[Stoves] Development of culturally appropriate stove testing methods

Fri Jun 8 13:09:46 CDT 2018

Dear Paul and All

I have a few comments on the content, mostly for clarification.

Re:
https://www.researchgate.net/project/Development-of-Culturally-Appropriate-Stove-Testing-Methods<https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.researchgate.net%2Fproject%2FDevelopment-of-Culturally-Appropriate-Stove-Testing-Methods&data=02%7C01%7C%7C5969836a85d44460ce7608d5cafe95bc%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636638117133194506&sdata=szGgIihrZ1%2FrxJvbf%2By0Vue3IWmBOIx2CY3bLcdldfE%3D&reserved=0>

>2.  It is about stove testing METHODS.   Key is the water heating test (WHT) as an alternative to the water boiling test (WBT).

The WHT was written up by Christina from YDD and me a few years ago with specifics on how it was applied in the WB Pilot in Central Java. I am sure that document was provided to this list.

>Bring the pot of water to 80 deg C and then put on another pot to continue heating, repeat as long as the test time.

This method is applied in the Indian IS13152 1992, as I recall. That test also requires the use of a specified pot size selected from 27 standard pots, selected on the basis of the firepower of the stove. The intention is to introduce some contextuality related to anticipated use.

>3.  The changing of the pot of water means no intentional changing of the power of the stove during the test.   That is, there is no "simmering" stage (which is a major contention in the WBT).

That is not a complete description. The firepower can be varies to reflect various patterns of use. Usually we operate the stove at three different power levels (minimum) and using two different common pot sizes.

>And no "fiddling" with the turn-down abilities.

Well, if you wish. The method can be applied to any burn sequence you like.

>A stove can be run at high power, and again SEPARATELY at middle or low power.  But not mixing the power levels.

You can do either. It depends on what you are investigation. If you are rating the performance for regulatory purposes, it is very likely there will be a test sequence that is relevant to the cooking culture.

>I am not so sure that the word "heterogeneous" is the right term, but that could just be my personal opinion.

The word is used to reflect that use of multiple conditions in order to produce performance curves, rather than a single performance number. The HTP is based on a concept of providing the sort of information you get when selecting a water pump. There are pump curves, not a single number. There are several SeTAR Centre publications containing performance curves for different pot sizes. The efficiency, combustion efficiency and PM vary on a curve and do not have a single value.

>…the publication does not make an issue about culturally appropriate testing of cooking methods.

It is implicit in the method: swapping pots is a very inexpensive way to get real time efficiency testing during any proxy cooking sequence you like.

>5.  "Solid-Fuel" is a key term, and in this publication does NOT refer to wood or dry biomass.   The fuels discussed are charcoal and coal.   That is fine, but they are a limited subset of the varieties of solid fuels.

The method is not restricted to certain fuels. We have even used it for electric stoves.

6.  …the common South African [Imbaula] (bucket burning of coal) that was IGNITED IN TWO DIFFERENT WAYS.    The traditional way is to ignite at the bottom (call it bottom lit or BL) and the other is at the top (top lit or TL).  See the report for the differences.   My one comment is that the use of the "TLUD" name (normally associated with wood micro-gasification) is a bit of a stretch when presenting a single-walled, metal, "largish" bucket with many side holes and filled with coal.

The TLUD combustion approach has been promoted by the South African government since at least 1975. In those days it was called ‘the Scotch method’ which dates back to at least 1895. The Mbaula can be (and is) constructed to optimise the combustion using primary and secondary air holes in various patterns. The hole patterns strongly affect the combustion quality.

>Maybe Crispin or Taffy can tell us about any further plans (or options) for stove testing with the WHT.

The CSI test method as currently employed in, for example, Indonesia, China and Mongolia, is the WHT in terms of the cooking performance assessment. However we no longer use pot-swapping. We have installed a heat exchanger in the pot so we can cool it continuously. Water is circulated in a copper pipe.

Considering the input and output temperatures, the mass of water inside the pipe, the water mass in the pot, and the pot mass and material, the total heat gained by the pot can be calculated on a continuous basis. This is automated in the HPT Spreadsheet.

Similarly, the water heating ability of a low pressure boiler (hydronic heater) is assessed using the same approach. Water is circulated through the heat exchanger, the volume is known, the metal mass of the heater portion of the stove is known, and the expansion of water within the heat exchanger is compensated for temperature changes. This, together with the flow rate and two temperatures (in and out)  yields the heat gained by the heat exchanger.

The cooking and water heating function can be conducted simultaneously. Using the Chinese Hebei test sequence, there is an ignition period, a high power heating period, a long low power heating period, a high power cooking period, and then a high power heating period. The total test is 6H45. This has been shown to replicate the comparative performance of 24 hr tests duplicating actual behaviour of farmers in Hebei province. Thus it is a WHT, it is contextual to Hebei, it is culturally appropriate, and it provides a comparative performance rating. This method was used to select stoves to be supported in the Hebei Clean Air Programme (800,000 homes). Many stoves already on the market were tested. Some of them were found to be very clean burning relative to a ten-year-old stove which served as the baseline.

Regards
Crispin
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