**Important Note** This system (though not necessarily all heat pumps) is essentially reversible. With clever valving, you can flip where you're rejecting heat. Instead of heating the cabin, you cool the cabin by pulling heat from it and moving it outside (again, flipping around the section 3 diagram).

Ben Bohannon

21 dag siden

So, does the Joule-Thompson effect get used in this process? Gas at high pressure cools when transitioning to an area of lower pressure. Perhaps at the expansion valve?

Charles Ingalz

3 måneder siden

@BLACKVIEW USA Depends on climate. In temperate parts of California near the ocean, heat pumps can make a lot of sense. First, we only use heating energy overnight, when electricity is 12c kw/h. The total electricity for heating is a small fraction of the cost of a gas furnace + maintenance, especially since code would have required us to have a high efficiency condensing type. Also we would lost a lot of the efficiency, comfort, and convenience gained by the variable speed air handler and compressor and zoning system. A gas furnace only supports one stage and two for the premium models and this configuration would also have hampered the effectiveness of the zone controller operation. Only a 2-3 nights a year does it get cold enough to goto backup resistive heating. Seasonal heating COP here (SF Bay area) is about 3.8 for an air exchanger.

Xtracoolnerd

3 måneder siden

@BLACKVIEW USA actually the science and technology on heat pumps has increased drastically since then. Just like 1990 computer pails in comparison to a 2020 computer. Over 50 years of heat pumps and there have been some improvements. And for your Norway comments, over 50% of new car sales last year in that country were electric. The leaf is not the best example because the battery thermal management system is extremely hampered in colder temperatures. Nissan discovered this the hard way with Canada and warranty battery claims and made software adjustments to help but still failed for battery life in the colder Canadian cities. But a Tesla with a proper thermal battery management system would most likely be quite effective. Heat pumps used to be only good to about -5C before needing an alternative heat source but now they are rated to -20C. But I suspect a geothermal heat pump should be able to over come that threshold as well. Lots of factors involved.

Santos Vazquez

3 måneder siden

In reverse, wouldn't you feel a vacuum instead of an air breeze coming out of the vents?

Florian Schlappa

3 måneder siden

The COP depends on various things: 1. refrigerant (new cars use R1234yf as an AC refrigerant, maybe it is the same for a heat pump) 2. efficiency of the compressor 3. efficiency of the heat exchangers (evaporator and condenser) or better said the surface and the capacity of the ventilator 4. how big is delta T (temperature difference between inside and outside) It could be that COP=1.0 is reached at -30 to -35°C !! Ask Tesla for specifications ;-P

they don't use the excess heat energy from the batteries to heat up the evaporator? that's... weird.

Very instructive video. Great job!

In the Model Y and the 2021 Model 3 all heat must pass through the heat pump into the cabin. There is no backup for the heatpump.

Thanks for running through this. So the heat pump is making the EV act more like a gas car in that it’s getting the heat from outside that which can move the vehicle. Outside air (EV) or waist heat (ICE) vs needing to use energy that can be used for motion. Helps me understand the benefits anyway. I know it’s adding another source vs taking advantage of an inefficiently.

does it have a resistive backup as my house is heated with a heat pump and around-5c the backup has to come on to keep house up to temp?

A good description. It looks accurate, but was missing one point. While it was stated that a heat pump essentially works just like an A/C unit works only the order of operations is reversed. It should have been mentioned that the heat pump IS the A/C unit with the order of operations revers. Some might assume this is an additional device, when the existing device is used, only some valves are added to change the order of operation whenever needed.

If combustion engine are so inefficient does it mean that if the place you live is using coal for exemple for electricity your EV is still greener than a combustion engine car? Thanks!

Go eat some chicken

Your thumbnail for this video shows an A/C unit from a Model 3, not a heat pump as indicated!

Modern heat pumps can work at 100% efficiency at ten degrees farenheit. The magic is in the characteristics of the refrigerant.

SASK Gang where you at.

Bypass valve for the evaporator or discharge of the compressor will increase the heat inside the car. Increase temp and pressures on the low pressure side of the system increases temperature. Works exactly same as ac system.

Well I live in Canada and -30 is normal

So I'll only loose 10% range instead of 30%?

