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EM 1 : Test sur le dossier Psychrometry, last minute : Evaporative cooling
1. Petit allègement de la matière : nous n’avons pas eu le temps de travailler la page 12 du dossier agrafé (Wet cooling towers); cette page ne fait donc plus partie de la matière du test.
2. Petit ajout : 3 vidéos sur Evaporative cooling :
1 – 2 surtout après la min. 0:58 (vous avez reçu les transcriptions)
3 (BREEZAIR – pas de transcription) montre bien les composants du système.
Vous ne serez pas interrogés sur ces vidéos dans la partie audition du test, mais regardez-les (en suivant sur la transcription) pour comprendre le fonctionnement concret des refroidisseurs adiabatiques.
TRANSCRIPTS
1. HOW AN EVAPORATIVE COOLER WORKS
(Dial Manufacturing, Inc : provides replacement parts and accessories for evaporative coolers)
Remember how a breeze feels on your skin as you come out of the swimming pool
or when you’re perspiring on a hot day ?
What you’re feeling is evaporative cooling.
An evaporative cooler draws draws hot, dry outside air through wet pads
and as water evaporates from the pads, the air temperature drops
and cool air is blown into the house.
0:27 Because evaporative coolers operate best in dry climates with low humidity,
they’re most often found in the Southwest United States.
Evaporative cooling have two important advantages over air conditioning.
An air conditioner doesn’t blow fresh air,
it just recirculates stale household air over and over;
but unlike an air conditioner,
the evaporative cooler constantly draws in fresh air.
0:55 And when that outside air passes through the cooler pads,
it doesn’t just get cooler, it gets cleaner
because the wet pads filter out dust and pollen
before the air goes into the house.
Homes equipped with Up-Dux* (= upduct) ceiling vents
(* exhausting evaporative cooler air into the attic)
receive the added bonus of lower attic temperatures.
1:16 The second advantage over air conditioning is energy savings.
Because a cooler uses much less electricity,
hundreds of dollars a year can be saved.
With these savings, a cooler can pay for itself in a year or two.
Evaporative coolers are available in several styles and sizes :
side draft (or discharge), down draft (or discharge),
window mount and single inlet.
Regardless of the style, the cooling principle is the same.
2. HOW EVAPORATIVE COOLING WORKS
(Air & Water Inc.)
Evaporative coolers, also known as swamp coolers,
are (the) cooling units that harness the power of evaporation
in order to provide cooling.
They are simple devices consisting of attractive, box-like frames
containing a fan that’s walled in moistened pads.
To cool you air the fan takes the hot air from the room and pushes it through the moist pads,
which cool the air up to 20 degrees.
The effect is very similar to when you’ve been exercising on a hot day and start sweating.
Once your sweat starts evaporating, a cooling effect is created.
0:27 Evaporative coolers use 75% less energy than air conditioners
and the units themselves often cost significantly less than air conditioners.
Evaporative coolers are also environmentally friendly.
They’re doing their part in this increasingly green world
by not using refrigerants like freon.
Noise pollution is curbed as well
because these coolers use blowers instead of axial fans * which are used by air conditioners.
(* see http://www.breezair.com/eu/why-evaporative/how-evaporative-works, min. 1:46 to 2:13)
0:52 The life span and durability of your furniture and fabric is ably maintained
by the help of an evaporative cooler,
which keeps everything moisturized.
Fresh air is channeled in every two or three minutes
while hot air, bad odors, dust and smoke are all pushed out.
There’s reduction of the risk of bacteria being trapped in the air
and the moisture pad acts as a filter, which helps trap dust.
Maintenance is a snap when you own an evaporative cooler
The refillable water tank shouldn’t have to be refilled before ten hours has passed
and sometimes a handy hose connection is supplied
so fresh water is continuously provided to your unit.
