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13#
樓主 |
發(fā)表于 2008-6-11 13:36:35
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請看由 美國麻省理工大學(xué)(MIT)教授對于2種高壓泵的說明http://www.omax.com/pumps_comparison.php' u* B7 a X# T' `9 j/ B& {
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At high pressures, liquid is compressible. At 40,000 psi, water is about 10 percent compressible. That means the plunger must move enough to fill 10 percent of the chamber volume before the pressure reaches 40,000 psi. At that point the outlet check will open against the pressure in the output line. At the end of the stroke, when the plunger reverses and the outlet check closes, any water that’s trapped in the cylinder expands, pushing on the plunger until the plunger has moved far enough to drop the pressure to the inlet pressure and open the inlet check valve. The energy put into the plunger motion by this expanding water can be recovered or not depending upon the drive type.
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In the crank pump this expansion energy is recovered in the same way that it is recovered from the expanding hot gasses in an internal combustion engine: it goes back into the kinetic energy of the rotating components. In the intensifier pump it gets dumped into the oil of the hydraulic circuit, which causes heating. That heat must then be removed, usually by an oil to water heat exchanger. As a result, intensifiers operate at about 70 percent efficiency whereas crank drive pumps operate at efficiencies of 95 percent and higher. Intensifiers also require extra water for cooling purposes, resulting in significantly higher electric and water costs to pay for energy wasted as heat. |
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樓主: 胡司令
發(fā)表于 2008-6-6 11:54:30
