Harperhendee
Member
I'm curious how much a heat pump gains over an electric heater in terms of power savings. It makes a big difference on whether to get this option or not!
Reddy said:Did you see the info Nissan provided? Looks like it is an improvement from -10C to +20C
Yeah good question, the trick of running the AC will obviously not work. To have adequate defogging ability I assume they'll bring in enough colder outside air containing less humidity which when heated back up will help evaporate the moisture on the windows.Randmac said:How will the heat pump be able to both heat and de-humidify when the windows fog over?
Don't know if this is what they did, but the ideal dehumidifier application would pull in the cabin air, run it past the heat pump's cooling coils to wring the water out, then past the heating coils to warm it back up and drop its humidity, and blast the warm air onto the windows. The heat-output end of the pump is rejecting some of the mechanical inefficiency of the system, plus the extracted moisture's recovered heat of vaporization, so there should still be a net temperature increase, despite the initial cooldown.QueenBee said:Yeah good question, the trick of running the AC will obviously not work. To have adequate defogging ability I assume they'll bring in enough colder outside air containing less humidity which when heated back up will help evaporate the moisture on the windows.Randmac said:How will the heat pump be able to both heat and de-humidify when the windows fog over?
Yeah, except you'd have the problem of what to do when you weren't trying to dehumidify. You'd still want the big radiator up at the front of the car for lots of air movement.Levenkay said:Don't know if this is what they did, but the ideal dehumidifier application would pull in the cabin air, run it past the heat pump's cooling coils to wring the water out, then past the heating coils to warm it back up and drop its humidity, and blast the warm air onto the windows. The heat-output end of the pump is rejecting some of the mechanical inefficiency of the system, plus the extracted moisture's recovered heat of vaporization, so there should still be a net temperature increase, despite the initial cooldown.QueenBee said:Yeah good question, the trick of running the AC will obviously not work. To have adequate defogging ability I assume they'll bring in enough colder outside air containing less humidity which when heated back up will help evaporate the moisture on the windows.Randmac said:How will the heat pump be able to both heat and de-humidify when the windows fog over?
Reddy said:Looks like it is an improvement from -10C to +20C
While true, I assume that the question about current heater versus heat pump has more to do with the range hit due to the current heater.Den said:The main problem at -10C is that battery (if you try to charge it to 100%) will charge only till 87,5% (3kWh less!!). How heat pump can solve this?Reddy said:Looks like it is an improvement from -10C to +20C
So I guess that with heat pump or without is absolutely not possible that -10C range will equal to 20C range.
This works for a freezer because the evaporator coil is in a mostly controlled dry environment inside your freezer. In a traditional heat pump, the outside coil will ice over if it's coil temperature drops below the dew point and the outdoor temperature is below freezing.Computerizer said:However it seems like a heat pump could be calibrated to work better at lower temperatures. A freezer is a good example of this -- it can obviously pull heat out of 2 degree air to make it 0 degree air just fine
This is exactly how direct expansion humidity control works on commercial package units with this option. When the unit is in dehumidify mode, the unit runs in cooling mode and a portion of the compressed refrigerant (hot gas) is sent to a condensing coil downstream of the evaporator coil to reheat the supply air.Levenkay said:Don't know if this is what they did, but the ideal dehumidifier application would pull in the cabin air, run it past the heat pump's cooling coils to wring the water out, then past the heating coils to warm it back up and drop its humidity, and blast the warm air onto the windows. The heat-output end of the pump is rejecting some of the mechanical inefficiency of the system, plus the extracted moisture's recovered heat of vaporization, so there should still be a net temperature increase, despite the initial cooldown.
Since there are no numbers, we cannot tell what the percentage improvement is. It is possible that the bottom of the graph is not 0 miles. For all we know, it could be 50 miles.Harperhendee said:There are no numbers, but the range looks improved from 10-20% in that main band.
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