Turbine Generator Design


#1

I need some help designing a test bed for the next stage of a long term turbine project. The goal is to measure the overall efficiency. Any books or reference material would be great.

On one end will be a small high pressure electric boiler. There will be some kind of watt meter to log the power consumption. The boiler steam will drive a turbine and that will then drive a high RPM alternator. I need to figure out how to measure the output of the alternator.

Cheers


#2

You could build two batteries banks… one for powering the electric boiler (“battery A”), and the other one you’d charge with the alternator (“battery B”).

Start with “battery A” fully charged and “battery B” completely discharged.
Time how long the boiler runs, measure the charge of “battery B” once the alternator stops spinning, then swap the batteries and repeat the experiment.


#3

Thanks! That is a great idea in the right direction. Unfortunately even as small as the steam boiler will be I believe the power requirements would require a nasty large bank of batteries. Should I power a row of light bulbs in series or something and have a watt meter between the two? Kind of like what those generator bikes would have? Am I right in assuming the power from the alternator needs to be going somewhere? I also want to be able to log the instantaneous efficiency as well as over long periods.


#4

A large bank of power resistors and an oscilloscope would tell you the
instantaneous power delivered, and something with logging would allow you
to characterise that over time. As long as you’re not worried about fast
spikes or super high accuracy, you could get away with a cheap USB
oscilloscope hooked up to a laptop.

Maybe you could borrow something like this from a VHS member:


#5

Thanks Jarrett!


#6

I’m curious, what’s the purpose of this project? Changing power forms always results in a net loss. you heat the water with electricity (loss) then you use steam to power generator (loss), then you convert the mechanical power from turbine to electricity again (loss)


#7

The goal is to evaluate the turbine. That’s the reason for the closed loop. The goal of the turbine is to provide power at a small density with good efficiency. Most turbines either have good density and poor efficiency or poor density and good efficiency.


#8

I see, and you have an idea that will yield high density and efficiency?


#9

It probably isn’t that effective at this point but I want to work towards something that will be by changing the design and testing it.


#10

did you build the turbine? design it?


#11

Yeah, both. I have another prototype on the way.


#12

Here is a picture.


#13

Could you use compressed air to power it…
You would have a known pressure and if you found a flowmeter for the air you would know the amount you are using

Use a generator dumping into a load to determine power output…

May be easier than dealing with a boiler, at least to benchmark things. Not sure what performance differences you would have with air vs steam…


#14

I have used compressed air to initially test things. This is a boundary layer (Tesla turbine) so there is a difference in the coefficient of friction of air and steam. I also want to validate how steam will function in the turbine with all of the variables it adds.


#15

cool! have you seen the Tesla valve he designed? I thought that these turbines were good for high pressure and high rpm only, and that the torque applied is low


#16

The valve looks neat. The classic turbine design has some major flaws. Even if the torque is low, power is power regardless of the torque. I have made some changes that I hope will make it work better. Some big issues with the original design were edge turbulence, flow control, and disc stability.


#17

the valve is amazing since it has no moving parts, the turbine is also amazing. I looked at them for nano bubble generation


#18

Bear in mind the measured efficiency will include the inefficiency of the alternator if you run it at suboptimal rpm, and the inefficiency if the load is mismatched to the generator.
I recall some interesting reads on variable pitch wind generators, basically attempting to maintain the sweet spot rpm of the generator/load.


#19

Oh wait. I see your challenge. You want to demonstrate the mechanical merits in isolation from the generator. Like with a dynamometer ?
How about just a rotary encoder and a big flywheel. The encoder gives both the rpm and angular acceleration… And then you would want to measure the volume of steam entering the turbine to filter out heat losses owing to the test setup. I’m not sure how that might be done. Maybe track the water mass in the boiler?


#20

Can you cite some reference material on alternators? The way I am thinking about testing it is as a closed loop which means I will also be measuring the efficiency of the alternator, boiler, and generator. That’s ok for what I want to do. I have been looking at http://www.windbluepower.com/mobile/default.aspx one model they claim can run at 10,000 rpm.