Inkjet Printing

Posted by PITHOCRATES - March 5th, 2014

Technology 101

A Sunday Afternoon on the Island of La Grande Jatte is similar to Ink Jet Printing

Stephen Sondheim and James Lapine created a musical based on the painting A Sunday Afternoon on the Island of La Grande Jatte by Georges Seurat.  Giving us Sunday in the Park with George.  Seurat used a technique called pointillism.  Where he painted dots of color.  Points.  Up close the eye saw only a mass of different colored dots.  But when you moved back from the painting the brain blended those dots together into an image.

This is the same technique our televisions use to recreate an image on the screen.  Using only the 3 primary colors of light.  Red, blue and green.  Different colors of phosphor are energized to glow.  Causing a combination of these three dots of phosphor to glow creates a pixel of color.  A screen full of different colored pixels creates an image.  It’s similar to inkjet printing.  Where a print head places dots of different colors on a piece of paper.  Much like George did in Sunday in the park with George.  Although an inkjet printer can do it faster.  And without destroying a relationship.

George painted one dot at a time.  So it took him a very long time to create an image.  —SPOILER ALERT—   So much time that Dot left him and had a baby with Louis the baker.  Leaving George alone.  A true suffering artist.  Who died young.  Never realizing that Dot’s baby was his.  Which gave us a second act.  A great musical.  With some of Sondheim’s best music and lyrics.  The original Broadway recording with Mandy Patinkin and Bernadette Peters should be in everyone’s collection.  Do yourself a favor and buy it.  Support the arts.  But I digress.

Droplets of Ink are shot out of the Print Head onto the Paper without any Physical Contact with the Paper

If you have a large art museum near where you live you can probably see a work of art done in the pointilism technique up close.  And if you do you’ll probably notice that the dots are rather big.  Unlike they are with an inkjet printer.  Where the dots are much smaller.  It’s the same technique.  Pointillism.  But it is much harder to see that with inkjet printing.  Why?

George painted with a paint brush.  And even when the bristles are smoothed into a point it’s still pretty thick.  And makes large dots.  An inkjet, on the other hand, doesn’t ‘brush’ on the ink.  It spits it on.  Droplets of ink are shot out of the print head, across an air-gap and onto the paper.  Without any physical contact.  The only physical contact with the paper is the roller that loads a sheet.  And the roller that advances the sheet.  While the print head glides above the paper.  Spitting droplets of ink.

Well, it doesn’t actually spit ink.  It boils it.  In the ink cartridge.  Which is a marvel of engineering.  For the ink cartridge not only contains the ink.  But it also contains the print head.  A few hundred holes where droplets of ink jet out of.  As well as a lot of copper etched circuits.  To take the information from the computer when printing a document.  And transferring it to the proper ink port.  Which are very, very tiny holes.  So tiny that the droplets they produce make for near photo-like quality compared to a pointillism painting.

The Ideal Gas Law tells us if we incrase the Temperature while holding the Volume Constant the Pressure Increases

The ideal gas law is PV = nRT.  Which can be solved such that P = nRT/V.  Where pressure (P) equals the chemical amount in moles (n) times the universal gas constant (R) times the temperature (T) divided by the volume (V).  A lot of information there.  But the only things we want to focus on are pressure, temperature and volume.  The ideal gas law tells us if we incrase the temperature while holding the volume constant the pressure increases.  Which is how inkjet printing works.

Each ink port has ink in it.  But the hole is so tiny that the ink in its normal state will not flow through it.  Because it’s too thick.  However, when you heat the ink to boil it into a vapor the pressure is so great that it pushes a droplet of ink out of the print head onto the paper to releive the pressure.  All of this happens in a fraction of a second in all of those hundreds of ink ports.  An electric circuit turns on.  Boils ink.  Forces out a droplet.  The electric circuit shusts off.  And the ink just used to print with is replaced with fresh ink.  Waiting for the next electric current to boil it.

Complex software and hardware to advance the paper and move the print head over the paper are all coordinated to place thousands of droplets of ink with each pass of the print head.  A black ink cartridge is used for text documents.  And a color ink cartridge (red, blue and yellow) is used to add color to a text document.  Or to print color images.  Doing the work of a thousand Georges.  Faster.  And with tinier dots.  So tiny that they are impossible to detect with the naked eye.  Unlike Seurat’s A Sunday Afternoon on the Island of La Grande Jatte.  But few printed items will look as good.

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Engine Block Heaters and Battery Heaters

Posted by PITHOCRATES - February 19th, 2014

Technology 101

As Matter loses Heat it shrinks from a Gas to a Liquid to a Solid

There is no such thing as cold.  Cold is simply the absence of heat.  Which is a real thing.  Heat.  It’s a form of energy.  Warm things have a lot of energy.  Cold things have less energy.  The Kelvin scale is a measurement of temperature.  Like degrees used when measuring temperature in Celsius or Fahrenheit.  Where 32 degrees Fahrenheit equals 0 degrees Celsius.  And 0 degrees Celsius equals 273.15 kelvin.  Not ‘degrees’ kelvin.  Just kelvin.

When something cools it loses heat energy.  The molecular activity slows down.  Steam has a lot of molecular activity.  At 212 degrees Fahrenheit (100 degrees Celsius or 373.15 kelvin) the molecular activity decreases enough (i.e., loses energy) that steam changes to water.  At 32 degrees Fahrenheit (0 degrees Celsius or 273.15 kelvin) the molecular activity decreases enough (i.e., loses energy) that water turns into ice.

The more heat matter loses the less molecules move around.  At absolute zero (0 kelvin) there is no heat at all.  And no molecular movement.  Making 0 kelvin the ‘coldest’ anything can be.  For 0 kelvin represents the absence of all heat.  As matter loses heat it shrinks.  Gases become liquid.  And liquids becomes solid.  (Water, however, is an exception to that rule.  When water turns into ice it expands.  And cracks our roadways.)  They become less fluid.  Or more viscous.  Cold butter is harder to spread on a roll than warm butter.  Because warm butter has more heat energy than cold butter.  So warm butter is less viscous than cold butter.

