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Dear Philip the Kerosene stove tester</div>
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I want you to clarify first which efficiency you are referring to so we are looking at the same result. </div>
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For the entertainment of the Group, Philip and I are both on the ISO Working Group that is compiling a list of definitions of terms and there are many 'efficiencies'. An efficiency is a good ratio, a fraction, so there are lots of choices of what to put on
top and bottom. </div>
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In the meantime I will have a look for some tests including the one mentioned below and something closer to the pressure head you describe. </div>
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On another note, a pressure head that is glowing red is <i>far</i><span> too hot to work properly. Even considering the delta T across the thickness of the material, being cooler on the inside, it will be impossible to avoid the decomposition of the fuel leaving
free carbon in the gas. Once free, it deposits in sharp surfaces, grows, breaks off in the flowing gas stream and blocks the nozzle. That's why pressure stoves and lanterns have a 'pricker' which is a thin wire used to unblock the nozzle. </span></div>
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<span>I had not noticed a relationship between the really hot evaporators and the overall efficiency. I did notice that the stove which had a pumped air bladder had a tendency to overheat the fuel with radiant heat from the head. I 'aged' the top surface by
making it black, as if burned food had accumulated here and there. This changed the reflectivity and raised the fuel temperature well above the legal limit. </span></div>
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<span>Is this radiation a large portion of the heat loss? If so it would be easy to fix. </span></div>
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<span>I'll get back to you soon with example(s). </span></div>
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<span>Thanks</span></div>
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<span>Crispin </span></div>
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<p class="x_MsoNormal"><span style="color:#1F497D">Dear Crispin</span></p>
<p class="x_MsoNormal"><span style="color:#1F497D">You say “</span><span lang="EN-CA">A good kerosene stove is going to be above 45-50% efficient</span><span style="color:#1F497D">.” I have yet to find one doing above 42%, and a good average value was 35%.
The better ones were pressure stoves; wick stoves were invariably poorer. </span>
</p>
<p class="x_MsoNormal"><span style="color:#1F497D">The interesting question is where all the losses come from. In the wick stove it is outward radiation from the heater, which glows red-hot in operation to provide the energy to evaporate the kerosene from the
wick. But the loss of efficiency in the pressure stoves really puzzles me.</span></p>
<p class="x_MsoNormal"><span style="color:#1F497D"> </span></p>
<p class="x_MsoNormal"><span style="font-size:10.0pt; font-family:"Arial","sans-serif"; color:#1F497D">Prof Philip Lloyd</span><span style="font-size:12.0pt; font-family:"Times New Roman","serif"; color:#1F497D"></span></p>
<p class="x_MsoNormal"><span style="font-size:10.0pt; font-family:"Arial","sans-serif"; color:#1F497D">Energy Institute</span><span style="font-size:12.0pt; font-family:"Times New Roman","serif"; color:#1F497D"></span></p>
<p class="x_MsoNormal"><span style="font-size:10.0pt; font-family:"Arial","sans-serif"; color:#1F497D">Cape Peninsula University of Technology</span><span style="font-size:12.0pt; font-family:"Times New Roman","serif"; color:#1F497D"></span></p>
<p class="x_MsoNormal"><span style="font-size:10.0pt; font-family:"Arial","sans-serif"; color:#1F497D">PO Box 652, Cape Town 8000</span><span style="font-size:12.0pt; font-family:"Times New Roman","serif"; color:#1F497D"></span></p>
<p class="x_MsoNormal"><span style="font-size:10.0pt; font-family:"Arial","sans-serif"; color:#1F497D">Tel:021 460 4216</span><span style="font-size:12.0pt; font-family:"Times New Roman","serif"; color:#1F497D"></span></p>
<p class="x_MsoNormal"><span style="font-size:10.0pt; font-family:"Arial","sans-serif"; color:#1F497D">Fax:021 460 3828</span><span style="font-size:12.0pt; font-family:"Times New Roman","serif"; color:#1F497D"></span></p>
<p class="x_MsoNormal"><span style="font-size:10.0pt; font-family:"Arial","sans-serif"; color:#1F497D">Cell: 083 441 5247</span><span style="font-size:12.0pt; font-family:"Times New Roman","serif"; color:#1F497D"></span></p>
