Dear Crispin,
<snip> >I think time spent in tending to the stoves is an important stove variable and >should fit there. Time and attention (attention demand) is an important metric for consumers. If we compare a fuel-fire-and-forget stove that runs by itself with one that needs attention every five minutes (for example a traditional 3-pot clay stove) there is a world of difference for the user. Frank –so we need to report Attention Demand along with any test results.. >Yes – the WBT as my understanding it from time back (I need to revisit) does >specify many of the variables. This is important. The WBT’s used to date specify much more than is necessary. The use of ‘normalisation’ means the variable is calculated to a normal, and does not have to be ‘fixed’. For example we do not have to fix the temperature of the day on which we test. Nor the temperature at which the water starts when put into the pot. These things are ‘normalised’ by calculations that account properly for the variations. Many of the elements of a test that are fixed can be handled correctly to allow for the use of, for example, more appropriate pots such as the ones in normal use in the community and ones for which a certain stove is designed. Frank – Thanks for this. Perhaps the WBT does have more usefulness to Real World (RW) interpretation that I first thought. I believe we still need the RW fuel and ‘attention demand’ that simulates RW when determining characteristics of a stove – at least report these values in the report so others using the report can make decisions. > I also think that the stove developer should be able to specify or veto the > fuel type (your 1 and 2). I don't know if that is always possible now. If you are trying to classify the performance of stoves using the same fuel this is wise. If you are testing the ability of stoves to burn a range of fuels, again it is helpful to use known fuel types and they properties. Some stoves handle wet wood much better than other so in a wet country, the comparison is important. Some stoves are operated in a manner that the fuel is dried by the stove before it is put into the fire. Some stoves can’t do that, some can. Comparisons cannot be arbitrary. Wisdom is needed to construct a valid assessment. Frank – This is the difference between research data and data that is RW and can be used for marketing. And if research data is used for marketing there need be Cautions to the consumer. The whole point of a testing toolbox is to have validated methods of dealing with such situations so that once an experiment (comparison) is designed, it provides validated results. You can’t just make up new metrics without check in they are valid. Many problems arise from this. Frank - Agree –some. There are so many variables (six boxes) and within each of the six boxes are many more so we can’t test all possible combinations for all stoves. But we can Control the variables in their group (Box) by systematically organizing them and Report the condition of the Test for each Box. So the matrices may differ but being reported along with results a consumer (NGO?) can ‘read between the lines’ when making decisions. And the NGO may request a set of stoves to be tested using one specific condition from each of the six boxes to simulate the RW location of the planned application. >The stove developer should have no say as to how this test (WBT) is conducted >except for possible suggestions as to his findings to what makes it work best. Well, when designing a stove one may need very particular information that is not required to get a performance comparison with respect to cooking. If you are trying to improve the heat transfer efficiency, you need a method of determining it accurately because the different between two models may be slight, but consistent. A regular WBT is a blunt instrument and cannot tell if one stove is 5% better than another. A heat transfer efficiency test can, however. Frank – All in Research and behind the curtain. Not for the public eyes. >…Anything to give a clue or info where a change can make the not-so-good stove >the same as the good stove and the good stove better. There are particular metrics which provide valuable information about performance. Designers need more information than policy managers. Frank –Agree. All the research concludes with ‘Ten Steps to Making the Perfect Stove’. Otherwise what good is it. Regards Crispin Thanks Frank Thanks Frank Shields BioChar Division Control Laboratories, Inc. 42 Hangar Way Watsonville, CE 95076 (831) 724-5422 tel (81) 724-3188 fax <mailto:[email protected]> [email protected] www.controllabs.com
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