Reducing draught problems in the cold working rooms.

This study is done by order of a Finnish air cooler manufacturer and it is founded to a master's thesis of the same subject matter. The company produces e.g. unit air coolers with electric fans and so the aim of the study was to reduce draught problems caused by cold air jets. The desired values were: - air throw 50 percent better than before - draught free working area 30 percent larger than before Because there are two different ways to reach and maintain low temperatures in cold working rooms we first compare the advantages and disadvantages of both method and then get acquainted with cold air jets and reducing draught problems they can cause. The cooling coil can be mounted in the ventilating unit in which case the cold air has to be blowed into rooms through ducts and conventional air outlets. Cooling coils can also be mounted directly to the ceiling in cold rooms. In that case there is often used forced convection which is carried out with electric fans. The forced convection improves heat transfer and so it is possible to make coils of compact size. The installation with cooler coils and electric fans is called unit air cooler. The former method makes it possible to have silent cold rooms with good and even air distribution. The air distribution can be still improved by using porous textile ducts and let the cold air flow through the cloth into the room. However, there can be some hygienic problems. Hygienic problems can be minimised with the latter method, unit air coolers, because they are quite easy to maintain and keep clean. The disadvantage is that there can be some noise and draught problems. Noise problems can be solved by using fans with low RPM, but the draught problem still remains. It can be reduced with air deflectors which intensify the so-called Coanda effect. The results of this study are utilised in a novel series of air coolers.