Passive passenger compartment cooling

[Piwoslaw]

Originally Posted by SC380D

3. Reflective sunshades in windows (when parked)
Self explanatory.

Why only when parked? You can block the rear side windows (semi-)permanently, as you do not need them during driving. This will reduce some of the greenhouse effect when the sun is lower.

How about parking in the shade? Sometimes you'll have to walk farther across the parking lot, but it may be worth it.
If you have a regular parking space or driveway, then maybe you can build a shade over it?

You can also try a thermal cover

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Here is another idea: Thermal insulation.
The metal chassis is great at conducting heat, so if you stick insulation between the metal and the interior liner and panels (some time-intersive work required) it will help keep the hot out and the cool in.

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An additional benefit is that it will help make the interior quieter.
A down side to fuel economy is the additional weight.

Many RVs and RV conversions have thermal insulation on the floor, sides and roof to keep warm at night.
More recently, EVs benefit from thermal insulation, to reduce both heating and cooling load.

Originally Posted by freebeard

When parked yes. But what about the aero penalty?

[freebeard]

But what about the aero penalty?

What about it? It needs A-B-A testing.

Of course it only works with approx. vertical windshields. The Beetles max camber is at the B-pillar so it's in a positive pressure gradient. It's a wing not a pocket.



With a properly sized and located gap, you'd have a Coanda nozzle/air curtain; it might improve the aero.

[freebeard]

Another entry or three, in the 'free AC' race:
Cooling Our Homes Without Electricity?
MIT combines insulation evaporation and radiation, by layering aerogel, hydrogel and a mirrored substrate.

It's basically a high tech swamp cooler. MIT uses an expensive aerogel, Universities in China and Germany have a cellulose-based aerogel that may be more viable.

There is promising research into anisotropic aerogel and single-pane insulating windows.

[Logic]

A good summary of the latest cooling paint tech, including a new thinner, lighter paint based on hexagonal boron nitride: (reflectivity of 97.9% vs barium sulfate at 98.1%)
https://www.gsbpainttools.com/news/t...ver-comes.html

But finding an available automotive paint based on any of these pigments; not so easy.

Of course the best way to keep the car cool is to keep it in the shade.
Various Land Rovers had double skinned roofs with an air gap in between to 'take the shade with you'
But they had a small air gap in which very little breeze could get, no overhang, and aerodynamics was a funny word those crazy aeroplane nutters used.

If one wanted to go this route and still be aero, I would say that you would want the 2nd roof to be exactly the same shape as the original roof.
That's doable if you can find an unscathed roof at a junkyard, but extending it out some to the back and sides while keeping the aero..? And, even worse, to the front!??
I guess you would want to follow the same shape as the front and rear windows, stopping where the 'aero hat' began to impede on your line of sight.

[cRiPpLe_rOoStEr]

Originally Posted by SC380D

Evaporative cooler
Especially in dry areas, and even more especially if it can be plumbed into the vent system on the firewall, downstream of the blower motor. Fill with water, turn the blower motor on, and voila.

That's still fairly popular for trucks in my country, yet I have never seen any evaporative cooler plumbed into the vent system on the firewall. Usually it's installed on a roof-mounted structure with its own vents, as the incoming air tends to go down right after going through the humidifier.

[Logic]

Originally Posted by cRiPpLe_rOoStEr

That's still fairly popular for trucks in my country, yet I have never seen any evaporative cooler plumbed into the vent system on the firewall. Usually it's installed on a roof-mounted structure with its own vents, as the incoming air tends to go down right after going through the humidifier.

There was or maybe still is a kit being sold locally, but I only ever heard of it.

But Piezoelectric or so called Ultra-Sonic pond misters are a dime a dozen and very compact vs all that sawdust or paper normally used.
They give you an unparalleled surface area for evaporation.
And should easily fit into the interior air's intake, located near the wiper area of most all cars and already equipped with a water overflow/rain drain pipe.

https://www.youtube.com/watch?v=5Ep0lWrprlE

You could maintain the water level using the same simple principle used in bird water feeders if your tank is higher than your mister's little bath.
Else a water level switch to start/stop a small pump.
A windscreen washer pump is overkill but would work, especially if you made your existing washer setup do double duty...

I used a mister to cool the radiator on my overclocked computer very successfully:
15C below ambient at times and NO chance of condensation on/around the processor.

[cRiPpLe_rOoStEr]

Originally Posted by Logic

There was or maybe still is a kit being sold locally, but I only ever heard of it.

I wouldn't be so surprised if such kit was exported from Brazil.