Vehicles in Sub-Freezing Temperatures can Start Easily if Equipped with an Engine Block Heater

In a car’s internal combustion engine an air-fuel mixture enters the cylinder.  As the piston comes up it compresses this mixture.  And raises its temperature.  When the piston reaches the top the air-fuel mixture is at its maximum pressure and temperature.  The spark plug then provides an ignition source to cause combustion.  (A diesel engine operates at such a high compression that the temperature rise is so great the air-fuel mixture will combust without an ignition source).  Driving the piston down and creating rotational energy via the crank shaft.

For this to happen a lot of things have to work together.  You need energy to spin the engine before the combustion process.  You need lubrication to allow the engine components to move without causing wear and tear.  And you need the air-fuel mixture to reach a temperature to burn cleanly and to extract as much energy from combustion as possible.  None of which works well in very cold temperatures.

Vehicles operating in sub-freezing temperatures need a little help.  Manufacturers equip many vehicles sold for these regions with engine block heaters.  These are heating elements in the engine core.  You’ll know a vehicle has one when you see an electrical cord coming out of the engine compartment.  When these engines aren’t running they ‘plug in’ to an electrical outlet.  A timer will cycle these heaters on and off.  Keeping the engine block warmer than the subfreezing temperatures.

The Internal Combustion Engine is Ideal for use in Cold Temperatures

At subfreezing temperatures engine oil because more viscous.  And more like tar.  This does not flow well through the engine.  So until it warms up the engine operates basically without any lubrication.  In ‘normal’ temperatures the oil heats up quickly and flows through the engine before there’s any damage.  At subfreezing temperatures oil needs a little help when starting.  So the oil sump is heated.  Like an engine block heater.  So when someone tries to start the engine the oil is more like oil and less like tar.

Of course, for any of this to help start an engine you have to be able to turn the engine over first.  And to do that you need a charged battery.  But even a charged battery needs help in sub-freezing temperatures.  For in these temperatures there is little molecular action in the battery.  And without molecular activity there will be little current available to power the engine’s starter.  So there are heaters for batteries, too.  Electric blankets or pads that sit under or wrap around a battery.  To warm the battery to let the chemicals inside move around more freely.  So they can produce the electric power it needs to turn an engine over on a cold day.

Once an engine block, the engine oil and battery are sufficiently warmed by external electric power the engine can start.  Once it warms up it can operate like it can at less frigid temperatures.  The engine alternator powers the electrical systems on the vehicle.  And recharges the battery.  The engine coolant heats up and provides heat for the passenger compartment.  And defrosts the windows.  Once the engine is warm it can shut down and start again an hour or so later with ease.  Making it ideal for use in cold temperatures.  Unlike an electric car.  For the colder it gets the less energy its batteries will have.  Making it a risky endeavor to drive to the store in the Midwest or the Northeast during a winter such as this.  Something people should think about before buying an all-electric car.

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Melting Snow and Ice

Posted by PITHOCRATES - February 5th, 2014

Technology 101

When Temperatures fall below Freezing Liquid Water turns into Solid Water

You know what the best thing about water is?  You don’t have to shovel it.  Well, that, and its life-giving properties.  Let’s face it.  We couldn’t survive without the stuff.  We couldn’t grow food.  We even couldn’t live without drinking water.  So perhaps its life-giving properties is the best thing about water.  But a close second would be that thing about not having to shovel it.

When it rains water soaks into our green areas.  It runs off driveways and sidewalks into green areas.  And into streets.  Where it runs off into a storm drainage system.  Which takes it to a river or lake.  The rain lets our gardens grow.  And any excess water conveniently just goes away.  We may have a puddle or two to slosh through.  But even those go away without us having to do anything.  Water is nice that way.  As long as the temperature is above its freezing point.

When the temperature falls below the freezing point of water bad things start to happen.  Liquid water turns into solid water.  And hangs around for awhile.  Accumulating.  On our driveways, sidewalks, porches and roads.  It’s pretty much everywhere we don’t want it to be.  Making it difficult to walk.  And drive.  We slip and fall a lot in it.  The sun may melt it a little during the day.  Creating puddles of water where the snow once was. But when the sun sets those puddles freeze.  And become even more slippery.  Making solid water more dangerous than liquid water.  So a big part of making it through winters in northern climes, then, is transforming solid water back into the liquid form.

Even though Bourbon melts Ice Cubes Bourbon would be a Poor Choice to melt Snow and Ice

All material can be in three different stages.  It can be a solid.  A liquid.  Or a gas.  What determines the phase of this material depends on a couple of things.  Mostly temperature and pressure.  And the chemical properties of the material.  At ambient temperature and pressure material typically exists stably in one phase.  Water, for example, is stable in the liquid phase on an 80-degree summer day.  Allowing us to swim in it.  While on a freezing February day it is stable in the solid phase.  Which is why we hold the Winter Olympics in February.  The cold temperatures give us the best solid water conditions.

If we raise the temperature of water we can turn it from a liquid to a gas.  We could also do this by lowering the ambient air pressure.  Such as putting it into a vacuum.  For a liquid remains a liquid as long as the vapor pressure (the tendency for particles to escape from the liquid they’re in) of the liquid is less than the ambient air pressure.  If we lower the ambient air pressure below the vapor pressure of the liquid we can lower the boiling point of that liquid.  This is why different liquids have different boiling points.  They have different vapor pressures.  Oxygen has a very high vapor pressure and requires a high pressure and cold temperature to keep oxygen in a liquid phase.

When we take ice cubes out of the freezer and add them to a glass of bourbon they melt.  Because the ambient temperature outside of the freezer is above the freezing point of water.  So the solid water changes its phase from solid to liquid.  It would follow, then, that pouring bourbon on snow and ice would help melt it.  Of course we don’t do that.  For wasting bourbon like that would be criminal.  Not to mention costly.  Even if you used the cheap stuff.  Making bourbon a poor choice for melting snow and ice.

Salt dissolves into a Brine Solution that lowers the Melting Point of Snow and Ice

We see that a material will change its phase at different temperatures and pressures.  Which is good to know.  But it doesn’t help us to melt snow and ice during winter.  For we can’t lower the atmospheric air pressure to lower the boiling and melting points of water.  And we can’t raise the ambient temperature above the melting point of water.  If we could our winters would probably be a lot more comfortable than they are now.  So because when we can’t change the air pressure or temperature of the ambient environment the snow and ice is in we do something else.  We use chemistry to lower the melting point of snow and ice.  And the most common chemical we use is salt.

