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</o:shapelayout></xml><![endif]--></head><body bgcolor=white lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='color:#1F497D'>Peter,<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'>Thanks – I realize there is energy in ice (water) based on deg K starting at zero so now I understand the zero at 0 deg c is just for convenience. Glad they did that. <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<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";color:windowtext'>From:</span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext'> stoves-bounces@lists.bioenergylists.org [mailto:stoves-bounces@lists.bioenergylists.org] <b>On Behalf Of </b>Peter Verhaart<br><b>Sent:</b> Wednesday, January 18, 2012 9:41 PM<br><b>To:</b> Discussion of biomass cooking stoves<br><b>Subject:</b> Re: [Stoves] Calculation help<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>If you start with ice you could define the enthalpy being 0 at 0 C. You always work with enthalpy differences so you should choose a convenient zero condition.<br><br>Peter<br><br>On 19/01/2012 04:32, Frank Shields wrote: <o:p></o:p></p><p class=MsoNormal><span style='color:#1F497D'>Dear Crispin,</span><o:p></o:p></p><p class=MsoNormal><span style='color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span style='color:#1F497D'>Not that this has anything to do with stoves, but if water has 0 enthalpy at 0 deg C and increases 4.186 j/c/g what would be the enthalpy of ice? And ice at -10 deg C.? And water being the densest at 4 deg C does this 4.186 j/c/g constant through the 4 deg C down to 0 deg C? Just wondering.</span><o:p></o:p></p><p class=MsoNormal><span style='color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span style='color:#1F497D'>And is the LHV ever calculated using the temperature of the stack gas? It seems it would not be because some water may have condensed on the cold surface meaning the total water would not all be in the gas phase.</span><o:p></o:p></p><p class=MsoNormal><span style='color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span style='color:#1F497D'>Thanks for your patience.</span><o:p></o:p></p><p class=MsoNormal><span style='color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span style='color:#1F497D'>Frank</span><o:p></o:p></p><p class=MsoNormal><span style='color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span style='color:#1F497D'>Frank Shields</span><o:p></o:p></p><p class=MsoNormal><span style='color:#1F497D'>42 Hangar Way</span><o:p></o:p></p><p class=MsoNormal><span style='color:#1F497D'>Watsonville, CA 95076</span><o:p></o:p></p><p class=MsoNormal><span style='color:#1F497D'>(831) 724-5244 tel</span><o:p></o:p></p><p class=MsoNormal><span style='color:#1F497D'>(831) 724-3188 fax</span><o:p></o:p></p><p class=MsoNormal><span style='color:#1F497D'><a href="mailto:frank@bioCharlab.com">frank@bioCharlab.com</a></span><o:p></o:p></p><p class=MsoNormal><span style='color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span style='color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span style='color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span style='color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span style='color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span style='color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span style='color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span style='color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span style='color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span style='color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span style='color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span style='color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span style='color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span style='color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span style='color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span style='color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span style='color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span style='color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span style='color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span style='color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span style='color:#1F497D'> </span><o:p></o:p></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"'> <a href="mailto:stoves-bounces@lists.bioenergylists.org">stoves-bounces@lists.bioenergylists.org</a> [<a href="mailto:stoves-bounces@lists.bioenergylists.org">mailto:stoves-bounces@lists.bioenergylists.org</a>] <b>On Behalf Of </b>Crispin Pemberton-Pigott<br><b>Sent:</b> Tuesday, January 10, 2012 2:20 PM<br><b>To:</b> Stoves<br><b>Subject:</b> Re: [Stoves] Calculation help</span><o:p></o:p></p></div></div><p class=MsoNormal> <o:p></o:p></p><p class=MsoPlainText><span lang=EN-CA style='color:#1F497D'>Dear Frank</span><o:p></o:p></p><p class=MsoPlainText><span lang=EN-CA style='color:#1F497D'> </span><o:p></o:p></p><p class=MsoPlainText><span lang=EN-CA style='color:#1F497D'>There is no need to over-complicate the issues for HHV.