R410A BASED AUTOMOTIVE HEAT PUMP SYSTEM THAT HITS CABIN HEATING GOAL SUCECCESFULLY IN -30 °C EXTREME AMBIENT 2019-01-0910
R410A BASED AUTOMOTIVE HEAT PUMP SYSTEM THAT HITS CABIN HEATING GOAL SUCECCESFULLY IN -30 °C EXTREME AMBIENT
KELVIN ZHAI, HAOJIE WANG, BAIC MOTOR CO. LTD.
XUEFENG CHEN, BYD AUTO CO. LTD
It is a big wave in the world towards to future to replace traditional vehicles by Battery powered Electric Vehicles (BEV). However, it’s also well known that there are critical technical barriers for BEV based AC systems to work in very low ambient to heat up the cabin sufficiently for human comfort requirement, due to weak battery output impacted by the low ambient.
The regular heat pump systems with R134A/R1234YF, even with Vapor Injection cycle (VI) added, due to -26°C boiling temperature limits, are still encountering serious challenges to meet -30 °C or lower ambient needs, although VI heat pump may reach COP>=1.7 at ambient -18 °C.
There are so many areas in the world where are so cold that lower than -30°C, and may last couple of months per year, in most Canada, northern USA and northern China. Somehow, limited by the weakness, BEV seems not be so suitable for the whole profile of weather like ICE powered vehicles do.
R410A (R125/R32, 50%/50%), a near boiling binary mixing refrigerant, has been using overwhelmingly in the world for residential air conditioning applications. R410A’s boiling temperature is -51.4 °C, plus VI participation, the combination provides potentials to operate in extreme low ambient like -30 °C.
A demonstration fleet consists of 3 vehicles had been built up as bellowed for road tests purpose:
A traditional vehicle (ICE gas heating)
BEV with PTC water heating system (R134A)
BEV with VI heat pump system (R410A)
The road trip was run in Yakashi, China (-39 °C) in last January, when was lowest season at that location. Besides, additional road tests were conducted in Harbin, China (-24 °C), Changchun, China (-18 °C). It looks that R410A VI cabin heating system successfully fulfills for all passengers needs and it also works well for defrosting and demising.
However, there may be some disputing points to use R410A for automotive applications as followed:
Traditionally, automotive AC systems only take pure refrigerants like as R12, R134A, R1234YF and CO2, and nerve adapt any kind of mixed refrigerants.
R410A GWP value is higher than R134A (GWP 1430), it may be environment unfriendly per EPA current regulations.
Authors like to bring the advantages and disadvantages to SAE forum for discussion by the experts over the world.
KELVIN Zhai, xuefeng Chen
BAIC Motor Corp., Ltd. New Energy, BYD Auto Industry Company Limited