Energy: Reducing Unwanted Energy Transfers

Energy: Reducing Unwanted Energy Transfers

Reducing Unwanted Energy Transfers

Heat Transfer Reduction

  • Heat energy can be transferred by conduction, convection, and radiation. Reducing these transfers can minimise energy wastage.

  • Insulation is a key method of reducing conductive and convective heat energy transfers. Insulators have poor conductivity, slowing down heat transfer.

  • In the home, loft and wall cavity insulation, double-glazing and draught excluders can reduce unwanted heat transfers.

  • Reflective surfaces can prevent radiated heat energy transfer. For example, shiny aluminium sheets behind radiators help to reflect ‘wasted’ heat back into a room.

Reducing Unwanted Energy Transfers in Machines

  • Machines, such as engines, transfer energy from fuel to useful outputs. But much energy can be wasted, often as heat or sound.

  • Making machines more efficient reduces unwanted energy transfers. The efficiency of a device is the proportion of energy supplied that is transferred in useful ways.

  • Efficiency can be improved by reducing friction using lubrication, like oil in engines.

  • Using lighter materials can reduce energy wasted overcoming inertia in moving parts.

Understanding Efficiency

  • Efficiency can be calculated using the formula: efficiency = (useful power out/total power in)*100%

  • The highest possible efficiency is 1, or 100%. But no device can be perfectly efficient due to energy dissipation, often as heat.

  • Efficiency is typically expressed as a percentage. A higher efficiency percentage means fewer unwanted energy transfers.

  • Comparing energy transfers and efficiencies can help to make choices about the best ways to reduce energy wastage. For instance, an LED light bulb is more efficient than an incandescent bulb, as less energy is transferred to non-useful heat.

Reducing Energy Waste in Everyday Life

  • Using energy-efficient devices can substantially reduce unwanted energy transfers.

  • Turning off appliances when not in use also helps to prevent energy waste.

  • Harnessing renewable energy sources, like solar or wind power, can reduce reliance on less-efficient and environmentally damaging fossil fuels.