slope of the
Based on the experience of ventilation hydrometallurgical (electrolysis) plants with considerable heat and moisture found in the room up to 5 m in the motion in the upper zone crane - beam temperature gradient barely reaches 0,5-0.6 feeding fresh air into the work zone . For higher space gradient is unlikely to be greater. Note that the presentation of some courses, ventilation, and in some norm values of the temperature gradient of up to 1,5 clearly overstated.
In general, the amount of total water - the selection (G + W) should be deducted the amount of moisture carried away by the air being removed from the work area.
In the formula (48) values are determined graphical-analytical method, using the diagram d, and the above considerations.
Angular coefficient can be expressed as follows:
Having determined the slope, build a ray of the process, carrying it through the point on the diagram d with parameters known to us for the supply or the outgoing air.
Here is an example definition of air in the joint allocation of heat and moisture, which is clearly visible from the method of calculation.
Let it be required to determine the air in the wet workshop for the transition and summer periods under the following conditions: heat from the equipment and the mirror bath Q = 350 OOO kcal / h (for 1 m3 of 40 kcal / h); vlagovydelenie at 60 В° C, G = 250 kg / h; heat loss during the transition period Qn = 75000 kcal / h; ceiling height of 7 m.
Overhead crane is used only for repairs. Supply air enters the work zone absent, away from jobs. Removes air from the room with mines with deflectors. Evaporation from the floor there. Lung function. Local pumps do not apply.
As can be seen, relative humidity in the working area and passing below is admissible. In this case, the dominant role played by heat and of no fogging can not be considered.
The calculations for the summer. Neglecting the heat losses and solar radiation, we determine the slope of the 350 000 1 - 250-623
For the summer heat even more prevalent.
In this case, the parameters are defined and fresh air are the parameters of external medium:
tn = + 20 В° C, cf = 57%; dn = 8,2 g / kg / n = 9.8 kcal / kg.
Plotted d point B, corresponding to the specified parameters, and through this point perform beam g = 2020. Since considerable heat, then take
Y = 20 + 5 = 25 В° C.
Zakapchivaya consideration of ventilation in the joint allocation of heat and moisture, we say a few words about its constructive execution. Aeration is not suitable, especially when the prevailing vlagovydelepiyah. In most cases, the cold period of forced ventilation mechanical. The air withdrawn from the outside, heaters or heated, or mixed with an internal recycle air. Of course, this is only possible with considerable heat.
Exhaust air for general ventilation is recommended natural - the shaft with baffles. This should take from the mines of the condensate. O r local shelters hood. As a rule, mechanical.