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In micro Pumped-storage hydroelectricity (PSH), the same pump/PAT could be used for pumping and generating phases [8] by changing rotational direction and speed. The best efficiency point in pumping usually differs from its reverse mode: [3] a variable-frequency drive coupled to the motor/generator would be needed in order to change from pumping to generating mode and to react efficiently to ...
Centrifugal pumps with an internal suction stage such as water-jet pumps or side-channel pumps are also classified as self-priming pumps. [10] Self-Priming centrifugal pumps were invented in 1935. One of the first companies to market a self-priming centrifugal pump was American Marsh in 1938. [citation needed]
Different types of pumps are suitable for different applications, for example: a pump's maximum lift height also determines the applications it can be used for. Low-lift pumps are only suitable for the pumping of surface water (e.g., irrigation, drainage of lands, ...), while high-lift pumps allow deep water pumping (e.g., potable water pumping ...
While centrifugal pumps impart momentum to the fluid by motion of blades, positive displacement pumps transfer fluid by variation in the size of the pump’s chamber. Centrifugal pumps can be of rotor or propeller types, whereas positive displacement pumps may be gear-based, piston-based, diaphragm-based, etc. As a general rule, centrifugal ...
A pump-jet, hydrojet, water jet, or jet drive uses a ducted propeller (axial-flow pump), centrifugal pump, or mixed flow pump to create a jet of water for propulsion. These incorporate an intake for source water and a nozzle to direct its flow out, generating momentum, and in most cases, employing thrust vectoring to steer the craft.
The Grand Coulee Dam in the United States was expanded with a pump-back system in 1973. [75] Existing dams may be repowered with reversing turbines thereby extending the length of time the plant can operate at capacity. Optionally a pump back powerhouse such as the Russell Dam (1992) may be added to a dam for increased generating capacity ...
Generally, axial pumps tend to give much lower pressures than centrifugal pumps, and a few bars is not uncommon. Their advantage is a much higher volumetric flowrate. For this reason they are common for pumping liquid hydrogen in rocket engines, because of its much lower density than other propellants which usually use centrifugal pump designs.
After electric generators were developed in the late 1800s, turbines were a natural source of generator power where potential hydropower sources existed. In 1826 the French engineer Benoit Fourneyron developed a high-efficiency (80%) outward-flow water turbine. Water was directed tangentially through the turbine runner, causing it to spin.