Heat Engines Heat Engines. Heat Engine cycles. Carnot cycle. Refrigerators & Air conditioners. Heat Pumps. 2 nd Law considerations. Entropy.

Presentation on theme: "Heat Engines Heat Engines. Heat Engine cycles. Carnot cycle. Refrigerators & Air conditioners. Heat Pumps. 2 nd Law considerations. Entropy."— Presentation transcript:

Heat Engines Heat Engines. Heat Engine cycles. Carnot cycle. Refrigerators & Air conditioners. Heat Pumps. 2 nd Law considerations. Entropy.

Heat engines Examples of Heat Engines – Steam engine – Coal plant – Nuclear plant – Automobile – Jet engine Each of these has – Hot source – Cold exhaust – Pathway from hot to cold that provides mechanical work Expanding piston steam engine, car engine Pressure difference across turbine blade

Heat Engines 1 Pathway from hot to cold that provides mechanical work – Expanding piston steam engine. – Pressure difference across turbine blade.

Heat Engines 2 Pathway from hot to cold that provides mechanical work – Expanding piston car engine. – Hot reservoir inside engine, cold reservoir tailpipe – “Internal combustion” engine.

Heat Engine Animations Otto Cycle (automobile) http://www.animatedengines.com/otto.html Otto Cycle (automobile) https://sites.google.com/site/physicsflash/home/otto

Energy flow and efficiency

Efficiency Example

“Everything” problem – getting efficiency ΔUΔUWorkQ a -> b+6000 J+4000 J10000 J b -> c-4500 J0 J-4500 J c -> d-3000 J-2000 J-5000 J d -> a+1500 J0 J1500 J entire cycle0 J2000 J

Carnot cycle – most efficient cycle

Carnot cycle animation Note cycle bounded by upper and lower isotherms (red/blue) and left and right adiabats (green) http://educypedia.karadimov.info/library/carnot.swf

Carnot cycle examples

Refrigeration Basic Operation 1.Compress gas to high temperature/pressure 2.Cool and liquefy at high pressure (Q out) 3.Expand gas to low temperature/pressure 4.Warm and evaporate at low pressure (Q in) Thermodynamic cycle running backwards.

Forward and reverse Carnot cycle Forward Carnot cycle (heat engine) Q H in Work, Q L out Clockwise cycle Reverse Carnot cycle (refrigeration) Work, Q L in Q H out Counterclockwise cycle

Forward and reverse Carnot animation Forward animation (heat engine) educypedia.karadimov.info/library/AF_2202.swf Reverse animation (refrigeration) educypedia.karadimov.info/library/AF_2205.swf

Efficiency, Coefficient of Performance

Example 15-13

Heat Pump - Problem 32

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