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DETERMINAZIONE DEL COEFFICIENTE DI SCAMBIO TERMICO TRA UNA SUPERFICIE CILINDRICA RISCALDATA ED UN GETTO RETTANGOLARE SOMMERSO Tesi di Dottorato di Ricerca in Energetica V Ciclo
No full text“MASSIMIZZAZIONE DELLO SCAMBIO TERMICO TRA UNA PARETE VERTICALE TRASPIRANTE ED ARIA IN PRESENZA DI CONVEZIONE NATURALE E MISTA: PRIMI RISULTATI"
No full textFREE AND MIXED CONVECTION HEAT TRANSFER ENHANCEMENT BETWEEN VERTICAL WALL AND AIR IN PRESENCE OF EXPIRED OR ASPIRED JETS
No full textIn the present paper a comparison between the heat transfer enhancements obtained by small pulsating air jets, respectively aspirated or expired, is carried out. These air jets go in or out an aluminum vertical wall, heated by Joule effect, in the presence of air. Experimental measurements have been conducted with three temperature drops between wall and air (25, 40 and 70K respectively) with or without pulsating and continuous expired and aspirated jets. The thickness of the boundary layer near the wall is locally reduced due to the presence of the aspirated jets or the boundary layer is destabilized near the holes by means of expired jets: both of these phenomena improve the heat transfer coefficient. The experimental results have demonstrated that the pulsating expired jets are more efficient than the aspirated ones with lower differences wall-to-air temperature; the opposite occurs when that difference is greater then 40K. Also the time intervals of presence and absence, the air velocity and the jets array maximizing the heat transfer coefficient have been computed
FAST TRANSIENT HEAT TRANSFER ANALYSIS AT GAS-SOLID INTERFACE
No full textIn this paper we propose a simple analysis of heat transfer between a gas and a wall in fast transient condition using complex temperature. This problem is very important because it represents the thermal exchanges in an inner combustion engine. First we analyse the correlations already proposed by other researchers, then we propose our formulation taking into consideration some cases with increasing complexity. Finally the theoretical results are compared with the experimental ones
FREE CONVECTION COEFFICIENT ENHANCEMENT BETWEEN INCLINED WALL AND AIR IN PRESENCE OF EXPIRED JETS
Full text linkThis paper aims to determine the heat transfer enhancement in natural convection between a downward facing inclined wall, heated by Joule effect, and air in the presence of small air pulsating expired jets, in conditions of medium temperature difference between wall and air, namely 40K. Experimental measurements have been taken both with and without pulsating expired jets. The wall is kept in condition of uniform temperature. The expired jets blow out perpendicularly from the wall surface. An infrared thermo-camera was used to check the wall temperature uniformity. Hot-wire anemometer and visualization with smoke were used to find information on the air velocity field.
The wall inclination angle which maximizes the convective heat exchange near the leading edge has been investigated too
STUDIO SPERIMENTALE SULLA OTTIMIZZAZIONE DEL CONDENSATORE DI CONGELATORI DOMESTICI: PRIMI RISULTATI
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CONFRONTO DEI VALORI DI ALCUNI PARAMETRI ACUSTICI MISURATI NEL TEATRO MANZONI DI PISTOIA UTILIZZANDO SORGENTI SONORE DI VARIO TIPO
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