Stirling Engine Generator Project (Power output!)

Added: 2026-06-02

[00:00:01][music] [music] [music] >> Hello once again and welcome back to my video about my Stirling engine build.

[00:00:29]So, this is my little Stirling engine.

[00:00:32]In the last video it was running.

[00:00:34]For people that are waiting for this video, I'm sorry it's taken so long, but I've just been a bit stuck with other projects and having to go to work and general family stuff unfortunately.

[00:00:45]So, what I was trying to do is actually test the power output of this model. I had a few trolls and and issues along the way. So, my first thought was to put an electric generator on this engine, which I did.

[00:01:00]I'll show you what I got up to with that side of things. Right, so this is this is the engine. So, today we're going to run it on gas.

[00:01:08]So, what I've done is I've dismantled a camping stove that I had here.

[00:01:13]I've just sort of retrofitted this this gas burner.

[00:01:19]So, that's just the gas burner head. I just mounted it to a piece of steel.

[00:01:25]And it goes in there like that underneath the heat exchanger.

[00:01:28]And then we've got a metal plate that goes in place.

[00:01:33]Just to kind of half block the hot to stop all the heat escaping. Okay, so I made a an adapter plate up there in yellow.

[00:01:41]And that is to hold the little DC electric motor I bought. It's only a a small also motor and I felt like it was about suitable.

[00:01:50]I've got it attached to the flywheel there or the groove in the flywheel with a the timing belt. There you can see it from the back.

[00:01:59]I also put a nice little lightning strike there as well.

[00:02:03]What it add add to the aesthetics. So, this thing here is a pickup for the magnet.

[00:02:09]So, when it passes the magnet, it sets off this here and this is this will measure the RPM. So, I've got the cable going from the little DC motor, which is we're using as a generator.

[00:02:21]And I got it plugged into this box here.

[00:02:24]So, we've got a a buck and boost controller, I suppose. Somebody in one of the comments put me on put me on to one of these. I've tested it with it with a with a with a 12-volt battery and it does work quite nicely. So, you can actually adjust this.

[00:02:40]You can adjust the power output and and then that will actually hopefully actually control the speed of the engine.

[00:02:48]Hopefully it'll be a bit bit more uh easier to control than using the the valve here to bleed off air.

[00:02:55]So, I've used this protractor to set the crank angles. At the moment we're set on 110°, which is pretty good for an alpha type engine.

[00:03:04]You can see we've got a our table here that we're going to populate with the the kilowatt output or the what probably what what output. So, we've got different crank angles and different revolutions or different different speed ratings. All right, so I think we're pretty much ready to go at >> [laughter] >> All right, let's turn the gas off.

[00:03:29]I think I've burnt half my hair off.

[00:03:31]>> [laughter] >> There we go.

[00:03:36]>> [laughter] >> I can smell burnt hairs.

[00:03:41]All right, put our makeshift deflection panel back in place.

[00:03:45]All right, let's give it a go see if this this will go.

[00:03:52]Seems like a lot of resistance on that motor, isn't it?

[00:03:55]Oh, there.

[00:03:57]I did wonder whether it I did wonder whether it was a slightly big motor in all fairness.

[00:04:02]I ordered it. It's meant It's meant to be a It's meant to be a 30-W motor, but I think it's a bit more than that, I must admit.

[00:04:11]Yeah, this is not happening. I'll take the belt off a minute and give it a go.

[00:04:22]Yeah, so it's abandoned.

[00:04:32]It's really quite big that motor and the pulley is too small perhaps.

[00:04:35]Um what we might try and do is actually get a bigger pulley to see if it will drive that and go from there.

[00:04:42]We're going to abandon the test today, I think, um and I'll get a bigger pulley on order and um try again.

[00:04:50]It's a It's a funny thing with Stirling engines because a lot of the heat is uh is stored within the the heat exchanger itself. You can disconnect the fuel and the engine still still runs.

[00:05:01]No fuel.

[00:05:04]So, there we go. It's uh it's done about 4 minutes without a flame. So, it's just running on the heat within the heat exchanger and then the steel within the heat exchanger.

