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Exterior Sunscreen

PostPosted:Mon Mar 07, 2005 3:19 am
by samuel
:-B I am a high school teacher in HK. Recently, I'm working with my students on a project of Car's sunscreen.
It is very hot (36C) in summer here, car drivers always use sunscreen inside their cars when they park the cars outdoor. The sun screen can reduce the temperature rise a bit but most of them are not effective. The temperature inside the car (after exposed to strong sunlight for a few hours) could reach as high as 35C. Many drivers will try to turn on the air-conditioners to a maximum level until the compartment cool down, it alway take them from 5 to 15 minutes. That was really a JOKE as I' m teaching student " environmental protection" ! This is not only a waste of fuel but also producing extra CO2 and other pollutants.
We have try some experiments in the lab. , the results show that if the sunscreen is placed outside(the top of) the car the temperature inside the car can be greatly reduced. Moreover, we are also trying o find out the best material for making hesunscreen and the most convenient way for installation.
Please give us some advices on those topics.


PostPosted:Mon Mar 07, 2005 12:18 pm
by Rishi
Dear Mr.Samuel,
Your idea of using an external screen is correct. The screen should reflect away the incoming radiation. Ideally the screen should be mounted with an air gap between the screen and the car roof. You can try fluted polypropylene sheet with uv stabilizer in white. A 5mm thick fluted sheet mounted about 2.5 to 5cm above the roof of the car should give adequate protection from 9 am to 3 pm, which is the period of the highest solar radiation.

I tried to attach a bmp picture of this concept. I failed.