The introduction of fan selection, roots blower yi tai - manufacturing experts

　　Ventilation rate

　　The number of fan Air changes according to the selected room. Calculating the total air volume required. Fan quantity are calculated. Calculation formula: N = N * N/Q: N - the number of fan (Taiwan), V - volume (m3), N - air changes (time/when), and Q - single air volume of the selected fan model (m3 / h). The selection of fan model should be based on the plant actual situation. Try choosing a window with the original size to match the fan model. Wet curtain ventilation fan and try to keep a certain distance (as far as possible in a workshop on both sides of the frontispiece) respectively, to achieve good ventilation effect. Exhaust side is not close to the nearby buildings as far as possible. In case of affect residents nearby. As from indoor and out of the environmental pollution in the air. You can install sprinkler systems in tuyere. Nearly pollutants concentration recovery. Don't pollute the environment.

　　The total thrust It

　　It = delta P * At (N)

　　Among them, the At: tunnel cross-sectional area (m2)

　　Delta P: the sum of the resistance (Pa); Generally accrued and four of the following items:

　　1) the tunnel air inlet and outlet resistance resistance;

　　2) the tunnel surface friction resistance, hanging fan device, support and resistance caused by road markings;

　　3) traffic resistance;

　　4) tunnel between import and export with different temperature, pressure, wind speed, pressure difference generated by resistance.

　　The fan arrangement

　　According to the tunnel length, the total thrust and the scope of the jet fan to provide thrust determined primarily in tunnel on the general arrangement group m fan, each group of n units, each thrust of the fan for T.

　　Meet a m * n * T of Tt or total thrust requirements, at the same time considering the following conditions:

　　1) n turbines parallel, the center line of horizontal spacing fan diameter should be greater than 2 times

　　2) fan tandem m group (Taiwan), the longitudinal spacing should be greater than 10 times the tunnel diameter

　　Parameters:

　　Jet fan performance, in terms of its thrust upon air fan to produce thrust is equal to the fan air import and export of the difference in theory (momentum is equal to the product of the air mass flow rate and velocity), in the fan test condition, first import air flow momentum is zero, so can be calculated under the test conditions, the fan thrust theory:

　　Theory of thrust = p * Q * V = pQ2 / A (N)

　　P: air density (kg/m3)

　　Q: air flow (m3 / s)

　　A: the fan outlet area (m2)

　　Test-bed measuring thrust theory of T1 is commonly 0.85 1.05 times that of thrust. Depending on the structure of the internal flow field distribution and fan and muffler. The fan performance parameters of the chart the fan thrust data are given in the test-bed is thrust measurement shall prevail, but measured thrust is not equal to fan installed in the tunnel will have available thrust T, this is because the fan assembly in tunnel will be affected by the effects of the unloading air velocity in tunnel (kodak effect) and the influence of the available thrust decrease. The degree of influence coefficient K1 and K2 to represent and computing available:

　　T = T1 x K1 x K2 / T1 = T/(K1 x K2)

　　T: installation in the tunnel jet fans available thrust (N)

　　T1: test-bed measuring thrust (N)

　　K1: average air velocity in tunnel and the influence of the thrust of the fan fan outlet wind speed coefficient

　　K2: fan axis displacement influence coefficient of the distance between the tunnel wall