Downloads & Free Reading Options - Results

Boiling heat transfer is an efficient means of heat transfer because a large amount of heat can be removed from a surface using a relatively small temperature difference between the surface and the bulk liquid. However, the mechanisms that govern boiling heat transfer are not well understood. Measurements of wall temperature and heat flux near the wall would add to the database of knowledge which is necessary to understand the mechanisms of nucleate boiling. A heater array has been developed which contains 96 heater elements within a 2.5 mm square area. The temperature of each heater element is held constant by an electronic control system similar to a hot-wire anemometer. The voltage that is being applied to each heater element can be measured and digitized using a high-speed A/D converter, and this digital information can be compiled into a series of heat-flux maps. Information for up to 10,000 heat flux maps can be obtained each second. The heater control system, the A/D system and the heater array construction are described in detail. Results are presented which show that this is an effective method of measuring the local heat flux during nucleate and transition boiling. Heat flux maps are obtained for pool boiling in FC-72 on a horizontal surface. Local heat flux variations are shown to be three to six times larger than variations in the spatially averaged heat flux.

1Cat: Its Natural History, Varieties and Management

By Philip M. Rule

"The origin of the domestic cat (Felis domestica) is a subject about which there has been much conjecture and scientific discussion, but without any positive issue. Very long before the cat was kept in this country as a domesticated animal it was possessed by the ancient Egyptians in a tame state, and was, moreover, held in reverence by that remarkable and superstitious people, being regarded sacred to the goddess Pasht. As the domestic cat in different parts of the world will breed occasionally with the wild races of the locality, and as cats are conveyed from country to country, it is probable that our cats are of somewhat compound pedigree. It is considered probable that our fine English tabbies have a trace of the British wild-cat blood in their veins, although it may be obscure." - Summary by the author