</span><o:p></o:p></p><p class=MsoPlainText><span lang=EN-CA style='color:#1F497D'> </span><o:p></o:p></p><p class=MsoPlainText><span lang=EN-CA style='color:#1F497D'>There are three stages of calculation involved:</span><o:p></o:p></p><p class=MsoPlainText><span lang=EN-CA style='color:#1F497D'> </span><o:p></o:p></p><p class=MsoPlainText><span lang=EN-CA style='color:#1F497D'>From liquid to boiling,</span><o:p></o:p></p><p class=MsoPlainText><span lang=EN-CA style='color:#1F497D'>From boiling to evaporated water at boiling</span><o:p></o:p></p><p class=MsoPlainText><span lang=EN-CA style='color:#1F497D'>From boiled vapour to hotter vapour</span><o:p></o:p></p><p class=MsoPlainText><span lang=EN-CA> </span><o:p></o:p></p><p class=MsoPlainText><span lang=EN-CA>>I realize for biomass the difference between J used in evaporation (2256</span><o:p></o:p></p><p class=MsoPlainText><span lang=EN-CA>j/g) and energy in water at 450c (2854 j/g) is well within the 'noise' of biomass fuel so doesn't matter which one we use.</span><o:p></o:p></p><p class=MsoPlainText><span lang=EN-CA> </span><o:p></o:p></p><p class=MsoPlainText><span lang=EN-CA style='color:#1F497D'>The energy 'at 450' includes parts of all three segments of the calculation. The number 2854 is the sum of three things. I was showing how to calculate them separately.</span><o:p></o:p></p><p class=MsoPlainText><span lang=EN-CA> </span><o:p></o:p></p><p class=MsoPlainText><span lang=EN-CA>> And if we all are using the 2256 value that is what I will do. </span><o:p></o:p></p><p class=MsoPlainText><span lang=EN-CA> </span><o:p></o:p></p><p class=MsoPlainText><span lang=EN-CA style='color:#1F497D'>2257 is probably the most accurate. Often people use 2260 for convenience being a rounder number.</span><o:p></o:p></p><p class=MsoPlainText><span lang=EN-CA> </span><o:p></o:p></p><p class=MsoPlainText><span lang=EN-CA>>But it seems since the hydrogen in biomass never is in a liquid state or never even water vapor before going from solid state to water vapor at ~450 that we should be using 2854 ((2256</span><o:p></o:p></p><p class=MsoPlainText><span lang=EN-CA>+(1.72 X 350)). </span><o:p></o:p></p><p class=MsoPlainText><span lang=EN-CA> </span><o:p></o:p></p><p class=MsoPlainText><span lang=EN-CA style='color:#1F497D'>Hydrogen is in the solid state in the fuel (not the H2 in the moisture, the H2 in the biomass). It is liberated as a gas and most of it burns to water, but not all. There can be quite a lot of H2 in the exhaust. See this graph. The lower line is free H2(EF) which means it is the measured concentration multiplied by (Excess Air +100%). You can see there is nearly a fixed ratio between the CO and the H2. This is common though not universal. Even after 3 hours, there is still lots of free floating H2.</span><o:p></o:p></p><p class=MsoPlainText><span lang=EN-CA> </span><o:p></o:p></p><p class=MsoPlainText><span lang=EN-CA><img border=0 width=378 height=174 id="Picture_x0020_1" src="cid:image001.jpg@01CCD697.52CCA1D0"></span><o:p></o:p></p><p class=MsoPlainText><span lang=EN-CA> </span><o:p></o:p></p><p class=MsoPlainText><span lang=EN-CA>>For the LHV calculation of methane; I see wiki says the HHV is product of water in liquid form </span><span lang=EN-CA style='color:#1F497D'>[and cooled to 0 degrees C] </span><span lang=EN-CA>and LLV is product of water in vapor form - same way you calculate biomass. </span><span lang=EN-CA style='color:#1F497D'>[It has nothing to do with the fuel type, it is how to calculate the heat content of combustion products] </span><span lang=EN-CA>But, of course water is never in the liquid form (until it completely condenses at below 100c.). Hydrogen is held by carbon or then water vapor at the combustion temp. so I am surprised they calculate (estimate) it the way they do. </span><o:p></o:p></p><p class=MsoPlainText><span lang=EN-CA> </span><o:p></o:p></p><p class=MsoPlainText><span lang=EN-CA style='color:#1F497D'>In fact it is pretty reasonable. Lower heating value is what heating can be done by the fire. That is a pretty real world attitude. Yes, it has not been done exactly. But it is easy to calculate.</span><o:p></o:p></p><p class=MsoPlainText><span lang=EN-CA> </span><o:p></o:p></p><p class=MsoPlainText><span lang=EN-CA>>So I will not bother anyone with more questions, will calculate as everyone does (subtract energy from water liquid to water vapor) </span><o:p></o:p></p><p class=MsoPlainText><span lang=EN-CA> </span><o:p></o:p></p><p class=MsoPlainText><span lang=EN-CA style='color:#1F497D'>Yes. The HHV from a bomb calorimeter minus the latent heat of evaporation of the moisture from combustion of Hydrogen gives the useable dry fuel heat called LHV. So far no one has come up with a difference between the latent heat of evaporation and latent heat of condensation. If you can create one, you will have a perpetual motion heat engine!</span><o:p></o:p></p><p class=MsoPlainText><span lang=EN-CA style='color:#1F497D'> </span><o:p></o:p></p><p class=MsoPlainText><span lang=EN-CA style='color:#1F497D'>Regards</span><o:p></o:p></p><p class=MsoPlainText><span lang=EN-CA style='color:#1F497D'>Crispin</span><o:p></o:p></p><p class=MsoPlainText><span lang=EN-CA style='color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'><br><br><br><o:p></o:p></span></p><pre>_______________________________________________<o:p></o:p></pre><pre>Stoves mailing list<o:p></o:p></pre><pre><o:p> </o:p></pre><pre>to Send a Message to the list, use the email address<o:p></o:p></pre><pre><a href="mailto:stoves@lists.bioenergylists.org">stoves@lists.bioenergylists.org</a><o:p></o:p></pre><pre><o:p> </o:p></pre><pre>to UNSUBSCRIBE or Change your List Settings use the web page<o:p></o:p></pre><pre><a href="http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org">http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org</a><o:p></o:p></pre><pre><o:p> </o:p></pre><pre>for more Biomass Cooking Stoves, News and Information see our web site:<o:p></o:p></pre><pre><a href="http://www.bioenergylists.org/">http://www.bioenergylists.org/</a><o:p></o:p></pre><pre><o:p> </o:p></pre></div></body></html>