'Portable' air conditioner...

WBahn

Joined Mar 31, 2012
24,850
It would be very wrong not to vent the Condenser air to outside. The point of refrigeration is to collect heat in the space, then either passively or by forced air from the space being refrigerated. In this case driving the condensate heat outside and away from the room.

Sucking air from the outside would only be relevant if the air outside is lower than room air. The evaporator water dripping down will lead to the condensate via drip tube to the hot air and be evaporated. Humidity would be a problem, here in Utah it's not an issue, it's so dry here it's less expensive to run a swamp cooler, effective until July and August when temps rise as and humidity increases. Then it's miserable, a well insulated home work well year round with an air conditioner, although the evaporator freezes up during lone runtimes. Again July to August, if liquid refrigerant makes it back to the compressor you will bend valves unless it's rotary, typically you won't see rotary in Air conditioners because you can't move enough volume quickly enough.

kv
Who said anything about not venting the condenser exhaust to the outside?
 

WBahn

Joined Mar 31, 2012
24,850
It’s not supposed to be a heat pump, but I accidentally found out that is worked as one.

I installed it at the beginning of the season. The second night, I woke up sweating. The room temp was 88°. So I reset the unit and turned the thermostat down. I woke up again and the room was 92°! So I shut it off and depended on the fans.

The next day, I was cleaning up the room and found that the exhaust pipe had fallen off the unit. I modified the adapter, bolted the tube to the adapter and duct taped the whole thing. Worked like a charm.

But this was early spring. In Boston, we have wild temperature swings in Spring and Fall. So one night the temperature dropped into the low 40s. Apartment management had shut off the heat and I was shivering. I got up, removed the exhaust pipe (stuffed the window exhaust with a T-shirt) and ran the unit. Warmed the room right up to a comfy level!
An air conditioner is, pretty much by definition, a heat pump. Common usage of the term has made many people think that heat pump is something used to heat a space in a particular way; but all a heat pump is is a device intended to transfer heat in the direction opposite spontaneous heat transfer (i.e., move heat from a cold reservoir to a warmer reservoir.

If you could find a way to duct your air conditioner cool air output to your window exhaust it would work even better -- and would be operating much more like a heat pump installation is intended to run. As it is right now, the only heat you are getting is from the electrical power being used -- the same as running an electric space heater.
 

djsfantasi

Joined Apr 11, 2010
5,687
An air conditioner is, pretty much by definition, a heat pump. Common usage of the term has made many people think that heat pump is something used to heat a space in a particular way; but all a heat pump is is a device intended to transfer heat in the direction opposite spontaneous heat transfer (i.e., move heat from a cold reservoir to a warmer reservoir.

If you could find a way to duct your air conditioner cool air output to your window exhaust it would work even better -- and would be operating much more like a heat pump installation is intended to run. As it is right now, the only heat you are getting is from the electrical power being used -- the same as running an electric space heater.
Actually, I did that to some degree. Just didn’t think it was important to the story. After stuffing the T-shirt in the exhaust, I figured it would work better if I exhausted the cool air. So I took out the T-shirt. I couldn't exhaust it all, but I used a couple of bungee cords to hold the exhaust adapter in front of the cool air vent.

Sometimes, being an engineer means you have to give up on sleep :rolleyes:
 

killivolt

Joined Jan 10, 2010
742
Who said anything about not venting the condenser exhaust to the outside?
Didn't understand this unit, but now I do, but as a Heat pump now makes more sense, if you physically change air flow you have a unit both able to heat and cool. I will say again, I get it. I live in the West we don't have such problems.


kv
 

Aleph(0)

Joined Mar 14, 2015
591
Dual hose to the same window is a valid point. You'd just be sucking back in the hot exhaust. These just don't make any reasonable sense to me. If you were in a windowless room and had some way to get the exhaust hose outside in a short insulated hose maybe...
SamR IMO another vry good idea would be design where condensate (by which I mean H2O condensed from cooled air on evap coil) is _sprayed_ on condenser after collection! Cuz that way you're getting rid of the condensate AND also improving heat-pumping efficiency of unit by taking advantage of H2O's heat of evaporation helping cool the condenser:cool:!

PS: So to avoid confusion when I say _condensate_ I just mean humidity condensed from atmosphere! Definitely NOT re-liquefied refrigerant in condensero_O!
 

Aleph(0)

Joined Mar 14, 2015
591
An air conditioner is, pretty much by definition, a heat pump. Common usage of the term has made many people think that heat pump is something used to heat a space in a particular way; but all a heat pump is is a device intended to transfer heat in the direction opposite spontaneous heat transfer (i.e., move heat from a cold reservoir to a warmer reservoir.

If you could find a way to duct your air conditioner cool air output to your window exhaust it would work even better -- and would be operating much more like a heat pump installation is intended to run. As it is right now, the only heat you are getting is from the electrical power being used -- the same as running an electric space heater.
Wbahn I'm sure you know all this but for benefit of people who don't I need to say it:)! So anyway a major problem running a unit designed just as full time unidirectional heat pump (so as example window a/c unit) _backwards_ (by which I mean dedicated evaporator to outdoor air and dedicated condenser to indoor air) is lubrication and metering issues! Also, if ambient outdoor air temp is ≤ 0°C you also need defrost heater or to use indoor air for defrost heating. Now o/c you'd still need defrost cycles for ambient outdoor air temps < ≈ 12°C (because of ≈ 12°C ambient vs evap ΔT) but o/c just shutting compressor off is all that's needed to defrost if ambient temp >0°C

So it could easily work as cheap heat source for ppl who think on like 60°F as _cold weather_:confused: But I just can't relate to that at allo_O:D!
 
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wwright12

Joined Aug 15, 2019
0
From: https://homeairguides.com/air-cooling/how-does-a-portable-air-conditioner-work/
Single hose versus dual hose units
How portable air conditioner works to cool down a room is through the use of a hose that’s vented to the outside.

Portable air conditioning units will either have one exhaust hose for hot air or they will have two.

If your unit has one hose, it takes air from the room that it is placed in and then returns most it after the cooling process. However, since a small amount of air is always removed from the room, it will cause some negative pressure.

If your unit has two hoses, one will be to bring air in from the outside, and the other will exhaust it. Dual hoses will not create the negative pressure like the single hose, but because of this design it does result in less efficiency.
In cooling the temperature in the room, dual-tube & 40% faster than a single one. At this point, I think double hoses are a better choice.
 

crutschow

Joined Mar 14, 2008
23,499
No drain... condensate is sucked up a tube and sprayed under pressure into the exhaust stream.
I've seen some units that spray the condensate on the condenser, both to improve efficiency slightly and to evaporate the water.
So one night the temperature dropped into the low 40s. Apartment management had shut off the heat and I was shivering. I got up, removed the exhaust pipe (stuffed the window exhaust with a T-shirt) and ran the unit. Warmed the room right up to a comfy level!
That works because the heat energy into the room equals the energy to power the unit, but for it to work as a heat pump the cold air outlet would need to be routed outside.
That way the heat into the room would be greater than the energy to power the unit, not just equal to it.
 
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