Comparison of Performance between Centrifugal and Positive Displacement Pump at Low Flow Rate

• Main Author: Suhaimi, Noorazreen
• Format: Final Year Project
• Language: English
• Published: Universiti Teknologi PETRONAS 2010
• Subjects: TJ Mechanical engineering and machinery
• Online Access: http://utpedia.utp.edu.my/8075/1/2010%20-%20Comparison%20of%20performance%20between%20centrifugal%20and%20positive%20displacement%20pump%20at%20low%20flow%20r.pdf; http://utpedia.utp.edu.my/8075/

In general, centrifugal pump is more preferable to industrial applications. When a centrifugal pump operates at its off-design condition; operating at low capacity and require high pressure conditions, pump will experience some unfavorable condition such as temperature rise effect. Positive displacement pump is more suitable to be used when low capacity and high pressure are necessary. Thus, this project is carried out to make a comparison between centrifugal and positive displacement pumps at low flow rate. The objectives of the project are to determine the best efficiency points for both centrifugal and positive displacement pump by using data obtained from the experiments, to suggest the suitable pump used at low flow rates and to monitor the temperature rise effects of both pumps when they are running at low flow rates for several hours. Experiments on single stage centrifugal pump and a gear pump are conducted. The objective of the experiments is to determine the efficiency of centrifugal and gear pump at low flow rate with four different types of liquids; water, heavy, medium and light crude and two different conditions; constant and variable speeds. From the experiments for both centrifugal and gear pump, the efficiency of centrifugal pump is nearly 0% as pump operates at low flow rate. As the viscosity of liquid increases, the efficiency decreases and temperature increases at constant speed. When the speed increases, the efficiency also increases whereas the viscosity of liquid is decreased. When gear pump operates at low flow rate, its efficiency value is higher than the centrifugal pump. As the viscosity ofliquld increase, the efficiency increases and temperature increases at constant speed. If the speed of the pumps increases, the efficiency increases. Positive displacement creates flow and centrifugal pump creates pressure. Thus, positive displacement pump such as gear pump is more preferable when the system runs at low capacity.