To melt snow and ice salt needs heat and moisture.  The moisture comes from the snow and ice.  Or from the humidity in the air.  The heat comes from the warmth of the earth or air.  Heated by the sun.  It also comes from the friction between tires and the road.  When salt comes into contract with water and heat it dissolves into a brine solution.  And this brine solution has a much lower melting point than water.  Which in turn lowers the melting point of the snow and ice it comes into contact with.  Allowing it to be in the liquid phase at temperatures below freezing temperatures.  Melting that snow and ice so it can run off like rain water.

The warmer it is when it snows the quicker salt will melt that snow.  While the colder it is the longer it takes to melt.  If it gets too cold (around 15 degrees Fahrenheit) salt proves to be ineffective.  In temperatures below 15 degrees Fahrenheit other chemicals work better.  Such as calcium chloride.  But calcium chloride is more costly than sodium chloride (salt).  Ambient temperatures, time of day, sunny or cloudy, wind, etc., all determine the chemical to use.  And the amount of chemical to use.  They consider all of these factors (and more) before sending those ‘salt’ trucks out on the roads.  Allowing us to drive in the worst of winters just as we drive in the best of summers.  It may take more time.  And there may be a little more cussing.  But we still go to work, take our kids to school, go shopping, etc., when it snows.  Thanks to chemicals.  Chemistry.  And the people that put those chemicals and that chemistry to work.

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Triple Expansion Steam Engine

Posted by PITHOCRATES - November 6th, 2013

Technology 101

Pressure and Temperature have a Direct Relationship while Pressure and Volume have an Inverse Relationship

For much of human existence we used our own muscles to push things.  Which limited the work we could do.  Early river transport were barges of low capacity that we pushed along with a pole.  We’d stand on the barge and place the pole into the water and into the river bed.  Then push the pole away from us.  To get the boat to move in the other direction.

In more developed areas we may have cleared a pathway alongside the river.  And pulled our boats with animal power.  Of course, none of this helped us cross an ocean.  Only sail did that.  Where we captured the wind in sails.  And the wind pushed our ships across the oceans.  Then we started to understand our environment more.  And noticed relationships between physical properties.  Such as the ideal gas law equation:

Pressure = (n X R X Temperature)/Volume

In a gas pressure is determined my multiplying together ‘n’ and ‘R’ and temperature then dividing this number by volume.  Where ‘n’ is the amount of moles of the gas.  And ‘R’ is the constant 8.3145 m3·Pa/(mol·K).  For our purposes you can ignore ‘n’ and ‘R’.  It’s the relationship between pressure, temperature and volume that we want to focus on.  Which we can see in the ideal gas law equation.  Pressure and temperature have a direct relationship.  That is, if one rises so does the other.  If one falls so does the other.  While pressure and volume have an inverse relationship.  If volume decreases pressure increases.  If volume increases pressure decreases.  These properties prove to be very useful.  Especially if we want to push things.

Once the Piston traveled its Full Stroke on a Locomotive the Spent Steam vented into the Atmosphere 

So what gas can produce a high pressure that we can make relatively easy?  Steam.  Which we can make simply by boiling water.  And if we can harness this steam in a fixed vessel the pressure will rise to become strong enough to push things for us.  Operating a boiler was a risky profession, though.  As a lot of boiler operators died when the steam they were producing rose beyond safe levels.  Causing the boiler to explode like a bomb.

Early locomotives would burn coal or wood to boil water into steam.  The steam pressure was so great that it would push a piston while at the same time moving a connecting rod connected to the locomotive’s wheel.  Once the piston traveled its full stroke the spent steam vented into the atmosphere.  Allowing the pressure of that steam to dissipate safely into the air.  Of course doing this required the locomotive to stop at water towers along the way to keep taking on fresh water to boil into steam. 

Not all steam engines vented their used steam (after it expanded and gave up its energy) into the atmosphere.  Most condensed the low-pressure, low-temperature steam back into water.  Piping it (i.e., the condensate) back to the boiler to boil again into steam.  By recycling the used steam back into water eliminated the need to have water available to feed into the boiler.  Reducing non-revenue weight in steam ships.  And making more room available for fuel to travel greater distances.  Or to carry more revenue-producing cargo.

The Triple Expansion Steam Engine reduced the Expansion and Temperature Drop in each Cylinder

Pressure pushes the pistons in the steam engine.  And by the ideal gas law equation we see that the higher the temperature the higher the pressure.  As well as the corollary.  The lower the temperature the lower the pressure.  And one other thing.  As the volume increases the temperature falls.  So as the pressure in the steam pushes the piston the volume inside the cylinder increases.  Which lowers the temperature of the steam.  And the temperature of the piston and cylinder walls.  So when fresh steam from the boiler flows into this cylinder the cooler temperature of the piston and cylinder walls will cool the temperature of the steam.  Condensing some of it.  Reducing the pressure of the steam.  Which will push the piston with less force.  Reducing the efficiency of the engine.

There was a way to improve the efficiency of the steam engine.  By reducing the temperature drop during expansion (i.e., when it moves the piston).  They did this by raising the temperature of the steam.  And breaking down the expansion phase into multiple parts.  Such as in the triple expansion steam engine.  Where steam from the boiler entered the first cylinder.  Which is the smallest cylinder.  After it pushed the piston the spent steam still had a lot of energy in it looking to expand further.  Which it did in the second cylinder.  As the exhaust port of the first cylinder is piped into the intake port of the second cylinder.

The second cylinder is bigger than the first cylinder.  For the steam entering this cylinder is a lower-pressure and lower-temperature steam than that entering the first cylinder.  And needs a larger area to push against to match the down-stroke force on the first piston.  After it pushes this piston there is still energy left in that steam looking to expand.  Which it did in the third and largest cylinder.  After it pushed the third piston this low-pressure and low-temperature steam flowed into the condenser.  Where cooling removed what energy (i.e., temperature above the boiling point of water) was left in it.  Turning it back into water again.  Which was then pumped back to the boiler.  To be boiled into steam again.

