-use consumption from high to low-cost periods and increase consumption during off-peak periods. They can be implemented by using the energy flexibility available in the final users' applications, energy storages or control systems...
An artificial neural network (ANN) to estimate the second virial coefficient, valid for organic and inorganic compounds, is presented. First, we statistically analyzed 6,531 experimental points, belonging to 234 fluids, collected from literature. The data were investigated with a factor analysis approach to identify the most significant parameters...
Different Cubic Equations of State (CESs) were used to represent Vapor-Liquid Equilibrium (VLE) of binary systems containing low Global Warming Potential (GWP) refrigerants. The calculated VLE data from some of the widely used CESs were compared with the experimental data collected from the literature. To extend CESs to binary systems, van der Waal...
Demand side management (DSM) can be defined as a set of measures adopted to modify customers’ energy
demand with the aim of improving the efficiency of the overall energy system. Indeed, DSM strategies can be
used to reduce customers’ demand at peak times, reduce energy consumption seasonally/yearly, change the
timing of end-use consumption from hi...
Clear-sky conditions are an essential need to allow proper high-temperature solar cooking. Moreover, it is not an easy task to accomplish evening cooking, especially during wintertime when solar radiation is available only for a few hours. A solution to bypass these drawbacks lies in adopting a cooker provided with a thermal storage unit. The stora...
This work presents a modification of the Kardos equation specifically oriented to refrigerants. The proposed equation was tested for both liquid and vapor thermal conductivities along saturation of the main refrigerants. In the Kardos equation, the thermal conductivity of liquids is a function of the density of the liquid, heat capacity at constant...
This work presents a method to calculate the surface tension of the inorganic family of silicon-based molecules starting from the knowledge of the liquid viscosity. As a first step, the raw experimental data of silanes were collected from the data available in the DIPPR database, both for surface tension and liquid viscosity. After the data analysi...
This paper provides eighty-four PvTx data points for binary blends of trans-1-chloro-3,3,3-trifluoroprop-1-ene (R1233zd(E)) and isobutane (R600a) in the vapor phase and ninety-seven PvTx data points for binary blends of cis-1,3,3,3-tetrafluoroprop-1-ene (R1234ze(Z)) and R600a in the vapor phase. The R1233zd(E)/R600a data were recorded along six iso...
The values of thermal conductivity λ at different temperatures for organic and inorganic compounds in the liquid phase is essential in the study of numerous processes, but experimental data are frequently not available with acceptable reliability or not available at all, since rigorous theoretical or semi-theoretical models of the liquid state are...
High temperature solar cooking allows to cook food fast and with good efficiency. An unavoidable drawback of this technology is that it requires nearly clear-sky conditions. In addition, evening cooking is difficult to be accomplished, particularly on the winter season during which solar radiation availability is limited to a few hours in the after...
In this paper, a literature survey of the available experimental surface tension data of both low global warming potential (GWP) refrigerants and binary systems containing low GWP refrigerants is provided. The experimental data were collected for 14 halogenated alkene refrigerants and 5 blends. The data were analyzed with the most reliable semi-emp...
Solar cooking is considered one of the most attractive ways to utilize solar energy. Therefore, in this work a high concentration ratio (11.12) solar box cooker prototype was manufactured and tested. The cooker has a cooking chamber with a glass cover on the top and is composed by two rows of booster mirrors. The prototype allows both an azimuthal...
The paper presents 96 PνTx vapor phase data values for binary blends of 2,3,3,3-tetrafluoroprop-1-ene (R1234yf) and isobutane (R600a) and 102 PνTx vapor phase data values for binary blends of trans-1,3,3,3-tetrafluoroprop-1-ene (R1234ze(E)) and R600a. The R1234yf/R600a blends were measured for five isochores (0.0751, 0.0944, 0.1280, 0.1666, 0.1701)...
This study investigates the applicability of artificial neural networks (ANNs) as an efficient tool for the description of thermal conductivity of liquid alcohols for a broad range of temperatures. The proposed multilayer perceptron has 1 hidden layer with 43 neurons, determined according to the constructive approach. The model developed was traine...
This work presents a new formula to calculate the liquid viscosity of the inorganic family of silicon-based molecules. As a first step, the raw viscosity experimental data of silanes were collected from the data available in the Design Institute for Physical Properties database. After the data analysis, a selection of experimental data was consider...
Hydrofluoroolefins (HFOs) and hydrochlorofluoroolefins (HCFOs) are two of the most promising families of low-GWP fluids being investigated as alternatives for HFCs in HVAC&R applications. Within the HCFO family, trans-1-chloro-3,3,3-trifluoropropene (R1233zd(E)) is a compound with a relatively high normal boiling point temperature (∼291.1 K) and wa...
The paper presents 86 PvTx measurements in the vapor phase for blends of 2,3,3,3-tetrafluoroprop-1-ene (R1234yf) and propane and 62 PvTx measurements in the vapor phase for blends of cis-1,2,3,3,3-pentafluoroprop-1-ene (R1225ye(Z)) and propane. The R1234yf and propane blends were measured along four isochores (0.047, 0.048, 0.072, 0.095) m3·kg–1 fo...
Energy demand in the world is continuously increasing and fossil fuels resources must be replaced by renewable resources with lower environmental risk factors, in particular CO2 emissions. Concentrating solar collectors appear to be very promising for that purpose. Thus, this work presents a numerical analysis for the evaluation of the yearly yield...
