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The ongoing Thermal Storage Battery topic has inspired a number of initiatives.
The goal of the equipment configuration is to consume 100 watts.
(th)
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The generator will consume some of the supplied energy.
An estimate of input to the generator is 133 watts.
An air motor might provide the input to the generator.
An available (and affordable) air motor consumes 7 cubic feet of air per minute, at room temperature. Whether the air motor in question can drive the generator remains to be determined.
A stored energy supply would need to provide 7 CFM for however long it can, and the output would be observed as current flowing into the load at 12 VDC and a rate of (about) 9 Amps.
(th)
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Here is some of the posts from Housekeeping
I've asked a manufacturer of small (model) marine steam engines for specifications for their $160 low end model. They make higher end engines for much larger ship models, apparently.
In earlier posts, you have mentioned an automobile generator as a possible option. I'm not sure if generators are still used. The market may have gone entirely to alternators. In any case, with the objective of consuming 100 watts of power over an hour, i asked Google about 12 volt lighting.
About 11,200,000 results (0.72 seconds)
Since amps times volts equals watts, this works out at 69 watts (230 times 0.3). Now to work out the amps at 12 volts you divide 69 watts by 12 volts and you get 5.75 amps.Estimating your Power Demands | Power Consumption Guide
Rainbow Power Company
https://www.rpc.com.au › faq › estimate-demands
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How many amps does a 12v bulb use?
The standard 12v incandescent bulb used in RVs draws 1.5 amp. The average, high quality, LED light draws . 3 amps and outputs 2x as much light. LEDs are about 10x as efficient at producing light when used in a 12v application.Nov 3, 2016P = IE
I = P/E
so current would equal 100/12 or 50/6 or 25/3 so 8 1/3 amps
9 / 1.5 >> 90/15 >> 18/3 or 6 bulbs .... 9 AMP X 12 Volts >> 108 watts
Can you determine what rotation is needed to deliver 9 Amps at 12 Volts from an automobile generator?
The rotation requirement needs to be fed back into the model steam engine calculation, to see if gearing is required.
(th)
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For SpaceNut ... apparently DC generators are still made for the golf cart market ...
https://www.amazon.com/Rareelectrical-G … 18&sr=8-16
Amazon has quite an assorment.
I would imagine a working 12 Volt DC generator could be found in a salvage yard for less than the price of a new one.
The requirement of this application is only 9 AMPs, so the generators shown at Amazon would be loafing.
(th)
12v x 1.5 A = 18 watts for each hour that you will want it to light for each bulb. so, 6 bulbs x 18 w = 108watts is correct for the circuit.
The particular alternator will produce at 600 rpm about 6 amps at best, but the voltage will drupe to less than 12 v value.
At 1500 rpm the alternator will be near 12 amp and at 2000 rpm above 20 amps while continuing to 2500 rpm to 3000 rpm for full power before getting too hot at full amperes of 25A. Also, a typical alternator is charging a battery so its normally going to be able to put out approximately 14v under lighter loads than it is spinning for.
For SpaceNut re #2917
Thanks for taking up the generator question .... I did a quick check with Google, and confirmed that alternators produce AC but (apparently) generators can produce either DC or AC.
The golf cart generator I showed in the Amazon link is (apparently) a "generator" (not an alternator). I am guessing that for the golf cart market, the generator remains the superior answer for the application, while in automobiles (apparently) only alternators are used these days.
In fact, Google says...
I managed to lose the citation ... the quote was to the effect that alternators replaced generators in cars starting in the 1960's
However, your estimates for output with rotation speed may be quite accurate .... Since the goal here is to deliver 9 AMPs at 12 VDC, it should be possible to obtain the precise rotation rate through experiment, and then run or gear the steam engine to deliver that rotation
I note that the generators shown in the Amazon ad are all belt driven, so the ratio between the pulleys would determine the run speed needed from the engine. And ** that ** presumes the engine can deliver the amount of power needed for the application.
This little $160 motor is designed to turn a propeller in a small model boat. It might be completely overwhelmed by a 12 VDC generator.