By restricting the amount of expansion in each cylinder the triple expansion steam engine reduced the amount the temperature fell in each cylinder.  Allowing more of the heat go into pushing the piston.  And less of it go into raising the temperature of the piston and cylinder walls.  Greatly increasing the efficiency of the engine.  Making it the dominant maritime engine during the era of steam.

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Residential Water Heater

Posted by PITHOCRATES - April 10th, 2013

Technology 101

When you Heat Water in a Sealed System that Prevents it from Expanding it produces Great Pressure

Most of us start our days with a hot shower.  If we’ve had a rough day we may relax in a hot bath with a glass of wine after work.  We don’t think twice about enjoying these things.  Because we take them for granted.  All we have to do is open a hot water tap.  And soothing hot water flows out of a faucet.  It wasn’t always like this.  Once upon a time we had to heat water over an outdoor fire and carry it to a tub.  Fully clothed.  Wearing shoes or boots.  Perhaps with someone helping us.  Today a lady can simply turn on the hot water after work.  Pour in some bath oils.  Undress.  Pour a glass of wine.  And settle into a soothing hot bath.  And let the stress of the day melt away.

This convenience is brought to us by our water heater.  That round tank in our basement.  Or in our utility room.  Which works similarly to heating water over an open fire.  And carrying it inside to a tub.  The difference is that we keep a tank full of heated water in our home to use at any time.  And instead of carrying it to where we want to use it we deliver it in a pipe.  That terminates at a faucet.  In our kitchen.  At our laundry tub.  And in our bathrooms.  Giving us hot water to wash our hands.  To use in our dishwasher.  To shave with.  And, of course, to shower or bathe in.

If you look at your water heater in your home you will notice something conspicuous by its absence.  A water pump.  Yet that hot water tank can supply water to an upstairs bathroom.  How?  Because of something that happens when you heat water.  It expands.  And when it tries to expand in a sealed system but can’t pressure builds up.  Like in a car’s cooling system.  If you squeeze the radiator hose when the engine is cool you will be able to compress the hose with your fingers.  Something we do before removing the radiator cap.  If the engine is hot and you squeeze the radiator hose you are not going to be able to compress it.  Because of the high pressure inside the cooling system.  Created from the water trying to boil inside a sealed system but can’t.  If you remove the radiator cap when it’s under pressure the water will explode out of the radiator in a scalding geyser.  Sending you to the hospital with severe third-degree burns.  So never, ever remove a radiator cap when there is pressure in the cooling system.

A Hot Water Tank does Two Things: it Heats Water and it Stores Hot Water

Hot water tanks come in two basic styles.  Gas-fired.  And electric.  There are others (oil-burner, solar power, etc.) but they are not as common.  The gas-fired and electric have their own benefits and disadvantages.  Burning gas requires air to aid with combustion.  And we have to vent the products of combustion outside of the house.  An electric water heater doesn’t need either of these.  And can therefore be packed away into a small utility closet in the middle of a house or apartment.  The advantage of the gas water heater is that it can heat water more quickly than an electric water heater.  So gas water heaters tend to be smaller than electric water heaters.  Electric water heaters have bigger tanks because it takes longer to heat the water.  So it heats and stores a larger volume of water to keep someone from using all of the hot water when taking a shower.  Whereas a gas-fired heater will be able to heat new water in time before someone else takes a shower.

A hot water tank does two things.  It heats water.  And it stores hot water.  An electric heater has one or two heating elements inside the tank to heat the water.  Something similar to the heating elements in an electric stove or toaster oven.  A gas-fired heater has a burner below the bottom of the tank.  The fire heats the bottom of the tank while the exhaust gas vents up through a pipe running through the middle of the water tank.  This hot exhaust gas heats the water in the center of the tank.  When the temperature of the water falls a heating element turns on.  Or a gas valve opens and a pilot light or an igniter ignites this gas.  After the temperature rises to the setting on the thermostat the heating device shuts down.

We make these tanks in layers.  The inner most layer is a glass lining.  Under this glass lining is a metal tank.  The glass lining is to prevent the metal tank from rusting.  (Also inside the tank is something we call a sacrificial anode rod.  Its purpose is to rust so the tank doesn’t.)  Around the metal tank is an insulating layer.  The final layer is an exterior decorative shell.  What you see when you look at your water heater.  Think of the tank as a coffee thermos that you pack with your lunch.  It keeps the coffee hot for an extended period of time.  Just like the insulating layer does on the water tank.

The Pressure inside a Hot Water Tank will push Water out of the Tank up to an Upstairs Bathroom

When we heat water it expands.  If it can’t expand it builds up pressure.  If it builds up too much pressure the tank can explode.  The escaping boiling water/steam turning the tank into a missile.  To prevent this from happening there is a temperature and pressure-relief valve installed at the top of the tank.  Running from this valve will be a pipe down the side of the tank to about 6 inches above the floor.  If the temperature rises too high building up an unsafe pressure the temperature and pressure-relief valve opens to allow this expanding water out of the tank.  Which brings us to how a hot water tank can pump water throughout a house without a water pump.

At the top of the tank you will see two pipes.  One bringing cold water into the tank.  And one taking hot water out of the tank.  To an open faucet somewhere in the house.  The cold water pipe enters the tank and extends to the bottom of the tank.  Bringing the cold water to the bottom of the tank.  As it heats it rises.  Bringing the hottest water to the top of the tank.  The hot water pipe extends down into the tank only a short way.  The bottom of this pipe is near the top of the tank.  In the hottest water.

A hot water tank is a sealed system with heated hot water under pressure.  Like a car’s cooling system.  Though not at quite at the same temperature or pressure.  But if you turn on the hot water to run a soothing bath after a trying day in an upstairs bathroom the pressure inside the hot water tank will push that water out of the tank and all the way up to that faucet.  And when this water leaves the hot water tank the city water pressure pushes more cold water into the tank.  Bringing the temperature of the water down.  Turning on the heating device.  Heating the new cold water inside the tank.  Causing more hot water to rise near the hot water pipe at the top of the tank.  Having hot water ready the next time someone opens a faucet.  Simplicity at its finest.  Using the physics of water and thermal dynamics to put hot water at our fingertips whenever we want it.  Without ever having to heat it over an outside fire and trudging it inside.