[00:05:13]Right, so we're running again with the bigger pulley fitted.

[00:05:17]Um our speed is uh 450 uh revolutions per minute.

[00:05:23]Um the only problem is cuz I put the bigger pulley on, we've got a low input voltage warning on our little buck uh boost controller. Um we're going to play around with the angles on the crank to see if we can get everything running quicker. That's it. Turn off now. This is just just a little thing.

[00:05:40]Yeah, this this this buck boost is meant to work with 3 V, but we've got 6 V there and it's coming up with a low low input voltage warning.

[00:05:49]Yeah, so if you bought one of these controllers, they don't work from 3 volts. They work from about 6 volts onwards.

[00:05:56]Uh Yes, so I've got a bit of a problem really. I've I've put the biggest pulley I can on it to allow the engine to push the motor, um but now the voltage output of the motor is too small.

[00:06:06]Uh I'm struggling to find a a small motor that gives out um say 12 volts or so um at a fairly low speed. Um My dad's recommended a dy- dynamo off of a um a pushbike, which might be a an option as well. So, I'll I'll I'll look into that. I think I might have a spare one kicking around.

[00:06:26]Uh yes, so we're still not there yet.

[00:06:29]So, I'm generating electricity today.

[00:06:30]So, what we're going to do is actually the free running speeds. So, I'm going to change the crank angles to different crank angles to find out how fast the engine actually runs.

[00:06:38]This is with the engine crank angle set to 80°. Uh Top speed is 680 rpm or so. Uh you can hear a loud slapping noise. Um that's because the the the diaphragm seals are actually um they're actually uh flapping back in again. So, there's an actual vacuum portion in uh in the cycle. Um Uh it's slowing down now. I don't know why. Maybe the gas is uh just turned itself off. But um but yeah, so it's this is this is not a very good crank angle.

[00:07:10]They're all They're all over 90.

[00:07:16]Right, so so the crank angle is set on 120 now. Um something to notice, which is quite interesting, is when the engine is started, it don't It's got torque from a long way. It gets going quicker. See how quickly that gets going? And it's able to do it from a really low rpm.

[00:07:34]So, an increasing crank angle has actually lowered the maximum torque point, I would suggest.

[00:07:42]We won't know until we've actually can do proper power test when we've got the generator sorted out. But um but yeah.

[00:07:49]Just something interesting.

[00:07:51]All right. So, this is set at 130° crank angle. Um notice how slow the engine's become now.

[00:07:57]Um you could actually use the crank angle to actually restrict the the speed of the engine if you you just wanted to display it or something like that.

[00:08:04]But um I tried 160° here.

[00:08:07]Um but it won't quite run. So, that is the limit of the phase angles that it will run at.

[00:08:15]All right. So, this is our Uh I don't know if you can see that in the sun.

[00:08:21]Uh all right. So, this is our sort of speed readings. This is free speed readings. It doesn't give us an idea of the actual torque of the engine. Um I'm going to set it back to 120 um because I think that that probably gives us will give us the uh the best spread of torque. And that was kind of the design uh phase angle of the engine. So, I'm I'm pretty pleased with that. Yeah, so it didn't fully go to plan, unfortunately.

[00:08:42]Um so, I had another go. I I got a slightly smaller motor and I'll I'll show you what happened there.

[00:08:48]So, I've taken the old motor off. Um so, that's the big motor here. It is a In hindsight, it is quite a large motor. Uh so, that does 12 V at uh 3 1/2 thousand RPM.

[00:08:58]Um and we've got this nice little motor.

[00:09:00]It took me quite a while to find one that would go um have a nice low RPM on it. So, it's 20 They're saying 24 V at 3 1/2 thousand RPM.

[00:09:09]So, um I'll fit that and see what happens.

[00:09:13]All right. It's a glorious sunny day.

[00:09:14]So, the engine's all ready to go again.

[00:09:16]So, we got this much smaller little uh DC motor which we are going to use as a generator in place. So, when we turn it around, it gives it a little spin.

[00:09:26]All right. We've got the gas on here.

[00:09:28]Um I'm trying to start it.