_____________________________________________________________________________________
A titre d’information complémentaire :
Examen blanc de mai 2014 (= examen de juin 2013) : Evaporative coolers
texte : Juin 13 EvapCool – Corrigé juin 2013 Evap coolers
Info 1 : Questions de rattrapage du test Networks + précision prochain test
Au vu des résultats, disons… décevants du dernier test, il y aura, à la suite du prochain test (Virtualization), deux questions de rattrapage pour un total de 6 points. Les points obtenus seront ajoutés à votre note actuelle qui restera sur 20.
Textes à emporter :
– Networking basics (y compris la correction + note que je vous avait fait ajouter au cours)
– How to boost your WiFi speed by choosing the right channel : texte distribué au cours d’aujourd’hui; rien de neuf par rapport à l’article de Computer Shopper sur les routeurs, sauf un schéma qui clarifie la notion de overlapping channels, visiblement mal comprise par l’ensemble de la classe.
RAPPEL pour le test Virtualization :
Vous étiez censés préparer le dossier pour pouvoir poser des questions aujourd’hui. Wishful thinking de ma part. Je m’attendais à certaines questions sur des points moins explicites du texte. Personne ne les a posées… c’est donc moi qui vous les poserai ! A bon entendeur…
EM 2 : Microgeneration (Test 4 sur les auditions préparées)
Stirling engine : bonne explication ici (Baxi) min. 1:26 à 1:50
1. Baxi Ecogen (4:37)
2. How the Baxi Ecogen works (1:58)
(This short film explains exactly how the Baxi Ecogen dual energy system, or micro-combined heat and power boiler, actually works. Using a cut-away model, Dave Willetts from Baxi’s R&D Department in Preston, which is Baxi’s European Centre of Excellence for micro-CHP, explains how electricity is generated in this wall hung replacement for a conventional domestic boiler.)
3. How does the Flow Boiler work ?
transcriptions ci-dessous.
___________________________________
Micro combined heat and power
Micro-generation technologies
Micro CHP products
Flow Boiler (pub)
You might also be interested in:
– the microCHP hub (the whole site is full of interesting articles on renewable energy !)
– How Stirling engines work
– The BedZed project (Beddington Zero Energy Development (BedZED) is an environmentally friendly housing development in the suburbs of London. The project is designed to use only energy from renewable sources generated on site. There are 777 square metres of solar panels. Tree waste fuels the development’s cogeneration plant (downdraft gasifier) to provide district heating and electricity.)
______________________________
TRANSCRIPTS
1. Baxi Ecogen
Climate change is real
and it is affecting life on every continent.
The evidence is conclusive :
globally the ten hottest years on record
have all happened since the beginning of the 1990s.
Greenhouse gas emissions caused by our activity are harming the planet
and have the potential to damage it beyond repair.
Along with the serious threat posed by climate change,
our planet is also rapidly running out of the natural resources that we all depend upon.
0:36 It’s time to act,
and the best place to start helping the planet is right here, at home.
The way we heat and light our homes at present is just not efficient enough.
Only around 30 percent of the fuel used to generate electricity at the power station
is actually converted into energy.
1:00 But more than 90 percent of the fuel used in Baxi Ecogen
will generate heat and electricity for the average home.
Baxi is an innovative company,
responsive to the changing world we live in.
We’re developing ways to improve energy efficiency
including fuel cells, internal combustion engines,
and external combustion engines like the Stirling engine.
1:30 The Stirling engine is very efficient, clean, and reliable.
It’s also the technology behind Baxi’s Ecogen boilers.
Baxi Ecogen converts the energy stored in the gas supplied to homes
into electricity and heat.
Here’s how the Baxi Ecogen system works.
1:54 Outside, it looks like a standard wall-hung boiler,
but inside it’s something altogether different.
The advanced electronic control system
allows the unit to modulate down to a very low thermal output
while still generating electricity.
Behind the cover is a boiler configuration that’s entirely new
but based upon tried proven technology.
Everything is managed by the electronic control unit,
from the volume of air and gas supplied
to switching on and off.
2:26 The spool valve* controls the air and gas supply.