(th)
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For SpaceNut .... actually, I don't think it makes a bit of difference for this project, whether we use a generator or an alternator.
By any chance does your friend with the garage have an alternator lying around that you could test in your home workshop?
It should be possible to put together a 100 watt load from odds and ends, and turn the generator/alternator with a drill, to see what it produces.
By discovering the power required to drive the generator/alternator, it should be possible to determine the power output needed from the steam engine.
That little model boat engine may be ** way ** under powered for this application.
A way to determine the power required to drive the generator is to use a small electric motor to drive the generator, and to measure the power consumed by the electric motor (ie, voltage and current).
(th)
Alternators require a battery to satisfy the regulator coil that creates the magnetic field that it's going to make use of with the turning of the shaft at rpm/
A permanent magnet does not require 1 to make it function.
Using a drill gets you into the torque for force for rpm
https://www.protoolreviews.com/truth-ab … que-speed/
While that might seem to complicate things, it’s still a good place to start. Let’s say you’re considering three drills with the following specs:
Drill #1
Torque: 1100 in-lbs
High-Speed: 2000 RPM
Low Speed: 550 RPM
Drill #2
Torque: 1150 in-lbs
High-Speed: 2100 RPM
Low Speed: 450 RPM
Drill #3
Torque: 1050 in-lbs
High-Speed: 1900 RPM
Low Speed: 600 RPM
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For SpaceNut re #2920 .... we appear to be heading toward generators and away from alternators, for this application.
Thanks for the tip about drill specifications!
Do you want to take charge of the electric circuitry?
We may be able to persuade NewMars members to contribute used parts they have lying around.
Let's start with your inventory. Given the goal of 100 (108) watts for an hour, do you have parts (new or used) in your inventory that could be adapted for this use?
I found a supply of 1000 watt generators (?alternators? not sure) that go for under $100 new (with shipping and taxes).
I just found a Generator 12v Permanent Magnet for $70 on eBay. it is rated for 1200 watts ... it provides AC or DC. It would be loafing at 100 watts.
The 1000 watt version costs $60 and shipping is free.
Item number is: 403952071897
To see the item, used the Advanced Search option and enter the 12 digits into the Item window.
(th)
For SpaceNut re steam engine ....
Here is a site with a wide assortment of devices for the model ship building community.
https://www.stirlingkit.com/collections … gine-modelThe collection includes a generator with a digital voltage display. The generator is rated at 12 Volts and 1 Amp.
My (wild) guess is that a builder might tap the output of the steam engine to provide power for lights and for radio control of the model, which (I gather) is at least 80 cm long (31 inches).
The steam engines for a model ship that size are priced just under $1000.
***
The input to the generator is 133 watts, if we assume 80% efficiency and 100 watts output.The conversion factor that Google found is 1 Watt = 0.00136 horsepower.
The steam engine needs to supply .18 horsepower.
(th)
For SpaceNut .... here are some folks who make serious steam engines for the off-grid community
https://claverton-energy.com/mini-steam … nergy.html
The smallest steam engine I found delivers 5 horsepower.
We only need .2 horsepower.
(th)
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For SpaceNut re Air Motors
This web site offers what appears to be a wide range of air motors, starting at a power level close to what we need.
https://globe-benelux.nl/airmotors/en/c … vanemotor/
An air motor would be the appropriate recipient of output from a hot+cold thermal energy store.
Such a design would hold liquid air in the cold compartment, and some suitable heat retaining material in the hot compartment. The output would be air at a pressure sufficient to drive the air motor mechanism.
(th)
For SpaceNut ...
I asked Bing (new enhanced ? not sure) to find me an air motor that could deliver 1/3 horsepower, and it came up with this site:
https://tools.cp.com/en/products/air-motors
Power ranging from 0.16 kW (0.21 HP) to 1.8 kW (2.45 HP). Most motors can be supplied as either unidirectional with a threaded shaft, or reversible with a keyed shaft. Alternative output options are also available. Chicago Pneumatic air motors are ATEX certified for environments with potentially explosive atmospheres. A complete range of accessories is available to ease air motors
(th)
Following up on Post #2925
***
The input to the generator is 133 watts, if we assume 80% efficiency and 100 watts output.The conversion factor that Google found is 1 Watt = 0.00136 horsepower.
