Jim, this is a good article that gets into the nuts and bolts of the heat calcs for mashing:

http://byo.com/malt/item/627-feel-the-mash-heatTo paraphrase:

"When you mash grain at room temperature into hot water you are transferring heat from one to the other. The water loses heat to the grain and the grain increases in temperature until the two reach equilibrium. The goal is for the temperature at which equilibrium is reached to be your desired strike temperature. By adding grain at a certain temperature to water at a certain temperature, you can predict the final temp. Precision comes from understanding heat transfer. Every substance you encounter in the mash (grain, water, tun, etc.) has a specific heat constant. Specific heat is the amount of energy in the form of heat required to raise 1 Kg of malt by 1 degree......."

This thread gives some considerable time and energy to the derivation of the equation and it's relationship to Palmer's well known equation from how to brew, which is essentially a simpler heat transfer equation:

http://www.homebrewtalk.com/showthread.php?t=481047The gentleman notes that the 0.2 constant from Palmer's equation comes from the fact that 20 lbs. of grain has as much specific heat as 1 gallon of water. Therefore 1 lb. of grain has the same specific heat as 0.05 gallons of water or 0.2 quarts of water.

Not sure if any of that helps.