Topic 5-Energy Transfer And Efficiency Flashcards
What diagram shows the transfer of energy from one form to other forms?
Through a sankey diagram, which shows not only the types of energy as they transform into different forms but also the amounts involved.
What are sankey diagrams?
Sankey diagrams are drawn to scale - the width of the arrow at any point shows the amount of energy being transformed. Conventionally, we usually write the type of energy (or power) on the arrow, and the useful forms of energy usually go along the top of the diagram, with the wasted forms curving off downwards. Sankey diagrams give us not only a good way of showing energy (and power) transfers by a device or during a process, they also show how efficient the process is - the bigger the useful energy arrow is compared to the input arrow, the higher the efficiency.
Why is energy efficiency important?
Energy-efficient devices are very important for the future. The more efficient a device is, the more of the energy input is output as useful energy and less is wasted.
Standard tungsten filament light bulb are typically only 2-3% efficient; ‘low-energy’ bulbs are about 20% efficient but LED light bulbs can be up to 90% efficient. Imagine the effect on electricity consumption if every light bulb in the UK was replaced by an LED bulb!