The steam engine needs to supply .18 horsepower.
.21 horse power divided by .00136 gives: 154.4 watts and change
That is well above what is needed for the little demonstration project, but it leaves plenty of room for testing beyond the initial goal.
(th)
For SpaceNut re selection of air motor....Fill in at least two of the three fields (torque, speed, power) to find the missing value
Torque (Nm)Speed (r/min)
Power (Kw)
The web site asks for two of three values .... can you supply those?
The speed would presumably be the speed needed by the generator.
I am trying to discover the price for one of these
(th)
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I took a look at the generator but what they are showing is from https://www.rareelectrical.com/ does not appear to be a dc generator but rather a motor.
found the one which was on Amazon
it is lacking the power curve information from the websites spec pages.
Yes, some motors can be used in reverse, but they are not at the same voltage output as a generator and take more input rpm to make it function.
Torque is going to increase from its initial amount of drag on the shaft as the load increases on the generator and since these are usually run with a gas-powered motor pulley belt to most it will not matter how much that is.
https://electronics.stackexchange.com/q … -frequency
https://www.bigrentz.com/blog/generator-amperage-chart
For SpaceNut re #2936
The Apache error is going to plague us until we find out how to fix it. I found a number of citations about the problem and posted the list in a topic a while back. I was hoping someone would study the list and solve the problem, but it appears the problem remains.
Regarding the web site your found ... that ** is ** definitely interesting.
It appears the site has no generators at all, as makes sense, since the generators I found is for golf carts, and the site you found is for automobiles, which haven't used generators since the 1960's (or so I'm told).
Unfortunately the post where I showed you a golf cart site is past the 25 post page marker, so I'd have to to back to a previous page to find it.
OH ho! I put this into Google: starter generator for golf cart
The result came back with many citations of "starter generator" devices for golf carts ... these (apparently) are used to start an Internal Combustion engine. and then generate 12 VDC. What I found amusing is that company you found was listed multiple times.
Pricing all seems to be in the $120-$130 range
I hope you can find a few minutes to go back to the post where I showed a web site that offers air motors.
They want to know two of three pieces of data in order to provide a price on an air motor.
Amazon found an air motor in the form of a pneumatic drill for $32 or so. The concern I have is the low efficiency of this device.
A ** real ** air motor should be more efficient, if machining tolerances are high.
I like the idea of an air motor compared to a steam engine, because the difficulty of working with hot steam is avoided.
The output of a Thermal Energy Storage batter that uses liquid air as the cold store, and hot material as the hot store, would deliver room temperature air as the output. That air would be fed into and air motor, which would drive a generator, which would light the incandescent bulbs.
By designing and building a system able to light 108 watts worth of bulbs for an hour, we would have demonstrated the practical value of kbd512's concept.
(th)
Air is a very common shop tool, and we supply it usually 45 to 90 psi for use connected to a large reservoir of it as that is where the cfm must come from as it an open loop use as what we are trying to do is closed loop, Making use of heat and cooling in the loop to make state changes in pressure.
Your application just means less heat and cooling are required for the cfm volume and pressure to make the tool function.
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For SpaceNut .... I went back and found the site where specifications are requested:
https://tools.cp.com/en/products/air-motors
The selector menu wants tWO of three of: Torque, Speed (rpm), power
The power output we want from the air motor is .21 horsepower (133 watts)
RPM should be whatever is needed for the 12 VDC generator to provide 9 Amps at 12 VDC.
Can you determine what the RPM needed might be?
(th)
Hi SpaceNut re #2941
It's ** good ** to see all that assembled knowledge brought to bear on this problem!
Please see if there is any chance you can determine what the vendor is asking. We have a plan for a 12 VDC generator to drive some incandescent bulbs. The amperage is chosen as 9 and the voltage is given as 12. From this we know that 108 watts are to be delivered by the generator. A wide variety of suitable generators are available, as we have seen from both the web sites I found and the ones you found.
