Fluid Heat-sinking an air conditioner?
- Thread starter Sparky
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I have not seen the video, but this is the concept:
www.energy.gov
Geothermal Heat Pumps
Geothermal heat pumps are expensive to install but pay for themselves over time in reduced heating and cooling costs.
Zoomyn
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Boat A/Cs usually count on an endless supply of water to pump through exchanger and carry waste heat away... Some really sexy compact & sturdy units available, imagine the entire hull heated to near 90*f when sailing in tropical waters, cooling and humidity control not optional for 1st World Yachties.
Now if you pumped water from a creek, stream or pond it might be a win - or closed loop circulating coolant through a 25-foot aluminum coil in cool running currents...
For dry camping the numbers are against you - in one hour 6000Btu carries 1750 watts heat, will heat 74 gallons of water... that is 600~ pounds of water and then we have to shed that heat or the A/C will be pushed outside of its design temperature in a short period.
Note that 1750w could also be carried away by evaporating 3/4s of gallon of water so a kiddy pool of water and some evaporation wicks might extend the use times BUT it'd still be an emergency thing.
Now if you pumped water from a creek, stream or pond it might be a win - or closed loop circulating coolant through a 25-foot aluminum coil in cool running currents...
For dry camping the numbers are against you - in one hour 6000Btu carries 1750 watts heat, will heat 74 gallons of water... that is 600~ pounds of water and then we have to shed that heat or the A/C will be pushed outside of its design temperature in a short period.
Note that 1750w could also be carried away by evaporating 3/4s of gallon of water so a kiddy pool of water and some evaporation wicks might extend the use times BUT it'd still be an emergency thing.
Right. "geothermal" also includes "water-source" heat pumps, which fits what you describe.
I looked, but I couldn't find anything. I'm very curious to see if adding multiple heat exchangers with additional power drains actually reduces overall power usage.
sunworshipper
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how long would it take to do this? certainly not in one hour
Yes. 1 hour and change. Calculate for yourself:
Water Heating Calculator for Time, Energy, and Power
The calculators on this page compute how long it takes to heat water, how much energy is consumed, and how much heating power is required.
You would never do this if you were transferring the heat to air, it is a fools errand. Just use a mini split and transfer the heat directly to air. There are not insignificant efficiency losses transferring heat from the refrigerant to water then to air. The less times it has to conducted from one medium to another the better.
I have installed a few through the wall A/C units similar to a larger window shaker. These units would accumulate the condensate in a tray as part of the condenser fan shroud. The condensate was atomized a bit and directed at the condenser by the fan. Seemed to work quite well to improve cooling and get rid of the condensate.
labeeman
Solar Enthusiast
I have one of those it requires 8 gals a minute for the condenser/evaporator depending on the mode. in heat mode, it has a cop of 4.2 in AC mode the seer is 14. 36,000 BTU I have 700' of ground loop
curiouscarbon
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i'm not sure about all of the specific parameters.
sealing the volume seems kind of challenging but doable.
if the secondary radiator for dissipating heat from the glycol to air were oversized, maybe it would work?
seems like using a different architecture might be more cost effective and reliable
if you are still really intent on hacking, these copper tube aluminum radiators are like 100-200 usd for 1-4 square feet of radiator area
efficiency can be defined on many dimensions. i can see this being useful if stuck with a window shaker and wanted to make it quieter and able to set up a secondary radiator somewhere else.
context: I use a midea-U 8000 BTU/hr U-shaped "window shaker" looking unit. it's great and efficient. however, the condenser fan PWM is very annoying. maybe it's the PWM whine of the compressor. I would love to make it quieter, and it's possible to set it up in a non-standard configuration.
if i ever wanted to do this approach, i would probably use epoxy or something to seal the coolant enclosure. hehe. would want to do lots of leak testing.
maybe affix a labyrinth structure to the faces of the condenser coil, to force the water/glycol to move sequentially through all the condenser and get lots of heat exchange. maybe have the water/glycol enter in at where the condenser input is. that's where it's hottest. i'm not sure if trying to go for serial or parallel fluid flow is better, but my gut says trying to focus on the corner of the condenser coil that's hottest is worth it.