The engine burner delivers precisely controlled heat
to elevate the temperature of the top of the engine compartment
to approximately 525°C.
The hermetically sealed Stirling engine generates the electricity.
At its heart is a displacer** (and ??) piston.
This is driven up and down at 50 cycles per second between electrical coils
to generate a current.
2:54 The engine can deliver up to 6 kW of thermal output on its own,
but it’s also supported by a supplementary heat exchanger,
giving an extra thermal output. (18 kW)
In standard mode, the engine burner operates first,
with the supplementary engine firing into action
only when the heat demand goes above 6 kW.
Cold water from the domestic supply
goes into the unit and picks up some initial heat
by flowing around the engine.
It then flows up to the supplementary heat exchanger
picking up more heat before flowing out of the unit.
3:28 The 1 kW of electrical output generated by the Stirling engine
can either be used in the home to reduce consumption
or exported back to the grid for an export tariff.
(NB : in the US this is referred to as net metering)
3:51 Baxi has an unparalleled combination of knowledge and experience
in developing, manufacturing and servicing home heating systems.
We are pioneers in a business
that will have major impact on the future of the planet.
With Baxi Ecogen we can all make a difference.
* spool valve : distributeur (?)
** displacer : see here (Stirling engines for microCHP generators)
Description of the Baxi Ecogen system : here.
2. How the Baxi Ecogen works
So this is a cutout (= cutaway ?) of the Ecogen unit
which helps to explain its operation.
The Ecogen unit is basically internally split into two areas :
The Stirling engine, which is the generator at the bottom,
and provides 6kW of thermal energy,
and the supplementary heat exchanger at the top,
which provides 18 kW of heat.
0:21 Gas enters the Ecogen unit at the bottom, through this pipe,
and is then distributed between two burners :
one for the Stirling engine, and one for supplementary heating.
Hot water leaves the Ecogen at the flow pipe here,
and travels to the central heating and domestic hot water system.
It then returns from the domestic hot water and central heating system through this pipe
and enters the Stirling engine here,
where it cools the bottom of the Stirling engine head.
0:51 The top of the Stirling engine head is heated by this burner here.
It’s that difference in temperature
which creates an oscillating pressure wave
and drives the power piston here.
This displacer piston
is moving the gas between the hot(s) and the cold end of the engine.
So when the displacer piston’s at the bottom of its stroke,
most of the gas is at the top end of the engine here and being heated.
1:18 That heat causes the gas to expand.
It moves the power piston down to displace a piston(s) on a spring.
As it returns to the top of the Stirling engine,
most of the helium gas is in this area here and is being cooled.
This causes the gas to contract
and pulls the power piston upwards.
1:37 It’s this movement of the power piston up and down
that moves these fixed magnets here,
as a result (they) move within this copper coil 50 times a second,
inducing an electromagnetic field and generating 1 kW of electricity.
This is then returned via this cable into your home
and on to the national grid.
3. How the Flow boiler works
From the outside,
the Flow Microgeneration boiler looks like any other boiler.
It has the same shape and the same size.
It’s only inside that it’s special.
The Flow boiler employs innovative technology
to generate low cost, low carbon electricity
while it uses gas to heat your home.
The clever engineers at Flow have used the finest quality parts and materials
sourced from the very best European manufacturers
and configured them in a novel way
in our state-of-the-art manufacturing facility in Livingston, Scotland,
to produce the world’s first affordable electricity-generating boiler.
0:35 The Flow boiler is unique, and it’s patented worldwide.
You can’t get a boiler like this anywhere else.
So here’s how the Flow boiler works.
Gas burns in the combustion chamber just like a normal boiler,
but instead of directly heating water for your heating and hot water tank,
this heats up a liquid within the boiler.
As the liquid is heated, it evaporates.
The resulting vapour moves to a device called a scroll expander.
As the vapour moves through the scroll,
it causes it to spin.
At this point the scroll is acting like a mini generator, or dynamo.