Given one of those generators and the defined load, the air motor vendor is asking how many RPM we need to deliver the stated current into the load.
We do know that the horsepower is on the order of .21. We are assuming 80% efficiency of the generator, so we are assuming the air motor must deliver 135 watts. The air motor vendor is asking for either torque or RPM. Of the two I am hoping you can estimate the required RPM.
Another way we could go is by observation (measurement). I'm hoping that there is enough theory available to be able to estimate the RPM needed to cause the generator to deliver the desired output.
In previous posts you have given a range of possible values for the RPM. I'd like a precise number to enter into the air motor vendor web site.
Do you have a friend with an old golf cart generator you could borrow for a day or so? It should be possible to set up the experiment without spending any money. It would take a bit of time.
(th)
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Already given above
12v x 1.5 A = 18 watts for each hour that you will want it to light for each bulb. so, 6 bulbs x 18 w = 108watts is correct for the circuit.
The particular alternator will produce at 600 rpm about 6 amps at best, but the voltage will drupe to less than 12 v value.
At 1500 rpm the alternator will be near 12 amp and at 2000 rpm above 20 amps while continuing to 2500 rpm to 3000 rpm for full power before getting too hot at full amperes of 25A. Also, a typical alternator is charging a battery so its normally going to be able to put out approximately 14v under lighter loads than it is spinning for.
If max load is the 9Amp then that is the 75% point of power meaning, we want to over produce by 25% to take care of voltage sag which should be near 1500 RPM of the 3 to 4 inch pulley.
If you interface that with a ration of a large pully to the small one with a belt, then the rpm of the large will drop by that ratio.
Where are the horse power and air motor wattage coming from as we do not care about either to turn the shaft of the pulley at rpm.
Those come into play for torque which is related to source air pressure for the tool to make use of.
Seems the calculator does not see values less than 1 kw thou the catalog equation shows the information.
you can actually pick a product from the catalog based on RPM and available pressure.
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For SpaceNut ... re air motor ...
Thanks for the RPM estimate of 1500 ...
That was enough to get me past the first state of the air motor selection process. At that point, I learned that Chicago Pneumatic has a gigantic global distribution network.
Here is the product code that popped out:
Documentation
Product nameM84-2400-K-ATEX
Product number
2051479154
I found a company that carries 133 of Chicago Pneumatic air motors:
https://airtoolpro.com/chicago-pneumati … tion-tool/
Out of those 133 there should be one that fits the requirement.
Please keep in mind that Amazon offers a pneumatic drill for $32 and change.
An air motor needs to exceed the performance of the drill by a good margin.
OK ... I filled out the contact form and will report if and when a reply arrives.
This outfit would be wanting to sell thousands of these, I'm guessing.
As you pointed out, the selector form does not accept horsepower less than 1, so the motor would be way over sized for the initial test goal of 108 watts. However, both the motor and the 12 VDC generator could produce a lot more output if the goal post is raised.
Once the generator and the air motor are agreed upon (decided) then we can approach Calliban and kbd512 for their deliverable of compressed gas.
(th)
Just check on the M84-2400-K-ATEX and on this website https://airtoolpro.com/air-motors/multi … eversible/ it's not cheap at $2,107.86...
The range offers non-reversible versions delivering a maximum power of 840 W (1.13 hp), with torque ranging from 0.74 to 299 Nm (0.55 to 221 ft.lbs) and speed from 45 to 20,000 rpm.
We can make use of other pneumatic tools that are less costly and modify howe to connect them for testing of design to create power on a less costly scale.
JET JAT-401, 1/4-Inch Pneumatic Die Grinder, 1/2HP (505401), Grey,black
We can even use something like this as we can set rpm and other such functions from the built in control.
Keep in mind that a pneumatic tool is not a turbine as they vent the air after use and a turbine will recirculate it.
This only proves that we can turn the shafts if we have pressure in the loop that we can make power.
