Demonstrations

  • What Is Denatured Ethanol and What Is It Used For?


    Ethanol is pure alcohol and while inadvisable, is drinkable and used in various amounts to make alcoholic drinks.

    Denatured ethanol has a small % of denaturing agent added to make the ethanol undrinkable. Aside from the denaturing agent, denatured ethanol is exactly the same as normal ethanol. The denaturants are added to ensure that the ethanol cannot be consumed as a spirit. In this regard, denatured ethanol is very similar to methylated spirits.

    Methylated spirit is ethanol mixed with methanol. It may have small amounts of other chemicals added, as well as a distinctive purple dye. Mixing ethanol and methanol gives meths a strong, unpleasant smell. Methanol is very toxic when consumed, when absorbed through the skin, or inhaled in high concentrations.

    Because it can't be consumed, no duty applies in the UK meaning it can be acquired quite cheaply.

    As with methylated spirits, denatured alcohol has a number of uses:




  • Running a Trangia or Esbit on EkoFuel Alcohol for Camping Stoves

     

    As you may be aware methylated spirit, the traditionally used fuel for alcohol camping stoves in the UK has been outlawed by European legislation as at July 2013. It was deemed unsafe because of its high methanol content, which was in the recipe as the denaturant to ensure the alcohol was unfit for human consumption.

    In place of methylated spirits sits a new European approved formula free from methanol. You will however continue to see methylated spirits in the shops for a few months until existing stocks are depleted.

    Here at Ekofuel, we have been working with denatured alcohol for a number of years for use on indoor bio-ethanol fireplaces. We are now probably the largest distributor of bio-ethanol fuel for fireplaces in the UK.

    As part of our continually expanding range of products, we decided to launch a bio-ethanol fuel for use on alcohol camping stoves. It will be available from sometime in October 2013. It will be available in 1L and 500ml bottles.

    500ml

    For all those unsure what the bio part refers to, it refers to the fact that the fuel has been made from a fermentation route, rather than a chemically produced route i.e. from the fermentation and distillation grain, sugar beet etc.

    As part of development of the fuel I decided to test the fuel on the long established Trangia. The kit selected was the Trangia UL-27 seen below. A slightly different pot with a larger capacity was used in place of the Trangia pot.

    Trangia

    The internet abounds with information about home made alcohol stoves and whether water should be added to meths to reduce sooting. It seems a common conception that 10% water should be added to the meths to reduce sooting. What it not clear, is whether this is 10% by weight or 10% by volume as there is quite a large difference.

    For my money, fuels should not be watered down. Why? Well, from a scientific view point water has a very high specific heat, higher than metals. What this means is that not only are the fuels less powerful per gram, but the fuels also need to heat up and evaporate the water added to the fuel!

    This wastes precious energy which could be used to heat the food or water in the pan.

    On this basis I decided to test the neat undiluted fuels in the Trangia.  When testing the fuel I was focusing on the following issues:

    Boil time: 1 litre of water from 21C to 100C (using data logger). The photo below shows the rig used (note larger pot capacity). The times quoted are from the very second that the Trangia was first lit. Approx 10-15 seconds was lost putting the pan and lid into position, this is included in the times quoted.

     Figure 1

    Figure 1

    This accurately recorded the temperature the water reached 100C rather than a rolling boil.

    1)      The amount of sooting on the pans – recorded via photographs.

    2)      Fuel consumption. Measured with electronic balance and data logger during burning trail.

    In testing the Trangia I found that the pans heavily sooted in high separation distance between burner and pan. This will be discussed below. In light of this, I tested an adaptation to the Trangia to improve the burning of the fuel, the results of which are also discussed below.

    The results are presented in the format Standard Trangia and Modified Trangia

    Findings:

    After conducting various test under laboratory conditions I found the following:

    Standard Trangia Setup

    1) Boil Times: Using EkoFuel, the times taken to heat up 1 litre of water from 21C to 100C  varied between 8 minutes 58 seconds and over 10 minutes. The difference was due to the changing separation distances between the burner and the underside of the pot. The faster time was achieved with the pot in the high setting (as in the set-up photo Figure 1) and the Trangia sat in its standard position.  I also found that adding 12.5% by weight of water had a dramatic effect of the boil times. Boil time increased to  11 minutes 24 seconds.

