Search results for "Superheating"
showing 4 items of 4 documents
A Photographic study of subcooled flow boiling burnout at high heat flux and velocity
2007
Abstract The present paper reports the results of a visualization study of the burnout in subcooled flow boiling of water, with square cross section annular geometry (formed by a central heater rod contained in a duct characterized by a square cross section). The coolant velocity is in the range 3–10 m/s. High speed movies of flow pattern in subcooled flow boiling of water from the onset of nucleate boiling up to physical burnout of the heater are recorded. From video images (single frames taken with a stroboscope light and an exposure time of 1 μs), the following general behaviour of vapour bubbles was observed: when the rate of bubble generation is increasing, with bubbles growing in the …
Metastability and hysteresis of the vortex states in rotating superfluid3He-B
1996
We have investigated the vortex core transition in 3He-B by measuring the associated changes in mutual friction dissipation within the superfluid. If rotation is continuously stopped and restarted while cooling or warming then the transition occurs at a clearly defined temperature, but temperature sweeps during continuous rotation show substantial supercooling and superheating. Moreover, the high temperature vortex shows a continuum of metastable states when supercooled to a constant, arbitrary low temperature, the mutual friction dissipaton depending on the temperature at which rotation was started. Our current interpretation is that the high temperature vortex state is a temperature-depen…
Computer simulation of disordering and premelting of low-index faces of copper.
1992
Molecular dynamics and the effective-medium theory have been applied to investigate the structure and dynamics of (110), (100), and (111) faces of copper in the whole temperature range from 0 K up to the bulk melting point, which has been determined to be 1240\ifmmode\pm\else\textpm\fi{}25 K. The observed order in the surface stability follows the order in the packing density. (110) disorders first via anharmonic effects (up to 700 K), then by vacancy-adatom formation and finally by premelting of the surface at about 1200 K. The (110) solid-melt interface is anisotropic and broadened, having a tendency to form small fluctuating (111) facets in equilibrium, which is suggested to be the atomi…
Application of Thermographic Techniques for the Detection of Failures on Photovoltaic Modules
2019
The paper focuses on thermography as a useful investigation tool for diagnosis, detection and prevention of failures of photovoltaic modules. The paper describes the faults detectable by thermographic investigations and how to conduct these investigantions. Then the results of some analyses conducted on a photovoltaic field are presented. The investigations made possible to identify faulty modules with hot spots by measuring localized superheat due to the presence of concentrated deposits on the exposed surface of the module and the superheating due to the presence of sand/dust deposits distributed on a significant portion of the module surface. The thermographic investigations can be used …