MACS Monthly Newsletter - 2017 - DEC1

Total Vehicle Climate and Thermal ManagementTM

December 2017

By Dave Hobbs - MACS Field Correspondent

Heating Up with Electric Vehicles (EVs) and Pluggable Hybrid Electric Vehicles (PHEVs)
You're probably aware that heating up coolant isn't restricted to just using the heat from an
internal combustion engine to do the job. Diesel
fuel burning coolant heaters have been around for
years. Going back even further, air cooled Volkswagens used gasoline fired coolant heaters to warm
up the passenger compartments of VW Beatles back
in the day when those old cars' air cooled engines
could not provide hot coolant for a heater core to
warm the passengers. Although EVs have been
around since the days of Edison and Ford, looking
at modern times, the world's 2nd EV was the GM
S-10 electric truck. It used a diesel fuel burning
heater module to heat up coolant for the passenger
compartment's heater core. That was back in the
1990's. Only a very limited number of these electric pick-up trucks were produced. In the over the
road trucking business, running the big rig's diesel
engine all night while the driver sleeps in the sleeper unit does provide a great source of heat for the
sleeper unit's liquid heating system but at the price
of increased fuel cost. Until fuel cells can really
come down in cost and be fueled up at more than
just a few hydrogen fuel refill stations, the need for
heating coolant with a more practical means will
continue to plague engineers who want to continue
to limit emissions and increase fuel economy.

geo-thermal units used in some homes in the more
moderate climates around the nation. Heat pumps
for automotive use are not new at all, actually. The
GM EV1 that was leased to customers in very limited numbers back in the 1990's used a form of a
heat pump.

Heat pumps - not just for homes anymore!

Figure 1: Nissan Leaf's optional heat pump uses valves to reroute refrigerant
flow in order to fill a condenser internal to the HEBA (Heater / Evaporator /
Blower / Assembly) with high pressure hot vapor in order to heat the interior
with refrigerant instead of cooling it.

SAE

Heat pumps reroute refrigerant flow in order to
make the heat shedding heat exchanger (normally
the A/C condenser) become the heat absorbing heat
exchanger (normally the evaporator). (Fig. 1)

A heat pump cabin heater has been adopted for
heating an electric vehicle (EV), using less power
than conventional models. It greatly improves power consumption when the heater is being used. Nissan LEAF is the first mass-produced vehicle in the
world to employ a heat pump cabin heater. When
you think of a heat pump, you might think of the

One advantage of a heat pump is that one refrigerant circuit can be used for both cooling and heating, with the heat from the outside air being trans-

MACS Service Reports is the official technical publication of the Mobile Air Conditioning Society Worldwide, Inc., P.O. Box 88, Lansdale, PA 19446. The material published in MACS Service Reports expresses the views of the contributors
and not necessarily that of MACS. Every attempt has been made to ensure

December 2017

the accuracy of the content of MACS Service Reports. MACS, however, will
not be responsible for the accuracy of the information published nor will MACS
Worldwide be liable in any way for injury, labor, parts or other expenses resulting
from the use of information appearing in MACS Service Reports.

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Table of Contents for the Digital Edition of MACS Monthly Newsletter - 2017