[Stoves] Box 6

Crispin Pemberton-Pigott crispinpigott at outlook.com
Wed Dec 2 12:33:53 MST 2015


Dear Frank

Pots are different in material and mass but we can easily normalise for that by using the mass and specific heat. For colour, the heat loss can easily be measured (paper forthcoming).

The losses from the ‎pot are the only thing that has to be overcome to simmer and at the moment it is not even included in the formula.

So the metal block is not good. It would be like using an empty pot. We can do much better. What really matters is the diameter because the diameter, as repeatedly shown, changes the performance of some stoves by changing the air flow through it.

The pseudo pot just creates combustion conditions. I already know what the steady state thermal efficiency is from lab tests (59%).

We learn from this simple test: power, stability, fuel capacity, char production, duration and if I wanted, control, but I didn't do that.

I said I would come to Dushanbe and talked about the design of a rural space heating stove. I will provide some social science inputs so everyone can follow along to give ideas. The first item is fuels: local not so good coal, good imported coal, wood, cotton stalks and dung. That is five fuels.

Tomorrow I will measure a couple of installed stove efficiencies to get a glimpse of their heating efficiency. ‎There are numerous models on the market. They have to be cheap, meaning under $100.

Regards
Crispin


Dear Crispin,

Therefore each lab doing the tests would be need to receive and use the same style pot? Rather than a pseudo pot? That would be more representative.

The other tasks are not that simple. Heat going into an oven. Heat at the surface of a griddle. Not sure the thermo transfer of heat through a block of iron but something to capture the heat then measuring what is captured  might work for pseudo work(?).

Many tests use a Standard to compare results against. Growing cucumbers we have a standard potting mix then compare the growth of cucumber plants using high dose of the test compost in the mix and compare to the growth and health  to the standard. Also different labs can be tested by making sure their Standard mix is consistent and the same as every other certified lab.  I am wondering if the block of iron could be what we use to do our comparing - somehow.

Dushanbe?  You are getting around and because of it I am learning a lot about geography.

Regards

Frank

Frank Shields





> On Dec 2, 2015, at 10:46 AM, Crispin Pemberton-Pigott <crispinpigott at outlook.com> wrote:
>
> Dear Frank
>
> I would prefer to use a real pot that is representative of one being used in the target community.
>
> I was just looking at the burn rate and the burn time. In other words I was only testing the combustor.
>
> Regards from Dushanbe
> Crispin
>
>
>
>
>
>
> Dear Stovers,
>
> Crispin writes:
>
>
>>
>>
>> There was no pot involved. I used a pseudo pot to prevent outside air diving into the combustion zone. The cooking power is calculated, not measured.
>
> I believe this has nothing to do with this stove. It is just an idea presented of how we might go about testing stoves and the terminology being used. Suggesting the same method can be used on other types of stoves. The pseudo pot is  likely a flat metal plate in place of a pot. So the values mean little until the energy of the metal plate is calibrated for the task it is to represent. Box 6.
>
> Box 6 idea.
> The plate is heated until water drops spatter on the surface. Then a cube of iron 10cm X 10cm X 10cm is placed on the plate for the time duration found to cook a pot of rice. Then the block is removed and placed into a bucket of water and the temperature rise determine. This same cube is used for the time it takes for flat bread etc.
>
> Once it is standardized for the different tasks we can determine if there was too much heat, too little or within the range required.
>
> Regards
>
> Frank
>
> Frank Shields
>
>
>
>
>
>
>
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