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1. Draw the Otto cycle on a PV diagram. Indicate the direction of each process, and label the processes where heat enters or leaves the system. 2. Calculate the net work done by the system on its surroundings, per cycle, in terms of the temperatures T, T2, T3 and T4 at points 1,2,3 and 4, respectively. 3. Calculate the heat input per cycle. Include only heat input; do not include processes where heat leaves the system. (This is because the output heat is lost to the environment; it cannot be recovered and fed back into the system.) 4. Calculate the thermal efficiency of the engine: net n = Qin Vmax/Vmin Represent your answer in terms of the compression ratio r = ratio y, and nothing else. (Hint: use the properties of adiabatic processes to relate the the specific heat temperatures to the volume ratios.)

1. Draw the Otto cycle on a PV diagram. Indicate the direction of each process, and label the processes where heat enters or leaves the system. 2. Calculate the net work done by the system on its surroundings, per cycle, in terms of the temperatures T, T2, T3 and T4 at points 1,2,3 and 4, respectively. 3. Calculate the heat input per cycle. Include only heat input; do not include processes where heat leaves the system. (This is because the output heat is lost to the environment; it cannot be recovered and fed back into the system.) 4. Calculate the thermal efficiency of the engine: net n = Qin Vmax/Vmin Represent your answer in terms of the compression ratio r = ratio y, and nothing else. (Hint: use the properties of adiabatic processes to relate the the specific heat temperatures to the volume ratios.)

Elements Of Electromagnetics
Elements Of Electromagnetics
7th Edition
ISBN:9780190698614
Author:Sadiku, Matthew N. O.
Publisher:Sadiku, Matthew N. O.
ChapterMA: Math Assessment
Section: Chapter Questions
Problem 1.1MA
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Thermodynamics of the Otto cycle (gasoline engine) A gasoline engine is an internal combustion engine, typically consisting of one or more piston-cylinder assemblies. The operation of a gasoline engine is approximated by the Otto cycle, composed of the following processes: Point 1: (start of the cycle), the cylinder is at its maximum volume Vmax: A cold mixture of fuel and air is introduced into the cylinder. Process 1 → 2 (compression stroke): The cylinder contracts until the volume of the cylinder reaches Vmin, compressing the fuel-air mixture adiabatically. Work is done by on the system by its surroundings. Process 2 → 3 (): A spark is generated within the cylinder, igniting the fuel-air mixture. The fuel burns very rapidly, such that the volume of the cylinder changes by approximately zero during this step. The combustion of the fuel corresponds to a heat transfer Qin into the system during this constant-volume, or isochoric, process. Process 3 → 4 (power stroke): The cylinder expands adiabatically, doing work on its surroundings until it reaches its original volume Vmax. Process 4 → 1 (exhaust/intake): In this isochoric process, the hot combustion products are quickly flushed out of the cylinder and replaced by cold fuel/air mixture. This corresponds to heat output Qout from the system into the environment. 1. Draw the Otto cycle on a PV diagram. Indicate the direction of each process, and label the processes where heat enters or leaves the system. 2. Calculate the net work done by the system on its surroundings, per cycle, in terms of the temperatures T1, T2, T3 and T4 at points 1,2,3 and 4, respectively. 3. Calculate the heat input per cycle. Include only heat input; do not include processes where heat leaves the system. (This is because the output heat is lost to the environment; it cannot be recovered and fed back into the system.) 4. Calculate the thermal efficiency of the engine: Wnet n = Qin Represent your answer in terms of the compression ratio r = Vmax/Vmin, the specific heat ratio y, and nothing else. (Hint: use the properties of adiabatic processes to relate the temperatures to the volume ratios.)
Transcribed Image Text:Thermodynamics of the Otto cycle (gasoline engine) A gasoline engine is an internal combustion engine, typically consisting of one or more piston-cylinder assemblies. The operation of a gasoline engine is approximated by the Otto cycle, composed of the following processes: Point 1: (start of the cycle), the cylinder is at its maximum volume Vmax: A cold mixture of fuel and air is introduced into the cylinder. Process 1 → 2 (compression stroke): The cylinder contracts until the volume of the cylinder reaches Vmin, compressing the fuel-air mixture adiabatically. Work is done by on the system by its surroundings. Process 2 → 3 (): A spark is generated within the cylinder, igniting the fuel-air mixture. The fuel burns very rapidly, such that the volume of the cylinder changes by approximately zero during this step. The combustion of the fuel corresponds to a heat transfer Qin into the system during this constant-volume, or isochoric, process. Process 3 → 4 (power stroke): The cylinder expands adiabatically, doing work on its surroundings until it reaches its original volume Vmax. Process 4 → 1 (exhaust/intake): In this isochoric process, the hot combustion products are quickly flushed out of the cylinder and replaced by cold fuel/air mixture. This corresponds to heat output Qout from the system into the environment. 1. Draw the Otto cycle on a PV diagram. Indicate the direction of each process, and label the processes where heat enters or leaves the system. 2. Calculate the net work done by the system on its surroundings, per cycle, in terms of the temperatures T1, T2, T3 and T4 at points 1,2,3 and 4, respectively. 3. Calculate the heat input per cycle. Include only heat input; do not include processes where heat leaves the system. (This is because the output heat is lost to the environment; it cannot be recovered and fed back into the system.) 4. Calculate the thermal efficiency of the engine: Wnet n = Qin Represent your answer in terms of the compression ratio r = Vmax/Vmin, the specific heat ratio y, and nothing else. (Hint: use the properties of adiabatic processes to relate the temperatures to the volume ratios.)
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