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Phase Transition, Expansion Valve, Evaporator, Compressor, Condenser and Air Conditioning

Posted by PITHOCRATES - April 3rd, 2013

Technology 101

We can use Volume, Pressure and Temperature to change Water from a Liquid to a Gas and back Again

Liquids and gasses can do a lot of work for us.  If we can control three variables.  Volume.  Pressure.  And temperature.  For example, internal combustion engines work best when hot.  But excessive heat levels can damage the engine.  So we use a special anti-freeze/anti-boil liquid in the cooling system.  A pump circulates this liquid through the engine where it absorbs some of the excess heat of combustion that isn’t used in pushing the piston.  After leaving the engine it flows through a radiator.  Air blows across tubes in the radiator cooling this liquid.  Ejecting some of the heat of combustion into the atmosphere.  Lowering the temperature of the cooling liquid so it can flow through the engine again and absorb more heat.

Our first cars used alcohol in the winter for a lower freezing point.  So this liquid didn’t freeze in the engine and crack the block.  Letting the coolant flow out.  And with no cooling available the excessive heat levels would damage the engine.  In the summer time we used plain water in the cooling system.  And kept the cooling system sealed and under high pressure to prevent the water from boiling into steam.  But the high pressure often caused a hose or a radiator cap to fail.  Releasing the pressure.  And letting the cooling water boil out leaving the engine unsafe to operate.

If this happened on a hot summer’s day and you got a tow to a gas station you may have sat there waiting for them to complete the repairs.  Sipping on a cool bottle of soda from a refrigerated soda machine.  Soon drops of water would condense onto your cold bottle.  The cold bottle cooled the water in gas form (the humidity in the air) and turned it back into a liquid.  So in these examples we see how we were able to use pressure to keep water a liquid.  And how removing heat from water as a gas changed it back into a liquid.  This phase transition of a material has some very useful applications.

The High-Pressure Refrigerant Liquid from the Condenser loses Pressure going through the Expansion Valve

The phase transition between a liquid and a gas are particularly useful.  Because we can move liquids and gases in pipes and tubing.  Which allows us to take advantage of evaporation (going from a liquid to a gas) in one area.  While taking advantage of condensation (going from a gas to a liquid) in another area.  By changing pressure and volume we can absorb heat during evaporation.  And release heat during condensation.  Allowing us to absorb heat inside a building with evaporation.  And release that heat outdoors with condensation.  All we need are a few additional components and we have air conditioning.  An expansion valve.  An evaporator.  A compressor.  A condenser.  A couple of fans.  And some miscellaneous control components.

We install the expansion valve and the evaporator inside our house.  Often installed inside the furnace.  And the compressor and the condenser outside of the house.  We interconnect the indoor and the outdoor units with tubing.  Inside this tubing is a refrigerant.  Which is a substance that transitions from liquid to a gas and back again at relatively low temperatures.  As the refrigerant moves from the evaporator to the condenser it is a gas.  As it moves from the condenser to the evaporator it is a liquid.  The transition between these stages occurs at the evaporator and the condenser.

The refrigerant leaves the condenser as a liquid under high pressure.  As it passes through the expansion valve the pressure drops.  By restricting the flow of the liquid refrigerant.  Think of a faucet at a kitchen sink.  If you open it all the way the water flowing in and the water flowing out are almost equal.  But if we just open the faucet a little we get only a small trickle of water out of the faucet.  And a pressure drop across the valve.  With the full force of city water pressure pushing to get out of the faucet.  And a low pressure trickle coming out of the faucet.

As the Warm Air blows across the Evaporator Coil any Humidity in the Air will condense on the Coil

As the liquid leaves the expansion valve at a lower pressure it enters the evaporator coil.  A fan blows the warm air inside of the house through the evaporator coil.  The heat in this air raises the temperature of the refrigerant.  And because of the lower pressure this heat readily boils the liquid into a gas.  That is, it evaporates.  Absorbing heat from the warm air as it does.  Cooling the air.  Which the fan blows throughout the ductwork of the house.

As the gas leaves the evaporator it travels through a tube to the condenser unit outside.  And enters a compressor.  Where an electric motor spins a crankshaft.  Attached to the crankshaft are two pistons.  As a piston moves down it pulls low pressure gas into the cylinder.  As the piston moves up it compresses this gas into a higher pressure.  As the pressure rises it applies more pressure on the spring holding the discharge valve closed.  When the pressure is great enough it forces open the valve.  And sends the high-pressure gas to the condenser coil.  Where a fan blows air through it lowering the temperature of the high pressure gas enough to return it to a liquid.  As it does it releases heat from the refrigerant into the atmosphere.  Cooling the refrigerant.  As the liquid leaves the condenser it flows to the expansion valve to repeat the cycle.  Over and over again until the temperature inside the house falls below the setting on the thermostat.  Shutting the system down.  Until the temperature rises high enough to turn it back on.  A window air conditioner works the same way.  Only they package all of the components together into one unit.

There is one other liquid in an air conditioning system.  Water.  As the warm air blows across the evaporator coil any humidity in the air will condense on the coil.  Like on a cold bottle of soda on a hot summer day.  As this water condenses on the evaporator coil is eventually drips off into a pan with a drain line.  If the evaporator is in the furnace this line will likely run to a sewer.  If the evaporator is in the attic this line will run to the exterior of the house.  Perhaps draining into a gutter.  If it’s a window unit this line runs to the exterior side of the unit.  These simple components working together give us a cool and dehumidified house to live in.  No matter how hot and humid it gets outside.

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Thrust, Drag, Lift, Weight, Concorde, Center of Pressure, Center of Gravity, Boeing 747, Slats and Flaps

Posted by PITHOCRATES - January 16th, 2013

Technology 101

The Drawback to increasing Thrust and Lift with more Powerful Engines is the Weight of Greater Fuel Loads

To get an airplane off of the ground requires two things.  To produce thrust that is greater than drag.  And to produce lift that is greater than weight.  You do this and you’ll get any airplane off of the ground.  Of course, getting these two things is not the easiest thing to do.  Primarily because of the purpose of airplanes.  To move people and freight.  People and freight add weight.  Which increases the amount of lift needed.  And they make the plane bigger.  A bigger object displaces more air increasing drag.  And thus requiring more thrust.

