Unit B Energy Flow in Technological Systems : Section 3.0 Flashcards
What is a system?
Objects or objects involved in energy transfers
What is an open system?
A system that exchanges both matter and energy with its surroundings. Eg. Earth
What is a closed system?
A system that cannot exchange matter but can exchange energy with its surroundings. Eg. A can of soup
What is an isolated system?
One that cannot exchange either matter or energy with its surroundings
What does work involve the movement of?
Matter from one location to another
What does heat involve the movement of?
Thermal energy from one location to another
What are the two ways a system can gain energy?
- Heat can be added to the system from surroundings
- Work can be done on a system from its surroundings
What is positive work?
Work done on a system by its surroundings, because the energy of the system increases
What are the 2 ways the energy of a system can decrease?
- Heat can flow out of a system from its surroundings
- Work can be done by system on its surroundings
What is negative work?
Work done by a system on its surroundings because the energy will decrease
What is the first law of thermodynamics?
The total energy, including heat, in a system and its surroundings remains constant
What will an ideal machine do?
- All the input energy is converted into mechanical energy. without any energy loss
- the amount of the mechanical energy produced by the machine should equal the amount of energy put into the machine
- Operate indefinitely
What is the second law of thermodynamics?
Heat always flows naturally from a hotter object to a colder object, but never naturally from a cold object to a hot object
What is a heat engine?
A device that converts heat into mechanical energy. Only some of the heat can be converted into mechanical energy. The remaining is expelled as exhaust heat.
What are heat pumps?
Devices that use mechanical energy to transfer heat
How does a thermo-electric converter fan work?
One end of metal is placed in hot water and the other end is placed in cold water. As heat flows through the metal to the colder end the thermal energy is converted into electrical energy which the fan converts into mechanical energy
What are some of the simple machines?
- Lever
- Pulley
- Wheel and Axel
- Screw
What were the original sources of energy for machines? List four.
- humans
- animals
- wind
- water
What was the first machine to use “hidden energy”
Hero’s Steam engine
What was Hero’s Steam engine?
A novelty device that did nothing useful
What was one of the major problems with coal mines?
Pumping out water
What were the two ways that they pumped water out of coal mines? Then what did Savery invent?
- Archimedes screw
- Persian wheel with the reciprocating pump
Then Savery came up with the steam pump that forces water through pipes (by boiling water with the coal) and can lift water up 6 m.
What were the downsides to the Archimedes screw?
-The water was too heavy to lift
What was the downside to the reciprocating pump?
- Atmospheric pressure can only push water up to height of 9m
- It was limited in the height it could raise water
By who and when was the Gunpowder Engine made?
- 1680
- Christian Hagans (mathematician and physicist)
(gunpowder was invented by the Chinese way before this)
How did the Gunpowder Engine work?
-Christian Hagans used gasses generated by an explosion to drive a piston downwards into a cylinder
What were the drawbacks to Gunpowder Engines?
- Hazards of explosions
- No powerful internal mechanism to pull the pull the piston back up
- Could not operate continuously
What were some scientific discoveries connected with a steam engine?
- The power of vacuums
- Water expands its volume 1300 times when heated to form steam
Who created the earlier heat/steam engine and when was it created?
- Denis Papin
- 1690
How does a Heat/Steam engine work?
- Water is heated so it turns to gas, the gas pushes the piston up
- Water is then pumped on the outside to condense the steam
What were the drawbacks to Heat/Steam engines?
-Manufactures had difficulty producing big enough drums where water could be heated
Who created the Savery engine and around when was the Savery engine created?
- Thomas Savery, English military engineer
- 1698
How did the Savery engine work?
Used pressurized steam to force water through pipes
It was a pump to pump water higher in order to clear the coal mines of water. It used heat to make this happen.
What were the drawbacks to the Savery engine?
The pump could not lift water higher than 6 meters
Who created the Newcomen engine?
Thomas Newcomen 1712
How did the Newcomen engine work?
A water pump:
A boiler produced steam that forced a piston up a cylinder. Cold water was then sprayed on the outside to condense the water and move the piston back down. The piston was connected to a rod which pumped water out
What were the drawbacks of the Newcomen Engine?
-The cycle of heating and cooling the cylinder was inefficient since the heating and cooling occurred in the same place (this quick shift between hot and cold damaged the equipment faster)
- the engine required tremendous amount of heat to function
Who created the Watt engine? Around when was it created?