Update tesla 3 refresh will have one

Orrrrr, Tesla could prime the evaporator side from within the car using resistive heating to get the cabin to boil the fluid....

I bought a 2017 Mercedes Benz B250e. Electric Car. This is my first winter with my car. Miles have drop by 20%. Do you think a heated pump will work for my car?

What happens if outside is even colder than -20C?

Very well explained! Great insight into the benefits and changes of the heating in the Model 3/Y.

Sentences have dots. You have the option to pronounce them. Please do. It will make listening to you much more relaxt.

not just antarctica, Canada goes well below -20C

took them long enough, People messing with EVs in the 90 and early 00 were already talking about it

You will now find it in Model 3 - 2021 :)

solution. get a hybrid

So.... It means that if the OAT is -20'c, efficiency is the same with PTC, right? I'm living in South Korea. Our winter is not 'that' cold(-10~10'C)

My New model 3 will have a heatpump 👍😃 Thanks for The Great videos!.

I had wondered why they didn't have a heat pump. My buddy wanted to buy a model 3 and I told him it's not done until they put a heat pump in it. Too inefficient the way it is, and cheap not to slap a reversing valve on and complete the car. Sure it went in one ear and out of the other but He didn't buy one.

Would be nice to talk about battery capacity thermal dependence for those in Antarctica.

This was one of the most eye opening things I learned from taking thermodynamics.

8:56 Did your mom ever yell at you to shut the door because it's cooling the outside? (in summer) Now we cool the outside to heat our environments.

Love that wing on the ICE car.

In college I was told 20F was the effective real world limit of a heat pump when “emergency” resistance heat is needed. Owning a home with a heat pump I can agree with about 20F. Does Model Y have backup resistive element?

No such thing as 100% efficient people believe you huh

-20 and -40 °C? Isn't the car a giant ice cube at that point. You will need a lot of something just to unfroze the door handle.

Davide Bacchi

3 måneder siden

I don’t think, when temperature is quite below freezing, say -7C for long time (say a week) humidity has condensed and air is so dry that “stiktness” is minimal. It worsen if there is a “crossing” of the 0C when there is humidity that can build up.

Does any car use the cabin exhaust air as energy source instead of outside air? That would be about 20 ⁰C even in winter. In Finland lots of appartments are partially heated with a heat pump using the exhaust air from the buildings.

Depending on the outside temperature and moisture in the air, my heat pump at home needs to reverse and defrost. It is worst just above and below freezing where it can be about every 45 minutes. (In foggy weather it is even worse). When it gets more than 10 below freezing, there’s usually so little moisture in the air that it doesn’t need to. So I wonder if it will be able to defrost while driving. Also the heat generated by the compressor motor in the compressor is available for heating unlike when running it as a AC where the heat generated by the motor is working against the AC.

Curious what happens in Wisconsin in January when it’s -15F outside? Edit: typed that before he explained the answer at the end!

How about a system with COP a little more than 1 but light and no moving parts?! The Peltier effect is the phenomenon that a potential difference applied across a thermocouple causes a temperature difference between the junctions of the different materials in the thermocouple. This effect is the opposite of the Seebeck effect (named after the scientist who discovered it in 1821).

You should have explained Carnot's Law to explain the dropping COP... Also, since all electric cars have air conditioners, it's not clear why they don't also use them as heat pumps. The difference for a household unit is usually a 10-20% cost premium.

Can be reversed and used for A/C and for battery cooling, could also use battery heat to pump into the cabin.

Thanks for feeding my random knowledge.

I custom fabbed a wood burning stove for my model 3.

So I live in Ottawa, we get -40C weather pretty frequently over the winter. Are all the model Y owner's I see driving around going to hate their lives because their model Y is not keeping them warm?

I have been saying for 3 years just use a bloody heat pump to heat rather than a traditional matrix heater. Finally tesla 🙌

Why not use battery and controller coolant to heat up up the A/C evap core

Officially witchcraft

Theoretical limit on heat pump is that COP gets to 1.0 at the absolute zero outisde, so I am very surprised that they woudn't be able to work with good efficiency with ratio of temperatures ~ 1.3

This is why i cant have an electric car.

Aren't they also connecting the heat pump to the coolant lines? That way they can use the small amount of excess heat from the battery and motors to maintain efficiency down to even sub -20c temperatures.