Engines provide thrust.  And wings provide lift.  So the obvious solution to overcome greater drag is to produce greater thrust.  And the solution to overcome greater weight is to produce greater lift.  And we do both with fuel.  Greater amounts of fuel can power bigger engines that can produce more thrust.  And larger wings can produce greater lift.  But larger wings also produce more drag.  Requiring additional thrust.  And fuel.  Or, we can produce greater lift by moving air over the wings faster.  Also requiring additional thrust.  And fuel.

Of course, the obvious drawback to increasing both thrust and lift is the added weight of the fuel.  The more fuel carried the more weight lift has to overcome.  Requiring more powerful engines.  Or bigger wings.  Both of which require more fuel.  This is why our first planes were small by today’s standards.  The thrust of a propeller engine could not produce enough thrust to travel at high speeds.  Or operate at high altitudes.  And the first wings were relatively fixed.  Having the same surface area to produce lift at takeoffs and landings.  As well as at cruising altitudes.  Big wings that allowed the lifting of heavier weights produced a lot of drag.  Requiring more fuel to overcome that drag.  And the added weight of that fuel limited the number of people and freight they could carry.  Or they could trade off that fuel for more revenue weight.  The smaller fuel load, of course, reduced flying times.  Requiring an additional takeoff and landing or two to refuel.

A Wing that produces sufficient Lift at 600 MPH does not produce sufficient Lift at Takeoff and Landing Speeds

The supersonic Concorde was basically a flying gas can.  It was more missile than plane.  To travel at those great speeds required a very small cross section to reduce drag.  Limiting the Concorde to about 100 revenue paying passengers.  Its delta wing performed well at supersonic flight but required a drooping nose so the pilot could see over it to land and takeoff due to the extreme nose pitched up attitude.  As Concorde approached supersonic speeds the center of pressure moved aft.  Placing the center of gravity forward of the center of pressure.  Causing the nose to pitch down.  You correct this with trim controls on slower flying aircraft.  But using this on Concorde would create additional drag.  So they trimmed Concorde by pumping the remaining fuel to other fuel tanks to move the center of gravity to the center of pressure.

They designed Concorde to fly fast.  Which came at a cost.  They can only carry 100 revenue paying passengers.  So they can only divide the fuel cost between those 100 passengers.  Whereas a Boeing 747 could seat anywhere around 500 passengers.  Which meant you could charge less per passenger ticket while still earning more revenue than on Concorde.  Which is why the Boeing 747 ruled the skies for decades.  While Concorde flies no more.  And the only serious competition for the Boeing 747 is the Airbus A380.  Which can carry even more revenue paying passengers.  How do they do this?  To fly greater amount of people and freight than both piston-engine and supersonic aircraft?  While being more profitable than both?  By making compromises between thrust and drag.  And lift and weight.

Jet engines can produce more thrust than piston engines.  And can operate at higher altitudes.  Allowing aircraft to take advantage of thinner air to produce less drag.  Achieving speeds approaching 600 mph.  Not Concorde speeds.  But faster than every other mode of travel.  To travel at those speeds, though, requires a cleaner wing.  Something closer to Concorde than, say, a DC-3.  Something thinner and flatter than earlier wings.  But a wing that produces lift at 600 mph does not produce enough lift at takeoff and landing speeds.

Planes need more Runway on Hot and Humid Days than they do on Cool and Dry Days

The other big development in air travel (the first being the jet engine) are wings that can change shape.  Wings you can configure to have more surface area and a greater curve for low-speed flying (greater lift but greater drag).  And configure to have less surface area and a lesser curve for high-speed flying (less lift but less drag).  We do this with leading-edge slats (wing extensions at the leading edge of the wing).  And trailing-edge flaps (wing extensions at the trailing edge of the wing).  When fully extended they increase the surface area of the wing.  And add curvature at the leading and trailing edge of the wing.  Creating the maximum amount of lift.  As well as the greatest amount of drag.  Allowing a wing to produce sufficient lift at takeoff speeds (about 200 mph).  Once airborne the plane continues to increase its speed.  As it does they retract the slats and flaps.  As the wing can produce sufficient lift at higher speeds without the slats and flaps extended.

But there are limits to what powerful jet engines and slats/flaps can do.  A wing produces lift by having a high pressure under the wing pushing up.  And a low pressure on top of the wing pulling it up.  The amount of air passing over/under the wing determines the amount of lift.  As does the density of that air.  The more dense the air the more lift.  The thinner the air the less lift.  Which is why planes need less runway on a cold winter’s day than on a hot and humid summer’s day.  If you watch a weather report you’ll notice that clear days are associated with a high pressure.  And storms are associated with a low pressure.  When a storm approaches meteorologists will note the barometer is falling.  Meaning the air is getting thinner.  When the air is thinner there are fewer air molecules to pass over the wing surface.  Which is why planes need more runway on hot and humid days.  To travel faster to produce the same amount of lift they can get at slower speeds on days cooler and dryer.

For the same reason planes taking off at higher elevations need more runway than they do at lower elevations.  Either that or they will have to reduce takeoff weight.  They don’t throw people or their baggage off of the airplane.  They just reduce the fuel load.  Of course, by reducing the fuel load a plane will not be able to reach its destination without landing and refueling.  Increasing costs (airport and fuel expenses for an additional takeoff and landing).  And increasing flying time.  Which hurts the economics of flying a plane like a Boeing 747.  A plane that can transport a lot of people over great distances at a low per-person cost.  Adding an additional takeoff and landing for refueling adds a lot of cost.  Reducing the profitability of that flight.  Not as bad as a normal Concorde flight.  But not as good as a normal Boeing 747 flight.

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Windmills, Waterwheels, Steam Engine, Electric Power, Coal, Heat Engine, Steam Turbine, Generator and Coal-Fired Power Plant

Posted by PITHOCRATES - July 11th, 2012

Technology 101

By burning Coal to Boil Water into Steam to Move a Piston we could Build a Factory Anywhere

We created advanced civilization by harnessing energy.  And converting this energy into working power.  Our first efforts were biological.  Feeding and caring for large animals made these animals strong.  Their physiology converted food and water into strong muscles and bones.  Allowing them to pull heavy loads.  From plowing.  To heavy transportation.  To use in construction.  Of course the problem with animals is that they’re living things.  They eat and drink.  And poop and pee.  Causing a lot of pollution in and around people.  Inviting disease.

