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  • buenijo's Avatar
    02-13-2025, 12:07 PM
    My electrical experience is very limited. I poked around many different sources to find a clear answer as to how the DC voltage changes when three phase AC is rectified to DC. I got many answers. The previous video and the video attached here provided a clear answer. The specs for the alternator I want indicates "24 VAC at 2000 RPM". But "VAC" is vague. Do they mean Root Mean Square (RMS), peak, line to line, line to neutral, etc.? Turns out they must have meant RMS line to line. Well, the DC voltage is about 1.8X the VAC in this case. Example 1) The previous video show 53vdc at 1520 rpm. The alternator specs for that unit show "48 VAC at 2500 RPM". So, at 2500 RPM, the DC voltage will be about 1.8(48) = 86.4v. Therefore, 53v will correspond to about (53/86.4)(2500) = 1530 RPM. Actual speed was 1520 RPM. That checks out. Example 2) The attached video shows about 14v RMS VAC. So, the expected DC voltage from the rectifier at the same RPM should be about 1.8(14) = 25.2. It checks out as well. So, if the alternator provides 24v VAC at 2000 RPM, then the DC voltage would be about 1.8(24) = 43.2v. The RPM for 28v (which is about right for the charging conditions I want) would be about (28/43.2)(2000) = 1300 RPM. If I were to use the alternator ME1603 shown in the previous video, then charging a 48v battery at 56vdc would require about 1620 RPM. So, it seems my engine would operate at 1300 RPM for the 24v version, and about 1600 RPM for the 48v version. Again, assuming the damned thing ever works at all. ALTERNATOR DISCUSSION: Just sharing a recent experience. I'm engaged in a discussion with someone who sells alternators designed primarily for wind turbines. He sells what are essentially automotive alternators with the rotors replaced with neodymium magnets. These have three phase windings, and the rectifier is either internal or external depending on the model. I'm sharing the details of the discussion because the details might help someone to understand more about how these alternators work. Anyway, the specs available on these alternators are limited. So, I contacted the seller asking about the stator resistance and the DC voltage output as a function of RPM. However, rather than provide the specs, he replied with questions about my application. This was frustrating because I don't need anyone to do the engineering. I just need the specs. The seller argued that knowing the voltage as a function of RPM is not useful because the actual RPM while battery charging will be A LOT higher than the cut in voltage.
    45 replies | 25206 view(s)
  • buenijo's Avatar
    02-11-2025, 01:03 PM
    This guy on YouTube has some interesting steam engine projects going on:
    237 replies | 119673 view(s)
  • buenijo's Avatar
    02-08-2025, 05:53 PM
    I came upon a video of someone testing the same alternator that I selected for my steam engine project. This is the 48v model. There is another unit with different windings suitable for a 24v battery. Based on comments, the amp rating is likely generous. He suggests no more than 1500 watts continuous and likely 1000 watts to ensure no overheating. Not terribly surprised. China is very bad about inflating specs. Comment from the person who made the video: "yes they are made in China. And like most things from China they are over rated somewhat. I would expect to get 1500w max from this turbine and it will get HOT. At 2kw it might catch fire. 1KW would be a conservative output and will last longer." NOTE: I have other alternator options. But I'm going with this one because it's about half the cost of the alternatives. The model I'm looking at uses 10 awg wire with 125C insulation. The rated current of this wire is listed as 70 amps. This implies 1700 watts is possible at 24v. However, the seller claims 2000 watts. Yeah, definitely inflated the specs there. Maybe the unit could handle 1500 watts (in part because a 24v battery is normally at 26v or higher). This would imply 58 amps at 26v. With good cooling it would probably pull it off. That noted, I wouldn't press it. I can always limit the output to 1 KWe which would take the current under 40 amps. It would also be a lot more efficient at the lower amperage.
