1,721,156 research outputs found
Calcolo per le verifiche termiche e igrometriche. Valutazione sperimentale del comfort termoigrometrico
No full textSteady state calculation of heat pump long term performances based on utilization factor method
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Prestazioni di una pompa di calore ad aria: valutazione semplificata
No full textLa normativa recentemente introdotta in applicazione della legge 10/91 risulta decisamente carente a riguardo delle procedure di calcolo delle prestazioni delle pompe di calore azionate da motore elettrico e che utilizzano l'aria esterna come sorgente esterna.
A tale proposito viene qui presentata una proposta in grado di colmare questa lacuna operando in conformità con il metodo del fattore di utilizzo previsto dalla norma UNI 10344. Lo scopo è quello di permettere una stima agevole ma corretta della frazione del fabbisogno termico dell'edificio effettivamente coperto dalla pompa di calore. Si vuole inoltre calcolare in modo più preciso il coefficiente di prestazione medio stagionale della macchina
Temperatura di esercizio di isolanti termici in copertura: simulazioni con modello di calcolo e verifica speriemntale
No full textThe effectiveness of thermal insulation materials in roof applications is affected by the thermal impact of solar radiation. This is particularly true for flat roofs where the insulation material is applied directly under a water-proof membrane.
The two most important aspects of this application are:
• The high temperature levels due to solar radiation;
• The significant temperature variations during the different periods of the day and of the year.
This research study examined the temperature spread inside a water proof kit and in particular the maximum temperatures that can be reached in the insulation layer. The research study consisted of two phases:
• Modelling: Using a calculation model, the temperature gradient was calculated for all the different layers of a typical water-proof kit configuration simulating the possible variation of several climatic parameters.
• Practical validation: the real conditions on two different roofs were measured to proof the validity of the model.
The study results showed that the insulation layer in contact with the external water-proof membrane of flat roofs can reach temperature peaks of more than 70°C during the period of highest solar radiation. In the hot Mediterranean climate of southern Europe, temperatures can reach 80°C. The maximum
temperatures on curved roofs in more moderate climate zones can reach 67°C.
The project showed daily temperature variations of close to 40°K inside the insulation material and about 50°K on the surface.
These temperature peaks exceed the maximum functional temperatures of several insulation materials. With a view to guaranteeing the quality and durability of roof kits, specifiers and architects should be aware of how high temperature levels reached in zones of intensive solar radiation affect the dimensional stability of insulation material
Convective Heat Transfer at Room Walls: Some Investigations
No full textAs well known, predictions of heating/cooling loads and energy consumption in buildings are significantly affected by the evaluation of convection at room surfaces. In this regard suitable heat transfer coefficients are usually applied: however, sometimes the agreement among the available correlations is quite poor and additionally the presence of particular factors (cold and hot portions of wall, plumes from panels or electric appliances, etc.) give rise to specific conditions, which must be studied as separate cases. In this context “Computational Fluid Dynamics” (CFD) is a very useful tool but it is not still suitable for extensive applications. Therefore, in this paper some correlations are summarised and their results are compared with those obtained by numerical CFD experiments; in doing this, some critical points of CFD (such as the choice of turbulence model and grid spacing) are also discusse
Misure fonometriche e valutazioni sull’acustica interna in un teatro storico veneziano: il Malibran.
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