As civilization advanced we needed more energy.  And we found it in wind and water.  We built windmills and waterwheels.  To capture the energy in moving wind and moving water.  And converted this into rotational motion.  Giving us a cleaner power source than working animals.  Power that didn’t have to rest or eat.  And could run indefinitely as long as the wind blew and the water flowed.  Using belts, pulleys, cogs and gears we transferred this rotational power to a variety of work stations.  Of course the problem with wind and water is that you needed to be near wind and water.  Wind was more widely available but less reliable.  Water was more reliable but less widely available.  Each had their limitations.

The steam engine changed everything.  By burning a fuel (typically coal) to boil water into steam to move a piston we could build a factory anywhere.  Away from rivers.  And even in areas that had little wind.  The reciprocating motion of the piston turned a wheel to convert it into rotational motion.  Using belts, pulleys, cogs and gears we transferred this rotational power to a variety of work stations.  This carried us through the Industrial Revolution.  Then we came up with something better.  The electric motor.  Instead of transferring rotational motion to a workstation we put an electric motor at the work station.  And powered it with electricity.  Using electric power to produce rotational motion at the workstation.  Electricity and the electric motor changed the world just as the steam engine had changed the world earlier.  Today the two have come together.

You can tell a Power Plant uses a Scrubber by the White Steam puffing out of a Smokestack

Coal has a lot of energy in it.  When we burn it this energy is transformed into heat.  Hot heat.  For coal burns hot.  The modern coal-fired power plant is a heat engine.  It uses the heat from burning coal to boil water into steam.  And as steam expands it creates great pressure.  We can use this pressure to push a piston.  Or turn a steam turbine.  A rotational device with fins.  As the steam pushes on these fins the turbine turns.  Converting the high pressure of the steam into rotational motion.  We then couple this rotational motion of the steam turbine to a generator.  Which spins the generator to produce electricity.

Coal-fired power plants are hungry plants.  A large plant burns about 1,000 tons of coal an hour.  Or about 30,000 pounds a minute.  That’s a lot of coal.  We typically deliver coal to these plants in bulk.  Via Great Lakes freighters.  River barges.  Or unit trains.  Trains made up of nothing but coal hopper cars.  These feed coal to the power plants.  They unload and conveyor systems take this coal and create big piles.  You can see conveyors rising up from these piles of coal.  These conveyors transport this coal to silos or bunkers.  Further conveyor systems transfer the coal from these silos to the plant.  Where it is smashed and pulverized into a dust.  And then it’s blown into the firebox, mixed with hot air and ignited.  Creating enormous amounts of heat to boil an enormous amount of water.  Creating the steam to turn a turbine.

Of course, with combustion there are products left over.  Sulfur impurities in the coal create sulfur dioxide.  And as the coal burns it leaves behind ash.  A heavy ash that falls to the bottom of the firebox.  Bottom ash.  And a lighter ash that is swept away with the flue gases.  Fly ash.  Filters catch the fly ash.  And scrubbers use chemistry to remove the sulfur dioxide from the flue gases.  By using a lime slurry.  The flue gases rise through a falling mist of lime slurry.  They chemically react and create calcium sulfate.  Or Gypsum.  The same stuff we use to make drywall out of.  You can tell a power plant uses a scrubby by the white steam puffing out of a smokestack.  If you see great plumes puffing out of a smokestack there’s little pollution entering the atmosphere.  A smokestack that isn’t puffing out a plume of white steam is probably spewing pollution into the atmosphere.

Coal is a Highly Concentrated Source of Energy making Coal King when it comes to Electricity

When the steam exits the turbines it enters a condenser.  Which cools it and lowers its temperature and pressure.  Turning the steam back into water.  It’s treated then sent back to the boiler.  However, getting the water back into the boiler is easier said than done.  The coal heats the water into a high pressure steam.  So high that it’s hard for anything to enter the boiler.  So this requires a very powerful pump to overcome that pressure.  In fact, this pump is the biggest pump in the plant.  Powered by electric power.  Or steam.  Sucking some 2-3 percent of the power the plant generates.

Coupled to the steam turbine is a power plant’s purpose.  Generators.  Everything in a power plant serves but one purpose.  To spin these generators.  And when they spin they generate a lot of power.  Producing some 40,000 amps at 10,000 to 30,000 volts at a typical large plant.  Multiplying current by power and you get some 1,200 MW of power.  Which can feed a lot of homes with 100 amp, 240 volt services.  Some 50,000 with every last amp used in their service.  Or more than twice this number under typical loads.  Add a few boilers (and turbine and generator sets) and one plant can power every house and business across large geographic areas in a state.  Something no solar array or wind farm can do.  Which is why about half of all electricity produced in the U.S. is generated by coal-fired power plants.

Coal is a highly concentrated source of energy.  A little of it goes a long way.  And a lot of it produces enormous amounts of electric power.  Making coal king when it comes to electricity.  There is nothing that can match the economics and the logistics of using coal.  Thanks to fracking, though, natural gas is coming down in price.  It can burn cleaner.  And perhaps its greatest advantage over coal is that we can bring a gas-fired plant on line in a fraction amount of the time it takes to bring a coal-fired plant on line.  For coal-fired plants are heat engines that boil water into steam to spin turbines.  Whereas gas-fired plants use the products of combustion to spin their turbines.  Utilities typically use a combination of coal-fired and gas-fired plants.  The coal-fired plants run all of the time and provide the base load.  When demand peaks (when everyone turns on their air conditioners in the evening) the gas-fired plants are brought on line to meet this peak demand.

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Trade, Steam Power, Reciprocating Steam Engine, Railroading, Janney Coupler and Westinghouse Air Brake

Posted by PITHOCRATES - January 25th, 2012

Technology 101

Early Cities emerged on Rivers and Coastal Water Regions because that’s where the Trade Was

The key to wealth and a higher standard of living has been and remains trade.  The division of labor has created a complex and rich economy.  So that today we can have many things in our lives.  Things that we don’t understand how they work.  And could never make ourselves.  But because of a job skill we can trade our talent for a paycheck.  And then trade that money for all those wonderful things in our economy.