1:10 This is how the Flow boiler generates electricity.
The electricity can then be used in your home
or exported to the national grid for other households to use.
The vapour that causes the scroll to spin and generate electricity
then enters a small heat exchanger
and condenses back into a hot liquid
which heats water for your heating system and hot water tank.
The liquid is then pumped around to be heated and evaporated again,
continuously converting heat from the burned gas
into electricity and heat for your home.
1:40 So that’s it : the unique Flow boiler,
intelligently engineered by the clever people here at Flow.
The Flow boiler launches in January 2015.
Our launch version is suitable for 3 to 5-bedroom houses
and needs a separate hot water tank.
But our team are working on versions for smaller houses and for bigger houses,
and they’re creating a combi version too.
So register your details now,
and you can be part of the most exciting vision for home energy
that has ever been.
Description of the Flow boiler : here.
Info 1 : Test sur le dossier Virtualization (Lecture préparée 2)
TEST ECRIT le 30 avril 2015 sur les lectures préparées (test 2)
(7 points sur 40 total année)
Le test comportera les mêmes types de prestations que celui du 2 avril.
Vous préparerez seuls ce dossier; vous aurez l’occasion de poser toutes vos questions le 23/4.
Vous avez reçu le 2 avril un texte d’introduction au sujet (Welcome to Oracle VM Virtual Box).
! attention au mot « consolidation » (= faux ami) à comprendre avec précision.
Avant de le lire, regardez ces trois vidéos :
1. Celle-ci (How to use VirtualPC, David McClelland) n’est pas toute récente mais elle a le mérite d’être très claire. Transcription disponible sur le site, mais commencez par essayer de comprendre sans la consulter. (Profitez-en pour découvrir VideoJug : des vidéos en vrac sur les sujets les plus divers, des plus sérieux aux plus légers – avec transcriptions ! )
2. Virtualization overview (VMWare) – (distinguer les informations réelles du blabla publicitaire)
3. A simple explanation of virtualization (vminformer)
mise à jour 12/4/15
– Lecture à préparer, suite et fin :
http://www.extremetech.com/computing/198427-how-to-install-windows-10-in-a-virtual-machine (pages 1 et 2)
S’il y a des notions inconnues pour vous (ex : image ISO…), à charge pour vous de chercher les informations nécessaires !
Vous recevrez à la rentrée la version papier de cet article pour le test (mais les saisies d’écran risquent de vous paraître très petites, aussi aurez-vous sans doute intérêt à les compléter à la main d’après la version en ligne).
…Et si vous essayiez de mettre en pratique ? cela vous permettrait de mieux comprendre l’article.
___________________________________
Transcripts :
1. VMWARE VIRTUALIZATION BASICS
Over the years, IT complexity has grown while efficiency has plummeted.
Virtualization reverses this trend,
simplifying IT infrastructure so you can do more with less.
Virtualization lets you run your applications on fewer physical servers.
To virtualization each app and operating system live in a separate software container
called a virtual machine or VM.
0:30 VMs are completely isolated,
but computing resources – CPUs, storage and networking – are pooled together
and delivered dynamically to each VM by software called a hypervisor.
Every application gets what it needs for peak performance.
With all your servers running at full capacity, you don’t need nearly as many.
Hardware count and overhead drop dramatically
while application performance improves by leaps and bounds.
Bottom line : greater value at lower cost,
with less complexity and faster maintenance.
Now you can spend more time on innovation to meet real business needs.
1:04 But all virtualization is not created equal.
For the smallest companies as well as the largest global enterprises,
VMWare is far and away the most trusted and widely deployed platform.
Out technology is the most mature, feature-rich and reliable,
generations ahead of any other.
With VMWare you get higher service levels,
two and three times higher for heavy workloads,
and IT management gets a lot simpler.
1:32 Tasks that used to take all night can be done over coffee in the afternoon,
freeing up work time for innovation
and evening hours for spending with your family.
