MM,
I know that you understand how it works, but many does not. On an other discussion, I got the question that I thought many should ask and the discussion is at the end of this mail. At 19:23 03/02/2004, you wrote: >Good one. I was just looking at some fountains yesterday for outdoors, and >thought of your comments as to how folks will be drawn to city areas where >fountains are placed. > >On Mon, 26 Jan 2004 13:55:33 +0100, you wrote: > > > > >MM, > > > >I am glad that you found rope curtains interesting and wrote, > > > >Ancient AC units or, humidity is more important. > ><http://energysavingnow.com/hvac/ropecurtains.shtml>http://energysavingno > w.com/hvac/ropecurtains.shtml > ><snip> You have to give it to the person who was skeptical, he did have the guts to voice it, many does not. This, because many do not understand it, even most of HVAC engineers and it is better that I explain it for them. I will try to insert the explanation in the original article. ------------------------------------ Answer on first mail My answer is inserted in the question, I will explain it. Click on the link, <http://energy.saving.nu/help/intro/IMG00001.GIF>http://energy.saving.nu/help/intro/IMG00001.GIF This is the Molliere diagram and show how much water (horizontal axis) air contains at different % of relative humidity (curves), with different temperature (vertical axis). The Air cannot contain more than 100% humidity. The body cannot use transpiration to get rid of its energy at 100% humidity, if it cannot compensate the body temperature will go up and fever will occur, which is very uncomfortable. In normal conditions the body use evaporation to get rid of 22% of its energy. If you do physical work it needs more evaporation and an athlete can produce up to 1 kW body heat during exercise. Look at 10 degree Celsius and 100% humidity and you find that the air contains 7.5 g/kg. If you then heat up the air and move along the vertical axis, you find that the relative humidity is around 73% and can take up 3 g/kg water more to reach 100% humidity. The body will be able to use this and feel more comfortable. Look at 10 degree again and change the temperature to 5 degree Celsius and follow it to the 100% curve and you can see that you end up at 5.5 g/kg air. The difference 7.5 - 5.5 = 2 g/kg cannot stay in the air and will fall out to surfaces. Inserted is the logic and how it works, At 18:00 26/01/2004, you wrote: >Thanks, Hakan, for spreading lots of good information on energy >efficiency. However, your latest subtlety regarding the rope curtain >has me a bit skeptical. I'm wondering if "rope curtain as dehumidifier" >is really a correct explanation of a mode in which a rope curtain can >operate? I can see how it would humidify via a wicking effect, I did not talk about wicking effect, that will not work. I talked about adding water and this must be done from the top of the curtain. >but >I don't see how to use it to dehumidify. Here's my logic. If we follow Mollier's logic it works as I said, it is a little bit different. >Rope curtain as humidifier: by keeping the rope wet (say, by putting >one or both ends into a pail of water), passing air can be >humidified. The enthalpy of the air stays the same, but its temperature >decreases as it gives up some heat to the evaporation process. Comfort >is enhanced (in times of dry heat) by reducing the temperature, and the >comfort "cost" if the increased humidity does not, hopefully, offset all >of that benefit (there must be a point on the psychrometric chart where >comfort is enhanced by an enthalpy-neutral move toward increased humidity). Cool down very humid air in the curtain and water will fall out to the cooler water that is constantly applied, since the air cannot have more than 100% humidity. Chiller towers in the AC technology works also in this way. >Rope curtain as dehumidifier: by keeping the rope curtain cool and/or dry, >passing air is dehumidified. (Presumably water must be removed from the >rope Water will flow from the top to bottom, where it is channeled out or in a deposit. >curtain as the condensation occurs -- how? -- and the rope curtain may >also be cooled but not by evaporation -- so how?) The enthalpy of the >air stays the same (or is decreased if the rope curtain is cooled) while its >temperature increases as it gains some heat from the condensation process. >Comfort is enhanced (in times of high humidity) by reducing the humidity, >and the comfort "cost" of the increased temperature does not, hopefully, >offset all of that benefit (there must be a point on the psychrometric >chart where comfort is enhanced by an enthalpy-neutral move toward decreased >humidity, unless active cooling of the rope curtain is used). Active cooling is applied with the cooler water that is added to it. The added heat will be carried away by the water. >Mostly, I don't see how to cool a rope curtain non-evaporatively. So, I >can't >see how it would implement "cooling-with-dehumidification". And I doubt >that >there exists a point on the psychrometric chart where decreased humidity and >increased temperature (with no enthalpy decrease) can increase comfort. > >How, then, to explain Hakan's "heater in Grandma's room" ? I'm not sure >I can. This is easier, as I already told you in my first sample. By lowering the relative humidity with heat, the body can use this possibility to evaporation to cool itself down. I hope that this and fountains etc. (including water chillers) is clearer now. --------------- His answer on this "Thanks, Hakan, yes, now I see how a rope curtain with a constant flow of cold water would be actively cooled, making dehumidification possible. I never knew that a waterfall could take moisture out of the air! But if the humidity is high, the air is hot, and the waterfall is cold, you've just shown how it can! Hm. I'll make sure I got this right. A waterfall usually adds moisture: to dry air (of course) and to cold wet air even at 100% RH (the water can warm the air and then add a bit of extra moisture). The exception is a cold waterfall in hot humid air, which subtracts moisture from the air (by cooling it below the dew point and by removing the heat given off by condensation of dew). In the case of the rope curtain (also a cold waterfall in hot humid air), a small part of the perceived benefit may be from direct reduction of the air temperature by sensible heating of the water ... but the majority of it will be from the reduction in water load carried by the air. When the air is then re-heated, it will be less humid and the whole "body evaporation" trick can start to work in earnest." ------------- My final answer Now you will always remember me, when you go to the beach on hot humid summer days. -:)) You will also think about this on many occasion, when you recognize the quite common conditions of utilization of the mechanism of the body. Wished we could make dwelling for people also. Our environment and adaption to it is a marvelous thing. For sure, God is not an Architect or HVAC engineer. Probably a self made tinkerer, who learned from experiences and I often wonder at which stage he made the mankind. Judging our waste of energy, email SPAM on internet, pollution, etc. It must have been early in the process and of course he made man before woman. LOL -------------- Ending of my answer to you That explain why I reacted when you said that you were thinking of me. -:) I bet you that many, who read the article will do that. Hakan Biofuel at Journey to Forever: http://journeytoforever.org/biofuel.html Biofuels list archives: http://archive.nnytech.net/index.php?list=biofuel Please do NOT send Unsubscribe messages to the list address. To unsubscribe, send an email to: [EMAIL PROTECTED] ------------------------ Yahoo! Groups Sponsor ---------------------~--> Buy Ink Cartridges or Refill Kits for your HP, Epson, Canon or Lexmark Printer at MyInks.com. Free s/h on orders $50 or more to the US & Canada. http://www.c1tracking.com/l.asp?cid=5511 http://us.click.yahoo.com/mOAaAA/3exGAA/qnsNAA/FGYolB/TM ---------------------------------------------------------------------~-> Yahoo! Groups Links To visit your group on the web, go to: http://groups.yahoo.com/group/biofuel/ To unsubscribe from this group, send an email to: [EMAIL PROTECTED] Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
