Posted 2/4/2019 20:14 (#7297251 - in reply to #7292954) Subject: RE: Idling/starting throughout day in cold
THERMODYNAMICS # !
I takes ( 1 ) BTU/lb of water to raise or lower the temperature of the water 1 degree F
It takes 144 btu/lb of water to change 1 lb of 32 degree water to 1 lb of ice ( this is called Latent heat of fusion )
It takes 1744 btu/lb of 212 degree water at sea level to 212 degree steam. ( this is called Latent heat of fusion )
HEAT flows from Hot to Cold
Heat loss/Heat gain formula = Area X TD ( temperature ) x Conduction factor = heat loss or gain
Single pane glass conduction rate is approx. 1.1 Double pane is .55 (Ex.) Heat = 10 Sq.ft of glass x Cond.factor 1.1 x 0* outdoor temp. 70* indoors Equals 10 x 1.1 x 70 = 770 btu /hour heat loss
So as the 100* and 60* water in the above example approaches the 40* temperature the conduction rate slows down ( temperature difference approaches 0 ) Remember 60-40 = 20 td ,100-40 = 60 td therefore both the 100* and 60* will eventually reach 40* ( 0 TD ) Then heat exchange ceases.
Also a term ( Coefficient of heat ) Water is the base Water = 1 Lead and heaver material has higher coefficient Basically it is how much heat a different material will hold for the same weight Ex. Water verses lead or steel, rocks etc.
Hot water will not freeze faster than cold water if put in seperate identicle containers based on the 1 btu/lb per degree temperature difference
Not trying to be a smart ass ,just stating laws of thermo Dyn.