Heat pump is the same thing as AC. If someone thinks it is not please tell me what is the difference.

Thanks a lot, well explained and beautiful drawings, as Always ! But isn't also the latent heat which give the HP a good COP? From the changing phase in the condenser.

The Nissan Leaf has incorporated a heat pump since the 2013 MY. At least on the SV/SL models if not all.

Maybe it’s just me but I just realized that the upper right diagram contains the symbol for an inductor, not a resistor... kinda bugs me.

Hyundai Kona, Ioniq electric uses this.

Uaing the coolant instead of the outside air might also work? (And possibly increase efficiency (unless it it run as an air conditioner...)

@Engineering Explained: Jason, I think this was an awesome video. I love heat pumps! We just installed a new one in our house that uses VFDs in both the compressor and air handler to further improve efficiency. Nuff about that... I think one thing that I would have liked you to touch on, that you only mentioned briefly: The icing effect that you described is a very common problem with heat pumps. Any latent moisture that is in the air freezes to the evaporator, preventing heat transfer. In home heat pumps, there is a defrost cycle, where the system operates like an HVAC system, and uses PTC heat strips, since the house would be cooled without a second source of heat. Does the Model Y have something similar? Obviously, if it's winter, you're going to be very upset if the heat switches to AC (even if for only a minute) to defrost the condenser. I checked out the Munro video about, but I didn't see this explained...

why not use the radiator as well as the outside air to heat up the refrigerant. maybe by putting the heat pump evapotator behind the radiator. 🤔🤔🤔

The truth is that I'm so used to listening to temperatures in Farenheit even though I don't use them, it took me a while to realize he meant celsius

Wait, how is this different than any other heat pump for home HVAC? I thought Tesla had some sort of breakthrough

If it gets even colder wouldn’t your efficiency eventually hit zero as the condenser freezes along with the refrigerant inside cause the flow to vault?

Would this work just fast as the resistor heaters in the other teslas? Or is it slower?

The porsche taycan can be had with a clever heat pump. At least in the Norwegian market.

So that's for the the cabin, what about the electronics/motors? a plain ole radiator? or do they use some of that heat for the cabin in the winter?

Air-Air heat pumps like this are common on houses here in Quebec to save on winter heating costs (electricity is cheap so most heating is electric). As far as the efficiency of the system in an electric car... Why not put the cold side direct on the motors? Could they get too cold to operate efficiently?

Does the Tesla model y uses that same heat pump unit for cooling the cabin in the summer?

The main reason for using the term coefficient of performance (COP) is to differentiate it from efficiency. As you pointed out the heat pump is not over 100% efficient, it's just doing something different. I think the most practical type of efficiency is exergy efficiency. In thermodynamics energy is a hard term to deal with because most of the energy is in the temperature itself and cannot be accessed. We cannot take the energy directly out of hot air, this would decrease entropy and violate the second law of thermodynamics. To describe how much energy we need to put into a system to move heat around, we use the term exergy. Exergy is also used to describe the maximum energy we can get out of a heat engine. The exergy efficiency of heat pumps is calculated by dividing the real COP by the Ideal COP. The Ideal COP can be calculated using the Carnot cycle which is an idealized heat pump with the highest possible COP. COPcarnot = T_hot / ( T_hot - T_cold ) (Must use absolute temperatures) The COP for the Carnot cycle is dependent on the temperature difference between the two sides. The Carnot COP is always above 1 no matter how great the temperature difference, but it's not practical to expect a real heat pump to be able to operate at really large temperature differences unless built for it. If the temperature difference is large enough that COP drops pretty low, then you might was well use a resistive heater. To give an example of just how good the performance of a heat pump could possible be I gave the following example Freezing outside = 273 K = 0 C = 32 F Comfortable temperature = 295 K = 21 C = 70 F COPcarnot = 295 / (295 - 273) = 13.4 A COP = 13.4 is the highest possible for those conditions. Notes. Processes that are 100% exergy efficient are often described as reversible. This is because the process does not increase entropy. Since entropy cannot be decreased (second law), any system that increases entropy is not reversible. You may come across another term called Carnot efficiency which is energy efficiency, and defined as n = net work done / heat absorbed by heat engine. This is used to describe the efficiency of heat engines and thus will have higher efficiency when the temperature differences are larger.

