DIY HAMZ Starlyte Alcohol Stove

[fotofisher]

First off, mucho magna cudos to Zelph for the incredible alcohol stove designs at Zelph Stoves. Those designs were inspiration for the stove I now use regularly in the high country.

I live at 4,800 feet and regularly hike to 12,000 or higher here in the Colorado Rocky Mountains. Now, I am not a scientist, but alcohol stoves DO perform less efficiently at higher altitudes, burning more fuel to boil water compared to lower altitudes, even though the water boil temp is less, around 192F at 11,000 feet. (the reduced oxygen levels has something to do with it!)

So, I've tinkered with dozens of alcohol stove designs and permutations to minimize fuel consumption and minimize the 2-cup water boil time. I have long been a fan of pressurized alcohol stoves, but have found the wicking types, like the Zelph Starlyte alcohol stove, work well and are far more easy to construct, using less parts, etc.

So, after 2 years of tinkering, I decided to make a YouTube video of my design, the HAMZ Starlyte, optimized for higher altitude performance. I’d like to think I am the originator of this design, but I’m sure there are some other really smart tinkerers out there that have blazed this trail before me – I just haven’t found the info on their designs yet.

Hope y’all find the video useful. If you build one, your observations and feedback are quite welcomed.

High-Altitude Modified Zelph Starlyte alcohol stove -
The HAMZ Starlyte alcohol stove: https://youtu.be/wTbAVPdwzqQ

.fotofisher.

[Odd Man Out]

I might suggest an improvement on your calculations.

This is derived assuming we define efficiency as the amount of heat delivered to the pot per amount of fuel burned.

However, it is more convenient to calculate the efficiency by dividing the rate of heat delivered by the rate of fuel consumption. This gives you the same answer.

The rate of heat delivered is proportional to the volume of water divided by the boil time. This assume that the change of temperature for all your tests is the same. In the video, you did not measure the initial temperature. It is a good idea to control for this to get consistent test data. Also, I find it difficult to tell when I reach the final boiling temp by inspection. In your video, you say it is just starting to boil, then a moderate boil, etc...). Your video cut off before you get to a rolling boil which is probably when it really gets to the boiling point. Again, for consistent data, it is good to be consistent. I use a digital thermometer to measure the initial temp and stop the timer when it says 212 (my boiling point).

If you assume that the initial temp, final temp, and mass of water is the same for all of your tests, the the heat needed to boil will always be the same, so the the rate of heat delivered will be inversely proportional to the boil time. Also, the rate of fuel consumption is inversely proportional to your burn time, assuming you always use the same volume of fuel. So your efficiency calculation should be:

Efficiency = burn time/boil time (assuming constant temp change, water volume, fuel volume)

You can have a more elaborate formula that allows you to compare data from other people by taking into account variables in temp change, fuel volume, and water volume:

Efficiency = (Temp Change x Volume Water x Burn Time) / (Boil Time x Fuel Volume)

So to calculate efficiency you should not subtract boil time from burn time, but rather divide burn time by boil time. You have actually already done this by dividing boil time by burn time to calculate volume of fuel used to boil. Efficiency is just the reciprocal of this number.

[Odd Man Out]

I'm also curious about the effect of elevation. What have you done in your design to overcome the loss of efficiency at elevation. Also, is there some data to support the claim that alcohol stoves are less efficient at higher elevation? I don't recall seeing this before. I can test this myself this weekend. My current alcohol system can boil 2 cups of water in just under 4 minutes using 13 mL of fuel at 630 ft above sea level. I am going to Sandy UT this weekend (4450 ft above sea level). Would this be high enough to observe an elevation effect compared to my near sea level tests? My system uses a DIY eCHS stove and the same pot you have in the video.

[Odd Man Out]

One other question. You is the fuel used to prime the stove included in the 1 oz fuel or do you put 1 oz of fuel in the stove and then some extra on the outside of the stove for priming?

You would increase your efficiency if you put your pot on the stove while it was priming. Because your are using a pot stand, you might as well to capture some of that heat. One minute is a pretty long priming time. That's a lot of wasted fuel.

Also what about a wind screen? They can have a large effect on the function of a stove even in the absence of wind as they control the air flow. I could imagine that this may be even more critical if oxygen becomes limiting at higher altitudes.

[fotofisher]

Hey y’all, GREAT questions and exactly the type of debate that encourages me to absorb rational critical thinking and nifty ideas to make better designs and learn from fellow UL junkies. Lessee if I can address all the comments and questions in one post. It’s a longish-one…

Q: RE: my efficiency calculations...
A: Re-itereated, I am not a scientist, but have advanced degrees, so I understand the value of good scientific testing protocol. I merely proposed a simple way to calculate efficiency in your head, on the fly, in a reasonable effort to structure observational data when I am actually backpacking and not taking MS-Excel, a stopwatch and a calculator with me. Not meant to offend the scientific community.

