Heat Transfer Enhancement on the Upper Surface of a Horizontal Heated Plate in a Pool by Ion Injection from a Metallic Point

The heat transfer characteristics of an electrohydrodynamically induced impinging liquid flow were studied in point-plane geometry. Points of four different metals were tested, varying the high voltage and the point-to-plane spacing. Heat transfer coefficients augmented more than 200%, with a negligible Joule dissipation. The Nusselt number on the stagnation point was successfully correlated to a dimensionless group, behaving similar to the Reynolds number in submerged jets

Development of a Light Absorption Technique for Mapping the Thickness of Falling Liquid Films

The paper shows the development of a photometric technique for mapping the thickness of liquid films. The phenomenonof light absorption through a layer of dyed liquid is used to evaluate its thickness. The layer receives a back-illumination from the wetted wall and the transmitted intensity of light is measured by means of a digital camera. Non-uniformities in the original intensity field force us to build a calibration curve for each measurement point. The filtering and interpolation algorithm needed for transforming the intensity field into the thickness field is described in detail. In addition to being non-intrusive and inexpensive, the technique is capable of determining the local film thickness with an accuracy lower than 10% of its measuring range amplitude

Enhanced nucleate boiling and CHF on a small horizontal plate under ionic jet impingement

The application of a strong electric field within a dielectric medium can produce a jet-like motion of ionized liquid from a high-voltage electrode to a grounded heated plate. Ionic jet impingement on the upper surface of a horizontal plate where boiling is occurring significantly modifies the boiling curve. The effect of ion injection on saturated boiling heat transfer, specifically on boiling inception, nucleate boiling, and CHF, in a small-size sample with a single point-electrode configuration, has been experimentally investigated; the working fluid is FC-72. Significant heat transfer enhancement has been observed for the entire nucleate boiling curve. Besides, CHF has been delayed to higher heat fluxes (up to a 40% increase) by means of the impinging ionic jet. This active technique requires a negligible power input (in the order of a few milliwatts) for the ionic current. A focus on the influence of the electrical parameters on the phenomenon has been performed and preliminary results are presented. Further tests and modeling effort are needed to optimize this very promising technique

Parabolic flight results of electrohydrodynamic heat transfer enhancement in a square duct

In the present work, we investigate the effect of the electrical and gravitational force fields on weakly forced convection (Reynolds numbers range from 500 to 5600) in a square duct heated from the bottom side. On the top side, we placed an array of sharp point electrodes. Microgravity conditions were obtained during a parabolic flight campaign. At the application of a sufficiently-high DC electric field, a plume-like motion is induced in the fluid by the mechanism of ion injection and heat transfer is dramatically augmented. The working fluid is the dielectric liquid HFE-7100. Local temperatures on the heated wall were measured by liquid crystal thermography and by electrical resistance thermometers. By means of the temperature field, we were able to characterize the behaviour of the ionic jets and their interaction with the crossflow. We also investigated the effects of the Reynolds number, the gravity level, and the major electrical parameters on the average heat transfer coefficients. When no electric field is applied, heat transfer coefficients are influenced by the gravity level, particularly at the low flow rates. On the other hand, in the electrohydrodynamic regimes, heat transfer rates are not only enhanced, but also no longer gravity-dependent, showing that the resulting convection is dominated by the electric field intensity, conveniently controllable by the applied high voltage. Relatively small pressure drop increases caused by the induced flow were also measured. Profitable implementation of electrohydrodynamics in the design of compact heat exchangers and heat sinks such as cold plates is foreseen; possible benefits are pumping power reduction, size and weight reduction, and heat exchange capability augmentation

Le Norme UNI/TS 11300 Parti 1 e 2 – Tutte le Novità della Revisione 2014

Questo testo ha lo scopo di rendere immediatamente disponibile, in modo schematico, l’insieme di novità introdotte con gli ultimi cambiamenti apportati alle norme sulla Certificazione Energetica. Ci si riferisce alle norme UNI/TS 11300, parti 1 e 2, pubblicate inizialmente nel 2008 e per le quali sono appena uscite (2 ottobre 2014) versioni aggiornate con notevoli revisioni e integrazioni. Tutte le modifiche e le aggiunte saranno opportunamente segnalate e brevemente commentate per dare un’idea, agli interessati, delle principali novità

SEAS (Software Energetico per Audit Semplificati - Simplified Energy Auditing Software), versione 3.0

Software con interfaccia grafica per l'audit energetico negli edifici ad uso residenziale, uffici, scuole e degenze ospedaliere, sviluppato in collaborazione con ENEA. Basato sul linguaggio Java, con database MySQL

SEAS (Software Energetico per Audit Semplificati - Simplified Energy Auditing Software), versione 3.1

Software con interfaccia grafica per l'audit energetico negli edifici ad uso residenziale, uffici, scuole e degenze ospedaliere, sviluppato in collaborazione con ENEA. Basato sul linguaggio Java, con database MySQL. Completo di videocorso e sezione FAQ