PH-79-01-2 -- Analysis of a Chilled Jet in a Thermally Stratified Environment PDF

The subject of worker comfort in industrial environments is one which has received much attention from a great variety of sources in recent years. Regardless of the pressures to "do something" about prevailing unsatisfactory environmental conditions, however, total volume air conditioning in many such cases would be impractical, because of the magnitude of the money and the energy costs. An example of such an impractical application of total volume air conditioning might be a high bay area in a factory. The energy costs to overcome the heating load of machinery, as well as the heat gains due to human occupancy, infiltration, and conduction through exterior walls, could well be staggering. Possible alternatives might be the spot cooling of worker stations or zone cooling of the occupied space only. Indeed, Nottage (1) made reference to such a possibility in his monumental work on "Ventilation Jets and Room Air Distribution" in 1951. However, the social, political, and economic forces seem to have provided motivation for such a possibility only in recent years. The concept has received considerable attention from Dean and Reese and their associates (2,3) among others. Some of the fundamental problems of air diffusion in such spaces remain unsolved.

The present paper deals with the penetration of a chilled jet projected vertically into a thermally stratified environment. Some of the early studies of non-isothermal ventilation jet behavior were those of Nottage (1), Helander et al. (5), and Koestel (6,7). Recent investigations into non-isothermal jets projected into various sorts of stratified environments and various cross-flow situations are those of Hirst (8), Fan (9), Wright (10), and Sforza and Mons (11); none of these studies however, have dealt with the specific problem described here.