Car a/c: dumping the heat

If you look in front of the car, you'll see one radiator on the inside of the radiator support, and one on the outside. The one on the outside is the AC Condensor, the 'radiator' for the AC system.

And, as far as being 'typical', they are all typical. You have a condensor, a compressor, a receiver/dryer and then the heat exchanger that draws the hot air out of the car.

AFAIK, all automotive AC systems work pretty much the same way, with a condenser, compressor, evaporator, and expansion valve. There are differences in controls, i.e., manual and automatic, with dampers mixing hot and cool air or moving temperature control valves to regulate temperature and moving dampers to control where the cool air enters the passenger compartment.

Basically, the compressor pumps liquid refrigerant to the expansion valve, which sprays the refrigerant into the evaporator. The refrigerant evaporates and cools as it changes from a liquid state to a gaseous state. Hot air from the passenger compartment moves past the evaporator and the refrigerant absorbs the heat from the air. The hot gaseous refrigerant goes to the condenser, where outside air cools and condenses the gas back to a liquid state, where it goes to the compressor to start the cycle again.

Thank you, Hachi and Ray. I gather the a/c will usually have its own mini-radiator. Combining it with the engine's would prove an inconvenient engineering puzzle, I suppose.

There are a few reasons why combining the AC condenser with the vehicle's radiator is impractical. A big reason is size - a combination unit probably would not have sufficient surface area to get rid of heat. Another is that the dissimilar contents would make a combo unit more expensive to make, and radiators tend to need more frequent replacement than condensers so separate units would be less costly to replace.

Thank you also, Jeff. Sticking to standard parts has to be a powerful argument. That way, besides the cost savings, there is also freedom to fit the a/c unit in a variety of vehicles.

Oh hum, idle curiosity, as I said. (I shall save the one about using standardised fuel.)

Yup. They make common components that can go in many different cars, like the AC compressors, magnetic clutches, evaporator and condenser coils, receiver/driers, etc., and they get the benefit of mass production on those parts.

Plus having common parts makes it simpler on the Parts Department, since they only need to stock two or three compressors to cover most of the cars. A "small" compressor for most cars and pickups, and a "large" for the SUV's and Vans with dual air conditioning.

(Oh, and now there's one set of compressors hoses and parts with the PAG or POE synthetic refrigeration oil and the right synthetic rubber seals for newer R-134 cars, and a set with different seals and Mineral Oil for R-12 use. In another twenty years they won't have to worry about that.)

The brackets for compressor to engine, mounting tabs for the condenser to the radiator support, the heater box to fit in the under-dash space in that car, the refrigerant lines and hoses - those are the parts custom-made to fit in a certain car model. But even then, they can design all the small sedans on that platform to use the same basic parts.

There are many standardized fuels out there, it's just two big problems that form a "Chicken or Egg, Which came first?" paradox - Car Mass Production and getting the fuels and the fueling systems deployed to be widely available.

Car Technology, teaching a fuel injection computer to deal with a totally different fuel (either singly or Dual-Fuel with Gasoline, or Flexible Fuel to handle varying Methanol/Ethanol blends with Gasoline) would be trivial at the Mass Production stage. All you need to do is add another set of injectors, and teach the computer how to switch back and forth and the running qualities of the other fuel. A few years of intensive research, and I could build a car that would automatically switch over between fuel sources (to Gasoline when the CNG tank runs out) with nary a hiccup...

But doing one-off end-user fuel conversions is a rather difficult PITA, especially if you want Dual-Fuel for Gasoline or Diesel compatibility depending on the base engine tech used.

Um... I _was_ joking about the "standardised fuel". OTOH, your answer proved interesting. Ta. :-)

I knew that. Many a serious subject was broached in jest...

(I've probably butchered the original quote horribly, and I'm not going hunting for citations. But you get the picture.)

We need better alternate fuels for the things that have to continue to move by individual vehicles, like tradesmen and their work vehicles, and cross country trips. And vastly improved Local and Regional Mass Transit for the people that move better that way.

in 1958-59-60-61 (somewhere in there) Walt Disney offered the Los Angeles City Council and the Los Angeles County Board of Commissioners (both principals in the LA Metropolitan Transit Authority) the base technology and engineering support for turning the Disney-ALWEG Monorail into a grade-separated regional transit system, for free. A perfect solution for the gridlock that was even then looming on the horizon.

And in their infinite dumbth, he was turned down flat by both government bodies. They were convinced by General Motors (bus maker) Goodyear Tire and Standard Oil that transit buses were the way to go for the future. That's why they shut down the old Red Car light rail trolley system in favor of buses, because "buses are more flexible".

(The back-story of "Who Framed Roger Rabbit" was 100% factual, it was collusion pure and simple. The Unholy Trinity above bought up the privately owned Red Car system solely to shut it down, and sell more cars and buses, tires, gasoline and diesel fuel instead.)

Now we don't judge our commute by the mile, but by the hour. It can take 2 hours to go 20 miles. And the buses are even slower.

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