    45 replies | 25206 view(s)
  • buenijo's Avatar
    02-03-2025, 04:47 PM
    I recently came across several compact car conversions on YouTube where the stock engine was replaced with a 670cc V Twin Predator engine via a centrifugal clutch. The result is essentially a large go cart. A subcompact car is able to reach modest highway speeds on level ground - with 40-50 seconds required to get up to speed. Adding a drive motor in a parallel hybrid configuration to significantly boost torque would not be terribly difficult. This configuration can provide several benefits. First, the vehicle can be driven by the motor, the engine, or BOTH. The battery capacity required is modest, and this relatively small battery system could fit in the engine compartment. The engine could power the vehicle on level ground up to modest highway speeds with the motor available for torque boosts as required for more rapid acceleration and/or hill climbing. Furthermore, the motor can be configured to act as a generator to charge the battery(*). Cost for parts for the drive system would be on the order of $5000-7000. The main benefits in my mind are the ability to eliminate fuel consumption on short trips, and the ability to maintain the vehicle indefinitely with relatively trivial maintenance (small engine maintenance is straightforward and the EV drive components are highly reliable). Also, such a conversion has the potential to show impressive fuel economy in highway driving as the engine would have near wide open throttle during operation (most of the time). NOTE: A Honda engine with similar performance costs about 2X the Predator. I would go with the Honda in this case. If it were 3X or 4X, then I might stick with the cheaper engine. But the Honda is worth the extra $ in this case. VIDEO This video is part of a series describing an EV conversion of a Geo Metro.
    1 replies | 466 view(s)
  • buenijo's Avatar
    02-01-2025, 10:15 PM
    I fired the steam generator today. The burner was not working well at all. I shut down after a short period and ordered a second blower fan. Previously, when I had the blower on the burner head to force primary air, the burner worked well at LOW outputs. Increasing the output would cause soot to be produced. I could literally see some black soot blowing out of the exhaust port. I also verified soot accumulation on the steam generator tubing. With the blower moved to the underside to provide only secondary air (bypassing the burner head), what I witnessed was a white haze in the exhaust and strong smell of propane. What I believe is happening is the increased pressure in the combustion chamber due to the new blower position is preventing the burner venturi from providing sufficient primary air. So, propane gas is getting forced UP into the combustion chamber from the burner head with the vast majority not mixing with primary air. So, much of the propane gas is just moving through the unit, getting blown out the exhaust ports, and condensing in air to cause the white haze. Makes sense. So, I need to provide a blower for BOTH primary air (on the burner head as before) AND secondary air (on the underside bypassing the burner head). This seems reasonable. Good news is I don't have to do additional fabrication. I just need to keep the blower on the underside, then add a second blower to the burner head as before (I already have the attachment). (02-02-25) The fan arrived this evening. I'll fire it up when I get a chance - hopefully this weekend. I will also enlarge the exhaust port as removing the steam generator and re-installing is not difficult. (02-04-25) Nothing material to share. Just thoughts. So far, I can see a final prototype as not terribly difficult to assemble for small production runs. Yeah, of course this assumes I can get the damned thing to even work! So far so good. But the deck is stacked against me. I have no illusions. I'll just keep plugging away slowly and see what unfolds. That noted, I'm liking the basic design right now. (02/07/25) Not gonna fire the unit today as it's raining. I removed the steam generator yesterday and added an additional exhaust port. I also placed some ceramic fiber on the base of the combustion chamber, then reinforced the seal for the secondary blower (the one on the underside). Everything appears to be ready for the next test. (02/08/25) Gonna wait till next week for next test. No time this weekend.
    45 replies | 25206 view(s)
  • buenijo's Avatar
    01-29-2025, 02:10 PM
    A TALE OF TWO BOILERS The first video depicts a large monotube steam generator with all safety systems disabled and low (or NO) water flow. The burner was allowed to continue firing until the tube ruptured. The second video shows a firetube boiler that exploded due to operator error. The lesson here is the monotube steam generator is VASTLY safer than traditional boilers. Indeed, I argue a monotube steam generator with all pressure contained within small diameter tubing does NOT present a material explosion hazard. The tube can rupture, but only at a localized point. The pressurized contents of the tube must move through the long tube before escaping. So there is no explosion. Furthermore, the mass of saturated water in a monotube steam generator is VASTLY lower than a traditional firetube boiler of the same power rating. So the quantity of energy contained in a monotube steam generator is a small fraction of the energy contained in a firetube boiler of the same power rating. A firetube boiler heats a large mass of water contained within a large pressure vessel. During a catastrophic failure, the pressure vessel shell rips apart to expose the large mass of saturated water to atmospheric pressure. Much of the water flashes to steam almost instantly. BOOM! Personally, I would NEVER build a steam engine system that uses a large pressure vessel to heat water for steam generation. This is why I designed my engine to operate at a constant output. A large mass of saturated water is very useful for meeting transients in engine output. This is very difficult for a monotube steam generator. So I just sidestepped the problem. The alternative I will try is using the engine-driven alternator to maintain charge on a small battery system, then either operate the engine ON/OFF or HIGH/LOW to meet variable energy demands.