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<p class="x_MsoNormal"><b><span style="font-size:10.0pt; font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt; font-family:"Tahoma","sans-serif""> Stoves [mailto:stoves-bounces@lists.bioenergylists.org]
<b>On Behalf Of </b>Crispin Pemberton-Pigott<br>
<b>Sent:</b> 30 July 2015 10:23<br>
<b>To:</b> Stoves<br>
<b>Subject:</b> [Stoves] New document from ESMAP</span></p>
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<p class="x_MsoNormal" style="background:white"><span lang="EN-CA">Dear Friends of Big Reports</span></p>
<p class="x_MsoNormal" style="background:white"><span lang="EN-CA"> </span></p>
<p class="x_MsoNormal" style="background:white"><span lang="EN-CA">There is a document you can get at
</span></p>
<p class="x_MsoNormal" style="background:white"><span lang="EN-CA" style="font-family:"helvetica neue"; color:black"><a href="https://openknowledge.worldbank.org/bitstream/handle/10986/21878/96499.pdf?sequence=1">https://openknowledge.worldbank.org/bitstream/handle/10986/21878/96499.pdf?sequence=1</a></span></p>
<p class="x_MsoNormal" style="background:white"><span lang="EN-CA" style="font-family:"helvetica neue"; color:black"> </span></p>
<p class="x_MsoNormal"><span lang="EN-CA">which is from ESMAP</span></p>
<p class="x_MsoNormal"><span lang="EN-CA"> </span></p>
<p class="x_MsoNormal"><span lang="EN-CA">It makes for very interesting reading, from great observations to howlers. It appears to have been written mostly by policy makers but makes many technical claims as well.</span></p>
<p class="x_MsoNormal"><span lang="EN-CA"> </span></p>
<p class="x_MsoNormal"><span lang="EN-CA">Some points are really worth debating here:</span></p>
<p class="x_MsoNormal"><span lang="EN-CA"> </span></p>
<p class="x_MsoNormal"><span lang="EN-CA" style="font-size:11.5pt; font-family:"Arial","sans-serif"">“LPG is a clean, non-toxic fuel that emits little particulate matter and burns efficiently. Compared
</span></p>
<p class="x_MsoNormal"><span lang="EN-CA" style="font-size:11.5pt; font-family:"Arial","sans-serif"">to kerosene, it delivers double the heat for the same quantity used.”</span></p>
<p class="x_MsoNormal"><span lang="EN-CA" style="font-size:11.5pt; font-family:"Arial","sans-serif""> </span></p>
<p class="x_MsoNormal"><span lang="EN-CA">Which quantity would that be? Certainly not per $. Mass? LPG has about the same energy content per kg as kerosene so this claim surprised me. A good kerosene stove is going to be above 45-50% efficient, fuel heat to
pot heat. LPG is about 65% efficient on a good day. I would say that is 30-45% better.</span></p>
<p class="x_MsoNormal"><span lang="EN-CA"> </span></p>
<p class="x_MsoNormal"><span lang="EN-CA">Maybe they meant LPG with a modern good condition burner compared with an old wick stove. In that case if could be more than double. If we compare really good kerosene stoves with LPG there is no difference. Peak efficiency
at, say, 1.25 kW is comparable though I have seen a cheap wick stove from China that outperformed a new LPG stove at that power level (71% v.s. 65%).</span></p>
<p class="x_MsoNormal"><span lang="EN-CA"> </span></p>
<p class="x_MsoNormal"><span lang="EN-CA">Why is anyone so certain kerosene is such a bad fuel? Is it perhaps bad stoves that cause the problem? The long term answer is low pressure stoves because they avoid all sorts of pressure-related problems and does
away with wicks at the same time (they lose effectiveness over time). We need some new inventions.</span></p>
<p class="x_MsoNormal"><span lang="EN-CA"> </span></p>
<p class="x_MsoNormal"><span lang="EN-CA">One of the objections raise against kerosene compared with LPG in South Africa was from the fuels industry. With LPG they control the distribution right to the last mile. With kerosene, all sorts of people are involved
in micro trading fuel in plastic bags (!) and bottles.</span></p>
<p class="x_MsoNormal"><span lang="EN-CA"> </span></p>
<p class="x_MsoNormal"><span lang="EN-CA">Unlicensed people! Ordinary folks! </span>
</p>
<p class="x_MsoNormal"><span lang="EN-CA"> </span></p>
<p class="x_MsoNormal"><span lang="EN-CA">Anyway, have fun reading. There are contributions from all the usual suspects. There are lots of great charts you can cite.</span></p>
<p class="x_MsoNormal"><span lang="EN-CA"> </span></p>
<p class="x_MsoNormal"><span lang="EN-CA">Regards</span></p>
<p class="x_MsoNormal"><span lang="EN-CA">Crispin</span></p>
<p class="x_MsoNormal"><span lang="EN-CA"> </span></p>
<p class="x_MsoNormal"><span lang="EN-CA">PS I see they once again have omitted the stellar performance of the super-clean TLUD coal stoves rolled out in Ulaanbaatar, the most expensive and most successful externally funded stove project ever. It is also the
first time a city’s air pollution has been substantially improved (-63%) without changing the fuel. Eat
<i>that</i>, London…</span></p>
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