Introduction to Thermodynamics Quiz

Introduction to Thermodynamics

• Energy exists in many forms: mechanical, electrical, chemical, and more.
• Thermodynamics focuses on how energy changes forms and its relationship with surrounding areas.

Types of Systems

• Open System: Exchanges both energy (heat, work) and matter with the environment.
  • Examples: Pumps, turbines, air conditioners, hair dryers.
• Closed System: Exchanges energy (heat, work) but not matter with the environment.
  • Examples: Piston-cylinder assembly, air in a balloon, mercury in a thermometer, pressure cookers.
• Isolated System: Does not exchange heat, matter, or work with the environment.
  • Examples: Thermos, picnic ice chest.

Thermodynamic Properties

• Matter: Anything that occupies space and has mass or weight. It exists as solids, liquids, and gases.
• Extensive Property: Dependent on the substance's mass.
  • Examples: Mass, weight, volume, energy.
• Intensive Property: Independent of the substance's mass.
  • Examples: Density, pressure, temperature, specific volume, specific weight, specific gravity, specific internal energy.

Temperature

• Measures a body's hotness and coldness.
• Common temperature scales: Kelvin (K), Celsius (°C), Rankine (R), Fahrenheit (°F).

Zeroth Law of Thermodynamics

• States that when bodies are in thermal equilibrium with a third body, they are in thermal equilibrium with each other, meaning they are at the same temperature.

Vacuum Distillation

• Distillation performed at lower than atmospheric pressure.
• This lowers the boiling point of liquids.
• Used in refining processes to separate petroleum products.

Cracking

• Process to break large hydrocarbons into smaller, more useful components.
• Achieved using high temperatures and pressures or lower temperatures and pressures with catalysts.
• Used in refining and fuel production.

Gaseous Fuels

• Manufactured Fuel Gas: Produced through gasification, typically at gasworks.
  • Biogas: Renewable energy source, a mixture of methane and carbon dioxide.
  • Producer Gas: Combustible mixture of nitrogen, CO2, CO, and hydrogen.
• Petroleum Gas (LPG): Non-renewable energy source, mainly hydrocarbons with 3 or 4 carbon atoms.
• Natural Gas: Non-renewable, mixture of hydrocarbons formed over millions of years from decomposing organic matter.
  • Primarily methane, cleanest burning fossil fuel.
  • Migrates through sedimentary rocks and can seep out of the ground.

Composition of Natural Gas

• Dry Natural Gas: Almost entirely methane.
• Wet Natural Gas: Contains liquefiable hydrocarbons (ethane, butane) in addition to methane.

Coal Combustion

• Ultimate Analysis: Determines percentages of carbon, hydrogen, oxygen, nitrogen, sulfur, and ash in coal.
• HHV (Higher Heating Value): Energy released from combustion of 1 kg of fuel.

Sample Problem: Coal Combustion

• Illustrates how to calculate air required, flue gas composition, gas constant, and minimum temperature to prevent condensation of liquid in the chimney.

Typical Coal Fired Thermal Plant

• Consists of several components:
  • Coal Conveyor: Efficiently moves coal.
  • Pulverizer: Enhances combustion efficiency.
  • Boiler: Generates steam by heating water.
  • Superheater: Heats steam after it is conditioned.
  • Economizer: Reduces energy consumption by preheating fluids.
  • Reheater: Reheat steam for added efficiency.
  • Steam Turbine: Converts thermal energy from steam into rotary motion.
  • Generator: Converts mechanical energy into electrical energy.
  • Condenser: Condenses steam back to water by cooling it.
  • Deaerator: Removes air and dissolved gases from feedwater.