Heat engine applications

what is the efficiency equation for a reversible heat engine?

thermal effiency = 1 - T(L)/T(H)

what is the efficiency equation for a general heat engine?

efficiency = 1 - Q(L)/Q(H)

Whenever there exits a temperature difference…

there exists the capacity to do work

What are some applications of heat engines?

geothermal energy, concentrated solar thermal power, nuclear & combustion, combustion

How does geothermal energy work?

Heat source: Earth

Heat sink: Ambient (local water source like lake, river or ocean)

typical source temperature: 400-600K

How does concentrated solar thermal power work?

Heat source: sun

Heat sink: Ambient (local water source like lake, river or ocean)

typical source temperature: 6000 K

How does nuclear work?

Heat source: nuclear fission

Heat sink: Ambient (local water source like lake, river or ocean)

How does combustion work?

Heat source: combustion (natural gas, biomass, coal and oil)

Heat sink: Ambient (local water source like lake, river or ocean)

what temperature is waste heat typically?

low temperature

what factors determine if heat is worth recovering?

economic and practicality

What is cold energy?

generating energy from cold sources

Heat source: ambient

Heat sink: something colder than ambient

W ≤ ( 1 - T(L)/T(H) ) x Q(H)

what are some applications of cold energy?

cryogenic fluids, sky cooling

how do cryogenic liquids work?

heat source: ambient

heat sink: cryogenic fluid (e.g liquid H2, liquid methane)

how does sky cooling work?

heat source: Ambient

heat sink: space (reduced to sub-ambient temps by radiating to space)