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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='color:#1F497D'>Thanks Crispin,<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#1F497D'>It seems that there may be enough moisture in the air to be a factor in cooling considering all the air that is needed? Especially when we get the noise level of fuel and un-even combustion under control.<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'>I was just wondering if there was a way to easily determine the amount of actual moisture in the air should we want to add that to the calculations.<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#1F497D'>Regards<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'>Frank<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#1F497D'>Frank Shields<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'>42 Hangar Way<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'>Watsonville, CA 95076<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'>(831) 724-5244 tel<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'>(831) 724-3188 fax<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'>frank@bioCharlab.com<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#1F497D'> <o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'><p class=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-bounces@lists.bioenergylists.org [mailto:stoves-bounces@lists.bioenergylists.org] <b>On Behalf Of </b>Crispin Pemberton-Pigott<br><b>Sent:</b> Tuesday, December 20, 2011 7:57 PM<br><b>To:</b> 'Discussion of biomass cooking stoves'<br><b>Subject:</b> Re: [Stoves] Water vapor calc.<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><span lang=EN-CA style='color:#1F497D'>Dear Frank<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-CA style='color:#1F497D'>Humidity is just a way of expressing the moisture content of the air. Instead of expressing it in % (of what it <i>could</i> hold without condensing at that temperature and pressure) one could express it as the mass of water per cubic metre of air at that temperature and pressure. For example you could say 14 g of water vapour per m<sup>3</sup>. <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-CA style='color:#1F497D'>Cooling that air causes the moisture to release its latent heat, warming the air (opposing the cooling) causing it to cool more slowly. If the humidity is really low, air will drop in temperature very rapidly at night.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-CA style='color:#1F497D'>You could calculate (in absolute terms) the quantum of energy in any particular cubic metre of air if you know the temperature, pressure and mass of water vapour in it.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-CA style='color:#1F497D'>Regards<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='color:#1F497D'>Crispin<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='color:#1F497D'><o:p> </o:p></span></p><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal><span lang=EN-CA style='color:#1F497D'>+++++++</span><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'><o:p></o:p></span></p></div></div><p class=MsoNormal><span lang=EN-CA><o:p> </o:p></span></p><p class=MsoNormal>Dear Stovers,<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>A few questions if you don’t mind. <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Enthalpy of water is 104.73 kj/kg at 25 deg. C<o:p></o:p></p><p class=MsoNormal>We need to add 4.186 kj/kg/deg. C (4.186 X 75) 314 to equal 419 to reach 100 deg. C<o:p></o:p></p><p class=MsoNormal>We need to add (2675 – 419) =2256 kj/kg to get to a vapor. And have enthalpy of 2675 kj/kg at 100 deg. C. <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>But then the water vapor goes up to 400 deg. C in a stack. <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>So we add 1.72 kj/kg / deg. C or 300 X 1.72 = 516. So 516 + 2675 = 3191 kj/kg in the water vapor at 400 deg C. (?)<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>When the vapor cools off it releases a lot of energy. Its interesting to me that water vapor at 25 deg. C has so much more energy than water in a liquid! <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>How does humidity calculate into all this? <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Thanks<o:p></o:p></p><p class=MsoNormal>Frank<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Frank Shields<o:p></o:p></p><p class=MsoNormal>42 Hangar Way<o:p></o:p></p><p class=MsoNormal>Watsonville, CA 95076<o:p></o:p></p><p class=MsoNormal>(831) 724-5244 tel<o:p></o:p></p><p class=MsoNormal>(831) 724-3188 fax<o:p></o:p></p><p class=MsoNormal><a href="mailto:frank@bioCharlab.com">frank@bioCharlab.com</a><o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p></div></body></html>