energy conversion calculation

It appears your units are torque and power.

It appears your interested in calculations for hydro-power.

First lets define (P)ower. Power is equal to (Work)/(t)ime. P=W/t.

Lets look at at the equation for (W)ork and (E)nergy as defined by (t)ime and

(P)ower. E = W = P*t

When dealing with gravitational energy (hydro-energy) the E=(m)ass * (acceleration of (g)ravity * (h)eight. E=m*g*h

P=E/t=m*g*h/t

Using the MKS system and then converting with the watt as the unit for power. The meter as the unit for length and the kilogram as the mass unit.

Converting to the MKS system

using the conversions of lbs*.4536=kg: ft * .3048= meters

10000lbs*.4536=4536 kg: 10ft*.3048=3.048 m : 9.8 m/s/s = g

E in joules = 4536 * 9.8 * 3.048

13855.5894 joules. Setting the time at 1 second means that

10000 lbs of water falling 10 feet every second would approximate a potential rate change in energy of 13855.5894 jouls per second or 13.855.5894 KW.

Given the above and an initial velocity of 0 m/s the water will increase the in velocity from

E=.5*m*v^2 = m*g*h

.5*v^2 = g*h

v squared = 2*g*h

V= sqrt(2*g*h)

7.7292 m/s = 2.355865 ft/s

Will the recovered energy approximate the .5 * m * (turbine inlet velocity - turbine outlet velocity)squared * coefficient of turbine generator efficiency?

If so then maybe we SHOULD produce our power DC, allowing us to reduce the turbine spin velocity, converting more of the gravitational potential, and then converting it to AC for transmission?

Would somebody tell me again the advantage of high voltage AC VS high voltage DC transmission. From memory, I thought the RMS value of a sine wave was somewhere around .707. Does this mean that I can send only 70.7 percent the power using AC VS DC at the same potential? Are there greater inductive losses using AC VS DC?

This decision couldn't possibly been influenced by some poor elephant martyr during the AC jihad of Mr. Edison could it ? Another decision made on sound and unemotional scientific evidence (poor elephant) by the experts; and probably made in the light of the earliest true altruistic medical/military/industrialist values.

Gavilan

Gavilan,

Ac had two advantages over dc: (1) you could change voltages in a transformer (cheap and readily available) so that you could transmit high voltage/low current/low losses long distances and then provide safer low voltage/high current for homes and businesses; and (2) Edison advertised that ac could be used to kill people and state governors all over America wanted that.

Tom

10,000 foot pounds equals 13.5 kilowatts

There is an inconsistency of units here. The foot-pound is a unit of energy. The kilowatt is a unit of power, which is a rate of energy, or energy per unit time.

http://www.simetric.co.uk/

550ft.lb/sec = 1hp = 0.746kW

↔ 10000ft.lb/sec = 18.2hp = 13.56kW

So the missing time quantity is the second.

The chart should read 10,000ft.lb/sec =13.56kW

Gavilan, PWSlack: The clarifications you supplied were helpful. Thank you.

Hi Gavilan,

I believe it was in the late 60's or early 70's that Southern Cal Edison built a DC transmission line from way up north, either Washington or Oregon State to Sylmore in southern California. A friend of mine was a power scheduler and I seem to remember him saying that there were many problems with the converter stations, and other interuptions that made the line less desireable than projected. I think it was later converted to a conventional AC line by adding a wire. All of this is going by my memory, which I often say is like a steel sieve! Of course also that was 60'd technology and probably would be much better today. May be some info on the net about this. -- JHF

Oh the joys of myriad units and quantities! Sometimes I wonder how any technological advancement could have occurred before the metric system! Foot-pound force is a unit of energy, pound-foots (or pound-feet???) are torque, watts are power and according to Mr Hawking even the unit of time is variable :-(

This free unit conversion utility I have used for years, it even makes interesting - if not a little frightening - perusal, just to see how many of the damn things there are!

http://www.esbconsult.com/esbcalc/esbunitconv.htm

For fun, check out the difference between Scottish, English & Irish miles!

Please refer to the definition of both Power and work, where Power = Work per Time.

1 KW = 2 655 223.71 lb_f-ft/hr

13.5 KW = 35 845 520.1 lb_f-ft/hr

So, to Generate 13.5 KW, you need 3 584 552.01 lb_f to move 1o ft through a time of 1 hour.