James Watt in 1763
Explain the Watt engine
Watt created an engine that used steam but instead of using the same boiler to heat and cool steam a separate boiler was used to condense steam. This made it 3 times more efficient
What were the drawbacks to the watt engine?
- Very large
- Needed big boilers (separate boilers were what was new here but they still needed to be huge)
- Hot, dirty, and very inefficient compared to our engines today, but still an improvement over having the hearing and cooling in the same boiler for efficiency
How did the internal combustion engine work?
Coal was ignited by an electrical spark. The coal releases energy under pressure. It was done under pressure because it produces more force
What were the drawbacks to internal combustion engines?
- Very inefficient and could not produce sufficient force
- Used coal as fuel and coal doesn’t burn very hot
What is the purpose of a machine?
To convert the initial energy added to it into types of energy needed to get work done
What is wasted energy in a machine?
The energy that is not used to get work done
What is energy input?
The initial energy source
What is useful energy output?
The desired energy needed to do the work
What is useful work output?
The work the machine is supposed to do
In a lightbulb what is the useful energy and what is the wasted energy?
The useful energy is the light output and the wasted energy is the heat output
How do systems with moving parts lose energy?
Through heat due to friction
Where is some heat always lost to in a thermal energy transfer?
To the surrounding
What is efficiency of a machine?
A measurement of how effectively a machine converts energy input into useful energy output
What is the formula for efficiency?
Efficiency = useful work output/total work input
What is the most reliable source of energy?
The sun
What are the 2 categories for primary energy sources?
Solar and Non-Solar energy sources
What are the 5 types of solar energy sources?
- Solar Radiation
- Wind Energy
- Water Energy
- Biomass
- Fossil fuels
What are solar energy sources?
Energy sources that are derived either directly or indirectly from the energy of the sun
What is solar radiation energy?
- The radiant energy emitted from the sun by the hydrogen-hydrogen nuclear fusion
- Travels through space as electromagnetic radiation
- Captured by plants, solar panels, solar cells, etcetera
What causes wind? What is wind energy?
- The result of heating of the earth’s surface by the sun
- Heating causes currents of air which is wind since land is heated differently than water due to the different specific heat capacities
- The energy in the movements of the air is used to turn turbines
What is water energy?
- Results when the surface of water is heated by the sun
- this warming is the cause of the hydrolic cycle
- Heating by the sun causes evaporation of water into the atmosphere where it condenses into rain.
- Falling rain creates kinetic energy which can be used to power other things
So water energy is really gravitational potential energy since when it falls it can cause things to move. This is hydro power.
What is biomass?
- Any form of organic matter
- They store energy from the sun through photosynthesis
What are fossil fuels?
- Oil, natural gas, coal
- Fossil fuels were formed by plants and animals years ago
What are non-solar energy sources?
Energy sources that have no relationship to the sun
What are the three types of non-solar energy sources?
- Nuclear-Energy
- Geothermal energy
- Tidal energy
What is Nuclear energy?
-The energy obtained from a conversion of mass to energy in nuclear reactions
For example, uranium loses protons and in the process releases energy.
What is Geothermal energy?
- Energy from the Earth’s interior
- Geothermal plants use superheated water to turn turbines
What is tidal energy?
- The movement of ocean water creating tides
- The kinetic energy can be converted to other forms of energy
- caused by the gravitational attraction if the moon
What are renewable energy sources?
Energy sources that are continually and indefinitely available
What are the types of renewable energy sources?
- Solar
- Wind
- Water
- Geothermal
- Tidal
- Biomass
What are non-renewable sources of energy?
Sources of energy that are limited and irreplaceable (Nuclear and Fossil Fuels)
What is the most important energy type to generate for the population?
Electrical energy
This is the energy type that is used the most often and thus has more importance to generate.
What percent of the energy consumed is electrical?
40%
What are the 3 factors that increase demand for energy supplies?
- Increasing energy consumed per person
- World population growing exponentially
- The use of non-renewable energy sources that are limited (scarcity) instead of something more limitless
How does burning of fossil fuels affect the world?
- Emissions create greenhouse gasses
- Greenhouse gasses contribute to climate change and acid rain
What would happen if everybody cut their consumption of fossil fuels by 25 percent?
It would extend reserves by 25%
What are the largest consumers of energy in industrialized countries?
Bussiness and Industry
What is Congregation?
Using the waste energy from one process to power a second process
What does sustainable mean?
Any process that will not compromise the survival of living things or future generations while still providing current energy for needs
What is sustainable development?
Economic development that meets current needs without compromising the ability for future generations to meet their needs
