RE: [Vo]:Manifold mispositioning makes measurements meaningless
This is a lot of good work, Alan. I am amazed at the number of high quality posts on Vortex. I am having trouble keeping up because each post warrants a good deal of thought. I examined pictures of the manifold and created a diagram to capture the important features. [I made a small .png version of the diagram that I am trying to include.] I am not sure it is schematically correct yet. A characteristic that I believe is very important in the analysis of the possible temperature contamination is the issue of the fittings used in the manifold. These use pipe threads, and appear to be NPT because of the use of pipe dope. At each junction of pipe threads, there will be a large thermal resistance compared to continuous brass. Analysis of these across-the-thread resistances are going to be hard, particularly with pipe dope and or Teflon tape present as is required to seal NPT. The resistance across the thread boundaries will be high and the net effect will be to significantly decouple the Tout thermocouple from the manifold. These thread boundary effects don't appear to be included in your model. If the 35kB .png of the diagram I created doesn't make it through the thread, email me and I will send it to you direct. Regards, Bob Higgins -Original Message- From: Alan J Fletcher [mailto:a...@well.com] Sent: Wednesday, October 26, 2011 6:49 PM I have built a SPICE circuit simulation model of the manifold --- and the results are VERY BAD An initial small-scale model indicates that the ENTIRE top of the manifold is contaminated by the HOT side. Even with a stepped manifold (representing the various pipe fittings) , and with the thermocouple at the END of the tube, I get a 10 C ERROR ! My preliminary results are at : http://lenr.qumbu.com/rossi_ecat_oct11_spice.php I can make a more accurate model with Spice, but a Finite Element Model is clearly needed. attachment: ExchangerManifold_sm.png
Re: [Vo]:Manifold mispositioning makes measurements meaningless
Maybe you have an error with your simulation since the number does not seem to match the real world results. What kind of flow did you assume in the primary? I think that vapor condensation is where the most action is since that takes so much more energy than cooling the hot condensed liquid. I wish someone would have been wise enough to place the thermocouple well. Dave -Original Message- From: Alan J Fletcher a...@well.com To: vortex-l vortex-l@eskimo.com Sent: Wed, Oct 26, 2011 6:49 pm Subject: [Vo]:Manifold mispositioning makes measurements meaningless I have built a SPICE circuit simulation model of the manifold --- and he results are VERY BAD An initial small-scale model indicates that the ENTIRE top of the anifold is contaminated by the HOT side. Even with a stepped manifold (representing the various pipe ittings) , and with the thermocouple at the END of the tube, I get a 0 C ERROR ! My preliminary results are at : ttp://lenr.qumbu.com/rossi_ecat_oct11_spice.php I can make a more accurate model with Spice, but a Finite Element odel is clearly needed. (lenr.qumbu.com -- analyzing the Rossi/Focardi eCat -- Hi, google!)
Re: [Vo]:Manifold mispositioning makes measurements meaningless
At 03:55 PM 10/26/2011, David Roberson wrote: Maybe you have an error with your simulation since the number does not seem to match the real world results. What kind of flow did you assume in the primary? I think that vapor condensation is where the most action is since that takes so much more energy than cooling the hot condensed liquid. I wish someone would have been wise enough to place the thermocouple well. My initial simulation assumes primary 100C water IN at 15 L / hour, and the secondary 30C water leaving the heat exchanger at 600 L / hour. The height of my manifold model is approximately right, but it's probably 1/2 the correct length. I plan to calibrate the water/water simulation and then consider steam/water. The manifold is so short that I don't think there would be significant condensation in it -- so the heat transfer will be the same for superheated or saturated (100% dry) steam.
Re: [Vo]:Manifold mispositioning makes measurements meaningless
Your simulation looks interesting and might generate good correlation when it is honed in. I would expect the heat exchanger manifold body to settle at a temperature somewhere between the ECAT exit temperature and the output water temperature of the exchanger. The relative flow rates must weigh into the equation as you seem to be suggesting. Do you think that the vapor condensation active area might be a big piece of the puzzle? One more issue that I think will be important is that the pressure within the heat exchanger must be near atmospheric. This should cause a modest amount of the liquid leaving the ECAT under pressure to flash into a large volume of vapor. Have you been able to make an estimate of the relative volume of vapor versus liquid entering the manifold? Keep up the great work. -Original Message- From: Alan J Fletcher a...@well.com To: vortex-l vortex-l@eskimo.com; vortex-l vortex-l@eskimo.com Sent: Wed, Oct 26, 2011 7:06 pm Subject: Re: [Vo]:Manifold mispositioning makes measurements meaningless At 03:55 PM 10/26/2011, David Roberson wrote: Maybe you have an error with your simulation since the number does not seem to match the real world results. What kind of flow did you assume in the primary? I think that vapor condensation is where the most action is since that takes so much more energy than cooling the hot condensed liquid. I wish someone would have been wise enough to place the thermocouple well. My initial simulation assumes primary 100C water IN at 15 L / hour, and the secondary 30C water leaving the heat exchanger at 600 L / hour. The height of my manifold model is approximately right, but it's probably 1/2 the correct length. I plan to calibrate the water/water simulation and then consider steam/water. The manifold is so short that I don't think there would be significant condensation in it -- so the heat transfer will be the same for superheated or saturated (100% dry) steam.
