So I could (some other day) set up a spreadsheet with a few cells. The critical factor is local humidity, which can be measured. All other factors considered, there'll be a humidity threshold beyond which evaporative cooling won't work.
Helpful, thanks! (Note to self: link to said spreadsheet (when done) from cooling wikipage (if that page exists). As usual, unless someone beats me to it. O:-)) Lucas El 04/09/2013 09:56, "Henner Zeller" <h.zel...@acm.org> escribió: > On 4 September 2013 00:51, Henner Zeller <h.zel...@acm.org> wrote: > > On 3 September 2013 23:54, Lucas González <lucas.gonzalez...@gmail.com> > wrote: > >> Interested. Would evaporative cooling work _at all_ in humid climates? > > > > If you are close to 100% humidity: no. In particular since you want to > > cool down the air, you need to look at the amount of humidity in the > > _target_ temperature range; if you already have a pretty humid > > climate, then this might already be oversaturated at the target > > temperature, so nothing can be evaporated more. Swamp coolers are only > > useful in dry climates. > > > > It is relatively simple: you really just need to calculate the partial > > gas pressure of water vapor in the given target temperature (colder > > air can hold less water), and how much more could 'fit in' given the > > dryness of the climate (how much water vapor is already there per m^3 > > and how much more you can add). This looks like a useful resource: > > > http://www.engineeringtoolbox.com/water-vapor-saturation-pressure-air-d_689.html > > With that, you can calculate the amount of water you can evaporate > > into a given volume. > > Given the required target temperature and knowing how much heat energy > > is supplied every second (estimate energy intake by the yurt area in > > sun in Joule (<< 1000 J/(m^2 * s) (1000W energy of sun per m^2, but > > most of it is reflected with aluminum covered sheets, hence the 'much > > less than' sign) + number of people * 100 J/s (typical heat 'exhaust' > > of a human is 100W) > > + temperature gradient outside/inside and energy flow due to that > depending on the insulation > of your insulation material. > > > and the amount of energy taken by the water->steam > > transition (2260 J/g water evaporation heat) - you can calculate the > > grams water you need to evaporate per time unit (to fit the energy > > bill) and flow rate (to keep the air dry enough to be able to take on > > this mass of water per time-unit). > > > > -h > > > >> Perhaps with some modifications? I think not but haven't tried. > >> Sleepbreeze.com.uk does seem to work, but that's one body, not one > room. > >> > >> Thanks, > >> > >> Lucas > >> > >> El 04/09/2013 08:32, "ken winston caine" <ken.winston.ca...@gmail.com> > >> escribió: > >> > >>> David is right. You definitely need to have an exhaust vent. Swamp > cooling > >>> cools by moisture evaporating in dry air -- not by creating > increasingly > >>> swampy air. You must draw fresh dry air in, and let the moist air out. > >>> > >>> Since the moist, cooler air falls to the floor, it is best not to > depend > >>> upon a roof exhaust vent. A mid-height window, or open door will do > the > >>> trick. > >>> > >>> RE: your test. You didn't tell us WHERE, what region, you were > conducting > >>> the test in. Were you in a region with 30% or less relative humidity? > If so, > >>> your test would be a good indicator of the effectiveness of the > evaporative > >>> cooling, once you have the intake and exhaust set up correctly. If you > were > >>> in a higher humidity zone, there is no point in running the test. It > simply > >>> won't give you any indication of how the evaporative cooling will work > in > >>> low-humidity, desert conditions. > >>> > >>> Hope that helps. > >>> > >>> ken winston caine > >>> > >>> > >>> On Tue, Sep 3, 2013 at 11:41 PM, David Kelso <david+goo...@kelso.id.au > > > >>> wrote: > >>>> > >>>> A swamp cooler needs to be constantly moving fresh air in, humid air > >>>> out in order to keep cool. So you should aim to have a directional > >>>> airflow path. It can go up to the roof, or out to the door. You need > >>>> to make sure the outlets are big enough that the fan isn't fighting > >>>> any extra pressure inside the yurt. An outlet fan would help with that > >>>> but isn't strictly necessary > >>>> > >>>> The major factor in swamp cooler effectiveness is fan speed. Which fan > >>>> were you using? > >>>> > >>>> For anecdotal evidence, last year I was in a 6ft stretch and was > >>>> getting at least 30 degree F cooling throughout the whole yurt. > >>>> > >>>> On Tue, Sep 3, 2013 at 10:19 PM, Jason Adams > >>>> <jasonadamspriv...