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For SpaceNut re #2949
Thank you for encouraging further development of this subtopic! A while ago, but not TOO long ago, I asked ChatGPT for help trying to figure out how long a pneumatic tank would power a tool. After a lot of back-and-forth, we arrived at a resolution that is reliable.
Given that we want 7 cfm to flow through our air motor for an hour, we can compute the total number of molecules that would need to be held in a tank. The tank is held at a pressure above the 90 psi where the tool operates. A critical feature of a pneumatic system is the pressure regulator, which has the ability to manage high pressure on one side, while delivering exactly 90 psi on the other.
Calculation of the size of the tank, and the pressure needed must include the volume that will hold gas at 90 psi after the supply of gas above 90 psi has ended.
Calculation begins with the count of molecules in that minute where the gas is passing through the air motor at 90 psi. Per our discussion, we appear to have settled upon 7 cubic feet of gas at 90 psi. I'd have to go back to refresh my memory of how to compute the molecular mass, but whatever the method is, it allows computation of the total volume/mass of gas that must be in the tank before the tool is turned on, above and beyond whatever base level of gas must be present.
There are two variables (as I recall) at work ... the volume of the tank, and the pressure to which the contents must be raised.
In the earlier study, I was looking at a specific commercial offering. it had a specific volume, and the system was designed to achieve a maximum pressure well over 100 psi, but at the moment I don't recall what that pressure was. By knowing the volume and the pressure, it was possible to compute the molecular mass that had to be present in the tank above the level needed to maintain 90 psi. The difference was the amount available to power the tool. My recollection is that the tool ended up able to run for a minimum of 15 minutes, which was sufficient for the application I had in mind.
In this case, we have flexibility in sizing the tank, and in setting the pressure before we start a run. Based upon the requirements for the test, we can compute the mass of molecules to be delivered, and then we can experiment with pressure and volume of the supply tank to arrive at a combination that makes sense.
Likewise, kbd512 and Calliban will need to deliver that exact same number of molecules, spread over an hour at a steady flow of 7 cfm.
How they design their system remains to be seen, but whatever they come up with is sure to be interesting and possibly even thought provoking.
(th)
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For SpaceNut ... someone (probably Google) thinks I am interested in the $32 air drill tool offered by Amazon. I could afford that. I notice the RPM given is 2500. That is above the RPM you suggested for the DC generator's we've been looking at.
Reversible Drill Pneumatic 2500 Rpm
Visit the Rockwood Store
3.8 3.8 out of 5 stars 13 ratings
$32.99
Get $60 off instantly: Pay $0.00 upon approval for Amazon Visa. No annual fee.
Brand Rockwood
Power Source Wind Powered
Voltage 110 Volts
Color Silver
Special Feature Variable Speed
About this item
The Rockwood 3/8 in. Inline Drill Is A Heavy-Duty Industrial Level Tool With Hardened Planetary Reduction Gears Ruggedly Designed For Many Years Of Reliable Service.
Slim And Compact Inline Design With Variable Speed Control
High-Torque 5-Vane Ball Bearing Air Motor
2,500 Rpm Free Speed ; Air Consumption: 7 Cfm [198 L/Min] ; Inlet Thread Size: 1/4 in. Fnpt ; Length: 8 in. ; Width: 1.5 in. ; Weight: 2 Lbs
Weight: 2 Lbs.
› See more product detailsIt should be possible to work out the size and pressure of an air tank able to serve that drill for an hour. Maximum tank pressure I've seen in recent searches is 200 and 175 looks like a popular value for commercially offered systems.
I wonder if a used generator is available somewhere in the US for $32. That amount is also affordable from my perspective. The entire downstream load might be put together for $100 or so.
(th)
During the day the bars has moved from wanting to calculate the mole for air
The molar mass of dry air with oxygen, nitrogen and the other components as indicated below is 28.9647 g/mol.
where the Oxygen has a molar mass of 15.9994 g/mol and nitrogen has a molar mass of 14.0067 g/mol.
to using AI to get the tools rough answer from a past exercise.
Where the standard bbq tank (25 gal) holds approximate 12 minutes of run time and for the hour we need 5 plus times that to ensure the cfm and pressure for the tool.
