johnrhansen
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Location: Seattle, WA

put the condenser for defrost mode inside the car.

Thu Mar 20, 2014 8:51 pm

Why does the system take the heat I paid so dearly for and reject it from the cabin when defrost mode is selected? Defrost mode burns up an incredible amount of range when it is on because of this. I can see why it was done. To cut costs and make it the same way your ice driven cars, where an installation like this makes sense. But it is wrong in this case. You need to either port the refrigerant to another condenser in side the car that just recirculates cabin air through both the condenser and the evaporator, just like a dehumidifier does, or duct the air from the existing condenser to accomplish the same thing.. of course it is routed the conventional way on hot days for air conditioning.
2013 S model with quick charge package.
AV 30 amp level 2 EVSE, Bosch PowerMax 30 Amp EVSE, EVSE upgraded EVSE.

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Nubo
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Re: put the condenser for defrost mode inside the car.

Thu Mar 20, 2014 11:01 pm

Interesting idea. I'd never thought of that.
I noticed you're still working with polymers.

QueenBee
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Re: put the condenser for defrost mode inside the car.

Fri Mar 21, 2014 1:00 am

Cost, complexity, space, and weight...

LeftieBiker
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Re: put the condenser for defrost mode inside the car.

Fri Mar 21, 2014 3:31 am

In very cold weather, moisture would build up in the cabin. Likewise in warm, very humid weather. That being said, I'd love to be able to use Recirculate mode when appropriate, in ALL vent settings. There is no need fore an extra condenser (?). Nissan is just too afraid we'll screw up and fog the windows.
2013 "Brilliant Silver" SV with Premium Package and no QC, and 2009 Vectrix VX-1 with 18 Leaf cells.

The most offensive, tasteless phrase in use here is "Pulled the trigger." I no longer respond to posts that use it.

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Nubo
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Re: put the condenser for defrost mode inside the car.

Fri Mar 21, 2014 2:29 pm

LeftieBiker wrote:In very cold weather, moisture would build up in the cabin.


It wouldn't.

Moisture (and heat) is removed when the air is blown over the cold coils of the evaporator. The moisture condenses and is allowed to run off.

The heat in the air is transferred to the evaporator coils (exposed to outside air) via the refrigerant. The OP suggests instead of letting that heat escape, route the refrigerant instead to a set of evaporator coils inside the car. This would conserve the cabin heat. The evaporator coils would still get cold, and still remove moisture. Just as an in-house dehumidifier removes humidity even though both its evaporator and condenser are in the same airspace. It neither heats nor cools.*

*-- well actually it heats a bit, due to dissipating the work of the electric motor and electrical resistance.
I noticed you're still working with polymers.

LeftieBiker
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Re: put the condenser for defrost mode inside the car.

Fri Mar 21, 2014 3:58 pm

Moisture (and heat) is removed when the air is blown over the cold coils of the evaporator. The moisture condenses and is allowed to run off.


It isn't likely to "run off" in single digit (F) weather. Instead, the condensate drain hose will likely freeze at the end, and the moisture will build up.
2013 "Brilliant Silver" SV with Premium Package and no QC, and 2009 Vectrix VX-1 with 18 Leaf cells.

The most offensive, tasteless phrase in use here is "Pulled the trigger." I no longer respond to posts that use it.

johnrhansen
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Re: put the condenser for defrost mode inside the car.

Fri Mar 21, 2014 5:16 pm

The only difference in operation is that the compressor would draw more power because the difference in temperature between the condenser and evaporator and the back pressure on the compressor is greater with the condenser drawing in warmer air. Id guess for dehumidification the optimum temp of the evaporator coils is around 40 degrees. The condenser about 90. As long as the compessor can take it, that would work great. The extra power draw of the compessor heats the cabin any way so you'd end up with a net savings.
2013 S model with quick charge package.
AV 30 amp level 2 EVSE, Bosch PowerMax 30 Amp EVSE, EVSE upgraded EVSE.

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Nubo
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Re: put the condenser for defrost mode inside the car.

Fri Mar 21, 2014 7:24 pm

LeftieBiker wrote:
Moisture (and heat) is removed when the air is blown over the cold coils of the evaporator. The moisture condenses and is allowed to run off.


It isn't likely to "run off" in single digit (F) weather. Instead, the condensate drain hose will likely freeze at the end, and the moisture will build up.


Again, there is no difference at the evaporator end. The coils would work the same as before. The same moisture would be removed as before. if there were a freeze problem then it would already be manifest.
I noticed you're still working with polymers.

QueenBee
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Re: put the condenser for defrost mode inside the car.

Sat Mar 22, 2014 10:52 pm

Nubo wrote:
LeftieBiker wrote:
Moisture (and heat) is removed when the air is blown over the cold coils of the evaporator. The moisture condenses and is allowed to run off.


It isn't likely to "run off" in single digit (F) weather. Instead, the condensate drain hose will likely freeze at the end, and the moisture will build up.


Again, there is no difference at the evaporator end. The coils would work the same as before. The same moisture would be removed as before. if there were a freeze problem then it would already be manifest.


Heh, I guess he doesn't understand that in the proposed solution the cool side coils are configured no differently then they are now....

LeftieBiker
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Re: put the condenser for defrost mode inside the car.

Sat Mar 22, 2014 11:01 pm

Miss Piggy misunderstands. I'm not arguing that the condenser placement would be a problem, I'm saying that moisture will build up in the cabin in Winter in *either* case, if fresh air is excluded.
2013 "Brilliant Silver" SV with Premium Package and no QC, and 2009 Vectrix VX-1 with 18 Leaf cells.

The most offensive, tasteless phrase in use here is "Pulled the trigger." I no longer respond to posts that use it.

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