Angela Simone - Academia.edu (original) (raw)

Papers by Angela Simone

Lo scambio termico tra uomo ed ambiente dipende da molteplici fattori, sia oggettivi (ambiente ci... more Lo scambio termico tra uomo ed ambiente dipende da molteplici fattori, sia oggettivi (ambiente circostante) sia soggettivi; in particolar modo si \ue8 voluto valutare come l\u2019area del corpo umano nudo interviene nel calcolo del contributo dovuto allo scambio termico radiativo sulla valutazione del comfort termoigrometrico indoor. Generalmente, in questo ambito, per calcolare il valore dell\u2019area della superficie del corpo umano nudo si utilizza la nota formula di Du Bois, che \ue8 funzione dei soli parametri di peso ed altezza del soggetto. In questo lavoro si vuole confrontare la formula di Du Bois con formule relativamente pi\uf9 recenti, presenti in letteratura, anch\u2019esse funzioni del peso e dell\u2019altezza del soggetto, per valutare le differenze nel calcolo del comfort termoigrometrico indoor. Pertanto, si \ue8 proceduto, inizialmente, ad un confronto grafico degli andamenti delle diverse formule nel massimo intervallo di peso ed altezza dei campioni estratti da un\u2019indagine statistica condotta sulla popolazione dell\u2019Italia meridionale (Sicilia e Calabria). Successivamente si \ue8 effettuata un confronto statistico tra le diverse formule, basato sempre sullo stesso campione, ed infine si \ue8 valutato il massimo scostamento nella valutazione dello scambio termico radiativo dovuto alla scelta della formula

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The paper on refrigerants has been divided in two parts. Refrigerants’ thermodynamic, physical, c... more The paper on refrigerants has been divided in two parts. Refrigerants’ thermodynamic, physical, chemical, safety – related and environmental properties have been presented and discussed in the first part of the paper. Influence of those properties, which is of the utmost significance on the vapor – compression process efficiency and design has been presented. The design of HVAC system is influenced by the choice of the vapor – compression process, which means that refrigerant choice defines HVAC design as well. Throughout the history, refrigerant development took place due to different reasons, such as safety, stability, durability, economic or environmental issues, thus giving the boost to new research and equipment improvement in terms of safety and efficiency. Recent legislation worldwide and in EU is still not quite completed concerning refrigerant issues. The delicate subject of refrigerants is widely discussed, viewpoints of different parties are opposite, depending on positio...

ABSTRACT Mixing and displacement ventilation are common systems in commercial buildings, while mi... more ABSTRACT Mixing and displacement ventilation are common systems in commercial buildings, while mixing ventilation is used in residential buildings. Displacement ventilation provides fresh air to the occupied zone in a more efficient way than mixing ventilation but it is important to know how well it works with a floor system for heating or cooling. Can, for example, a floor heating system warm up the supply air too fast and destroy the displacement effect? Will floor cooling, combined with displacement ventilation, result in too high a vertical temperature difference and too low a temperature at feet level? The required amount of ventilation depends on the ventilation effectiveness. In standards, the recommended values for ventilation effectiveness depend on the position of the supply and exhaust device and on the difference between supply and room air temperature. Among others, for warm air heating the ventilation effectiveness is always less than 1 and can be as low as 0.4. This would then require an increased amount of ventilation. A combination of floor heating/cooling, radiators, air cooling, displacement ventilation, mixed ventilation and different combinations of supply and return grilles have, in this study, been experimentally tested. The studies on a displacement ventilation system show lower vertical air temperature differences and higher ventilation effectiveness when it is combined with a floor heating system. With floor cooling, the displacement ventilation system should be designed with a higher supply air temperature. Furthermore, the buoyancy flows from warm or cold windows and occupants influence the airflow pattern and increase the mixing of supply air into the occupied zone.

In warm climate regions the opening of windows and/or the use of desk or ceiling fans are the mos... more In warm climate regions the opening of windows and/or the use of desk or ceiling fans are the most common systems used to generate increased airflows that compensate for higher environmental temperatures at the expense of relatively low energy consumption. When using desk fans, local air movement is provided around the upper body part of seated occupant generating a certain cooling effect. In warm office environments (26˚C to 34˚C with constant absolute humidity of 12.2 g/m 3) the local cooling impact and the possibility to keep comfortable conditions for the seated occupants, commonly adapted to cold climate, were investigated by using thermal manikin, physiological data collection, and subjects´ assessment. Results show that, also for Scandinavians, comfortable thermal conditions with high acceptability and satisfaction of the thermal environment can be achieved in an office room temperature of 28 ˚C, and improved a bit if personal control is guaranteed.

Common experiences, standards, and laboratory studies show that increased air velocity helps to o... more Common experiences, standards, and laboratory studies show that increased air velocity helps to offset warm sensation due to high environmental temperatures. In warm climate regions the opening of windows and the use of desk or ceiling fans are the most common systems to generate increased airflows to compensate for higher environmental temperatures at the expense of no or relatively low energy consumption. When using desk fans, local air movement is generated around the occupant and a certain cooling effect is perceived. The impact of the local air movement generated by different air flow patterns, and the possibility to keep comfortable conditions for the occupants in warm environments were evaluated in studies with human subjects. In an office-like climatic chamber, the effect of higher air velocity was investigated at room temperatures between 26°C to 34°C and at constant absolute humidity of 12.2 g/kg. By a thermal manikin the effect of direct air movement generated by a person...

BOOK – SYMPOSIUM PROGRAMME ELCAS 2011 39 quality is solar radiation, and as such its about time a... more BOOK – SYMPOSIUM PROGRAMME ELCAS 2011 39 quality is solar radiation, and as such its about time and space occupied to establish quality that should provide the real evaluations of exergy. This implies also that its not only about energy but also about food and mass derived from solar radiation which determines the exergetic performance of any function/action in the system. And it turns out that mass and materials are far more decisive for maintaining quality, or avoid system quality decrease, as is energy in its current forms. IV.4. Exergy Analysis of Extractive Vacuum MetallurgySustainability prospects E. BALOMENOS*, D. PANIAS, I. PASPALIARIS National Technical University of Athens, Laboratory of Metallurgy 9, Heroon Polytechneiou str., 157 73, Zographou Campus, Greece, Email: thymis@metal.ntua.gr Based on the fundamental Le Chatellier principle, gas producing reactions can be pushed at lower temperatures if an appropriate vacuum is applied. A basic thermodynamic analysis is used t...

The present study investigates the type of temperature sensor that best represents the operative ... more The present study investigates the type of temperature sensor that best represents the operative temperature, i.e., the type of sensor that will integrate the influence of air and mean radiant temperature in the same way as a person. Size, shape and colour of the sensor will have an impact on the relative influence of air and mean radiant temperature in a space. In an experimental chamber different combinations of air temperature and radiant heated or cooled surfaces were tested. Several types of sensor (flat, sphere, ellipsoid, half-sphere, grey, black, white) were used to measure the operative temperature. Besides comparing the type of sensor, the influence of the sensor position in the room was experimentally investigated. The results show that a grey sensor of 3-5 cm diameter is the best size. The best shape, however, depends on the position of the sensor in the space.