In the end the value of the tank is about what we need for the total loop volume in closed loop give or take.
https://www.compressorworld.com/categor … ssor-tanks
I have looked in the past for the junk yard gas generator heads but to no avail.
For SpaceNut re #2954 and subtopic of pneumatic air motor >> electric generator >> incandescent bulbs concept
Thanks for your summary of previous work on how to estimate run time in a pneumatic system!
Here is the lowest cost generator I've been able to find so far:
https://www.partsworldusa.com/PW03-101
This item is offered for $60, and that is just over (but within range) of the budget amount I had estimated for the generator component.
That would put the investment in generator and air drill right at $100, not counting shipping and taxes.
Meanwhile, I notice that Calliban and kbd512 are now talking about steam as a possible way to harness Thermal Stored Energy.
(th)
For SpaceNut re generator ....
This was a surprise:
https://www.amazon.com/Starter-Generato … NrPXRydWU=
New Starter Generator compatible with EZ GO Golf Cart GXI875 GXT Medalist MG2 TXT 1980-2008
Brand: ESellSimple
4.0 4.0 out of 5 stars 73 ratings | 6 answered questions
$99.90
Get $10 off instantly: Pay $89.90 upon approval for the Amazon Store Card.
100% Brand New - Manufactured with New Premium Quality Components -- Engineered to Meet or Exceed OEM Specifications -- All Items Tested for Reliability, Durability and Performance
One Year Hassle Free Warranty
See Product Description for Fitment Chart - Matchup Reference Numbers to Assure Proper Fitment
Multiple Locations Nationwide to Assure You Lightning Fast Delivery
Motor Generator 12 Volt 20 Amps Reversible
› See more product detailsI've decided this is worth taking a chance.
Due date is June 14th.
While we wait, please think about what instrumentation we need to measure current / voltage / power flow.
This is an automotive scale electrical system, so there may well be automotive instruments able to assist.
(th)
For SpaceNut re electrical circuit ...
https://www.amazon.com/Multifunction-Ba … RydWU&th=1
Please evaluate this device ... I'm wondering if it could sit between the generator and the load, to provide accurate data about voltage level and current flow.
DC Multifunction Battery Monitor Meter,0-200V,0-300A (Widely Applied to 12V/24V/48V RV/Car Battery) LCD Display Digital Current Voltage Solar Power Meter Multimeter Ammeter Voltmeter
Visit the MORNING GROUP StoreAs reported earlier in the archive, I picked up a battery tester to (at least try) to anticipate battery failure in equipment. I've had equipment fail because I lost track of the purchase date for batteries. The tester consists of a load that heats up in a 12 volt circuit.
The device above would appear capable of showing current flow in real time, similar to the analog amp meter I remember from 1940's era automobiles.
(th)
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The device looks more than adequate for measuring the voltage and currents provide from the generator to the load and then some.
The 200-gallon tank if it were, of 1 inch diameter pipe would be 60,000 inches in length or 5,000 ft to have the same cubic inches of air with in it or slightly over at 203 gallons.
Of course, the typical AC unit is just 25 feet of smaller tubing size.
For SpaceNut re Thermal Energy Battery live demo mini-project.
The 12 volt generator arrived today. It was shipped by UPS and the weight stamped on the package was 18 pounds.
That's 8.165 kilograms for our members so inclined.
Either way, it's heavy from ** my ** point of view, and I was glad to set it on the work bench.
In order to test it my tentative plan is to build a scaffolding to hold it vertical next to the drill press already installed on the work bench.
I'll need a v-belt at some point, but I'll worry about that after I can measure the distance between pulleys.
Update later the same day:
I was happy to find that the mounting holes on one side of the generator are precisely 1/2 inch diameter. I have a threaded rod that slips snugly through the holes. That rod can be secured to a 2x4 framework to provide firm support for the generator held in the vertical position.
I think it is reasonable to guestimate that the generator will be ready for live testing by mid-July.
(th)
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Looks like things are shaping up for the mini power project.
About all that seems to be needed is a compressor and tank that can achieve the pressure for the duration of operation.
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