Unwilling to research
California to reduce carbon emissions by... banning black cars?!
This is beyond idiotic. These legislators obviously did not bother to research automitive climate controls before going off half-cocked and riding the wave of environmentalist sentiment.
The flawed premise here is that the climate controls on darker-colored cars have to work harder to keep them cool than those in lighter-colored cars. The only difference between a car painted black and a car painted white is the paint itself. Sure, the darker car will absorb more heat. Problem is, both cars have identical air conditioning systems that work the same way, put the same load on their engines, and have the same effect on power output and fuel economy. A dark car will take more time to cool, but its air conditioner will function at the same rate as that in a lighter car.
Allow me to explain: With a car's air conditioner on, a compressor circulates refrigerant through the system. In the passenger compartment there is a condenser, where high-pressure liquefied refrigerant is expanded to a gas. This expansion dissipates heat, causing rapid cooling in the evaporator. Air is blown through the condenser box, and water vapor condenses on the evaporator coils. this air is sent through a valve that mixes air from the evaporator box with ambient air or air from a separate heater core (the temperature control on your dash controls the setting of this valve. Regardless of your temp setting, the evaporator functions at its maximum capacity as long as the air conditioner is on and the compressor is loading the engine.
The upshot of this is that if you think that reducing your temp setting but still receiving some cooling benefit will save you gas, you are mistaken. The only way to improve fuel economy is not to run your air conditioner at all-- try that in a traffic jam in July!
Yet you still hear radio ads and see TV spots advising you to "turn down" your air conditioner to save fuel. These dumbasses never bothered to check their premises before going on the air and wasting money on uninformed advertising.
Don't suffer needlessly- If you need air conditioning, set it for your own comfort. A thermostat set to 65 degrees in a car will put just as much of a load on an engine as an AC set to 80 degrees.
It's even more important not to suffer the idiocy of an uninformed, petulant nanny-state. If you live in California, call your representatives and lean on them to shoot down this travesty of a bill.
Thursday, March 26, 2009
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5 comments:
Not quite. The AC compressor is connected to the pully that runs it by an electric clutch. The compressor is disconnected, allowing the pulley to freewheel when it isn't needed. If you sit in a car with a small engine at idle, you can hear and see on the tach when the compressor kicks in.
A car that absorbs less heat needs the compressor running less of the time.
I feel so unclean when I agree with enviro-leftists.
It disengages and re-engages in a heartbeat. Matter of fact that's a bit shortsighted-- it's an even greater load on the engine to constantly break the inertia of a stopped compressor.
The insanity is not lost on me.
Won't asn Air conditioner set at 80 run for less time than one set at 60?
Its not the Cooling Rate that gives you savings, its the length of time it actually runs...
As far as stopping and reatrting, sure, theres probably a point of diminishing returns, but where is that point?
Russ,
GorgeH is right, the load placed on the engine is varied by the clutch on the condenser. Furthermore auto AC has used this clutch design for years, it is efficient and effective. As for banning black cars, this is more a talking point than reality. Below is a link to a presentation that supports the measure. its heavy on science light on flying off the handle.
-Justin Fritz
http://www.arb.ca.gov/cc/cool-paints/final_cool_cars_workshop_presentation31209.pdf
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