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Delphi Developing Heat Pump For EVs.

8K views 15 replies 15 participants last post by  DaleDe 
#1 ·
One of the biggest issues for EVs is how to generate cabin heat. Currently heat is generated using resistive heating, which while simple, consumes a lot of battery power. This, and the fact that the battery thermal management system also uses resistive heating is the culprit behind reduced range in the winter. Posters on this forum have wondered why a heat pump isn't used. A heat pump is simply an air conditioner that can run in two directions, carry heat away from the cabin to the outside (A/C mode), or carry heat from the outside into the cabin (heating mode). The advantage of the heat pump over resistive heating is it is 3 to 4 times more efficient in generating heat. Unfortunately, this advantage dwindles as the outside temp drops. While a bit more efficient than resistive heating at freezing temperatures, heat pumps simply do not put out enough heat to be comfortable. For this reason heat pumps are generally installed with supplemental resistive heating.

Now, it appears heat pumps are coming, Nissan has announced that the next model of the Leaf will have more efficient heating, probably via a heat pump. Recently Delphi, who has close links with GM, announced that they are developing a heat pump for EVs. The twist on the Delphi approach (see lInk below) is they are looking to scavenge waste heat from the drivetrain components in addition to the outside air.

Whatever happens, I think the emergence of heat pumps in EV applications will be a step forward.

http://www.4-traders.com/DELPHI-AUT...-Increase-EV-HEV-Range-While-Cuttin-14294734/
 
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#2 ·
I only wish they make this true! I did post on this in the past, and would put heat pumps in my wish list.
Heat pumps are very very effective for temperatures between -10 Celcius/ -14 Farenheit and hotter.
And they become "effective" from -20 C / -4 F to -10C/-14F.

This will be a very nice addition to energy conservation.

Francois
B-2653
 
#4 ·
That would be a big step forward for most American climates and the Canuks would benefit at least some of the year. Ya Sure! ;)
 
#5 ·
The EV1 had a heatpump, but GM chose not to put one on the Volt. I'm not 100% certain why, but I suspect it has to do with defrosting in the winter, when the Volt (and most other cars,) runs the A/C and heat simultaneously to produce warm dry air to clear windows. Unless you had a second complete A/C/heat pump system, I don't see how you could do this with a heat pump.

(of course, if the upgrade to a heat pump is simple enough (frequently just a couple of valves, I believe,) you could retain the existing architecture and just add the heat pump function, and add a bunch of code to use the heat pump most of the time but the 6.5 kW heating element sometimes. More complexity and a little more cost, but I don't see any other reason not to do it.)
 
#8 ·
The EV1 had a heatpump, but GM chose not to put one on the Volt. I'm not 100% certain why, but I suspect it has to do with defrosting in the winter, when the Volt (and most other cars,) runs the A/C and heat simultaneously to produce warm dry air to clear windows. Unless you had a second complete A/C/heat pump system, I don't see how you could do this with a heat pump.
You are absolutely correct, the EV1 had a heatpump, and it was not much to write home about. I can't tell you how many times I drove around Phoenix wanting something (anything) better. The Volt A/C performance is far superior to the EV1 heatpump.

BTW the the EV1 had a thin metallic coating on the windshield which cleared any fogging practically instantly. I think this was taken from the aircraft world, and I suspect replacement windshields were very expensive.

VIN # B0985
 
#6 ·
This is another example of why the EV tax credit is a great idea. It accelerates other advances by helping create a mass market for EV's.
 
#10 ·
I replaced my electric hot water heater with an energy star heat pump water heater, it uses less than half the electricity to heat the water and saves the avg. person $350 per year. I can see a heat pump in combo with resistance heating for very cold weather...

MrEnergyCzar
 
#11 ·
The EV1's heat pump was a rather miserable beast. It was loud, vibrated a lot, and didn't clear the windshield. It also sucked as an air conditioner. The resistive element in the windshield used almost as much power as a proper resistive cabin heater.

Aaannnyway, I suspect that this new Delphi system will run an 80/20 duty cycle in each direction when used as a heater. A quick switch to A/C and some clever routing of cabin air will likely dehumidify the car without impacting the comfort of passengers.

Sounds like this is definitely going to be included in the next Voltec revision. I can't wait!

-Drew
 
#12 ·
The Delphi HPAC is expected to enter production for the 2015 model year.
For which model? Sounds like 2015 may bring a significant refresh to the Volt. How many of you will trade your 2011/2012 Volt for a new one? :)

I suspect one of the issues with heat pumps is that they tend to accumulate a lot of ice requiring them to switch to deicing cycles by basically running in A/C mode to heat up the condenser (actually evaporator in HP mode). With the densely packed radiator block of the Volt ice accumulation may be dangerous as it may bend and rupture the other cooling systems.

As far as windows fogging is concerned, check the research these guys are doing:
http://web.mit.edu/newsoffice/2012/glare-dust-and-fog-free-glass-0426.html

It is a very exciting time for new technology.
 
#13 ·
Electric defrosting windshields have been around in automotive since the 80's Ford used the metallic-coating method for while (driven a separate high-voltage alternator!), and now uses a system of wires embedded in the glass (mostly on European-designed Fords).

ANY product that adds metal to the windshield is a concern for any type of windshield-dependent communication device: Radar detectors, garage door openers, toll passes, GPS, etc.

I've driven the Euro Fords at night and find the "star" pattern produced by oncoming headlights hitting the mini-wires is annoying.
 
#14 ·
I was wondering why GM did not already use a heat pump in the Volt. A heap pump would probably be OK for maintaining a temp... But it's probably not good enough to warm the car up on a cold day. You will still need some extra help from the IC engine or a resistive heater.

Heat is not much of a problem in sunny California. I suspect the heat pump would be just fine for us Californians.
 
#16 ·
I would agree most of the time, even for northern California. I do think we are not realizing we already have the solution for really cold times. The Volt has an engine! Imagine that. The Engine with an electric water pump to keep the heat coming with the engine off would be a reasonable solution IMHO.

Dale
 
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