I think the solar gain has less to do with the glass than the small cabin size.
While involved with designing climate controlled cabins (at Caterpillar) I learned that that any glass you have - whatever tint level - re-radiates the absorbed energy into the cabin. The main effect of tint is to reduce the heat felt on the skin - the AC load remains the same. Likewise, the roof, walls, everything basically sinks heat until equilibrium. No amount of insulation mitigates this when you are just out in the sun for long periods. Insulation slows the conduction, it can't really stop it. Convection from motion helps, but absorption and conduction carry on as always. If you could make the cab into a vacuum bottle... The load on the AC ends up being pretty simple to estimate - how much area is in the sun. It is hard to win this game. Reflecting light back out when not moving is always effective. Reflective tints (not generally legal in US) don't actually reflect much energy - the glass still absorbs the bulk of it, and it is radiated in as IR. On Sat, Aug 2, 2014 at 3:26 AM, EVDL Administrator via EV <[email protected] > wrote: > On 2 Aug 2014 at 2:03, Dennis Miles via EV wrote: > > > On the other hand a friend in St Petersburg, FL. uses a 7,500 BTU ac in > his > > S-10 Pickup (About a 400 watt load) and runs it from a 1,000 Watt 110v. > > inverter... > > I can absolutely believe that. Pickup cabs are typically fairly small. > They also usually have relatively vertical glass, for less solar gain than > most cars. > > Besides ... > > http://evdl.org/images/aircon-daewoo.jpg > > ;-) > > > Your 25000 to 30000 btu/hr are two to two and a half tons (Same as HP > > or similar to Kw. ) and that is as much a a small house. > > Exactly! A passenger car with lots of glass area and poor insulation can > easily take that much capacity to cool. > > However, now that I think about it, I'd guess that much of that capacity is > there so the car cools down quickly after it's been sitting in the hot sun. > You could no doubt use a much lower capacity aircon unit if you allowed > plenty of time to pre-cool it. (Or always parked in the shade. ;-) > > David Roden - Akron, Ohio, USA > EVDL Administrator > > = = = = = = = = = = = = = = = = = = = = = = = = = = = = = > EVDL Information: http://www.evdl.org/help/ > = = = = = = = = = = = = = = = = = = = = = = = = = = = = = > Note: mail sent to "evpost" and "etpost" addresses will not > reach me. To send a private message, please obtain my > email address from the webpage http://www.evdl.org/help/ . > = = = = = = = = = = = = = = = = = = = = = = = = = = = = = > > > _______________________________________________ > UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub > http://lists.evdl.org/listinfo.cgi/ev-evdl.org > For EV drag racing discussion, please use NEDRA ( > http://groups.yahoo.com/group/NEDRA) > > -- Put this question to yourself: should I use everyone else to attain happiness, or should I help others gain happiness? *Dalai Lama * Tell me what it is you plan to do With your one wild and precious life? Mary Oliver, "The summer day." To invent, you need a good imagination and a pile of junk. Thomas A. Edison <http://www.brainyquote.com/quotes/quotes/t/thomasaed125362.html> A public-opinion poll is no substitute for thought. *Warren Buffet* Michael E. Ross (919) 550-2430 Land (919) 576-0824 <https://www.google.com/voice/b/0?pli=1#phones> Google Phone (919) 631-1451 Cell (919) 513-0418 Desk [email protected] <[email protected]> -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20140802/72277c31/attachment.htm> _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
