Researches on New Heat Transmitting Tubes : 3rd Report, Formula Expressions of Heat Transmission Characteristics of Tube Bundles

抄録

We have been studying experimentally the heat transmission characteristics of our tubes of a new type in the cases of the air flowing across the bundles of tubes, and have already reported a portion of the results two times. Putting together all the results of our researches, we obtained the design data for a heat exchanger which consists of our new heat transmitting tubes. The main design formulas are as follows : 1) The heat transfer coefficient of 1 st tubes in staggered arrangement for ratios p₁/d₀=p₂/d₀=2.11 is given by the equation N_u=0.602 R_e^0.527 in which p₁ is the longitudinal pitch of tubes and p₂ is the transverse pitch of tubes, d₀ is the outer diameter of tube, and R₆ is the Reynold's number calculated with the maximum velocity between the tubes. 2) The pressure loss Δp of the air flow through the bundle is given by the equation [numerical formula] in which n is the number of tube rows in the flow direction, γ is the specific weight of the air, and U_max is the maximum velocity between the tubes. The coefficient of resistance ψ may be determined from the equation ψ=2.81R₆^-0.224