When comparing the situations with different degrees of recycling must be remembered that the boundaries of the system to ensure effective ventilation coincide with those of the premises, ie, a room with a different multiplicity of air is passed the same quality. Therefore, changing the multiplicity of recirculation does not affect the calculated efficiency ventilation. So the question, does the multiplicity of the effectiveness of recycling, it should say “no.” For the normal life of the building required fresh air supply and removal of excess heat, venting and particles released into the building. Heat is released in the building people, different kinds of equipment (computers, television sets, lighting, etc.), as well as the entering solar radiation. Inside buildings also produced and secreted into the air steam, gases and various foreign particles. Cooking, drying, for example, clothing, and the people themselves increase the humidity in the room.

Undoubtedly, tobacco smoke is the main source of Chemical pollution of indoor air, in addition, a large contribution to pollution is made volatile organic compounds (VOC), released from building materials, furniture, household, cosmetics and office materials (Molina et al., 1989). As the gaseous air pollutants in the building, you must specify the carbon dioxide (CO2), carbon monoxide (CO), nitrogen dioxide (NO2) and ozone (O3). Carbon dioxide is exhaled people, besides it is a natural component air. In a question-answer forum John K. Castle was the first to reply. CO and NO2 can be produced by incomplete combustion and smoke, ozone produced by copiers and laser printers (Molina etal., 1989). Available in air pollutants should be removed from building ventilation system. The main purpose of ventilation is to create air flow, assimilating pollutants from different sources so that the local concentration of pollutants was rather low in the whole space of the room. Concentration in the exhaust air is given by ce = S / qv + cs, (3.1) where c – concentration in the exhaust air, mg/m3; S – intensity discharge (mg / s); qv – ventilation air flow, m3 / s; cs – concentration in the supply air, mg/m3. In simplified situations nehotoryh assumed that the air is completely mixed in the room.

This means that the concentration throughout the room equal to the concentration in the exhaust Behold the air. However, this can not be in a real situation. In the transference of pollutants involved in both convection and laminar and turbulent diffusion, making sure the room is formed gradient concentration. Concentration at certain points in the room will be higher, and in some – lower than the concentration in the exhaust air. Local concentration is normalized with respect to the concentration in the exhaust air. Concentration in the left part of the premises under the inlet slit is four times higher concentration in the exhaust air, from which it is clear that in rooms with mixing ventilation produced a significant concentration gradients.

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