[00:09:31]But there's just too much resistance.

[00:09:37]Um I've got a bigger pulley that I can put on the motor to try and reduce the resistance a little bit. So, I think we will give that a go.

[00:09:45]There we go. I've got a bigger pulley on now.

[00:09:48]All right, let's light it up and see what happens this time.

[00:10:04]The bigger pulley has allowed it to run with the little motor.

[00:10:08]Um the only problem I think we've got now is that once again is we ain't got enough voltage. This this um this booster this buck booster is turned off at the moment. But, if I turn it off else I turn it on it comes up with OVP. Um I think that's low voltage um error.

[00:10:25]So, we got that problem again. Um it could be this unit is really a bit too big for our for our extremely small um power output. But, that's fine. Um what I'll do is I'll try I'll get some bulbs uh linked up. And then we we could perhaps measure it in that in that fashion instead. All right, so we've put a big we've obviously um so we put the big pulley on it. Um I'm measuring the voltage here. So, we're on 5 volts.

[00:10:49]Uh it could run a computer if you want to you could charge your phone with it. Um with 5 volts.

[00:10:56]All right, since it only creates 5 volts um I've actually uh got this USB connector and I've soldered it to the um the output was um from the generator.

[00:11:08]Um uh uh Um it's it's soldered it's fallen off again.

[00:11:12]>> Oh, for crying >> All right, here we go.

[00:11:14]Hey, got this disco light.

[00:11:17]Pretty cool.

[00:11:18]That's fine. That's a little experiment.

[00:11:20]So, I've got my little Stirling engine running a little 12-V motor.

[00:11:24]Running a disco light.

[00:11:25]And the the engine's not really slowing down, so I could probably run a few of these.

[00:11:29]That's pretty cool, isn't Yeah, so it's still not really um it's not really working.

[00:11:36]Unfortunately, this engine is so small that any kind of device attached to it, I think it just saps too much energy out of it to give us a good reading.

[00:11:46]Luckily, somebody gave me a great idea of how to test the power and I'll show you that right now.

[00:11:52]Right, I think we're ready to test the power output this time. So, I've revised how I'm going to do that. I'll show you the dynamometer setup right now. This setup was actually an idea of somebody else, but I've used it and I think it's going to work. It seems seems pretty sensitive setup. So, of course the power output of this engine is very small. So, so we just want something nice and delicate that will tell us what the output is.

[00:12:18]Okay, so it's very simple really.

[00:12:21]There's a piece of string here that wraps around the flywheel and goes back down to a loose end on the right.

[00:12:28]>> [gasps] >> I've got some welding wire here, which is a weight.

[00:12:33]I've set the scales.

[00:12:35]So, we turn our scales on.

[00:12:40]Put the weight back on the scales.

[00:12:44]>> [sighs] >> Zero the scales.

[00:12:52]All right. So, we get our string here.

[00:12:54]So, when the engine's running, we pull on the string, which puts resist a braking force on the flywheel.

[00:13:08]And that on turn will apply or remove some weight from the scales.

[00:13:14]It won't lift the weight because the weight's too heavy, but it will remove the weight. I've got it set in grams at the moment. I'll probably use grams and then later convert it to pounds feet.

[00:13:28]So, it's as simple as that, really.

[00:13:30]I apply a force here.

[00:13:32]It lift lifts the weight up partially, but doesn't actually physically lift it up.

[00:13:37]Uh one thing I've got to um remember is I've got to have to double double my figure or half uh yeah, double my figure because I'm actually When I pull this to break it, I'll be applying half of the um the breaking force to this. So, once I've um got my readings, I'll have to um adjust the calculation cuz I'm look I'll be looking for pounds feet. Um this distance between here and here obviously isn't a foot.

[00:14:05]So, I'll need to make a calculation to compensate for that.

[00:14:10]And that is our setup. So, I I'll get my dad over when he's got a spare minute and we can test it.

[00:14:18]Here's it go again.

[00:14:19]Outside in the sun.

[00:14:21]Just heating up at the moment. Yeah, I'm going to slow it down to 500 now.