Re: [Vo]:Manifold mispositioning makes measurements meaningless
http://www.engineeringtoolbox.com/overall-heat-transfer-coefficients-d_284.html water-copper-air is 13.1 (W/m2 K) steam-copper-air is 17 And for flowing water/steam, I think that the MASS flow is what counts, not the volume flow, so there isn't a big transferdifference between the two.
Re: [Vo]:Manifold mispositioning makes measurements meaningless
There is a problem with you simulation, in my opinion. The number of cells in your model increases linearly with the distance from the flow. But it increases linearly because your model is 2D. If it were a 3D model, the number of cells would increase by the square of the distance, and the diffusion of heat would be much slow. 2011/10/26 Alan J Fletcher a...@well.com I have built a SPICE circuit simulation model of the manifold --- and the results are VERY BAD An initial small-scale model indicates that the ENTIRE top of the manifold is contaminated by the HOT side. Even with a stepped manifold (representing the various pipe fittings) , and with the thermocouple at the END of the tube, I get a 10 C ERROR ! My preliminary results are at : http://lenr.qumbu.com/rossi_** ecat_oct11_spice.php http://lenr.qumbu.com/rossi_ecat_oct11_spice.php I can make a more accurate model with Spice, but a Finite Element Model is clearly needed. (lenr.qumbu.com -- analyzing the Rossi/Focardi eCat -- Hi, google!)
Re: [Vo]:Manifold mispositioning makes measurements meaningless
I was referring to the fact that the steam is condensing and not just loosing heat slowly along the entire distance. We know that the stream consists of entirely water some where near the end of the primary exchanger output port. The pipes from that point forth are in the form of a plumbing trap and hold liquid water throughout. Since the water traps steam somewhere within the exchanger, it seems like the active condensation region will change as the net flow into the condenser changes. Do you think that this active condensation region must vary with net flow? What happens as the net flow approaches zero as a thought experiment. The last point that allows condensation must finally get to the manifold as the remainder of the exchanger fills with liquid water. Am I wrong in thinking that the major heat transfer is due to condensation? This is a complicated issue but I am sure you can get it resolved. -Original Message- From: Alan J Fletcher a...@well.com To: vortex-l vortex-l@eskimo.com Sent: Wed, Oct 26, 2011 7:26 pm Subject: Re: [Vo]:Manifold mispositioning makes measurements meaningless http://www.engineeringtoolbox.com/overall-heat-transfer-coefficients-d_284.html water-copper-air is 13.1 (W/m2 K) steam-copper-air is 17 And for flowing water/steam, I think that the MASS flow is what counts, not the volume flow, so there isn't a big transferdifference between the two.
Re: [Vo]:Manifold mispositioning makes measurements meaningless
At 04:44 PM 10/26/2011, Daniel Rocha wrote: There is a problem with you simulation, in my opinion. The number of cells in your model increases linearly with the distance from the flow. But it increases linearly because your model is 2D. If it were a 3D model, the number of cells would increase by the square of the distance, and the diffusion of heat would be much slow. I already noted that --- it is more easily done by changing the values by row (eg C is proportional to volume), and the horizontal R-values are proportional to the circumference.
Re: [Vo]:Manifold mispositioning makes measurements meaningless
At 04:48 PM 10/26/2011, David Roberson wrote: I was referring to the fact that the steam is condensing and not just loosing heat slowly along the entire distance. The manifold section of pipe is very short compared to the length of the hose from the eCat, and the (effective) length inside the heat exchanger. SOME steam will condense, but without a nucleating site it will tend to become supercooled, : see http://lenr.qumbu.com/rossi_ecat_steam_v410H.php#hosecondense Cantwell's simulation showed little condensation in the hose.
Re: [Vo]:Manifold mispositioning makes measurements meaningless
Well, are you sure? If you see the object in 3D, the object is not symmetrical, so, it is not a matter of just increasing the radial value. 2011/10/26 Alan J Fletcher a...@well.com At 04:44 PM 10/26/2011, Daniel Rocha wrote: There is a problem with you simulation, in my opinion. The number of cells in your model increases linearly with the distance from the flow. But it increases linearly because your model is 2D. If it were a 3D model, the number of cells would increase by the square of the distance, and the diffusion of heat would be much slow. I already noted that --- it is more easily done by changing the values by row (eg C is proportional to volume), and the horizontal R-values are proportional to the circumference.
