While only having 3% efficiency, OTEC is a renewable energy technology that unusually uses the ocean as one of these systems, which are potentially useful to locals with deep ocean access. For 10 points each:
[10e] Name these systems that convert thermal energy to mechanical or electrical work, whose most common modern variant uses the heat from internal combustion.
ANSWER: heat engines [accept just engines]
[10h] It’s not the Carnot cycle, but since OTEC heat engines involve heat extraction while flowing from heat source to sink, they are best modeled with these cycles, which ideally have isentropic compression and expansion.
ANSWER: Rankine cycle
[10m] Pencil and paper may be helpful. Assuming Carnot’s theorem applies, what is the maximal Carnot efficiency of an OTEC heat engine that operates between a surface temperature of 300 Kelvin and a benthic temperature of 100 Kelvin?
ANSWER: 2/3 [accept equivalents like 66.67%]
<Jim Fan, Physics>