Methodology for calculating the cooling of a liquid during its movement in extended pipeline systems

Based on the fundamental laws of thermal conductivity and hydromechanics, a method for calculating heat losses to the environment and temperature changes of a liquid or gaseous medium during its transportation in extended and branched hydraulic systems has been developed and numerically implemented. The technique applies to vertical and horizontal sections of pipes with various thermal insulation coatings and external heat exchange conditions. The dependences of changes in the thermophysical characteristics of the transported liquids on temperature are used, which are presented for the convenience of computer implementation in the form of regression relations obtained on the basis of reference information. To carry out the calculation, the hydraulic network is divided into separate sections transporting a constant flow of the medium, and those, in turn, into a finite number of cylindrical elements determined based on the convergence conditions of the solution. For each such component, heat transfer and heat transfer coefficients are calculated using well-established criteria equations, the amount of heat passing through a single-layer cylindrical wall, and the amount of liquid cooling. As applied to the hot water supply systems of multi-apartment residential buildings, the results of calculations are presented.