Rheology and flow characteristic of urban untreated sewage for cooling and heating source

Urban untreated sewage is a kind of excellent cooling and heating source. The rheology and flow characteristic of sewage is the basis of the application of sewage cooling and heating source system. They are studied based on the theoretical assumption of single flow model, principle of tube-type rheometer, and field experiments. The rheological basic equations and flow characteristic of urban untreated sewage are developed. The results of research indicate that sewage has the characteristic of non-Newtonian power-law. The rheological basic equation is τ=0.0031γ˙0.92. The distance coefficient of drag in turbulence of sewage in circle pipe is λt = 0.186(Re′)−0.208. The equations of velocity distribution of sewage are, respectively, v+ = 2.5 ln y+ + 5.7, v+ = 5.11 ln y+ − 3.22, and v+ = y+ in turbulence, intermediate, and laminar current zone in circle pipe. Those can be used to instruct engineering application, design, analysis, and farther research of the system.