At 8:12 PM 1/16/5, thomas malloy wrote: >Horace Heffner posted; > >> >>Cooling may be a luxury, but people in hot climates demand it. Heating on >>the other hand, is a matter of health and safety here in Alaska. It is >>often difficult just to keep the ice off the windshield here > >White man invent gas powered heater and absorption chiller.
The objective is energy efficiency. You snipped the relevant part. As fuel efficiency grows, the power requirements of vehicle cooling and heating then begin to loom large. Meeting heating requirements by burning fuel directly instead of using waste heat, to the extent possible, only makes that problem worse. > >> >>The only way to combat the heating and cooling problem is insulation, which >>is poor to non-existent in most cars. Good thermal insulation also has the > >Insulation only holds heat that is in the vehicle in. It would be nice if insulation could really hold the heat in, but it can't even do that. Increased insulation only reduces the *rate* of heat exchange, which is always finite unless ambient temperature = internal temperature. Increased insulation reduces the amount of fuel required to maintain a given delta T, for that delta T which can not be maintained by waste engine heat. As engine horsepower drops, or engine efficiency increases, waste heat drops. A given HVAC heat exchange loss rate has to be made up via burning more fuel whenever the remaining waste heat is insufficient or unable to handle the heating or cooling power requirement. Air conditioning has not to my knowlege ever been produced in cars using waste heat, so 100 percent of AC requirements must be met by buring more fuel. Insulation then always has a direct effect on reducing that fuel requirement. A metal and glass vehicle with no insulation is a giant heat conductor. The glass turns it into a greenhouse in the summer. The greenhouse effect is of little use here in Alaska in the winter though, becuse it is dark or overcast most of the time. Insulation, properly incorporated in a design, can make a car much more comfortable, quite, safe, and fuel efficient. Regards, Horace Heffner
