Gas heat pump for cabin heating. COP of ~ 2 at 14F and quickly rises to over 4.LeftieBiker wrote:Can someone tell me exactly what kind of heater or heaters the Prime uses aside from the engine?
The 'gas' part of the name is a partial re-cirulation of refrigerant vapor through a bypass shunt before the expansion valve. Not exactly thermodynamically intuitive but it is a well known approach that is not often built due to engineering difficulties and cost.
Really, really smart on Toyota's part since the drop in range in a cold winter is a substantial stumbling block in EV use. Toyota has engineering optimization down to a fine art, and they recognize that improving a 1000 different areas, albeit each one not by much, adds up to a superior product. This is why no other company has ever duplicated the Prius fuel economy. An Atkinson ICE helps, but is only one improvement amongst hundreds that went into the Prius -- most of them not specifically hybrid related.
The 25 miles of range from 5.6 kWh is a rare efficiency seen in the *EV market and represents the same attention to detail. It also lets them re-use a lot of the Gen4 Prius design because the battery is small(er) than competitors with ~ equal EV performance, and thus keep costs down. They really have the integrated, system-wide philosophy at the heart of the cars they build.