Efficiency Matters Minimizing Pumping System （效率问题最小化泵系统）.pdfVIP

Efficiency Matters Minimizing Pumping- System Friction Losses Curtis Dietzsch Reducing the causes of friction and choosing the proper pump will increase efficiency and cost savings. magine a major-league pitcher standing on the mound. through pumps, pipes and fittings, there is resistance, result- He looks for the signal, nods in agreement, starts his ing in a decrease in pumping pressure and velocity, which I adversely affects pumping efficiency. windup, rears back and propels the baseball toward home plate. The pitch’s maximum velocity is reached at the The amount of energy lost due to friction depends on moment the ball leaves the pitcher’s hand. From that point, a number of factors. The losses are caused by the following: studies have shown that the velocity decreases by one mile- • Friction between the fluid and piping walls per-hour (mph) for every 7 feet traveled. If a pitch leaves the • Friction between the adjacent fluids (higher viscosity pitcher’s hand at 100 mph, by the time it covers the 60 feet, fluids have higher losses) 6 inches to home plate, it will be traveling at around 92 mph. • Amount of surface roughness on the interior of the pipes Conversely, if the mound were only 30 feet from home • Turbulence created when redirecting the fluid, via a bend plate, a 100-mph pitch would be moving at 96 mph upon in the pipe or a restriction, such as a valve, fitting or arrival at the plate, making the pitch much more efficient reducer and harder to hit. A 100-mph pitch thrown from second base to home plate—a distance of approximately 128 feet— Physics also play a role in the amount of friction that is would have a velocity of only 82