Heat Definitions Flashcards
State the only condition necessary for the transfer of heat energy.
The temperature of heat energy is only possible when there is a temperature difference between two objects
Outline the mechanisms of heat transfer by conduction
Vibration - As high energy particles vibrate, they collide with neighboring particles. Therefore transferring some kinetic energy.
Collision - As particles collide, kinetic energy is passed from particle to particle, causing a gradual movement of energy.
Equilibrium - Due to the transfer of kinetic energy, an overall increase in temperature across the material occurs. Heat continues to flow until a state of equilibrium is achieved.
Outline the mechanisms of heat transfer by Convection
Heating & Expansion - Heated fluids become less dense and expand. The heated fluid becomes lighter and rises, creating an area of reduced density near the heat source.
Cooling & Contraction - As the fluid moves away to cool down the fluid becomes denser and sinks due to gravity. Creating an area of higher density away from the heat.
Circulation - Due to the raising and sinking fluids, this causes a circulation known as convection currents. A continuous flow of fluid taking heat away from the source.
Transfer of heat - Movement of fluid due to convection currents.
Explain the difference between Conduction and Convection
Conduction is heat transferring through direct particle to particle interactions. Where as Convention is transfer heat through a movement of fluid.
Explain why thermal insulation of marine plant is necessary and beneficial.
Energy Efficient - Reduces the need for excessive heating and cooling. therefore being cost effective and minimal energy consumption required to maintain good working conditions, cargo/pax or equipment.
Crew Comfort/ Safety - Extreme hot and cold environments can lead to discomfort, fatigue and health issues. Insulation makes it more habitable and conductive to crew performance.
Cargo - Transporting sensitive goods such as food, pharmaceuticals or chemicals could spoil. Maintaining temperature helps preserve the cargo.
Corrosion Prevention - Poor insulation can lead to condensation forming. This could cause long term damage to the affected area over time.
Structure Integrity - Extreme temperatures could cause thermal stress, having insulation reduces the chances of warping and cracking.
Regulatory Compliance - Could require temperature standards for crew and cargo. Proper insulation keeps within compliance.
Noise Reduction - Can contribute to a quieter and more comfortable environment. This helps with crew well being and noise related health issues.
With the aid of a labelled sketch, describe the operation of a thermocouple.
A thermocouple is a temperature measuring device based off the Seebeck principle. When two different metals (Thermoelements) are heated the free electrons move towards the cold end from the hot junction. This is know as the temperature gradient. The generated voltage in relation to the temperature differences will be measured by the voltage measurement to give an actual temperature reading.
State 4 Applications of a thermocouple
Engine cooling system - Monitor the temperature of the engine cooling system. Ensuring it stays at optimal temperature.
Exhaust System - Monitor exhaust gas temperatures which are critical for engine performance.
Room Temperatures - Integrated into t he thermostats to sense room temperatures.
Refrigeration - Monitors temperatures within the cold stores to keep goods safe and ensure freshness.
Define latent heat of evaporation.
The amount of heat energy required to change a substance from its liquid state to its gaseous state at a constant temperature and pressure.
Describe how a mercury in glass thermometer is calibrated.
By using well defined physical temperatures, such as freezing and boiling points of water at standard atmospheric pressure. The mercury in glass is placed into a calibration bath. The temperature on the glass is compared to the calibration bath. Adjustments are then made on the scale on the glass, then tested again.
State 5 modes of heat transfer
Conduction
Convection
Radiation
Evaporation
Condensation
Give an example of Conduction
Give an example of Convection
Give an example of Radiation
Give an example of Evaporation
Give an example of Condensation
