When pumped from one production unit to another, molten cheese spread is a highly viscous liquid, which inevitably affects all hydraulic calculations for optimal pipeline characteristics. However, such calculations often miss out the effect of the viscosity on the pump efficiency. This article introduces a new method for determining the optimal pipe diameter to transport liquid media during food production. It takes into account the viscosity of the liquid and the technical characteristics of the rotary lobe pump. The research featured a lobe-pump hydraulic system for transporting highly viscous cheese spreads. The calculations involved the technical parameters of the lobe pump and pipelines, as well as electricity tariffs. To determine the annual electricity costs, we used electricity tariffs for small businesses as of June 2024 in three random regions of the Russian Federation. The parameters of different cheese spreads (55–95°C) came from scientific publications in the public domain. Among the various factors that affected the optimal pipe diameter, the greatest impact belonged to the temperature-related changes in viscosity. As the operation time of the lobe pump increased, so did the share of electrical energy costs. As a result, the optimal diameter of the pipeline increased significantly to compensate for the hydraulic pressure losses and energy costs. The optimal diameter also depended on the investment parameters. Bigger Life-Cycle values correlated with larger optimal pipe diameters, i. e., the reduced costs went down. Higher interest rates, on the other hand, correlated with smaller optimal pipe diameters, i. e., the reduced costs went up. In general, the overall efficiency of the pumping station depended quite strongly on all the factors featured in this research. The new method made it possible to determine the optimal pipe diameter for inter-operational transportation of cheese spreads in particular and highly viscous laminar fluids in general. It relied on viscosity values and lobe pump specifications. Numerically, it was based on a step-by-step calculation of economic and hydraulic parameters. The method demonstrated good prospects for food pipeline design.
Akhmedova et al. (Mon,) studied this question.