Pelton Turbines Generate Free Energy
By
Nathan E PetersonPelton TurbinesPelton turbines work best with heads of 50 feet or more. The high speed jet of water that results from such heads twists the bladed runner up to initiator speed without the need of added hardware. Pelton Runners can be any size from 12 foot width for megawatt installation down to 4 to 18 inch thickness for home installations.
Very small surge is mandatory to run a small Pelton turbine, in some cases no more than the water issuing from a reserved spring. The need for a high head, however, confines installations to mountainous places. Also, springs tend to parch up throughout some parts of the year and ice over other parts, so care must be in use to choose a water supply that will provide year-round power. A new improvement in impulse turbines is to orient the jet at an angle to the blades, as in Turgo turbines. These units are smaller and faster than Peltons.
Cross-Flow TurbinesCross-Flow turbines work well when the head is greater than 3 feet. Water from a rectangular chops passes through a barrel-shaped runner in such a way that the water strikes the ring of blades on the runner tow times. This turbine is a comparative new comer; it has not yet been built in megawatt sizes but displays a great deal of security for use in undersized installations.
In addition, it's simple enough for someone with a home machine shop to make; yet it can match the performance of the other turbines whose fabrication requires a high level of technology. It works well over a wide range of water flow, is relatively free from problems caused by silt and trash, and is not affected by cavitation. To improve competence the rectangular orifice can be partitioned and parts of it blocked off during periods of low flow. Some step-up gearing may be needed for optimum generator speed.
Propeller TurbinesPropeller turbines are most efficient at relatively low heads of from 3 to 30 feet. The propeller is fully submerged and is driven more by the dull weight of the water than by the water's quickness. In high-head installations, propeller turbines undergo wear from cavitation. In addition they work well only over a slim range of tempo, so care is required to equal the size of the turbine to the existing steam flow.
For example, when flow drops to 50% of propeller turbines most advantageous, the power production will drop by about 75% and when the flow drops to 30% the output becomes zero. To rise above this constraint some large hydroelectric installations use several turbines in tandem, shutting down on or more whenever the flow lessens. Others employ Kaplan turbines, which have automatically adjustable blades that balance for flow changes.
Francis TurbinesFrancis turbines can be used over a broad collection of heads 4 feet and more. As with a propeller turbine, the runner is wrapped up in the head water, which is guided onto the blades of the runner by a ring of adjustable vanes. The Francis turbine is highly efficient at its optimum flow but easily damaged by grit and cavitation. It is regularly used in large hydroelectric stations and is relatively expensive.
As with propeller turbines and other interior swamped turbines, a draft tube beneath the unit with its bottom rim immersed at all times in tail water is a valuable adjunct: as water drops from the turbine runner down the draft tube, it sucks more water down with it, adding to the effective head of the system. This added head can be of considerable importance whenever the overall head of the remainder of installation is small.
More outstanding energy saving tips on
http://www.keep-green.comTo make your own renewable energy you can find out more on
http://www.make-solar-panels.comArticle Source:
http://EzineArticles.com/?expert=Nathan_E_Peterson
