general ventilation in the fight against moisture and fog
General ventilation in the fight against moisture and fog, is usually performed in a "bottom - up". Anyway, drawing is always done from the upper zone. The influx is served or in the work zone with a temperature close to room temperature - in the absence of fogging, or the working and upper zone - when dealing with fog.
When fogging, and the lack of heat to the natural dissolving it is recommended part of the air - no more than two-thirds - serve in the upper zone of overheating. Submission of superheated air is produced at a height of 4 - 5 m above the floor. In this overheated air is permitted to 35-40 В° C if the ceiling height of about 6 m, and up to 50-70 В° C - at a higher altitude plant. In some cases, non-intensive formation of fog instead of feeding the superheated air in the upper area of the premises set retsirkulyatsnonno - heaters or heating devices - usually registers of smooth or finned tubes.
For areas less than 4.5 m tall plant heaters in the upper zone is the most rational method of elimination of the resulting haze.
This applies to general ventilation. The formation of fog in the shelters, such as a floor under the veil, it is permissible. You should only worry about removing condensation. When the device curtain overlap, limited by it, should be insulated and made vapor tight.
Submission of fresh air in the two zones, with the top of overheating, and is used when dealing with moisture without fogging. This is done to reduce the amount of general ventilation, as well as in cases where the premises has been a lack of heat. Raising the temperature of outgoing air from the upper zone dramatically increases its moisture content. However, it must be borne in mind that the unit two of the band inflows greatly complicates the ventilation installation.
general ventilation in the fight against vlagovydeleniyamn most unfavorable for air flow, which in this case amounts to 130-150 kg / kg. In the presence of superheated flow of air consumption is reduced to 90-120 kg / kg.
Determination of the amount of air removed by local suction devices, performance similar to that suggested in the fight against toxic hazards. The difference lies in the value of design speeds.
For covers all types of shelters and shop air velocity in the working aperture (as well as in cracks and leaks) may be taken:
under intensive allocation of water vapor with the formation of fog
v - 0,35 m / sec, and at least 111 N and with a different allocation of water vapor,
v 0,3 m / sec;
with a slight vaporization and relatively low (<5 () В° C) temperature, evaporation
y - 0,15: 0,2 m / sec.
For individual umbrellas speed in a predetermined section should be
V = 0,2: 0,25 m / sec.
Depending on the temperature and evaporation: for large screens
v - 0,1: 0,18 m / sec;
for small screens
v = 0,12; 0,2 m / sec.
The value of d depends only on the condition of the outer environment, since the air handling its water - the content often does not change. This value is quite definite. With regard to the value of moisture content of the outgoing air, it depends on its parameters - the relative humidity and temperature. If, by analogy with the heat taking into account only the amount of moisture, the provider, the impact of air quality parameters of the working zone, and the value of d taken in accordance with the parameters of air in it (regulated sanitary standards), the coefficient will express the percentage of the total vlagovydeleniya retained in the working zone.
Advised to take the following values of n:
when local suction ventilation in the working area gets only the moisture escaping from the shelter, ie
n = 0,2 -: - 0,3;
for general ventilation, natural lifting of moist air to overlap and vysote1 premises for more than 5 m
n = 0,6 0,8;
for general ventilation and room height less than r) m
l = 0,7: 0,9;
for general ventilation, feed flow focused on jets of room height not less
n = 1.
This refers to the ventilation on a "bottom - up" when applying the flow is not overheated in the work zone. In all the above cases, the d2 is the moisture content of air in the working area.