Getting to market to trade for those things, though, hasn’t always been easy.  Traders helped here.  By first using animals to carry large amounts of goods.  Such as on the Silk Road from China.  And as the Romans moved on their extensive road network.  But you could carry more goods by water.  Rivers and coastal waterways providing routes for heavy transport carriers.  Using oar and sail power.  With advancements in navigation larger ships traveled the oceans.  Packing large holds full of goods.  Making these shippers very wealthy.  Because they could transport much more than any land-based transportation system.  Not to mention the fact that they could ‘bridge’ the oceans to the New World.

This is why early cities emerged on rivers and coastal water regions.  Because that’s where the trade was.  The Italian city-states and their ports dominated Mediterranean trade until the maritime superpowers of Portugal, Spain, The Netherlands, Great Britain and France put them out of business.  Their competition for trade and colonies brought European technology to the New World.  Including a new technology that allowed civilization to move inland.  The steam engine.

Railroading transformed the Industrial Economy

Boiling water creates steam.  When this steam is contained it can do work.  Because water boiling into steam expands.  Producing pressure.  Which can push a piston.  When steam condenses back into water it contracts.  Producing a vacuum.   Which can pull a piston.  As the first useable steam engine did.  The Newcomen engine.  First used in 1712.  Which filled a cylinder with steam.  Then injected cold water in the cylinder to condense the steam back into water.  Creating a vacuum that pulled a piston down.  Miners used this engine to pump water out of their mines.  But it wasn’t very efficient.  Because the cooled cylinder that had just condensed the steam after the power stroke cooled the steam entering the cylinder for the next power stroke.

James Watt improved on this design in 1775.  By condensing the steam back into water in a condenser.  Not in the steam cylinder.  Greatly improving the efficiency of the engine.  And he made other improvements.  Including a design where a piston could move in both directions.  Under pressure.  Leading to a reciprocating engine.  And one that could be attached to a wheel.  Launching the Industrial Revolution.  By being able to put a factory pretty much anywhere.  Retiring the waterwheel and the windmill from the industrial economy.

The Industrial Revolution exploded economic activity.  Making goods at such a rate that the cost per unit plummeted.  Requiring new means of transportation to feed these industries.  And to ship the massive amount of goods they produced to market.  At first the U.S. built some canals to interconnect rivers.  But the steam engine allowed a new type of transportation.  Railroading.  Which transformed the industrial economy.  Where we shipped more and more goods by rail.  On longer and longer trains.  Which made railroading a more and more dangerous occupation.  Especially for those who coupled those trains together.  And for those who stopped them.  Two of the most dangerous jobs in the railroad industry.  And two jobs that fell to the same person.  The brakeman.

The Janney Coupler and the Westinghouse Air Brake made Railroading Safer and more Profitable

The earliest trains had an engine and a car or two.  So there wasn’t much coupling or decoupling.  And speed and weight were such that the engineer could stop the train from the engine.  But that all changed as we coupled more cars together.  In the U.S., we first connected cars together with the link-and-pin coupler.  Where something like an eyebolt slipped into a hollow tube with a hole in it.  As the engineer backed the train up a man stood between the cars being coupled and dropped a pin in the hole in the hollow tube through the eyebolt.  Dangerous work.  As cars smashed into each other a lot of brakemen still had body parts in between.  Losing fingers.  Hands.  Some even lost their life.

Perhaps even more dangerous was stopping a train.  As trains grew longer the locomotive couldn’t stop the train alone.  Brakemen had to apply the brakes evenly on every car in the train.  By moving from car to car.  On the top of a moving train.  Jumping the gap between cars.  With nothing to hold on to but the wheel they turned to apply the brakes.  A lot of men fell to their deaths.  And if one did you couldn’t grieve long.  For someone else had to stop that train.  Before it became a runaway and derailed.  Potentially killing everyone on that train.

As engines became more powerful trains grew even longer.  Resulting in more injuries and deaths.  Two inventions changed that.  The Janney coupler invented in 1873.  And the Westinghouse Air Brake invented in 1872.  Both made mandatory in 1893 by the Railroad Safety Appliance Act.  The Janney coupler is what you see on U.S. trains today.  It’s an automatic coupler that doesn’t require anyone to stand in between two cars they’re coupling together.  You just backed one car into another.  Upon impact, the couplers latch together.  They are released by a lifting a handle accessible from the side of the train.

The Westinghouse Air Brake consisted of an air line running the length of the train.  Metal tubes under cars.  And those thick hoses between cars.  The train line.  A steam-powered air compressor kept this line under pressure.  Which, in turn, maintained pressure in air tanks on each car.  To apply the brakes from the locomotive cab the engineer released pressure from this line.  The lower pressure in the train line opened a valve in the rail car air tanks, allowing air to fill a brake piston cylinder.  The piston moved linkages that engaged the brake shoes on the wheels.  With braking done by lowering air pressure it’s a failsafe system.  For example, if a coupler fails and some cars separate this will break the train line.  The train line will lose all pressure.  And the brakes will automatically engage, powered by the air tanks on each car.

Railroads without Anything to Transport Produce no Revenue

Because of the reciprocating steam engine, the Janney coupler and the Westinghouse Air Brake trains were able to get longer and faster.  Carrying great loads great distances in a shorter time.  This was the era of railroading where fortunes were made.  However, those fortunes came at a staggering cost.  For laying track cost a fortune.  Surveying, land, right-of-ways, grading, road ballast, ties, rail, bridges and tunnels weren’t cheap.  They required immense financing.  But if the line turned out to be profitable with a lot of shippers on that line to keep those rails polished, the investment paid off.  And fortunes were made.  But if the shippers didn’t appear and those rails got rusty because little revenue traveled them, fortunes were lost.  With losses so great they caused banks to fail.

The Panic of 1893 was caused in part by such speculation in railroads.  They borrowed great funds to build railroad lines that could never pay for themselves.  Without the revenue there was no way to repay these loans.  And fortunes were lost.  The fallout reverberated through the U.S. banking system.  Throwing the nation into the worst depression until the Great Depression.  Thanks to great technology.  That some thought was an automatic ticket to great wealth.  Only to learn later that even great technology cannot change the laws of economics.  Specifically, railroads without anything to transport produce no revenue.

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