Earlier quoted context omitted.
It already has. There is a noticeable shift in temperatures here in the Netherlands. Hot days are getting hotter and much more frequent. Snow is getting rare. We had a yearly ice skating event that never happens anymore because there is no ice. Weeks of 30C weather are getting more common while not long ago, hotter than 25C was considered exceptional. It’s like daily temperatures are just shifted +5 degrees within 2…
Which yearly event was this?
“Cold Tube” cooling system uses half the energy of an air conditioner
91–100 of 137 posts
Re: “Cold Tube” cooling system uses half the energy of an air conditioner
#92Re: “Cold Tube” cooling system uses half the energy of an air conditioner
#93Earlier quoted context omitted.
That's true of the ones that have only one hose to the outside. Those with two hoses are much better, especially if you insulate the hoses: https://news.ycombinator.com/item?id=24023979
I was recently shopping for an AC unit and had to get a portable one because I have bars over my windows. Having seen the Technology Connections video I naturally tried to get a dual-hose model, but after seeing the specs (and the prices) I ended up getting a single-hose model anyway. If we go by the DOE SACC ratings, this single-hose toshiba [0] has a 14% higher SACC rating than this dual hose whynter [1], for the s…
The reason dual hose are more efficient is mainly that single hose portable A/Cs pull the air used to cool the radiator and compressor (and expel hot air outside) from the same room they're cooling.
That air has to come from somewhere, so it's going to pull warm air from everywhere it can, door, windows, any creaks/holes/openings, etc. And the fans have some serious airflow/CFM.
Dual hose designs pull air from outside and expel it back outside.
So technically it should be capable of getting your room colder and keeping it that way with less compressor usage.
The cold part of the A/C just circulates air around the room on any model.
Looking at my model, I could turn it into a dual hose design - it pulls air from the rear, right below the exhaust vent. That seems to be the case for a lot of these. Creating an attachment/adapter to connect another hose seems easy enough.
Re: “Cold Tube” cooling system uses half the energy of an air conditioner
#94Earlier quoted context omitted.
That's true of the ones that have only one hose to the outside. Those with two hoses are much better, especially if you insulate the hoses: https://news.ycombinator.com/item?id=24023979
I was recently shopping for an AC unit and had to get a portable one because I have bars over my windows. Having seen the Technology Connections video I naturally tried to get a dual-hose model, but after seeing the specs (and the prices) I ended up getting a single-hose model anyway. If we go by the DOE SACC ratings, this single-hose toshiba [0] has a 14% higher SACC rating than this dual hose whynter [1], for the s…
If you're suffering just get the single tube and look for a dual tube unit some time in the future. Singles aren't as great but they still do the job well enough that you're not dying from the heat.
I went years without any AC and my bedroom wall faces south. My room would get so hot in the summer I couldn't get any sleep. Tried an evaporative cooling unit because they're cheap which did absolutely nothing for me. Eventually broke down and got a portable AC which unfortunately was a single hose unit. You really need to look carefully at what you're buying because the whole single/dual tube thing doesn't seem to be something the sellers put out there. Even though it it was a single it still made a world of difference. On really hot days it doesn't get super cold but cool enough that I don't notice the heat.
Re: “Cold Tube” cooling system uses half the energy of an air conditioner
#95The author doesn't really explain it well because his explanation breaks some physics laws, so it doesn't "suck" your body heat away. Instead, it lowers the amount of heat radiating onto you from your environment by replacing hot walls with cold walls, which will lower the temperature of your skin. It's efficient specifically because it doesn't cool by convection (like every other cooler). This allows the designers t…
Thermal radiative coupling is bidirectional. Sucking away is appropriate and important as you do actually have to displace the energy somewhere. It works the same way when sucking air. A simpler non-radiating equivalent would be a reflective foil, or a polished metal - you could enclose yourself within it, get no radiating heat from environment, yet it wouldn't help cool you, because your radiation has no place to go…
I still feel like "sucking" is misleading because it doesn't change how much heat you radiate, only how much heat is radiated on to you. A better analogy would be like a curtains for heat.
Re: “Cold Tube” cooling system uses half the energy of an air conditioner
#96I saw a very promising AC technology at CES in january that people may find interesting: https://www.oxicool.com/ I don't have the material science or chemistry background to know how effective it is, but I hope everything they claim holds water, it sounds pretty good. There's also a DIY water based AC with pipes and a cheap pump you can find widely on the internet, but I haven't done it yet. Here's an example https:…
They bury it slightly, but in the FAQ:
"The primary energy for HomeCool™ is derived from clean open flame burn of natural gas. This can be converted with an optional kit to propane and also hydrogen* (*once commercially available)."
