11 Next, for each style (fill thickness and mist diameter), the relationship between air flow velocity and collection efficiency is as shown in graph 4, and each style reaches maximum efficiency at 1 to 2 m/s, and the efficiency tends to decrease due to reaccompanying above the allowable flow velocity. When actually using Demi Star, there are many mist types and the average diameter of the mist is unknown, and there is a slight error in the efficiency calculation above, but if you take an example of water droplets and air systems, it looks like graph 5. As can be seen from graph 5, it is difficult to collect and remove with high efficiency at a mist diameter of 1 to 2 μm or less, and a considerable number of layers must be increased in order to achieve satisfactory effects. Collection efficiency Demi Star's theoretical formula for collection efficiency has been published by C, L, Carpenter, etc. E＝ １－ （1 －Et/C）N …………Equation (3.1) C = N/k2F ……………………Equation (3.2) E ：Demi Star's theoretical capture efficiency Et ：Mist collision efficiency C against one line of Demi Star ：Modification characteristics of Demi Star (Table 3) N ：Number of filling layers k2 ：Non-dimensional ratio F ：It is known that Et is affected by the line diameter, mist diameter, operating conditions, etc., and that there is a relationship between the Stalk number K and Et defined in the following equation as shown in graph 3. ……………Equation (3.3) K ：Stokes number ρl ：Mist density kg/m3 U ：Air flow velocity m/s dl ：Mist diameter m μg ：Fluid viscosity Pa・s Df ：The theoretical efficiency E obtained from the line diameter m equations (3.1 to 3.3) is well matched with the experimental values, and from these equations, the collection efficiency can be estimated from the parameters and variables associated with the actual conditions of use of Demi Star. From graph 3, Et can be approximated by the following expression as a function of K. ……Equation (3.4) However, 0.1 ≤ K≤ 100 As can be seen from the above relationship, airflow velocity, mist diameter, and mist properties have a close relationship with the collection efficiency. （dℓ）2ρℓU K＝1 9 μgDf 1 －10 Et＝ －0.22(log 10K）2
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