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DaveSchouweiler
Minneapolis, Minnesota, USA
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Jason asked, "Why do some people say an engine is a chemical process and others say it is thermodynamic cycle." I am also curious. I long ago informally made the distinction that a Carnot engine cycle is a thermodynamic process, whereas an adiabatic engine cycle is a chemical process. The reason I find a distinction between the two is the former formally transfers heat through a bulkhead to perform work and the latter uses the kinetic pressure of the chemical reaction to perform work. A specific type of adiabatic cycle, in which heat addition is isochoric and heat rejection is isobaric, takes this distinction to a limit which results in an engine with both high thermal efficiency and low volumetric efficiency. With sufficiently high friction and flow efficiencies, this can result in an engine with high thermal efficiency.
I find myself troubled by the term "conventional hybrid". Did the original "hybrid" have to lose its clean and simple name because a so-called "plug-in hybrid" snuck into the theater? I'm not fond of the term "plug-in hybrid". Similarly, "battery electric" is a strange term for a car, as if an "extension cord electric" is an alternative or something. An electric car is an electric car, and nowadays these all use batteries. "Battery electric" is a redundant term. A so-called "plug in hybrid" starts out the day as a full-blooded electric car, and often ends the day the very same, if a certain number of miles are not exceeded. If driven farther, the so-called "plug-in hybrid" car ends the day as a full-blooded hybrid car, with all the rush-hour traffic efficiency benefits of a hybrid. For the first part of the day the so-called "plug-in hybrid" can be economically described with simple "driving range" data, and when the battery runs out, if the battery runs, out the latter part of the day can be economically described with "fuel mileage" data. It is senseless to advertise a so-called "plug-in hybrid" only in fuel mileage, since some applications never use fuel. Ever. These applications are run in true electric mode, get infinity miles per gallon, and contain an "engine assist" only for unexpected emergencies. It is senseless to call this a "plug-in hybrid", since it is an electric vehicle foremost, and may only occasionally become a hybrid. I hereby proclaim that a so-called "conventional hybrid" vehicle should go back to being called a "hybrid", a so-called "battery electric" vehicle should be called an "electric", and that a so-called "plug-in hybrid" should be called a "schizoelectric". That is what it is. When medicated with electricity, it is a pure electric vehicle defined primarily by driving range. When the medicine runs out, it becomes a pure hybrid vehicle, with the associated economies of a hybrid defined entirely by fuel mileage. Since electric vehicle technology remains entrenched in a "pre-standards" era, we can change specifications and naming conventions willy-nilly. For this reason, I formally recommend naming the three popular categories of electric vehicle: Hybrid, Electric, and Schizoelectric. Had this press release stated "schizoelectric" in the title, I may have stayed on the sidelines. I do not ever want to hear a car company telling me how many miles I must drive in a day to achieve the fuel mileage ratings they heap upon us. The Chevy Volt must apparently drive something like 52.3 miles to get 230mpg, and the EPA and GM are apparently working to make this "the standard distance". Similarly, I DON'T want to know what distance I must drive to achieve 43mpg.
I've just learned that popular terminology which describes the three types of electric motor vehicles are "conventional hybrid", "plug-in hybrid", and "battery electric", so the title of the above press release follows convention. I do hope to someday see standardized mileage and range specifications for plug-in hybrids like the Volt and AltE projects.
I have come to realize the EPA and SAE may not offer test standards for electrically propelled vehicles. These organizations have petrol vehicles down to a science, and vehicles driven by an electric motor may just get a nod and smile. This explains Chevy Volt’s vacuous mileage specification and how this nonsense extends to an entire hybrid and electric vehicle industry. If the EPA and SAE have not yet bothered with hybrid and electric vehicle standards, perhaps there is another world body we can look toward for this guidance. I’m not one to know where to find this body, so I will simply create standards that placate my needs. First, we must define what constitutes an electric vehicle and what constitutes a hybrid vehicle. I proclaim that an electric vehicle contains a convenient plug supplied by the manufacturer for routine recharging of the traction battery, and a hybrid vehicle does not contain a convenient plug for routine recharging of the traction battery. Vehicles containing fuel cells will not be considered at this primitive stage of standardization. A hybrid vehicle will provide valid city, highway, and combined city/highway fuel mileage much the same as a petrol vehicle, with the additional requirement that the hybrid’s fuel mileage test must assure the traction battery holds the same charge at the start of the test as at the end. This charge can, perhaps, be predefined to a 55% energy level, since traction batteries often have a practical “working range” between 80% and 30% of full charge. Charging above 80% generates waste heat and discharging below 30% degrades battery lifespan, though this depends on the battery technology. Perhaps the battery technology must be pre-certified by the standards organization to define an optimal “working range”, assuring honest comparison between battery technologies. An electric vehicle falls into two categories: A pure electric vehicle, and an engine assisted electric vehicle. A pure electric vehicle will only provide “driving range” specifications for city, highway, and combined city/highway driving. The specifications will be based on the “working range” limits of the traction battery, to assure valid comparison between competing vehicles. An engine assisted electric vehicle is both a hybrid and an electric vehicle, and must provide data which defines both fuel mileage and driving range information for city, highway, and combined driving. The fuel mileage specification requires the battery hold an identical charge at the start of the mileage test as at the end. The driving range test requires the engine be disabled and the traction battery be operated within the pre-defined “working range”. It seems the “missing link” may be that “engine assisted electric vehicles” have not previously been distinguished from “hybrid vehicles” and “electric vehicles”. This recognition may resolve a chief ambiguity in defining operating specifications. I regularly complain when I come across illogical science, but I always provide an alternative, for better or worse. I do find that an alternative proposal such as the one I’ve presented here would cause me to better appreciate the hybrid and electric car industry.
I've got no problem seeing fuel mileage ratings attached to a hybrid vehicle like the Prius. The 2kWh battery of the Prius can be tasked during a fuel mileage test to generate true fuel consumption data. I get irritated when I see fuel mileage ratings blindly attached to engine assisted electric vehicles. The Crown Vic mileage of this article is claimed to increase from 14mpg to 43mpg without technical qualification at how these numbers are derived. I was quite upset a couple months back when the Chevy Volt was introduced with a worthless 230mpg EPA rating. As if I am supposed to be impressed that a fuel mileage value has somehow converged with an international electrical standard. This little gimmick only makes me believe the EPA is in bed with GM. The Chevy Volt now bugs me. I refuse to call it a hybrid, since I like hybrids. Instead, I call the Volt an "engine assisted electric car" by virtue of its battery capacity. Same for this Crown Vic retrofit, since its 20kWh battery pack is just too large to qualify as a hybrid. The 230mpg and 43mpg numbers simply have no comparative value. If I am to gain any comfort level with the current generation of engine assisted electric cars, I need to begin seeing "true fuel mileage" listed proudly along side "true battery driving range", or some honest variant which clarifies real operating characteristics and cost. Getting past the 43mpg ambiguity, a taxi will discharge the battery in the first 30 minutes of the day and have to lug discharged batteries in the trunk (instead of luggage) for the next 7.5 hours, assuming the driver is among the few with access to an outlet and the driver bothered to plug in overnight to get the 30 mile battery range. What is the real fuel mileage in a taxi application? Wouldn't a small Prius battery make more sense in this Crown Vic?