●? What can heat pump air conditioning bring to electric vehicles?
The battery life of electric vehicles is one of the most concerned points. When designing electric vehicles, major automobile manufacturers not only make a fuss about the most basic aspect of "battery enlargement", but also make efforts in energy saving to ensure the maximum efficiency of vehicles. Moreover, heat pump air conditioning is also a key step in energy saving of electric vehicles, and its function is just like the removal of the whole car interior in the lightweight of racing cars.
As we all know, because pure electric vehicles don't have an engine, they can't use the waste heat of the engine as a heating source like fuel vehicles, so most pure electric vehicles generally rely on the heat generated by PTC plates to achieve heating, and its working principle is similar to that of household heaters. Although it has simple structure and good heating effect, it consumes a lot of energy. The maximum power of PTC board commonly used in general pure electric vehicles can reach 5~6kw, and it consumes a lot of power when heating, which obviously affects the cruising range.
For example, in some early pure electric vehicles with short cruising range, their battery activity is not high in cold areas where heating is needed, and the use of high-power heating equipment will directly hurt the cruising range.
The heating mode of heat pump air conditioner is completely different, and the biggest difference from PTC board is higher efficiency and lower energy consumption.
●? Principle of heat pump air conditioning
To understand heat pump air conditioning, we need to understand its principle first. In fact, the principle of heat pump air conditioning is not complicated. It is like a water pump, pumping water that should have flowed from a lower place to a higher place. A heat pump pumps heat from a high temperature to a low temperature. The compressor will send high-pressure steam to the condenser through the on-off valve, and the steam will also be converted into liquid, which will flow into the evaporator, and the evaporator will absorb heat and cool the internal space. For example, in summer, after the car owner turns on the air conditioner, the heat pump will "pump" the heat inside the car, and then convert the external heat into cold air through the compressor and transport it to the car.
The heating conditions are just the opposite. When it was cold, the owner heated the car, the electric compressor pumped up the heat from the external environment, and the air conditioner began to heat the car. The heating process is just the opposite of the cooling process, that is, the heat source outside the car is "pumped" into the car to heat the car. In a word, this system can only transfer and convert heat under the condition of cooling or heating, which is not the heating function of traditional PTC plate.
The whole heat pump air conditioning system consists of four core components, namely: external heat exchanger, internal heat exchanger, four-way reversing valve and electronic expansion valve. Taking the heating condition as an example, the external heat exchanger absorbs heat from the external environment and enters the system, and the low-pressure air is compressed and heated, then enters the internal heat exchanger to heat the air inside the vehicle, and finally is sent into the vehicle.
To sum up, the working process of heat pump air conditioning is a process of transferring heat, that is, transferring heat from one place to another. Whether heating or cooling, heat pump technology can be realized. According to relevant experimental tests, the efficiency coefficient of heat pump is 2-3 times higher than that of PTC board, which can effectively extend the cruising range of electric vehicles by about 20%.
However, heat pump air conditioning also has limitations. Generally speaking, when the outside temperature is lower than-10℃, the efficiency of heat pump to obtain heat from the outside will be obviously reduced. Because the external heat itself is too low, no heat can "move" from the outside to the car, so the heating of air conditioner mainly depends on PTC plate for auxiliary heating, but overall, its comprehensive energy consumption is still much lower than that of pure PTC plate.
●? Tesla is not the only pure electric vehicle equipped with heat pump air conditioning.
In fact, Tesla is not the first person to eat crabs. Bmw i3, jaguar I-PACE, Audi? Roewe Marvel Comics? X, Weilai ES6, etc. All of them are equipped with heat pump air conditioners, and their structures are basically the forms introduced in the above article (heat pump air conditioner +PTC board auxiliary). As can be seen from the new patent announced by Tesla this time, Tesla Model? The heat pump air conditioner installed on Y is optimized.
Although its essence is still heat pump air conditioning +PTC plate auxiliary heating, its PTC plate is driven by the same voltage of 12V as that of traditional fuel vehicles, and the model? Y is also equipped with a 12V battery, which has relatively low power consumption and cost.
In addition, Tesla also designed a more complex eight-way reversing valve, which can get more heat than the four-way reversing valve commonly used in other models.
For example, in a low temperature environment, Tesla may only need to use PTC plate for heating when the vehicle is just started, and basically does not need PTC plate for heating after the vehicle is running. At this time, the heat pump will automatically absorb the heat of the main heating components such as motor, electronic control and battery pack, and transport it to the passenger compartment.
This system is simple to say and very complicated to implement in practice. This requires extremely accurate computer control to determine when PTC plate and heat pump work at the same time, when they work independently, and which pipes need to conduct heat in different working modes under different external environments and working conditions.
In a word, Tesla integrates more heat sources that could not be obtained originally through its own powerful technology, including certain heat generated by the driving system during operation and battery discharge, thus minimizing the working conditions that require PTC plate to assist heating.
●? Write it at the end
As one of the few means to reduce energy consumption and improve battery life at present, it is believed that more and more new pure electric vehicles will choose to be equipped with heat pump air conditioning system in the future. With Tesla's lessons, more and more car companies will continue to optimize the software and hardware of heat pump air conditioning systems. It is hoped that in the near future, users of pure electric vehicles will no longer hold back the heating in the cold winter for battery life.
This article comes from car home, the author of the car manufacturer, and does not represent car home's position.