Jed Rothwell wrote:
> From my book, Appendix A., p. 179-180: > > Waste Heat > > Strictly speaking, this is: "heat energy produced in an energy > conversion or transfer process that is lost during conversion or > transfer and is not available for useful purposes" (as defined by > Pacific Northwest National Laboratory). For example, a typical > automobile engine is 20% efficient, meaning that 80% of the heat from > the burning gasoline goes out of the exhaust system, and 20% converts > to vehicle propulsion. . . . What is a "useful purpose". If it is does not lead to a profit does that make it waste heat? > However, the 80% of the waste heat from an automobile engine is not > all necessarily wasted in the literal sense. In wintertime, you move > a lever to open a baffle, directing a stream of fresh air across the > hot engine block into the passenger compartment. In other words, you > use waste heat to keep yourself warm. At a typical electric power > plant, 66% of the heat is wasted, producing billowing clouds of steam > from the cooling towers. This leftover heat is not hot enough to > generate electricity with conventional turbines, but it can be used > for space heating and other purposes. See: Cogeneration. > > Harry