    45 replies | 25206 view(s)
  • buenijo's Avatar
    01-24-2025, 06:15 PM
    https://flic.kr/p/2qGXzc7 I made the necessary changes (see attached pic - for reference, the steam generator casing is 8" diameter). I removed the steam generator and cut a hole in the base next to where the burner head mounts. I then replaced the steam generator. I did not have to disconnect the feed water or steam fittings because the feed water line is a flex hose, and the steam line connects to the condenser coil inside the pot still. I then adhered a PVC fitting to the underside on which the blower fan will connect. I removed the steam generator lid for inspection, and sure enough there is a lot of soot on the tubing. This is a consequence of a rich propane mixture (i.e. insufficient air). During the next run, I intend to run it very lean and hot to burn off the soot. Then I will see how high the burn rate will go. I need 5 gallons of condensate vaporized each hour. ADDENDUM: The adhesive I used didn't work out. So, I just put a coupling nut on the bolt that secures the burner head to the base of the roll cage, then used a second bolt to secure the PVC fitting along with gasket material. It's not going anywhere now. NOTE: If you reference the pic, you can see the pot still in the background along with the needle valve and pressure gage I use to set system pressure. The water enters the steam generator coil at the base of the coil via the check valve seen in the pic. Steam leaves the coil at the top, and this section of the tube is surrounded with three layers of ceramic fiber sleeve. The steam line then connects to the top of a separate SS coil that is INSIDE the pot still and submerged in water. The steam line penetrates a hole in a stainless steel bowl placed on top of the pot still. This bowl shields the steam line fitting underneath to provide protection in case of a steam leak (I also wear safety goggles, a face shield, and high temperature gloves). All steam condenses as it passes through the condenser coil, then the condensate leaves through the needle valve. The position of the needle valve sets the pressure. The steam temperature is controlled by varying the speed of the feed pump (steam line has a temperature probe connected via a copper tee fitting clamped onto the steam line and insulated with ceramic fiber). This configuration is set up only for steam generator testing. When the steam expander is installed, then all steam will move through the steam cylinder. The pressure in that case will be set by a combination of the clearance volume in the steam cylinder head and the load on the crankshaft which will be an alternator connected to a heating element installed in the pot still.
    45 replies | 25206 view(s)
  • buenijo's Avatar
    01-20-2025, 05:29 PM
    I fired the steam generator again today. It held around 700F at around 800 psig for about an hour. Took about 20 minutes to get it dialed in. I took the temperature over 800F for a while. I also took pressure to 1200 psig for a while as well. No leaks in the steam and condensate systems. No leaks in combustion chamber plug. No leaks in the burner. The main problem is LOW burner output. I previously considered this is caused by the combustion chamber being too small. But I am now convinced it is caused by insufficient air. I am forcing all air through the burner head. But I realized these burners are designed to burn in open air where a rich flame can mix with plenty of excess air. I know what I have to do to fix this - and it's gonna be a pain. Basically, I need to reconfigure the blower to force air into the combustion chamber bypassing the burner head. Yeah, I have no doubt I can do this. But I need to remove the steam generator. Good news is it seems to work well (albeit at half the output that I would like). ADDENDUM: I figured out a clever way to fix the burner problem. Should be a bit easier. I might not even have to remove the steam generator. We'll see.
    45 replies | 25206 view(s)
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  1. I began studying politics in 2002 after returning from Afghanistan on active duty military service. I quickly discovered Ron Paul. I started studying economics in 2005. By late 2005 I was buying gold and silver bullion for long term savings. Few individuals today have a clear understanding of economics. What remains of the U.S. Republic is in constant danger of destruction as long as this condition persists. As the economic collapse continues, the ignorant public will blame what they incorrectly believed to be a "free market" and "capitalism". They will then likely abandon what liberty remains for greater central control.
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