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“Cold Tube” cooling system uses half the energy of an air conditioner

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Re: “Cold Tube” cooling system uses half the energy of an air conditioner

#81

Post by labawi »

ladberg wrote: post #39

The 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.

Re: “Cold Tube” cooling system uses half the energy of an air conditioner

#83

Post by tobyhinloopen »

CarbyAu wrote: post #41
eggsnbacon1 wrote: post #13

Earlier 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…

Best marketing voice : "Why migrate to the sunbelt? Burn gas and wait for climate change to bring the warmth to you!" ...sigh. I really hope it doesn't go this way.

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 decades.

It’s not just my gut feeling, there are plenty of statistics

Re: “Cold Tube” cooling system uses half the energy of an air conditioner

#84

Post by hoseja »

heisenzombie wrote: post #45

An idea I was told about relatively recently that kind of blew my mind: - Space is cold (~3K) - The atmosphere is really quite transparent in the wavelegth 8-13 μm - If one can construct an optical filter (e.g. grating) which is highly reflective except for a bandpass at 8-13μm, it is possible to reflect most solar energy but still "see" the cold of deep space - It's possible to build a box with sufficiently low ther…

This feels like tricking Maxwell's daemon.

Re: “Cold Tube” cooling system uses half the energy of an air conditioner

#85

Post by yourapostasy »

sd_mikey wrote: post #58
akeck wrote: post #55

Earlier quoted context omitted.

For regular posts on this topic, see the @buildingsciencefightclub Instagram account. Christine writes delightfully clear posts about modern building science.

I also suggest Matt Risinger’s YouTube channel. Lately he’s been talking about Passive House construction, which supposedly uses only 10% of the energy of a standard built house.

Adding to PassiveHaus and Passive House (separate standard from the original PassivHaus) standards, look into NetZero, and Perfect Wall (especially Lstiburek's institutional Perfect Wall).

Re: “Cold Tube” cooling system uses half the energy of an air conditioner

#86

Post by the-dude »

tobyhinloopen wrote: post #83
CarbyAu wrote: post #41

Earlier quoted context omitted.

Best marketing voice : "Why migrate to the sunbelt? Burn gas and wait for climate change to bring the warmth to you!" ...sigh. I really hope it doesn't go this way.

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?

Re: “Cold Tube” cooling system uses half the energy of an air conditioner

#87

Post by yourapostasy »

kristopolous wrote: post #75

I 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:…

That's neat and I'm going to keep an eye on it. The -15° F ambient differential somewhat limits its usefulness, and I'd like to see an induction-powered heater as an option instead of conduction-based heating. I'm guessing the 10-year lifespan is due to the fan bearings and the molecular sieve lifetime, and I'd like to see the overall system lifespan increased by 10X.

Would be interested in the papers behind this tech, as I think there are a lot of caveats they're glossing over.

[1] seems to be a paper on adjacent technology.

[2] seems to indicate the service lifetime of the molecular sieve is the controlling factor in the estimated lifecycle. 10 years sounds like the upper range.

[1] https://aip.scitation.org/doi/abs/10.1063/1.4822041?journalC...

[2] http://www.yyindustry.com/news_show.asp?id=28

Re: “Cold Tube” cooling system uses half the energy of an air conditioner

#88

Post by kristopolous »

yourapostasy wrote: post #87
kristopolous wrote: post #75

I 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:…

That's neat and I'm going to keep an eye on it. The -15° F ambient differential somewhat limits its usefulness, and I'd like to see an induction-powered heater as an option instead of conduction-based heating. I'm guessing the 10-year lifespan is due to the fan bearings and the molecular sieve lifetime, and I'd like to see the overall system lifespan increased by 10X. Would be interested in the papers behind this tec…

They're trying to get version 1 out the door. Hopefully there's a dramatic improvement and optimization curve still available given it's such early days still

Re: “Cold Tube” cooling system uses half the energy of an air conditioner

#89

Post by ekianjo »

sparker72678 wrote: post #7

> The notoriously bad energy efficiency of air conditioners Air conditioners are actually pretty fantastically efficient for what they do. The problem with air conditioners is that there's no way to move a ton of heat without using a lot of energy. So, they do use a lot, but they make the most of it. What's truly bad are our buildings that have the minimal insulation and sealing possible, leaking all that cold air ri…

> The notoriously bad energy efficiency of air conditioners

Their efficiency is based on thermodynamics, so there's not much you can do to break the physical barriers.

Re: “Cold Tube” cooling system uses half the energy of an air conditioner

#90

Post by aeternum »

thescriptkiddie wrote: post #62
userbinator wrote: post #52

Earlier 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 problem with an efficiency rating that includes air ingress is that the outdoor air temperature is an unconstrained variable.

The dual hose unit will likely outperform significantly if the temperature delta is high, but if the temp delta is low then the single-hose unit is probably better as it likely has a more efficient compressor.

It looks like DOE SACC tests assume the outdoor air temp is 83 degrees for 80% of your usage and 95 degrees for 20% of your usage.

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