Stirring the heat carrier in a heat exchanger by twisting the stream

A theoretical-experimental study was made of the effective diffusion coefficient in longitudinally streamlined helically twisted tubes with an oval profile, using as the basis a homogenized model of flow and applying the method of diffusion from linear heat sources of finite dimensions.Notation D_t effective diffusion coefficient - u stream velocity - d_e equivalent diameter - S pitch of the tube profile - d largest profile dimension - N_Re,b Reynolds number - q_v volume heat emission - density - x and r coordinates - P pressure - N_Pr,t Prandtl number for turbulent flow - hydraulic drag coefficient - c_p specific heat - T temperature - G mass flow rate of heat carrier - m porosity of the bundle of tubes relative to the heat carrier - L length of the bundle of tubes - r_h radius of heated tubes - r_c radius of the bundle of tubes - k dimensionless effective diffusion Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 40, No. 5, pp. 773–779, May, 1981.