It burns gas. It may work in a similar manner to absorption refrigerators often found in RVs. https://en.wikipedia.org/wiki/Absorption_refrigerator
Burning gas isn't exactly a clean energy source. In fact, we need to be aggressively exploring ways to stop burning gas for heating - not starting to burn more for cooling!
Re: “Cold Tube” cooling system uses half the energy of an air conditioner
#97Earlier quoted context omitted.
New buildings are rather efficient in US. The problem is old buildings that use 5X the energy for HVAC. I echo that AC is quite efficient. Far more efficient than traditional heating. There's a misconception that hot areas are less environmentally friendly due to AC. The opposite is true. Hot areas are only 25 freedom units hotter than humans prefer. Cold areas have months of 50+ temperature difference. The misconcep…
> New buildings are rather efficient in US. The problem is old buildings that use 5X the energy for HVAC. I was describing my home renovation project to someone who lives in Brazil. I don't how true this is for that entire country, but she said that it's very uncommon for Brazilian homes to have insulation.
This is the same for many homes in Spain and Portugal too. For most of the year it's warm enough outside and you can be comfortable without AC (especially if you are in an older building with thick stone walls), but then for the one or two months of winter it is so cold inside, even though it may only get down to 10C (50F) outside. Most houses rely on resistive electric heaters (if they have any) which end up being very expensive to run.
I live in a modern house in Northern Europe, and we don't even turn our heating on until it gets below freezing. Because we have good insulation, only then it starts to drop below 22C (72F) inside.
Re: “Cold Tube” cooling system uses half the energy of an air conditioner
#98Earlier quoted context omitted.
Thermal radiative coupling is bidirectional. Sucking away is appropriate and important as you do actually have to displace the energy somewhere. It works the same way when sucking air. A simpler non-radiating equivalent would be a reflective foil, or a polished metal - you could enclose yourself within it, get no radiating heat from environment, yet it wouldn't help cool you, because your radiation has no place to go…
I still feel like "sucking" is misleading because it doesn't change how much heat you radiate, only how much heat is radiated on to you. A better analogy would be like a curtains for heat.
I think that the analogy is used because people underestimate how much heat is lost to radiation. Human body radiates energy away at about 800W. It's not noticeable, because normally it is balanced by a similar flux of thermal radiation coming in from the environment. If the apparent radiative temperature of the environment is reduced it can indeed feel like it is sucking heat out.
Re: “Cold Tube” cooling system uses half the energy of an air conditioner
#99Earlier quoted context omitted.
https://en.wikipedia.org/wiki/Elfstedentocht
This event took place 15 times in the last century. How can this be yearly?
I agree it's hardly a yearly event, but this is definitely the even he is referring to. Theoretically yearly would be a better term.
Re: “Cold Tube” cooling system uses half the energy of an air conditioner
#100Earlier quoted context omitted.
Here's something I don't understand though, if we put a blackbody in deep space, would it eventually be cooled/heated to the temperature of the cosmic background radiation? The space around us is filled with photon coming from Sun at ~5500K, but it doesn't heat anything to anywhere near that. So given the current density of cosmic background radiation at 411 photon cm -3, would it be sufficient to place a blackbody t…
> if we put a blackbody in deep space, would it eventually be cooled/heated to the temperature of the cosmic background radiation? No. As you note, in space in our vicinity there is a hot object, the Sun, in the sky, so the "temperature" of space in our vicinity is not really the 3K of the CMB, because an object placed in space in our vicinity will not come to thermal equilibrium at that temperature, but at some high…
Nice. Seems related to: https://en.wikipedia.org/wiki/Planetary_equilibrium_temperat...
The temperature of a perfect black body in earth’s orbit would be ~255K (-18C)
(This is not the case for the technology under discussion because it’s very much not a black body)
I will point out that even at modest (astronomically speaking) distances, the solid angle of a star gets preeeeetty small. For example, a black body at just 1 light year from the Sun (just a quarter of the way to Alpha Centauri) would come to an equilibrium temperature of ~1K (assuming an otherwise empty universe). So that’s already a smaller effect than the CMB.
I think in intergalactic space, the thermal equilibrium of a black body would be absolutely dominated by the CMB.