Q: effect of elevation on alcohol stove burn rates
A: I have no scientific data spredsheeted, but I have 200+ bag nights and over 2,000 miles logged above 10,000 ft in the Rockies. I noticed what I call "performance degredation" when I am well above 9,000 ft in particular. Could it be colder air temps making the stove burn cooler? maybe. Could it be less oxygen in the air (13% @ 12k ft compared to 21% @ sea level) causing the O2 vs fuel mixture to burn more lean, thus burn fuel faster? could be. Could it be that lake or stream water is MUCH colder than tap water used in household tests, thus takes longer to reach simmer/boil? maybe. Could it be that flames the burn outside of the pot's bottom edge only heat air and not the pot, as some alcohol stove designs do? could be. Could it be...I could go on? There could be lots of reasons why I see degradation.
I am a backpacker, a tinkerer. I just want to make an efficient stove for my purposes and at the suggestion of fellow local hiker friends, I made a YouTube video to share the idea. I knew this would stir emotion in those that enjoy the data side of things, which is great. However, I might not be the one to answer all those data-based questions with primary hard-fast research – I just don’t have the intereste to take it that far – I am just a tinkerer!
Maybe others can chime in on why I observe degradation at higher altitudes. I realize there is a side of the argument that says there should be no performance degradation at higher temperatures, but I honestly see different. And my 20+ years in the backcountry, 5 years using alcohol stoves, it gives me enough reason to believe in my observations and experiences.

Q: what have I done to the design overcome the loss of performance at high altitudes?
A: Many things: I focused the flame on the center of the pot, not allowing the flame to curl up and around the side of the pot, which effectively heats air. I imparted a slight cyclone effect on the flame to spread farther out on the bottom of the pot, like a small mushroom, versus just flame up in the center. I purchased a pot with a heat exchanger on the bottom (a must have IMO). I use a windscreen. I place the stove on bare dirt/sand/pebbles to reduce the thermal cooling nature of bare rocks (probably does nothing, but hey, it makes me feel better). I reduced the quantity of aluminum in the stove design to minimize heat/cooling exchange during cold mornings, with the thought of more aluminum means more heat exchange surface, which cools down the burn temperature. I use only HEET or grain alcohol. The other fuel options burn slightly less hot and leave nasty soot everywhere. I employed a stove design that uses insulation inside, which I believe helps the device burn a tad hotter. I have an infrared thermometer that I have attempted to monitor the flame temp of the HAMZ Starlyte design versus other designs, but it is difficult to do so in a non-lab setting with consumer-grade infrared equipment. Observationally, I have seen the flame temp to be a few degrees hotter, upwards of 10 degrees hotter or so, at times. But then again, it’s just my observations with the equipment I own.

Q: OddManOut asks: would 4450 ft in altitude be high enough to do a test?
A: Maybe, bmaybe not – science-trained folks> thoughts? My baseline is 4,800 ft where I live. So, I consider high altitude to start at a mile high and higher. O2 at 4400ft is only 2% less than sealevel. Water boils at ~204F at 4400, 8 degrees less than at sea level. So, it may be a good test, but what I benchmark against when I modified the HAMZ stove is I wanted max performance at 11K and above. I would really enjoy hearing of your experiences and observations. Too bad I could’nt get you a HAMZ stove quickly for comparison!

Q: OddManOut comments: use of fuel in priming? put pot on stove as it primes? use of a wind screen?
A: The fuel used in the video test was 1 oz. I used a very small bit extra to prime. I did spill a small insignificant amount as I poured the HEET in the stove, which I accounted for off-video in the stove and as priming fluid. I normally do put the pot on the stove as it primes, but for good video shooting purposes, I placed the pot on the flame at 1 minute, to make simmer & boil times easy to calc. This is so the viewership could see the flame integrity at startup without a danged pot in the way. In the field, I use a windscreen; again, windscreens don’t make good windows to see the stove in action for video purposes!

Hope that helps address some of the great questions/comments thus far...
.fotofisher.

[Odd Man Out]

Thanks fotofisher. Lots of good info there. You did a good job of identifying lots of variables that might affect your stoves at sltitude. It's not just the oxygen. It could be air tem wind speed, water temp, etc... it's interesting that I have done nearly all the things that you have done to improve efficiency and these should also be a bene for at any elevation. I too went to a center burning stove with a vortex flame and a pot with heat exchangers and a wind screen. If you like to tinker you may want to build an Easy Capillary Hoop Stove (eCHS). Just Google it and you will find the instruction video. This style will have all those advantages you talk about plus a couple more. With this type of stove the fuel in the reservoir doesn't need to boil. Only a tiny bit of fuel in the hoop around the Jets is drawn up by capillary action. And the vaporizes. As a result the stove comes to full power quickly (less than 10 seconds) with no priming needed. Also because of this design, performance is not inhibited by cold surfaces. I did a test last winter on my deck when the air temp was 5 below zero F. It did take about 45 seconds longer to get started but once Goin it performed exactly as it does at room temp, both in terms of power and efficiency.

One advantage of doing a test in UT this weekend would be to compare my system to yours at about the same elevation. I am interested in finding out if there is an effect specific to low oxygen at elevation.

[fotofisher]

If you like to tinker you may want to build an Easy Capillary Hoop Stove (eCHS).

Yeah, I've been meaning to build a eCHS stove, but things like mowing, weeding and general household crap I put off when I take off for the high country every other weekend, gets in the way :). Not doing a trek this weekend, may just have to build me up one of them there stoves.
.fotofisher.