    In order to test the lowest separation distance between burner and pan, I changed to  a Trangia 1L pan with 700ml of water in it. The boil time for this low setting was 10 minutes 48 seconds.

    2) Amount of Sooting*:- For me this is a key issue. What a user wants is relatively clean pans. At the start of the testing I ran the Trangia on meths purchased at our local hardware store.

    I ran it pure and I ran it with 10% by weight water. On both occasions the underside of the pans were heavy in soot, the 10% water mix slightly less sooty than the 100% meths. The results from using EkoFuel on the Trangia were no better. Figure 2 below shows the first result taken using pure EkoFuel when a boil time of 8 minutes 58 seconds was achieved in the high separation distance setting shown in Figure 1.

    Figure 2Figure 3

         Figure 2                                                                           Figure 3

    Figure 3 shows the sooting with 12.5wt% water. Although slightly better than the pure EkoFuel, I would still class it as a lot of soot. Figure 4 below shows the underside of the pans when EkoFuel is burnt in the low pan/burner separation distance setting.

    Figure 4

    Figure 4

    It can be seen that the low  separation distance setting creates less sooting, however it also dramatically increases the boil times as it slowed down the rate of fuel consumption.

    3) Fuel Consumption: Fuel consumption to heat the 1 litre of water from 21C to 100C was around 25g for pure Ekofuel and for the water diluted fuel it was around to 27g both in the high separation setting. For the low separation setting, the fuel consumption was less, normalised out for 1 lt of water, it was around 21g suggesting that the low clearance setting is more slightly more efficient that the high clearance setting.

    Modified Trangia Setup.

    1) Boil Times:- Using the modified Trangia setup the best boil time was 7 minutes 42 seconds in the high clearance setting. An improvement over the standard Trangia of boil times. Water boiled in approx 14% less time than the standard Trangia arrangement. Again the fastest time was achieved in the high pot position. The low clearance setting was not investigated as reasonable results were achieved with the standard Trangia at this setting.

    2) Amount of Sooting*: – Here’s where the big improvements were noticeable. Figure 5 below shows the underside of the pan used with the modified Trangia in the high clearance setting.

    Figure 5 Figure 6

       Figure 5                                                                  Figure 6

    Contrast this with Figure 2 and the improvement is obvious. The small amount of sooting in our opinion would be classed as acceptable. When 10% water was added, the improvements were even better see Figure 6 where the pans are clean.

    3) Fuel Consumption: Pretty similar to those exhibited by the unmodified Trangia maybe slightly more efficient at around 22 to 23g, but I would need to conduct more research to prove this.

    Conclusions

    1) A litre of EkoFuel will heat approx 43-44 litres of water from 21C to 100C in a standard Trangia. I have not calculated the efficiency of this arrangement but will do so in due course and post the result.

    2) EkoFuel bioethanol is suitable for use in alcohol stoves, it is a high powered alcohol fuel and can yield fast boil times. Whether the pans will soot or not, is a function of the alcohol burner design. The better the burner the less the sooting.

    3) The low separation distance between pan and burner leads to cleaner pans, but a significant decrease in boil time as a result of reduced rate of fuel consumption. This low separation distance  appeared to be more efficient that the high clearance setting.

    4) Fast boil times are achieved by having a large separation distance using the standard Trangia setup.

    I have shown that EkoFuel can be burnt cleanly, what the industry needs now is alcohol burners capable of burning bio-ethanol cleanly.

    In light of the improvements I made to the standard Trangia, I am now trying to decide if we should embark on manufacturing an improved cleaner burning alcohol stove for bio-ethanol. If you like the idea, please follow us on Twitter and spread the word.

    If we get enough support and request over the next few months then we may well do so. In the meantime, if you have or know of an alcohol stove that you want us to test with bio-ethanol then feel free to send it to me at Ekofuel. I will test it and post the results for the world to see; I am looking for the cleanest burning stove.

    I look forward to hearing from you.

     

    *Please remember that these results are under laboratory conditions with little or no breeze. Outdoor conditions may reduce the amount of sooting.

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