U-bends with the reduced pressure losses to fluid distributing networks

A method of operating a fluid distributing network for fluid transport or for fluid distribution or for recycling a fluid in a heating or a cooling system comprising:

• providing the fluid distributing network with at least one U-bend and at least one pipe connected to the U-bend,
• wherein the U-bend comprises an inlet, an outlet, and a bend;
• said U-bend having individually or in co-operative arrangement a flow passage having a continuously smooth and differentiable perimeter and centerline and a smoothly varying cross-section along the flow passage such that in the 5% of the flow passage from the inlet and the 5% of the flow passage from the outlet ARQ is from 1.0 to 1.02 and over the remaining 90% of the length of the flow passage not less than 5% of the flow passage has an ARQ from 1.02 to 1.15;
• operating the fluid distributing network in a manner that allows for fluid transport or for fluid distribution or for recycling a fluid in a heating or a cooling system;
• and further wherein the presence of the at least one U-bend reduces the overall pressure drop within the fluid distributing network by 10% or more when compared to the calculated pressure drop for a comparative fluid distributing network operating under the same conditions for the same purpose, but having only conventional bends with a comparative flow passage with an ARQ along its length from 1.00 to 1.02, wherein ARQ is the ratio of aspect ratio (AR) to isoperimetric quotient (Q) of a section or segment of the flow passage perpendicular to the direction of flow (AR/Q), wherein L is the length of the at least one pipe and D is the inner diameter of the at least one pipe and further wherein L/D of the at least one pipe is greater than 0 and less than 55.