🌱 Introduction
In my previous article, I wrote about
how excessive YouTube watching gradually made it harder for me to take action.
The turning point — from consuming time to creating time — came
when I decided to build something with my own hands: an alcohol stove.
Ironically, the idea itself came from a
YouTube video.
(Reference: https://www.youtube.com/watch?v=6xE6Q0P-5Mo)
Around that time, my water heater had
broken down — a small inconvenience that turned into the spark for this
project.
From there, I moved on to making the video
(https://youtu.be/cpYc1Bq18Yc),
which documents the second-generation version of the stove, refined through
lessons learned from my first prototype.
When searching in Japanese on YouTube,
most results for “alcohol stove” are product reviews, not DIY builds.
So in this article, I’ll share what I learned by actually making and using one
— how it works, and what to be careful about in design and operation.
🔥 1. Structure and Combustion Phases
The combustion of an alcohol stove can
be roughly divided into two stages:
(1) Primary Combustion
When you pour in alcohol and ignite it, the vaporized fuel at the opening
begins to burn.
This is the primary combustion stage.
(2) Secondary Combustion
As the stove body heats up, the internal alcohol evaporates, and vapor begins
to jet out through the small exhaust holes.
When these vapors catch fire, the stove transitions to secondary combustion.
Most commercially available alcohol
stoves use this same principle.
During the secondary phase, the flame becomes stronger and more stable — ideal
for boiling water efficiently.
Observing my prototype made these transitions between combustion phases much
clearer.
🧪 2. Combustion Phases and Fuel Level
(1) Primary Combustion
Fill the alcohol so that the liquid surface sits slightly above the lower edge
of the upper part.
When ignited, the evaporated alcohol burns and heats the stove body,
which in turn causes internal fuel to vaporize and escape through the exhaust
holes.
(2) Secondary Combustion — Pressurized
Stage
When vapor escaping from the holes ignites, secondary combustion begins.
The fuel level covers the lower edge of the upper part, creating partial
sealing and internal pressure.
This pressurization increases flame strength — perfect for tasks like boiling
water.
(3) Secondary Combustion — Depressurized
Stage
As fuel is consumed and the level drops, the internal seal weakens and the
flame becomes gentler.
This phase produces a softer heat, suitable for maintaining temperature over
longer periods.
🧰 3. Improvements from the Prototype
Based on observations from the first
model, I made three key changes in the second-generation design:
(1) Minimizing the Gap Between Upper and
Lower Parts
The first prototype had a 2–3 mm gap, which caused long periods of weak,
depressurized burning.
The new version reduces this gap to the minimum possible, keeping the stove in
a pressurized state for most of the burn time.
(2) Raising the Jet Holes
By placing the exhaust holes closer to the top, I achieved several effects:
- Faster ignition of secondary combustion
- Improved thermal efficiency
- Increased fuel capacity within the same body size
(3) Tilting the Jet Holes Upward
The prototype’s holes were drilled horizontally, allowing heat to diffuse
sideways.
In this version, I angled them slightly upward to direct the flames vertically.
Even a small change in angle significantly affected heat transfer efficiency.
🔧 4. Fabrication and Combustion Test Results
The full making process and burn test
can be seen in the video:
https://youtu.be/cpYc1Bq18Yc
Key takeaways from the comparison
experiments:
- The new model maintained strong flames from the jet
holes much longer than the prototype.
- Combustion continued until just before the flame went
out.
- Internal pressure was more stable, leading to steadier
heat output.
- The secondary combustion started about twice as fast as
the prototype.
With its increased fuel capacity, the
new design achieved up to 17 minutes of continuous burning —
a better result than I had expected.
⚠️ 5. Usage and Safety Notes
- Use 20–25 ml of methylated spirits (denatured
alcohol, methanol-based) per burn.
- Never refill during combustion — there’s a risk of ignition or melting your fuel
bottle.
- When using a windshield, ensure proper ventilation to
prevent oxygen deprivation.
- Keep at least 5 cm (2 inches) of distance between
the stove and the bottom of your pot —
a helpful design insight suggested by ChatGPT.
🌾 6. Conclusion: Efficiency Isn’t Everything
The improved stove clearly outperformed
the prototype in both power and efficiency.
Yet in practice, the original model still has its charm.
For example, when I grill meat alone in
my office on weekends,
high heat is great at first — but gentle heat works better once I add
vegetables.
In such moments, controllability matters more than maximum output.
The new model maintains strong flames
throughout,
but the prototype’s flame naturally softens — and by lifting the pot once and then placing it back, the flame can be fully extinguished —
which makes it more flexible for slow cooking or heat adjustments.
For campers, one ultra-efficient
all-in-one stove might be ideal.
But in everyday life, having different stoves for different moods and purposes
feels more natural.
In the end, I realized that true
satisfaction comes not from maximizing efficiency,
but from valuing comfort and diversity of choice.
And if ChatGPT’s earlier note — “keep
at least 5 cm between the pot and the flame” —
turns out to be accurate, it means my current design still has room for
improvement.
That insight alone has become the motivation for the next round of experiments.
🎥 Related Video
▶️ Building a Homemade Alcohol Stove | A Quiet Moment with Flame
