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-   -   Ways to make The Mini Split More Efficient (https://ecorenovator.org/forum/showthread.php?t=3781)

nokiasixteth 08-20-17 05:46 PM

Its cool when you look back at projects that get abandoned due to funds . I still on extremely hot days go outside and do a light mist every now and then on my mini split . Here were i am yea it gets hot but the humidity is what is the kicker . It is awful feels like your constantly drowning .
I have been thinking again on doing the earth tubes . But am trying to figure out a way to do it by directional drilling .Already have access to well water but with the tubes and a small fan to shove cooler air in its direction anything helps it .

oil pan 4 08-20-17 06:22 PM

I have an old evap cooler that I want to duct onto the back of my big 2 ton inverter split.
I don't have to buy anything except for maybe some 26ga sheet metal.

ecomodded 08-20-17 07:20 PM

Could use a pool as a ground source Btu bank. the bigger the pool the more available Btu's.

nokiasixteth 08-20-17 07:52 PM

I have an above ground pool . But i swim in it and its already hot enough in there . I am thinking of doing my method of drilling a few shallow water wells and using a light mist with a dc motor . Not very smart on the energy efficient of that type stuff though

jeff5may 08-21-17 10:20 PM

Quote:

Originally Posted by nokiasixteth (Post 55256)
I have an above ground pool . But i swim in it and its already hot enough in there . I am thinking of doing my method of drilling a few shallow water wells and using a light mist with a dc motor . Not very smart on the energy efficient of that type stuff though

Rig your shallow well pump and misting system up to a solar panel and see how it goes. Cool water takes lots of BTU power and efficiency from the ground and deposits that power indoors. It's amazing how just a few degrees cooler of condenser temperature really boosts the comfort indoors.

The process relies on this formula:

gpm = btu/hr / (Delta-T x 500)

For example, at 1 GPM and a 20 degF Delta T, you can cover up to 10k of the heat load with the cool water. How much more air is blowing through the outdoor unit? Thousands of times more.

Even better, these factors add up:

Air heat + water heat = total heat

I'm sure you could get the most out of the existing mini split this way. With the sun providing pump energy and the water washing away the heat, the upgrade would be essentially free to operate after the initial investment. Definitely worth a try.

If the water cooling rig works well on the existing rig, you might want to consider a pump and dump heat pump system instead of the recirculating ground loop setup. If you have the well capacity, it's a lot easier to build and take care of than a massive ground loop. Plus, the supply water temperature remains the same year round. A loop will float around in temperature every cycle as well as with mode of operation.

jeff5may 08-21-17 10:43 PM

If dehumidifying your indoor air is a major priority, the add-on to the existing air conditioning system can address this priority. Most air conditioning units are made to provide some dehumidification (latent) and lots of air cooling (sensible). To cool lots of air, you need lots of airflow. Not so true with dehumidifying.

The moisture in a humid room has to be removed at constant temperature by the heat exchanger, so the first few minutes of every run cycle, the unit is not actually cooling the room at all. Once enough water is removed to lower the dew point, the room temperature starts to drop. As more and more water is removed, the air conditioner becomes much more effective at lowering the air temperature, because it takes a lot less energy to cool dry air than to dehumidify.

To dehumidify, you need a colder heat exchanger and not as much airflow. The water cooling mister outdoors will help keep the indoor coil cold, so it will help the unit gather more water. It is common for dehumidifying units to operate below freezing, collect frost and/or ice, and then run a lengthy defrost cycle to drain all the moisture they just collected. As long as there is still ice on the indoor HX, it is cold enough to keep grabbing moisture while the ice melts. Needless to say, you don't want your minisplit to freeze its indoor coil, so it can only do so much.

Other members have been down that road, and it doesn't take a lot of added capacity to get rid of lots of water. Jake (Memphis), Randy (Randen) and Gary (Xringer) have chronicled their experiments in this realm. They have found that their heat pump water heaters have another purpose: they make effective dehumidifiers. Unlike stand-alone portable dehumidifiers, they don't add heat to the interior space: the heat goes into the water tank.