A new semi-empirical scaled correlation for the second virial coefficient of refrigerants, based on the corresponding states principle, is proposed. Starting from the consideration that refrigerants have different chemical structures, the considered experimental dataset, which includes 63 refrigerants and 3595 points, was split into five main subgr...
This work presents a new formula to calculate the surface tension of the important organic family of carboxylic acids. As a first step, the raw surface tension data of acids (experimental, smoothed and predicted) accepted by DIPPR database were collected. After the data analysis, only the experimental data were considered for the calculations. The...
This book provides a technical overview of low-cost parabolic trough collector (PTCs) prototypes for low-temperature heat demand. It begins with a comprehensive but concise summary of the state-of-the-art in PTCs, and presents a detailed mathematical model of such systems. Subsequent chapters describe the construction and materials used in the manu...
Receivers are the parts of a PTC where the solar radiation is concentrated and collected. PTC receivers are tubes of various diameters located in the focal line of the concentrator and can be distinguished into two parts: the absorber, i.e. the metallic tube in which the heat transfer fluid (HTF) flows, and the cover, an external tube generally mad...
PTCs are solar collectors made by several components, nonetheless they can be divided into two different parts which have distinct functions: the concentrator and the receiver. The former is the subject of the present chapter. The scope of PTC concentrators is to reflect the maximum amount of solar radiation to the receiver. In PTCs, concentrators...
This chapter presents a detailed mathematical analysis of PTCs. It is divided into three sections: tracking of the Sun, optical analysis and thermal analysis. The first section is an overview of equations and relationships used in solar geometry to determine the position of the Sun and, hence, the slope and the angle of incidence that in each insta...
The performance of solar thermal collectors such as PTCs can be assessed by performing specific procedures described in standards. Standards generally followed in the solar energy field are the ISO 9806, the ANSI/ASHRAE 93 and the EN 12975-1, which will be presented in this chapter. The measurements and the procedures required for testing PTCs will...
This paper reports 136 compressed liquid density measurements and 104 vapor phase PvT measurements of cis-1,2,3,3,3-pentafluoroprop-1-ene (R1225ye(Z)). The compressed liquid density data represent eight isotherms evenly spaced approximately from (283 to 353) K for pressures from close to saturation to 35 MPa, and the vapor phase PvT data represent...
This work presents a new formula to calculate the surface tension of silicon based molecules.As a first step, the raw surface tension data of silanes (experimental, smoothed and predicted) accepted by DIPPR database were collected. After the data analysis, only the experimental and smoothed data were considered for the calculations. The selected da...
The manufacture of low-cost parabolic trough collectors (PTCs) for industrial process heat applications ranging from 70 to 250 °C is crucial for the widespread availability of this solar technology. Thus, we present a prototype of a PTC with a 90° rim angle and a small concentration ratio of 9.25 built in fiberglass and extruded polystyrene, called...
A previously proposed general correlation relating thermal conductivity to reduced temperature is improved by the complete characterization of the refrigerant family. A total of 41 fluids and 1372 experimental points were considered. After analyzing the statistical effects, a new simple empirical correlation to represent the thermal conductivity of...
Il presente studio esamina il tema dell’utilizzo di accumuli termici accoppiati a fonti di calore solare per il soddisfacimento dei servizi di ACS, riscaldamento e raffrescamento nel contesto di edifici particolarmente prestanti, ed in particolare nell'ottica del raggiungimento di prestazioni nZEB. Lo studio espone innanzitutto le caratteristiche d...
In this paper, a mathematical model of a parabolic trough collector (PTC) is described in detail and tested by comparing the efficiency predicted by the model with the efficiency measured through outdoor tests on a PTC prototype. The model accounts for optical and thermal losses, thus allowing the calculation of optical, thermal, and global efficie...
Questions
Question (1)
Dear Colleagues,
I would like to invite you to submit contributions to a Special Issue of Energies on the "Experimental Evaluation of Solar Thermal Engineering”. The growth in energy consumption over the past 20 years has been significant, and demand for energy will continue to grow in the future. The global commercial low-temperature heat consumption is estimated to be more than 10 EJ per year for hot water production alone, while industrial energy consumption in industrialized countries accounts for 30% of the total required energy; in Europe, two-thirds of this energy consists of thermal energy. The only way to meet this global thermal demand without contributing to climate change implies the utilization of renewable sources, and in particular of the solar source, which is the most abundant energy resource on Earth. Advancement in solar thermal engineering is therefore paramount to improve the efficiency, reliability, and sustainability of solar collectors and all related energy systems. This Special Issue will deal with innovative experimental applications and systems belonging to the solar thermal engineering field.
Topics of interest for publication include, but are not limited to:
- Measurement of solar radiation;
- Thermo-optical properties of materials and heat-transfer fluids;
- Solar collectors: flat-plate, evacuated tube, compound parabolic, linear Fresnel, parabolic trough, parabolic dish, heliostat field;
- Solar cookers;
- Solar ponds;
- Solar-thermal-based applications: water heating, space heating and cooling, industrial processes, drying, distillation, power systems;
- Thermal energy storage: solid, liquid, phase change, chemical.
Please note that a certain discount can be offered to selected contributions. Contact me if you are interested. Additional information can be found at:
Dr. Gianluca Coccia
Guest Editor
