Heat Engine: Carnot Cycle

Also called

Carnot cycle · Carnot engine · heat engine · isothermal expansion · adiabatic expansion · isothermal compression · adiabatic compression · efficiency of a heat engine · P-V diagram · indicator diagram · work done by a gas · refrigerator · heat pump · second law of thermodynamics · reversible cycle · hot reservoir · cold reservoir · ऊष्मा इंजन · कार्नो चक्र · समतापी प्रसार · रुद्धोष्म प्रसार

Topics

• A Carnot engine takes heat Q₁ from a hot reservoir at T₁, does work W and gives heat Q₂ to a cold reservoir at T₂.
• Isothermal expansion on the hot reservoir: the gas takes in heat Q₁ and pushes the piston out at constant T₁.
• Adiabatic expansion on the insulating stand: no heat flows, the gas does work and cools from T₁ to T₂.
• Isothermal compression on the cold reservoir: the gas is squeezed at T₂ and gives out heat Q₂.
• Adiabatic compression warms the gas back to T₁ and closes the cycle; the gas is back in its starting state.
• On the P–V diagram the area inside the loop is the net work done in one cycle: W = Q₁ − Q₂.
• Efficiency η = W/Q₁ = 1 − T₂/T₁; no engine working between the same two temperatures can do better.
• Here T₁ = 1.5 T₂, so η = 1 − 1/1.5 = 33 %: one third of the heat taken in becomes work.
• Run backwards the cycle is a refrigerator: work W pumps heat Q₂ out of the cold body into the hot one.

About this model

A GLB file of about 511 KB, shown in Lably's 3D viewer and, on a phone, placed in your room with AR. Credit: Model, science and animation: Lably (built procedurally with three.js; no downloaded meshes). | CC BY 4.0. Original geometry and animation made for Lably.

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