@gmail.com> wrote: > >>>> > So I setup an H12, with two swamp coolers, with insulated ducts into > >>>> > opposite ends of my Yurt. Just cut a hole for the ducts. > >>>> > > >>>> > Its going to be hard to describe, but I still felt like the swamp > >>>> > coolers or > >>>> > the yurt wasn't really cooling much. I felt like being out in the > sun, > >>>> > but > >>>> > in the breeze was way more cooling that in a h12 with two swamp > coolers > >>>> > running. The airflow really close to the duct holes was nice, but > once > >>>> > you > >>>> > got more than a foot away from duct, you didn't really feel it. > >>>> > > >>>> > It also felt hot inside, maybe thats just the moisture or sticky > icky > >>>> > feeling you get from releasing that much moisture in the air. > >>>> > > >>>> > It's definitely nice not having the intense light on you, the yurt > >>>> > certainly > >>>> > kept alot of that sun off the ground , probably getting a cooling > >>>> > ground > >>>> > effect, but I feel like I was missing some comfort. > >>>> > > >>>> > I feel like my options are to basically vent the yurt, or do a fan > >>>> > exiting > >>>> > air at the top of the yurt. Which would ideally get more airflow in > the > >>>> > yurt > >>>> > -- however I feel like that would lose some of the effect of the > swamp > >>>> > cooling (after all I'm sealing the bottom to keep the cool air in > >>>> > right?). > >>>> > > >>>> > Maybe what I really needed was some type of airflow in the yurt, > either > >>>> > up > >>>> > the power of the swamp cooling fans -- or hang a big fan from the > top > >>>> > of the > >>>> > yurt. > >>>> > > >>>> > Just trying to figure out how to make this thing more comfortable, > >>>> > because I > >>>> > honestly felt cooler under a shade structure, with some pillows and > the > >>>> > breeze coming through. > >>>> > > >>>> > Thoughts? > >>>> > > >>>> > -- > >>>> > You received this message because you are subscribed to the Google > >>>> > Groups > >>>> > "hexayurt" group. > >>>> > To unsubscribe from this group and stop receiving emails from it, > send > >>>> > an > >>>> > email to hexayurt+unsubscr...@googlegroups.com. > >>>> > To post to this group, send email to hexayurt@googlegroups.com. > >>>> > Visit this group at http://groups.google.com/group/hexayurt. > >>>> > For more options, visit https://groups.google.com/groups/opt_out. > >>>> > >>>> -- > >>>> You received this message because you are subscribed to the Google > Groups > >>>> "hexayurt" group. > >>>> To unsubscribe from this group and stop receiving emails from it, > send an > >>>> email to hexayurt+unsubscr...@googlegroups.com. > >>>> To post to this group, send email to hexayurt@googlegroups.com. > >>>> Visit this group at http://groups.google.com/group/hexayurt. > >>>> For more options, visit https://groups.google.com/groups/opt_out. > >>> > >>> > >>> -- > >>> You received this message because you are subscribed to the Google > Groups > >>> "hexayurt" group. > >>> To unsubscribe from this group and stop receiving emails from it, send > an > >>> email to hexayurt+unsubscr...@googlegroups.com. > >>> To post to this group, send email to hexayurt@googlegroups.com. > >>> Visit this group at http://groups.google.com/group/hexayurt. > >>> For more options, visit https://groups.google.com/groups/opt_out. > >> > >> -- > >> You received this message because you are subscribed to the Google > Groups > >> "hexayurt" group. > >> To unsubscribe from this group and stop receiving emails from it, send > an > >> email to hexayurt+unsubscr...@googlegroups.com. > >> To post to this group, send email to hexayurt@googlegroups.com. > >> Visit this group at http://groups.google.com/group/hexayurt. > >> For more options, visit https://groups.google.com/groups/opt_out. > > -- > You received this message because you are subscribed to the Google Groups > "hexayurt" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to hexayurt+unsubscr...@googlegroups.com. > To post to this group, send email to hexayurt@googlegroups.com. > Visit this group at http://groups.google.com/group/hexayurt. > For more options, visit https://groups.google.com/groups/opt_out. > -- You received this message because you are subscribed to the Google Groups "hexayurt" group. 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