Methos for defining hydraulic losses during power-law fluids flow

Introduction. Current paper introduces the method for defining hydraulic losses during coolants flow in conduits and channels of heat exchangers of food production equipment. The viscosity of these coolants has a power dependency on shifting velocity. Materials and methods. The power-law fluid were taken into consideration as a special case of silicone fluids. The method for determining hydraulic developed is obtained based on the method of analogies which consists of: analyzing how local resistances and friction resistances depend on Reynolds number of Newtonian fluid; changing the real Reynolds number for Newtonian fluid to Reynolds number for power-law fluid; and thus obtaining analytical formulas. These formulas allow to define hydraulic resistances during contraction and expansion of the channel and to define local resistances during flow of power-law fluids. Results and discussion. In order to construct expressions for defining local resistances during power-law fluids flow in stepped channel and in a turn (which are the most prevalent in technological equipment) the origins of Newtonian fluid flow in channels with the same hydraulic resistance were analyzed. Using the known expressions with the aid of method of analogy, the formulas for describing the hydraulic resistance during contraction and expansion of the channel were constructed. These formulas are represented as a sum of values, which are associated with acceleration or deceleration, contraction or expansion and turning of the flow. Using the principle of analogy for different cases of Reynolds formula, the formulas for defining the local resistances of power-law fluids were obtained. Conclusion. Obtained expressions can be used to determine coefficients of local resistances during power-law fluids flow. They are equally applicable in a wide range of Reynolds number, which allows to carry out an entirely new design of technological equipment for food industry in the direction of reducing energy consumption and material cost.