Dale Andreatta, Ph.D., P.E.
November 18, 2013
A series of tests was done to compare the Cajun Rocket Pot (the finned pot) with an ordinary pot of effectively the same size. The finned pot has 70 round fins (pin fins) on the bottom with a diameter of 13 mm and a length of 14 mm. The diameter of the bottom of both the regular and finned pots is 248 mm.

The area of the bottom of the flat pot is 0.04828 m2, and the area of the bottom of the finned pot is 0.0883, or 83% greater. Moreover, the flow is impinging on one side of the fins, which typically gives much better heat transfer than gas flowing parallel to a surface, which is what happens over most of the bottom of a flat bottom pot. It would therefore be expected that the finned pot would have much better heat transfer efficiency.

Both pots were tested on 7 different heating devices, with the fire conditions set up to be as close as possible between pot tests. Only one test was done on each pot. There are a variety of ways to compare the effectiveness of the two pots, and as many ways were used as were meaningful for that stove.

The 7 heating methods were:

  • 1. Natural gas range
  • 2. Propane stove
  • 3. High performance charcoal stove
  • 4. Open fire burning wood
  • 5. Simulated open fire burning natural gas
  • 6. Fan powered stove burning wood
  • 7. Rocket stove burning wood.

The heating methods will be described in more detail in the sections on test results for the individual
In general, possible methods for comparing the pots are:

  • 1. Time to boil, corrected to 5000 g of water and 80 degree temperature rise
  • 2. High power efficiency
  • 3. High power heat transfer
  • 4. Low power efficiency
  • 5. Low power heat transfer
  • 6. Overall efficiency (weighted average of high power and low power)
  • 7. Average efficiency (simple average of high power and low power)
  • 8. Total fuel consumed.

There are advantages and disadvantages to each of these methods, and there is no one right way to compare the pots. Some methods are not appropriate to use for some stoves, but in general, results will be given for as many ways as possible to compare the two pots. The reader can decide which is the most valid way of comparing the pots.

File attachments: 

Dale Andreatta, Ph.D., P.E. and Alex Wohlgemuth, January 2010

An Investigation of Skirts

Predicted heat transfer to various surfaces of the pot with a 10mm steel skirtPredicted heat transfer to various surfaces of the pot with a 10mm steel skirt

Finned Pots as a Means of Increasing Efficiency Dale Andreatta, Ph.D., P.E.,, February 13, 2009

Finned PotFinned Pot

Executive Summary A pot with heat transfer fins has much greater surface area than pots with no fins. In theory, this could lead to greatly increased heat transfer to the pot for a given stove, and the pot would theoretically improve the performance of the stove under all conditions. While we often concentrate on the stove as the primary element of a cooking system, the efficiency of a stove is mainly determined by the heat transfer to the pot, and designing a better pot would be an easy way to make a more efficient stove. A variety of types of finned pots were built and tested. The best designs were separated out in the lab, using natural gas to simulate a wood flame. Several types of fins can be retrofit to existing pots. The better designs of finned pots performed well over a range of conditions using simulated stoves, and sometimes also with an actual wood burning stove modified to use natural gas to simulate a wood flame. With fins on or near the bottom of the pot the finned pots typically gave around a 1.76-fold improvement in heat transfer. If the fins were on the sides of the pot a greater than 2-fold improvement was achieved. Tests on actual stoves using wood as the fuel generally gave smaller improvements in performance, generally 1.33 or less, corresponding to a 25% or smaller reduction in fuel usage. These tests were done under a variety of conditions with a variety of stoves, including the open fire (3-stone fire). On industrial fuel stoves using kerosene or alcohol, improvements were even less, with the finned pots giving 1.2 fold improvements or smaller. In some tests the finned pot used more fuel than an unfinned pot. The reasons for this wide range of results is not known. It is not recommended that finned pots be pursued as a means of increasing the efficiency of stoves. Better results can probably be achieved with less effort by using skirts around the pot. These skirts could be attached to the pots with optimum dimensions. See attached report presented to ETHOS 2009

Dale Andreatta November 14, 2004, Updated January 17, 2005

Executive Summary

Dale Andreatta, April 30, 2003

Background and overview

Recently, success has been achieved in making insulative bricks for stoves. My work here seeks to answer the following questions:

  1. What are the thermal properties of these bricks? The properties of interest are density, specific heat, and thermal conductivity.

Heat Flux Report January 2006, Dale Andreatta, January 2006

Omega Engineering makes a small heat flux sensor, a thin device about 25 mm by 25 mm
with 40 embedded thermocouples, which puts out a voltage proportional to the heat flux
through the device. This device was used to perform a series of experiments designed to
begin to answer the following questions:

  1. In a cooking pot that is being heated, where does the heat enter the pot, the bottom
  2. center, bottom edges, the sides, or uniformly?
  3. How much of the heat is transferred through radiation vs. how much of the heat is
  4. transferred through convection?
  5. Can one measure the temperature distributions in the gas around the pot, and can
  6. anything be learned about the heat transfer from these temperature distributions?
  7. Can the heat flux sensor be used to determine the effectiveness of skirts?

Heat flux is defined as heat flow per unit area, and the units are Watts/m2. Another
concept is heat flow, which is the total amount of heat being moved, in Watts. Heat flow
is the integral of the heat flux over the total area, or in other words, the average heat flux times the total area.
In science, it is often useful to compare the conclusions and results with conclusions
drawn from other measurements. If the measurements are consistent, this gives us
confidence that the measurements are accurate. If the measurements are not consistent,
the results may be reported, but the inconsistencies must also be pointed out. In this
report, a rigorous effort will be made to find inconsistencies, both within the data that
was measured, and in comparison with other data that was previously measured.

For more detail, see the attached report:

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