Actually no. The temperature measurements were made in 6 minutes of time. The Lewan report said that the collected the sample at 18:57 and the temperatures were measured at + 6 minutes 19:03. If you use the temperature readings just before the 18:57 you get a difference of 5.5 degrees. This was at 18:53 by his record. So where is the 12 minutes you speak of? I also felt like the addition of the cooling of the condensed water down from 100 was expected, but I decided to use Mats Lewan's calculation as he posted it. Now, the actual quality of the .91 grams/second water vapor mix is questionable. There is evidence that the quality is not 100 % as I posted within my last document. So, in actuality, the error is probably even more than I allowed. I asked Mats about his measurement technique. He told me he was very careful to maintain the height of the hose.
Mats told me that the water came out smoothly and without bubbles. He said that the water filled the tubing within virtually no time, seconds at most. The water was collected for 6 minutes of time, certainly enough to detect any pulses of flow or large variations which he did not see. He collected enough water to measure with no difficulty. I trust his data much more than I have faith in the thermocouples readings. Mats went to extreme lengths to ensure that he did not disturb the test setup as he gathered his sample. The evidence is overwhelming. There is very little chance that these particular thermocouple readings are even close to correct. Dave -----Original Message----- From: Jed Rothwell <jedrothw...@gmail.com> To: vortex-l <vortex-l@eskimo.com> Sent: Thu, Nov 10, 2011 9:04 pm Subject: Re: [Vo]:Oct 6 Heat Exchanger Manifold Thermocouple Placement. David Roberson <dlrober...@aol.com> wrote: .91 grams/second x 2260 joules/gram = 2056.6 watts. Water all assumed to be vapor which is not being conservative. You forgot to add the heat required to go from tap water temp to boiling, 267 J. (29.8 C - 24.5 C + .8 C) = 6.1 C Measured at time of water collection with correction factor included. No, this was 12 minutes after he began collecting the water. The maximum power available is approximately 2056.6 watts versus a reading of 4538.644 watts. This is far too much to neglect. Please explain how the small error expected could allow this? Possible sources of error: 1. As noted, the measurements were 12 min. apart. The power was fluctuating rapidly when this occurred, as you see in the graphs. Both answers might be right. 2. It is difficult to measure this flow rate with precision using Lewan's method. He had to make sure the hose was full before he started, and then let it dribble out into the collection flask. He measured 328 g in 360 seconds. It could easily have been more. Granted it might have been less, too, but I suppose it was more. A few bubbles in the hose or unexpectedly high back pressure from holding up the hose will retard the flow. Not much will make it go faster. That is my experience with hoses of this dimension and ornamental pond pumps, in my 200 L outdoor pond. You can retard the flow easily with those things. Just look at 'em cross-eyed. You can measure it three times and get three different answers. The flow rate from the tap, on the other hand, is extremely reliable and predictable. I have measured that often and found remarkably small differences. It has way more pressure behind it. If the flow was higher, that would bring it closer in line to the cooling loop measurement. I am not suggesting that either method constitutes ideal calorimetry! But measuring the condensate is a rough-and-ready approximation at best. The cooling loop flow method is better. I would trust it more no matter where the thermocouples are placed. I am not saying that Lewan's measurement of the flow is useless. But I expect it is an approximation. - Jed
