A human powered thermal electric generator (i.e, an engine that uses the human body as the heat source) has been developed using carbon nanotube tecnology. It has been suggested that the device may eventually be able to power a smart phone.
A) Estimate the maximum efficiency of an ideal (i.e, Carnot) heat engine using a body temperature of 37 degrees Celcius as the high temperature heat source and an ambient temperature of 15 degrees celcius as the low temperature heat sink.
B) If the human body rejects heat at a rate of 1/3 of the typical 2000 Cal/day diet (1 Cal=4.1868 kL), would the ideal heat engine produce enough electric power to supply a smart phone that requires 1.5 Watts in stand-by mode?