No business can afford application downtime
and VMWare Virtualization makes sure it won’t happen to you.
High availability and fault tolerance are built right into the platform.
If a server ever fails, your apps stay up and running,
with no downtime, no data loss and no need for human intervention.
1:58 VMWare Virtualization brings you the biggest savings
by letting you run more apps on many fewer servers
at the industry’s lowest net virtualization cost.
Even better, the savings in efficiency multiply with every application you virtualize.
Of course protecting IT against intrusions is critical.
That’s why VMWare shields virtualized apps and data
with unified, easy-to-use security across all levels.
In fact, VMWare protection makes your virtual assets even more secure
than the most fortified physical environments.
2:30 Virtualization is a must for today’s IT environment.
At the same time advancing and protecting your business
means choosing your virtualization solution wisely.
Go with a trusted platform that delivers the greatest benefits,
the largest savings and the highest responsiveness to your business : VMWare.
2. A SIMPLE EXPLANATION OF VIRTUALIZATION
Hello, and welcome to vminformer’s videoguides on virtual computing.
The first question to answer is : Why virtualization ?
Well, its simple : it saves money and resources.
Of course you’d like us to tell you how it works,
so here is a simple introduction.
Virtualization, or virtual computing,
makes one physical computer act and perform like many computers.
0:26 Every computer, irrespective of its power, size or age,
from the smallest PC to the biggest mainframe,
has four attributes.
Each one has a processor – the chip that does the work;
some memory – the chips that remember the task and how to do it;
some storage – which files everything away,
and a network connection.
Because we rely on computers for every aspect of our business life,
there are hundreds of servers, PCs and laptops in most organizations,
but they all have the same name need for these four things.
1:01 So virtualization works as follows.
A big piece of hardware with plenty of power
and processing, memory, storage and network capacity
is loaded with a piece of software called a hypervisor.
The hypervisor is sometimes called the abstraction layer
because it abstracts the physical resources
and reallocates them more efficiently.
1:25 In this diagram, above the abstraction layer is a guest computer,
or as some people call it, a virtual machine.
These virtual machines are just very big files.
The guest computers run inside the physical hardware,
which is called the host.
An example of how virtual machines run inside a computer
is the sending and receiving of some data through the network.
Sent data leaves the guest computer,
it travels through the hypervisor to the network card on the host
and forward (?) to its eventual destination.
The same works in reverse when receiving data.
2:04 Why would you do this ?
Well simply because you can run many machines simultaneously
over one physical hardware
so it can save money on hardware,
consolidate management,
reduce energy use,
and it becomes a much more efficient use of resources.
Most computers operate using between only 4 to 7 percent of their resources.
By virtualizing these computers,
you can get many guests onto one host.
2:32 Immediately you’re gonna get much greater efficiencies in power consumption,
physical space and energy used for cooling.
Of course you should need less people to look after that equipment.
Now when you need a new server, you don’t need to buy new hardware,
you can make a virtual one.
If you need more memory or CPU on a device,
your administrator just changes the resource allocation with a few mass clicks.
2:59 So what can you virtualize ?
Well, anything that has the four attributes of a computer.
Even a network and switching between computers
can be consolidated onto the same platform.
There are more benefits.
When you have two host servers,
then you have the ability to move machines around
so valuable resources are optimized at all times.
It’s quite possible to move a powered on guest computer from one host to another.
You might do this because the first host is overloaded
or because there has been a catastrophic hardware failure of the original host.
Maybe you get cheaper processing power somewhere else,
which introduces the concept of cloud computing.
3:41 However, this flexibility does raise some questions :
where are your machines ? who has access to these systems ?
how are they managed ? what security is in place ?
Our other videos on virtualization with management
outline what is involved in these and other risks
and what you can do to address them.
Understand and address these issues,
and you should be able to continue your virtualization journey with confidence.
