Re: [Vo]:Test of boiling water in a frying pan
wrote: > ...but you are not actually producing wet steam. You are producing dry > steam > that then condenses to some extent upon contact with the cool air. Also with the sides of the pot. I figured that out after I wrote it. With the flow calorimetry I think it does entrain some unboiled water and splash some out, especially when the water level is high. I did not think to add the tissues to test for that until 2:21 when the water level was down considerably. > "Real" wet steam might be produced in a situation where the flow of steam > was very rapid > and it passed across a wet surface . . . > I figured that out after I wrote it. With the flow calorimetry the water and steam are being pushed out. I can see how this would remove more unboiled water than a pot. However, I do not think it can reduce the amount of power by a factor of 17, and in any case I expect the RH meter does the job. You can see it is close to the site where the reaction occurs, in the upper leg which is wrapped in insulation. I doubt that segment cools down or that water leaves the lower section. Quoting the report: http://www.journal-of-nuclear-physics.com/files/Levi%20and%20Bianchini%20Reports.pdf "The main origin of possible errors in [Test1] measure was that the steam was not checked to be completely dry. During [Test2 ] this measure was done by Dr. Galantini a senior chemist who has used an “air quality monitor” instrument HD37AB1347 from Delta Ohm with a HP474AC probe." For now I think I trust the judgement of Dr. Galantini more than some anonymous person on the Internet who thinks you can boil a flow of 292 ml/min with 700 W. That is enough to raise it to 47 deg C. As I said before, the probe is intended to measure temperatures up to 150 deg C and RH. The probe measures those two only. What would be the point of doing that except to establish that the steam is dry? What other use would there be? The meter has other applications at other temperatures, but this probe measures only those two parameters. If the thing is not adequate to that task, and if the readings might mean that the enthalpy could be as much as 80% lower, or lower by a factor of 17 according to Dr. Anon Guest, why would anyone purchase that probe? I assume the manufacturer and Dr. G. know how to measure enthalpy. If it turns out they don't, then I am making an appeal to authority logical fallacy: http://www.nizkor.org/features/fallacies/appeal-to-authority.html (If Dr. G. really is an expert, then I got lucky, and that is not an appeal to authority after all. You never know.) - Jed
Re: [Vo]:Test of boiling water in a frying pan
In reply to Jed Rothwell's message of Sun, 23 Jan 2011 15:29:03 -0500: Hi, [snip] ...but you are not actually producing wet steam. You are producing dry steam that then condenses to some extent upon contact with the cool air. "Real" wet steam might be produced in a situation where the flow of steam was very rapid and it passed across a wet surface so that water could be entrained in the steam, e.g. a narrow pipe rather than a large open surface. In that situation it could transport water droplets that had never been vaporized. >In the discussion her: > >http://pesn.com/2011/01/21/9501749_Fighting_the_Infection_of_Cynical_Skepticism_with_Cold_Fusion/ > >Someone named Guest insists that it is possible to boil 8.8 kg of water in >30 min with 700 W input. He give a set of reasons similar to the ones cited >here by Horace Heffner; i.e. the enthalpy of wet steam is much lower than >dry steam. If that were true, it would be possible to boil away water much >faster than the textbook heat of vaporization of water indicates, with a >method that produces wet steam. > >I tested this assertion by boiling 500 ml of water in an electric frying >pan. I uploaded the results along with a photo. > >Boiling Water Test > >See attached photo [NOT HERE -- AT WEB SITE] of frying pan with boiling >water and orange indicator light and control set for top temperature. 500 ml >cup in foreground. Data: > >2:11 Power on to highest level 425°F (218°C), nominal 1.5 kW >2:14 Orange indicator shows terminal temperature reached >2:14 500 ml room temperature water added >2:15 Indicator light on again. Pan partly covered to bring to boil >2:16 Boiling >2:17 Pot top removed >2:17 Lots of visible vapor, just above water. Very wet steam. Condensation >on top of pan. >2:21 Not too hot to hand 30 cm above pot. Tissues on table next to pot not >wet. >2:25 Take photo >2:29 Indicator light on steady the whole time; power is continuous >2:32 Tissues remain dry; water is not falling back into pot. >2:32 Close to bottom >2:36 Dry! > >FIRST PHASE Water from room temperature to boiling took 2 min > >2 min * 60 s =120 s >120 s * 1,500 W = 180,000 J = 180 kJ > >Heat capacity of water (4.2 kJ/kgK) and >Temperature change nominally 80°C >Energy to bring water to 100°C: 80°C*4.2*0.5 kg = 168 kJ > >~ 93% heat recovery but probably less because pot was pre-heated to 218°C > >SECOND PHASE 20 min to boil dry > >20 min * 60 s = 1,200 s >1,200 s * 1,500 W = 1,800,000 J = 1,800 kJ > >Heat of vaporization of water (2260 kJ/kg) >Energy to vaporize 0.5 kg of water: 2260*0.5 = 1,130 kJ > >It takes much more than the expected amount of heat to boil the water >because the pot poorly insulated, heat is lost from the bottom and sides of >the pot. Note that the Rossi device is also is also poorly insulated and >loses heat to other paths. The flowing water does not recover all the heat. > >If this were dry steam, heat recovery would be 63% (1130/1800). > >CONCLUSION Boiling water in a pot to produce wet steam gives a value >reasonably close to the textbook heat of vaporization of water (2260 kJ/kg). >It is not possible to boil away water with wet steam in far less time than >predicted by the heat of vaporization. > >Website http://www.engineeringtoolbox.com/wet-steam-quality-d_426.html is >right, and Guest is wrong. Regards, Robin van Spaandonk http://rvanspaa.freehostia.com/Project.html
Re: [Vo]:Test of boiling water in a frying pan
And his wife said Jed can't cook. T
Re: [Vo]:Test of boiling water in a frying pan
Thank you, Jed. That was a worthwhile experiment.
Re: [Vo]:Test of boiling water in a frying pan
Below is a follow up posting at the web site. As far as I can tell, this would apply to Heffner's calculation as well. Assuming the frying pan makes 1% wet steam, it should have taken about 4 minutes for all of the water to leave the pan, by his calculation. I do not think my frying pan is inherently superior to the Rossi device and likely to make much drier steam. - - - - - - - - - - - - - - - - - - Let me add that I have done this test with much better equipment: a well insulated vessel with a submerged joule heater. The recovery rate was much higher. In that test, the steam was quite wet, with entrained droplets of water that fell onto the tissue placed next to the vessel. Yet the overall value was close to the textbook heat of vaporization of water. Guest asserts that it is possible to generate very wet steam with 700 W where dry steam would take 12,000 W, a factor of 17 less. The tests I performed and the formulas at http://www.engineeringtoolbox.com/wet-steam-quality-d_426.html prove this is not the case. Given the flow rate during the Rossi device tests, 700 W would not even be enough to heat the water to boiling. Whatever the dryness of the steam from the Rossi device may be, I am sure that my frying pan is no dryer, so if it is possible to appear to generate steam with 17 times less energy than the textbooks indicate, all of the water in the frying pan would have been gone in 1.2 minutes, instead of 20 minutes.