after watching the temperatures on the midea 8000 BTU/hr unit, the air outflow from the condenser coil does not regularly exceed 140 °F / 60 °C
these temperatures are normal to deal with in a PC water cooling setting, so I personally think it's something that could work, but would require extra attention to leak management, and maybe end up being a frustrating and ineffective endeavor.
there is also precedent for other fluids, for example:
good luck !
sealing the volume seems kind of challenging but doable.
if the secondary radiator for dissipating heat from the glycol to air were oversized, maybe it would work?
seems like using a different architecture might be more cost effective and reliable
if you are still really intent on hacking, these copper tube aluminum radiators are like 100-200 usd for 1-4 square feet of radiator area
efficiency can be defined on many dimensions. i can see this being useful if stuck with a window shaker and wanted to make it quieter and able to set up a secondary radiator somewhere else.
context: I use a midea-U 8000 BTU/hr U-shaped "window shaker" looking unit. it's great and efficient. however, the condenser fan PWM is very annoying. maybe it's the PWM whine of the compressor. I would love to make it quieter, and it's possible to set it up in a non-standard configuration.
if i ever wanted to do this approach, i would probably use epoxy or something to seal the coolant enclosure. hehe. would want to do lots of leak testing.
maybe affix a labyrinth structure to the faces of the condenser coil, to force the water/glycol to move sequentially through all the condenser and get lots of heat exchange. maybe have the water/glycol enter in at where the condenser input is. that's where it's hottest. i'm not sure if trying to go for serial or parallel fluid flow is better, but my gut says trying to focus on the corner of the condenser coil that's hottest is worth it.
after watching the temperatures on the midea 8000 BTU/hr unit, the air outflow from the condenser coil does not regularly exceed 140 °F / 60 °C
these temperatures are normal to deal with in a PC water cooling setting, so I personally think it's something that could work, but would require extra attention to leak management, and maybe end up being a frustrating and ineffective endeavor.
there is also precedent for other fluids, for example:
good luck !
curiouscarbon
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Would the efficiency of heat transfer not be improved with water over air at the condenser interface specifically?
Do you mean that the specific heat capacity of the water is higher than air and therefore the secondary radiator cooling the water will need to rise to a higher temperature than the original condenser coil itself?
Thermal conductivity of water is like 0.6W/(m•K) but air is like 0.02W/(m•K) and the specific heat capacity of water is 2-4x higher than air at the operating temperature range.
Tesla uses stacked plate heat exchangers in their HVAC system on some vehicles to directly move heat from the glycol loop to the refrigerant. Stainless steel is not that great of a heat conductor compared to aluminum and copper.
Most people buy AC units that sink the pumped heat into the outdoor air via a heatsink with aluminum fins on outside and hollow copper tube on inside, with refrigerant running through tube.
There are aquarium chillers that can do 1000-4000 BTU/hr and more. The nice ones have titanium evaporator interfaces to pump the cooled fluid through.
curiouscarbon
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my midea-U window shaker uses the fan that blows air across the condenser fins to kick up the drained condensate onto the fins, to increase heat transfer via evaporative losses
anti-corrosion material approach mandatory
anti-corrosion material approach mandatory
Partimewages
Solar Addict
The real reason these are designed this way is to evaporate the condensation so it doesn't drip out of the unit.
curiouscarbon
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absolutely not trying to be contrarian..
it does not prevent that at all in my unit. there is a drain for condensate as well. and i absolutely must properly drain the condensate
in some conditions it does indeed evaporate it all away before accumulation occurs
just sharing experience with the midea u 8000 btu/hr ac unit
it does not prevent that at all in my unit. there is a drain for condensate as well. and i absolutely must properly drain the condensate
in some conditions it does indeed evaporate it all away before accumulation occurs
just sharing experience with the midea u 8000 btu/hr ac unit
It also aids in heat removal from the condenser coil. I designed a very large system years ago to cool liquid cooled power supplies, and the final answer was a series of heavily finned radiators with a squirrel cage blowing through them as a constant heat dump, and if the temp exceeded 80deg it turned on stage 2 which was micro misting nozzles to dump substantially more heat. It had to cycle on and off as it would bring the process fluid temps down far enough to cause condensation on the power supplies (more than 20 deg below ambient). Type of water is important, tap water would create terrible deposits, DI water would eat the radiators, so RO water was used.
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