4:08 (…)
EM 1 : Test sur le dossier Psychrometry (Lecture préparée 2)
TEST ECRIT du 12 mai 2015 sur les lectures préparées
(7 points sur 40 total année)
Le test comportera les mêmes types de prestations que celui du 31 mars (HP & AC)
La formule des préparations change quelque peu (à ce stade de l’année, vous allez vers plus d’autonomie) : l’agenda des préparations est donné ci-dessous; au cours, vous aurez l’occasion de poser toutes vos questions, mais nous ne reprendrons pas systématiquement ensemble tout ce que vous aurez préparé, nous travaillerons de la matière qui vient se greffer sur les parties préparées.
A PREPARER POUR LE 21/4
1. lire soigneusement la feuille Psychrometric chart 101 (distribuée le 2/4) – qui correspond à la présentation rapide du diagramme de l’air humide (psychrometric chart) que j’ai faite le 24 mars.
2. regarder ces 2 vidéos (qui expliquent les idées du texte) : Psychrometric chart 1 and 2 (Bry-Air) [youtube]https://www.youtube.com/watch?v=xKoVpR0gUDE[/youtube] [youtube]https://www.youtube.com/watch?v=brS2rtWDYek[/youtube]
Attention : « imperial » units (>< metric / SI units)
Sous-titres un peu fantaisistes par endroits, mais utilisables (commencez par essayer de comprendre SANS afficher les sous-titres !)
3. Modern Refrigeration and Air Conditioning (feuilles A3 distribuées au cours)
parcourir rapidement les passages suivants
(avec une attention toute particulière à la figure 21-4) :
- p. 502-503-504 à partir de » The density of air… » (colonne 1 p.502) jusqu’à « this indicates the dew point temperature » (colonne 1 p. 504) – passer le § Indicators of low humidity p. 503.
- p. 505-506-507 : uniquement colonne 2 p. 505 (à partir de « 21.2.3 Air temperature ») et la suite p. 506 jusqu’avant le titre « Perception of temperature », + fig. 21-11, 21-12, 21-13.
- p.508 à 511 à partir de « 21.2.4 Psychrometric properties of air » jusqu’à la fin du § Enthalpy, colonne 1 p. 511 (NB : voyez la reproduction en couleurs des fig. 21-17 (ainsi que 21-18 et 21-19, que vous n’avez pas reçues sous forme papier).
En fait, mis bout à bout, les passages sélectionnés ne représentent pas plus de 3 pages A4, qui répètent en partie, en les développant, les informations présentées en 1. et 2. !
NB : pour les 3 cours consacrés à ce dossier, vous aurez besoin d’une latte (si possible transparente) pour consultation précise du diagramme de l’air humide.
A PREPARER POUR LE 28/4
1. Retravailler en profondeur les pages de Modern Refrigeration and Air Conditioning.
2. Relire les feuilles numérotées 3-4-5 (il n’y a pas de pages 1-2) extraites de ÇENGEL & BOLES (feuilles agrafées distribuées au cours), que nous aurons consultées au cours.
A PREPARER POUR LE 5/5
les pages 8 à 11 (il n’y a pas de pages 6-7) de ÇENGEL & BOLES; nous travaillerons ensemble la page 12.
TRANSCRIPTS
BRY-AIR PSYCHROMETRIC CHART #1 : BASIC DEFINITIONS
(2012)
Welcome to the first in a series of educational videos provided by Bry-Air Inc,
THE choice for dessicant dehumidification.
This video is the first in a series that deals with understanding the properties of air
and how to use this knowledge to solve moisture and temperature problems
in industrial type applications.
This video explains the very basic elements of the properties of air.
We hope you enjoy these videos,
but more importantly, we hope you find them to be useful.
0:28 The psychrometric chart displays the properties of air.
Knowing how to read it is fundamental to determining the elements required
to change those properties.
With knowledge of any two points
(= any two properties !)
all others can be calculated.
In this video, the first of a series brought to you by Bry-Air,
we’ll define the terms related to the chart.
0:48 Dry bulb temperature
is the temperature of air determined with an ordinary thermometer.
