POWER TOTAL INDEX, LIMIT AND AREA OF EFFICIENT MAIN FANS OPERATION IN MINE VENTILATION SYSTEMS

摘要

A fan is described by three basic curves of total accumulation, power applied to rotor shaft and of efficiency, in the function of air volume jet flowing through fan inlet - which are usually given for the determined rotational speed of an and standard density of air. Working point of fan determined by a resistance curve of reception network, which among others, is a mine ventilation network, should lie along on total accumulation curve in the area of stable and economical fan operation. The first extremity of this area is determined by an approximate stability, criterion required by a Polish standard, and the second extremity - by he accepted fan efficiency. The article gives a total power index (a) based on the factors of fan efficiency and power output and an area (b) of efficient operation of fan determined by means of three curves of fan efficiency, a total power index and a straight line called a limit of efficient fan operation. The abscissa of two points where the mentioned three lines cross, make the abscissa of the points which on the curve of total accumulation make the mentioned extremities of economical area of the fan operation. The objective of work was motivated and the tests on three main fans of equal total accumulation curves but of different lines of power put to rotor shaft viz. adequately constant, growing and diminishing in a linear way were conducted. Studying the test results it has been noticed that when estimating main fan operation or matching a fan to network/sub-network one should keep the principle according to which the working point of fan should lie within the both mentioned areas: stable and sparing operation and efficient one.