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</o:shapelayout></xml><![endif]--></head><body lang=EN-CA link="#0563C1" vlink="#954F72"><div class=WordSection1><p class=MsoNormal>Dear Friends<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Here is a new example of a copper tube heat exchanger in a pot:<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><span style='mso-fareast-language:EN-CA'><img width=425 height=266 id="Picture_x0020_1" src="cid:image007.jpg@01D0ACFB.82EA0D10"></span><o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>This was made at the YDD Lab in June.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><span style='mso-fareast-language:EN-CA'><img width=425 height=346 id="Picture_x0020_2" src="cid:image008.jpg@01D0ACFB.82EA0D10"></span><o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><span style='mso-fareast-language:EN-CA'><img width=425 height=229 id="Picture_x0020_3" src="cid:image009.jpg@01D0ACFB.82EA0D10"></span><o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><span style='mso-fareast-language:EN-CA'><img width=425 height=288 id="Picture_x0020_4" src="cid:image011.jpg@01D0ACFB.82EA0D10"></span><o:p></o:p></p><p class=MsoNormal>The white cable ties were covered with epoxy to seal them.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>This is a smaller pot that normal and holds 5 litres. Now we have two and can test a two pot stove.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Here is a set of temperature profiles during a test.<o:p></o:p></p><p class=MsoNormal><span style='mso-fareast-language:EN-CA'><img width=472 height=399 id="Picture_x0020_5" src="cid:image015.jpg@01D0ACFB.82EA0D10"></span><o:p></o:p></p><p class=MsoNormal>The top Cyan line is the water temperature in the pot not rising higher than 60 degrees.<o:p></o:p></p><p class=MsoNormal>The second brown line is the temperature at the gas sample point.<o:p></o:p></p><p class=MsoNormal>The 3<sup>rd</sup> green line is the heat exchanger (water out)<o:p></o:p></p><p class=MsoNormal>And the 4<sup>th</sup> line, light blue, is the inlet side of the heat exchanger. The difference can be read to 0.01 degrees and the noted drift between the two RTD’s was 0.004 max.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>The two low lines, red and blue, are the chiller temps – the gas is chilled using a vortex tube and compressed air to drop the water vapour before going to the gas analyser. This approach is very simple, cheap, and can be used in a high humidity environment for continuous testing even with very high water vapour loads. By changing the compressed air pressure, the chiller can be brought down to 2 C or even lower. The gas warms on the way to the analyser and the relative humidity drops dramatically ensure the cells are not contaminated. The system has no moving parts after the compressor.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>The calculated heat gain by the pot is <o:p></o:p></p><p class=MsoNormal>Water mass x 4.186 x Delta T in the pot, <o:p></o:p></p><p class=MsoNormal>plus the flow rate though the heat exchanger x Delta T x 4.186.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>The shorter 3-metre tube in the large pot is able to handle more than 3 kW of heat gain. The second pot has about 6m of tubing. The flow rate is typically 34-35 cc/second. This is calibrated before and after each test using a bucket and a scale and has proven to be very constant. The 10 second resolution is a few tens to a few hundreds of Joules.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Any burn cycle can be conducted on the stove and the heat gained by the pot determined for any selected interval. It can faithfully report the heat transfer efficiency at any time when combined with a gas analyser that detects water vapour, O2, CO2 and CO (at a minimum).<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Regards<o:p></o:p></p><p class=MsoNormal>Crispin<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p></div></body></html>