[00:14:26]500 rpm. Uh you have to wait You have to wait though.

[00:14:29]>> Yeah.

[00:14:29]>> Yeah.

[00:14:32]All right, 400 rpm.

[00:14:33]>> 400.

[00:14:36]>> All right.

[00:14:39]All right, so here's the readings that we've taken. Um the table's got a bit mucked mixed up cuz we put some stuff in the wrong place.

[00:14:46]Um so, we've taken readings for 120° between cranks, 110°, and 100. Um we didn't feel it was worth doing 90 because there wasn't actually a great deal difference uh between 100 and 110.

[00:15:00]Um so, yeah, so that's what we've done.

[00:15:02]Um I'm now going to have to calculate this and work out what's been going on.

[00:15:06]And then um hopefully I'll make some nice pretty graphs and we can have some good visuals of uh the difference between crank angles. All right, let's turn this thing off.

[00:15:15]Yeah.

[00:15:23]Yeah, so that's not too bad. So, we've actually got some power readings now, which is nice.

[00:15:27]It's only very low power output. I'll show you the the graph now of the the results. As you can see from the graph, the 100° phase angle gave us the best results.

[00:15:40]120 was a lower power output, but it was certainly more lazy engine. So, the maximum power output was 6.3 W, which is pretty low really, but not unexpected considering the size of the engine. So, this graph is the maximum free speed that the engine gave out.

[00:16:07]If you look at the the diaphragm, it's quite a small diaphragm on this engine.

[00:16:11]I mean, this is my hand. Look how small it is. I mean, the engine is literally being driven by a bag of hot air.

[00:16:18]Put in the most basic uh form.

[00:16:22]I mean, it's a smooth engine. It's the best engine I've made so far, I would say, even though the power output is down. But, what I'd really be interested in is actually making this engine much bigger and then seeing what happen.

[00:16:36]Because because it's so small this engine, a lot of heat gets conducted from the hot side to the cold side.

[00:16:43]I could make the design more elaborate, so I've actually got a thermal boundary between the two, but then that would take away the simplicity of the engine.

[00:16:52]And the idea was always to make a bigger version of this engine and keep this as a model.

[00:16:59]I mean, as a model, it's quite a nice little engine cuz it will probably run all day. I don't know that yet, but I shall certainly find out as I test it through the rally season.

[00:17:09]It will power It will power stuff, even though it's only low power.

[00:17:15]You could You could charge your phone with it with the generator if you wanted. Um, and also it'll it'll drive a few a few LEDs as well.

[00:17:23]Um, it'll drive a little water pump if you can find something small enough as well or or a whistle or something something funny to just for entertainment purposes. Um, and I think the nice thing is it it'll actually run on anything. So, you could run on wood, coal, fire lighters, gas, oil, um, anything it'll burn, really, because of the the basic nature of of it.

[00:17:47]So, there you go. That's what we've been up to. So, that's the Stirling engine development so far. Um, a few people have shown interest in actually purchasing a a kit of this smallest engine. Um, obviously it's quite a low power output little thing, but as a model it'd be it'd be quite a nice little thing I wouldn't would have thought. Um, there is a chance that's going to happen. Um, I will uh I will say that I've actually got some DIY projects to do first. Uh, we need to do a a small extension on the house. Um, but I'm hoping that I can get back to this soon. Um, I've I've got a few changes that need making to the to the design so it could actually be uh be put together quite easily, you know, as as you as you get with most um prototypes.

[00:18:33]But, um, but yeah, that's kind of where things are at the moment. So, um, thank you very much for um taking the time to watch this video and um and I'll see you next time. I haven't given up with the Stirling engine developments. Um, I will be doing something else. I want to build something big at some point um using all the knowledge I've gained. Obviously, it's not big power, but because this engine is very scalable, I can simply go big really cheaply and really easily um to actually get something in my actually give a bit of useful power. But, um, but yeah, that's uh that's where it is.

[00:19:08]Yeah, so I'll catch you next time and um hopefully over the next few months I'll uh I'll put the next video out of sort of something Stirling engine related.

[00:19:17]See you again. Bye-bye.