Another add-on idea that is much less wacky than it sounds is wet desiccant dehumidification. Big dogs, such as FEMA, the Army, the Navy, and others call these rigs atmospheric water generators. They build the units on trailers for huge portable sources of emergency drinking water. A cooling tower collects moisture from the air by pumping a saltwater solution and outdoor air through the tower. The saltwater is then heated, and the water vapor produced is collected for distribution. The remaining saltwater is then pumped back up the tower. Common figures for these systems are 5 gallons of water produced for every gallon of gas consumed and up to 1200 gallons of water output per day per unit. Many a university has won an award by including this type of system to boost energy efficiency of their design home. No longer do the zombie apocalypse shelters need a massive fresh water store: these things work equally well off of solar energy.

nokiasixteth 08-22-17 08:37 PM

Quote:

Originally Posted by jeff5may (Post 55267)
Rig your shallow well pump and misting system up to a solar panel and see how it goes. Cool water takes lots of BTU power and efficiency from the ground and deposits that power indoors. It's amazing how just a few degrees cooler of condenser temperature really boosts the comfort indoors.

The process relies on this formula:

gpm = btu/hr / (Delta-T x 500)

For example, at 1 GPM and a 20 degF Delta T, you can cover up to 10k of the heat load with the cool water. How much more air is blowing through the outdoor unit? Thousands of times more.

Even better, these factors add up:

Air heat + water heat = total heat

I'm sure you could get the most out of the existing mini split this way. With the sun providing pump energy and the water washing away the heat, the upgrade would be essentially free to operate after the initial investment. Definitely worth a try.

If the water cooling rig works well on the existing rig, you might want to consider a pump and dump heat pump system instead of the recirculating ground loop setup. If you have the well capacity, it's a lot easier to build and take care of than a massive ground loop. Plus, the supply water temperature remains the same year round. A loop will float around in temperature every cycle as well as with mode of operation.

My only concern with doing the spraying to much is damaging the fins or getting them gunked up. We have iron in almost all of the water sources i have found . But ive been doing it on and off for about 3 years so far nad it has only made mud . Guess i need to plum a drain off if i done it constant . Fix a snap disk controller to mist at certain temps.

Roshani 08-24-17 06:52 AM

i am new to this forum ...but i really appreciate what you have discussed here..

Regards
Roshani

jeff5may 08-24-17 07:30 AM

My previous post mentions nothing of the latent heat of evaporation. As the water spray is warmed by the outdoor unit, it's temperature rises above the dew point of the air flowing through the condenser heat exchanger. Some of the water is vaporized, forcing it to resist the rise in temperature. This latent heat component is not trivial. For water, the latent heat of evaporation is around 500 times more than the sensible heat component.

Most window shaker air conditioning units have a ring around the outdoor fan, which takes the indoor water generated and slings it onto the condenser. When it is hot outdoors, the latent heat component keeps the indoor side producing ice cold air. Without the water slinger, the indoor side would run much closer to room temperature, reducing useful cooling substantially. Some portable units actually have a spray head in them that operates just like the rig discussed in this thread. The water vapor is blown outdoors through a vent, so the water generated indoors never has a chance to fill up the reservoir.

With this specific setup, I would be tempted to run the spray pump with a delay rigged to the compressor. When the unit starts, running, the delay would start. Once the unit ramped up to full output, the delay would time out and start the spray pump. During periods of low demand, the spray pump might not run at all. When the compressor stopped, so would the spray pump. The delay function is built into the window shaker style units: the outdoor fan cannot sling water unless there is water in the drain pan.

DEnd 08-25-17 07:09 AM

Quote:

Originally Posted by jeff5may (Post 55268)
Another add-on idea that is much less wacky than it sounds is wet desiccant dehumidification. Big dogs, such as FEMA, the Army, the Navy, and others call these rigs atmospheric water generators. They build the units on trailers for huge portable sources of emergency drinking water. A cooling tower collects moisture from the air by pumping a saltwater solution and outdoor air through the tower. The saltwater is then heated, and the water vapor produced is collected for distribution. The remaining saltwater is then pumped back up the tower. Common figures for these systems are 5 gallons of water produced for every gallon of gas consumed and up to 1200 gallons of water output per day per unit. Many a university has won an award by including this type of system to boost energy efficiency of their design home. No longer do the zombie apocalypse shelters need a massive fresh water store: these things work equally well off of solar energy.

You don't even need salt for this type of system. Water itself will act as a desiccant as long as its temperature is below the dew point. With this type of system when you do the heat removal process you are effectively only removing latent heat. there is no need to add heat to power evaporation then remove the left over heat from that process.


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