- #1
RobertD
Let's assume you have a perfectly insulated closed liquid loop with a pump who's motor is cooled by the liquid its pumping. Assume steady state operation, so the pump is operating at some pressure difference and flow rate based on intersection of pump curve and back pressure curve. Does this mean that essentially all of the electrical power input/draw goes into heating the fluid? I first thought that only the inefficiencies of the motor and pump went to heating the fluid and the rest went to doing work on the fluid (maintaining flow against back pressure), but it seems that this work on the fluid goes right back into the fluid as heat due to friction losses in the boundary layer. It seems even if you had a perfectly efficient motor and pump, to where all the power goes to maintaining flow rate against back pressure, you would still be continuously converting the kinetic energy of the fluid to heat because of the frictional losses in boundary layer. Is this correct? Should I assume all pump power turns to heat and ignore efficiency?