Heat Radiation

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Heat Radiation

Heat is transferred by convection, conduction and radiation.

All objects emit infra Red radiation.

REMEMBER: The bigger the temperature difference between the object and surroundings the faster the heat is lost/emitted.

Matt/Dark surfaces:These are good absorbers and emitters.They are better then white shiny surfaces.

White/shiny surfaces:They are good reflectors of radiation.

EXAMPLE'

Solar Panel has black pipes as the radiaation from the sun is abosorded and underneath shiny surfaces keeps the heat in as it reflects it.

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Kinetic Theory p1.2

Particles in a solid:They are in a fixed arrangment, They have the strongest attraction forces and they vibrate very little in fixed positions.

Particles in a liquid; They are in irregular arrangment, They have weaker attraction forces and they vibrate more meaning they move at low speeds in random directions.

Particles in a Gas;There is no arrangment they are free to move, The vibrate and move at high speeds in random direction and there is no attraction forces.

In a gas this is when particles have the most energy and vibrate the fastest.

In a solid the attraction forces are the strongest.

When a solid is heated the particles vibrate more and when they do they collide into neighbouring particles passing on there kinetic energy.

When a liquid or gas is heated gain more enrgy and vibrate quicker.In a gas the particle can vibrate very fast leading to evaporation.

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Energy Transfer p1.3

Conduction in non metals:The object gains heat this then makes the particles will gain energy and vibrate faster.Collidiing into particles, transferring kinetic energy.

Conduction in Metals:Metals are good conductors.

This happens faster as in the metal there are free elcetrons.When heat is applied the particles gain energy and vibrate faster passing on frree elctrons throughout the metal.

Convection in liquid or gas:Particles near the heat source will gain energy and vibrate more.Then, The liquid or gas becomes less dense.The liquid/gas rises and the particles lose energy and the gas or liquid becomes less dense ans sinks back.

Condensation is when a gas turns into a liquid.

The gas cools and the particles slow down and lose kinetic energy.The attraction forces get stronger and pull the particles closer together.

Evaporation is when a liquid turns into a gas and this happens if the particles are travelling in the right direction and if there travelling fast enough and overcome the attractive forces.

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Energy Transfer p1.3

Rates of evaporation are faster if:

Temperature is higher

Density is lower

Surface area is larger.

Rate of condensation are faster if;

Temp of gas is lower

Temp of surface gas is touching

Desity is higher.

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Heating and Insulating p1.4

U-Value- show how fastheat can transfer through a material.

Lower the uvalue=is the better insulator.

REMEMBER --- Payback time =Intial cost      

                                              Annual saving

Specific Heat Capacity

E= m x c x feta

Energy= mass  x Specific heat capacity x Temperature change

Most effective would be the one giving you the  biggest annual saving.

Most cost efective is the cheapeast.

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Energy and efficiency

Energy types:Electrical,light, sound, kinetic, nuclear, thermal, Gravitational potential, elastic potential and chemical.These are all the types of energy.

Conservation of energy;

Energy CAN be TRANSFERED but CANNOT be DESTROYED or CREATED.

Effciency:

Most energy transfer some if lost this is mainly as heat.

There is simple equation to calculate efficiency=useful energy out

                                                                           Total energy out

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Energy, Power and Time

Energy= Power x Time

Power=Energy divided by Time

Time=Energy divided by power.

Energy is in Joules (J)

Power in Watts(W)

Time in seconds(s)

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Generating Electricity

Fossil fuel-The fossil fuel is burnt this this then boils the water.This water is now steam turns the turbine which is connected to generator.

Nuclear Fission:Neutron urainum and plutanium is fired at this then splits realeasing tonnes of energy.This thenheats up the water that then turns a turbine which is connected to a generator.

Wind power: Wind turns the blades on a turbine connected to a generator.

Solar cells;Sunlight goes onto the solar cells causing an electric current the electrical componment.

Hydroelectric:Water stored in a dam this has gravitational potential.Water is realeased from the dam the water is allowed thorugh  the turbines at a steady pace connected to a generator.

Geothermal: Water is pumped below the ground into the ground onto the hot rocks.The rocks cause the water to become steam.This then rises up and turns the turbine which is connected to the generator.

Biofuels:Fuel placed into a boiler which then is burnt.This heats up the water.The steam turns the turbine which is connected to a generator.

 

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Generating Electricity

Fossil fuel-The fossil fuel is burnt this this then boils the water.This water is now steam turns the turbine which is connected to generator.

Nuclear Fission:Neutron urainum and plutanium is fired at this then splits realeasing tonnes of energy.This thenheats up the water that then turns a turbine which is connected to a generator.

Wind power: Wind turns the blades on a turbine connected to a generator.

Solar cells;Sunlight goes onto the solar cells causing an electric current the electrical componment.

Hydroelectric:Water stored in a dam this has gravitational potential.Water is realeased from the dam the water is allowed thorugh  the turbines at a steady pace connected to a generator.

Geothermal: Water is pumped below the ground into the ground onto the hot rocks.The rocks cause the water to become steam.This then rises up and turns the turbine which is connected to the generator.

Biofuels:Fuel placed into a boiler which then is burnt.This heats up the water.The steam turns the turbine which is connected to a generator.

 

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Generating Electricity

Carbon capturing:This reduce the impact of Carbon Dioxide.

Carbon capture and storage;You collect the carbon dioxide from power stations before it is realeased.

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National Grid

Its starts with a powerstation this is were combustion happens and fossil fuels is burnt.

Then a STEP UP transformer:Thia Increases the VOLTAGE and decreases the CURRENT.

The current is the rate and which electricity flows.

If you dont then in the overhead cables.If there was a high voltage then there would be more heat wasted meaning less efficent and less energy.

Then there is underground cables and over head.

Underground cables:

High setup cost, Hard to access for repairs, Hard to set up and Disturb landscape a lot.

But they  need minimal maintenance, they are hidden, not affected by weather, and very reliable.

Overhead have a low setup cost, easy to access, easy to set up and minimal disturbance.

But they need lots of maintenance, affected by weather, less reliable.

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National Grid

Then there is a step down transformer: Decrease VOLTAGE and Current to 240 VOLTS.

This then goes to homes, businesses and etc....

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