Columbia University in the City of New York


Rear and side walls is carried out at This indirect role of secondary emitters. Finally, the radiation is directed upwards, falls on the sloping walls of vertical flue outlet and, after repeated re-radiation is lost in the environment. Significant feature fireplace is that when working in a virtually sucked more air than is theoretically necessary for combustion. Large excesses of air are harmful to the thermo-respect, because, on the one hand, reduce the temperature of the emitting layer and the useful radiation heat transfer. On the other hand, lowering the temperature of the combustion products reduces the disposable hydrostatic head created by the chimney. Products combustion of fuel layer mixing with the air sucked from the room through the open doorway unregulated bound for dymosbornik further in the chimney. When working fireplace must maintain a balance between aerodynamic vertical flue temperature and disposable pressure created by all the smoke tract. If the fireplace chimney has a specific section, then at small values of the coefficient of excess air volume of flue gas is the least wind resistance and thus reduced – can stop thrust in the absence of air suction from the outside.

If, during the intense burning (excessive loading, aiming draft) exhaust gas temperature reaches a maximum, then the disposable hydrostatic head at the same time sharply increases and reaches a maximum, resulting in perhaps a deviation from the normal operation of the fireplace. In the upper zone of the furnace hearth is set more negative pressure under the influence of which will be sucked into opening an additional amount of air. By increasing the volume of products combustion increases the resistance of the chimney, and in view of reducing the gas temperature decreases disposable pressure. As a result, some of the gas flow there equality of aerodynamic drag and disposable temperature difference. In the fireplace can be distinguished two streams of air: the one used for direct combustion, and a second redundant transit, which is mixed with combustion products before they are entering into a vertical chimney. A layer of burning fuel radiates heat into the room, due to heat transfer products of combustion are cooled.

Further cooled by radiation products of combustion are mixed with the second flow of air sucked from the room, and then sent to the chimney. The larger cross-section of chimney, the lower gas velocity and pressure drop respectively. Due to this, the furnace will podsosano greatest amount of air. At the same time lowers the temperature of air sucked combustion products in the chimney, which reduces the useful thrust, and when the section of flue resistance increased, and suction of secondary air decreases. This increases the temperature of the gases in the chimney and a corresponding increase in traction. Aerodynamic mode fireplace set has the property of self-leveling, and limited extent, given the many factors … In an open fire under the big chimney draft sucked the air mass. The average fireplace (area of a room of about 30 mg), sucks 700 – 800 m3 of air per hour. This is approximately 10 times the amount required for ventilation. This whole air must enter the premises through the rarefaction created by a chimney fire. At the informal flow of air enters the room through looseness of doors, windows, adjoining rooms, slots, etc. This creates unfavorable conditions for the development of the combustion process. In a fireplace with an organized air supply disposable pressure created by the chimney, must overcome the resistance that occurs in conduits and in the supply duct if it is …

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