3:46 Literally spitting those facts!

Some things are better at making mechanical energy and some things are better at making heat energy. Why not use propane to heat the car?

Why not connect the pump evaporator tubes to the battery which will warm them up and cool the batteries at the same time? Since in cold weather it will have the outside temperature at the start of the car anyways, it will gradually warm up when using the car.

-20f, also known as February. Midwest USA. The jet stream sometimes plunges south and an arctic front moves down. Only -40f/c a few times that I remember.

a disadvantage of heatpump is the fact that it is mechanical device (the compressor) which decreases performance over time and also also have higher probability of failure!

If you would use the (low) amount of waste heat from the electric engine and brakes, you would be able to harvest even more heat. The heat pump can also be used to condition the battery to have the most optimal temperature for use. Since batteries do not work so well when it's cold. Also it could be used for A/C as is will pointed out since A/C is also a heat pump. So clever use of a heat pump could not only help you use less energy to heat up your cabin, but would also make use of excess heat from the car itself AND make sure the battery performs better as well as cooling in very hot environments (well, basically your A/C is a heat pump anyway). My Volvo EV that will be delivered somwehre this year will also have a heat pump. Gives about 30 kilometer (20 miles) of added range. Also preconditioning your care while it's plugged in will help greatly - you would only need to make up for loss of energy instead of heating up a cold cabin.

Why don't they use the heat generated by the motors to heat the refrigerant in cold temperatures? Or even in general

So does the model y have another unit for cooling?

Finally Tesla invented a Perpetual Motion Machine! Just feed hot air to the cooling element and with the coefficient of 2-3, you will have a source of free unlimited energy. At this point you can ditch the battery altogether.

The heating cycle isn’t such a brain teaser when you just change your perspective; your refrigerator is heating your home by removing heat from inside the refrigerator. (Kind of a closed system since your fridge is inside your house).

Heat pumps simply move heat.

So if it is really cold it wouldnt work

I'm actually amazed that Teslas were not using a heat pump already. Especially since it's essentially the already existing A/C system just hooked up in reverse. Maybe was a matter of parts availability? Since most parts are made for ICE cars.

But Y?

Tesla, only the rich people understand. Gas car's heat is FREE. My friend's house heat pump's replacement costs $3k. Good luck to the model Y.

At the model y I couldn't see all components. Is there an extra evaporator on the outside for the heat pump mode?, or is the radiator with its coolent used in the winter to absorb the heat from the ambient and transfer it to the plate heat exchanger?

So if the temperature gradient turns negative and the ambient outside temp is lower than the refrigerant, does it just switch to regular resistive heating again?

I Sweden we use heat pumps to heat homes so as long as the refrigerant is one that is adapted for the cold it's no problem. These often stay efficient down to -30C which makes them manage even the worst of cold snaps unless you live in the far north. Plus they make for excellent AC in the summer.

Surely, it's just an aircon with a reversing valve. Nothing new here?

Why don't they wrap the heat exchanger around the drive motors? There would always be a higher delta T there even in minus 20C

What's the green tape for? At 11:11

Used only in the Y, and practically every other brand of half decent EV's...

Nissan Leaf had heat pumps long ago

Why can't the heat pump be used as an Air conditioner also? By just re-routing the intake and exhaust of the system?

My Family's 2014 E-Golf has a heat pump :) did the nissan release earlier than that ?

Heat pump is a very efficient heater with built in AC, doesn't work all that well in very cold areas though.

Does the system not also pull waste heat from motors, inverters and batteries? That could help out on those really cold temperature days, and raise the "effective" heating COP across all exterior temperatures.

Tell about Yamaha's 425hp outboard motor

Could you design a system that depending on which way the refrigerant is running can either be an heat pump OR an air conditioner?

Does this compressor work in reverse to also serve as AC?

Hello everyone! Thanks for your nice videos! Just a detail, ai conditioning is also a heat pump right? So heat pumps have already been in cars for a while.

Thank you for putting this together. I was really curious about how heat pumps worked and why they were said to be better to have in EVs.

I was hoping you would cover the octa valve at the end. This