Here it’s shown in degrees Fahrenheit.
Wet bulb temperature is the lowest temperature that can be reached
by the evaporation of water only.
It’s the temperature you feel when your skin is wet
and it’s exposed to moving air.
Enthalpy is the total energy, in BTUs,
of a sample of dry air and its water vapor.
Enthalpy can’t be measured directly,
but changes in it can.
1:16 Dew point is the temperature at which water vapor begins to condense from moist air.
Dew is formed because the air is saturated
and can’t hold any more water vapor.
Relative humidity is the ratio of the amount of moisture present in a sample of air,
compared to how much moisture the air could hold at that temperature,
given as a percentage.
It’s the factor that determines how comfortable we feel
at a specific dry bulb temperature.
1:42 Humidity ratio is the weight of water in a sample of air,
compared to the weight of the same sample of air with no moisture in it,
measured in grains of water per pound (lb) of dry air.
For example, at 70°F with 30% relative humidity,
the humidity ratio is 34 grains of water vapor per pound of dry air.
2:03 Water vapor pressure is the pressure exerted by water vapor molecules
on the surrounding environment,
causing air to move.
For example, when you open a door to an air-conditioned space,
water vapor pressure causes the moister air from the outside to be pushed inside.
2:23 Specific volume is the volume of space occupied by a pound (lb) of air,
measured in cubic feet per pound.
That concludes the first video in the series on psychometrics,
the properties of air.
Our next video will be posted shortly.
If you would like to learn more about this subject, or Bry-Air,
visit our website : www.bry-air.com , or call us toll-free at 877-4-BRYAIR.
BRY-AIR PSYCHROMETRIC CHART #2 : LINES ON THE CHART
(2012)
Welcome to the second in a series of educational videos brought to you by Bry-Air,
the choice for dessicant dehumidification.
This series deals with understanding the properties of air
and how to use this knowledge to solve moisture and temperature problems
in industrial type applications.
In the first, we defined the terms used on a psychrometric chart.
Here we’ll show you where each property lies on the chart
and demonstrate using the intersection of two properties to find the others.
Please note that the sample charts are for illustration purposes only
and the examples are based on the standard barometric pressure at sea level.
0:35 Dry bulb runs along the x axis
and is indicated by the evenly spaced vertical red lines.
Humidity ratio runs along the y axis
and is indicated by the evenly spaced horizontal red lines.
Wet bulb temperature is indicated by the red lines
that begin at the top of each dry bulb saturation temperature line
and run down toward the right
at an angle of approximately 45 degrees.
But the distance between the lines increases
as the dry bulb temperature increases.
1:06 Air that is fully saturated with moisture has reached its dew point.
This saturation, or dew point, temperature
is indicated by the intersection of the dry bulb temperature
and the far left curved line.
Fog is the real world representation of saturated air.
Relative humidity is denoted by the red curvilinear lines.
1:26 To make it easier to differentiate the various lines,
we’ve been using a somewhat simplified chart.
Water vapor pressure, however, measured in inches of mercury,
can only be seen in the more complex version.
It’s the vertical measurement at the far right,
parallel to the humidity ratio.
Enthalpy, the measure of specific total heat
measured in BTUs per pound of dry air,
is indicated by the bracketed numbers on the left.
1:52 Specific volume is shown by the red, oblique lines equidistant from each other.
This is in contrast to the wet bulb temperature lines.
With wet bulb temperature the angle is wider
and the distance between the lines increases proportionately
from lower left to upper right.
Specific volume increases as the temperature and/or moisture increases.
2:13 Here are some examples of using the intersection of any two points
(= lines / properties !)
to find a third value.
We’ll begin with the intersection of 72°(F) dry bulb and 40% relative humidity.
If we read to the right, we can see that the humidity ratio is 46.8 grains per pound.
If we read to the left, we can see that the dew point is 46.4°(F).
The enthalpy is 24.58 BTUs per pound.
The dew point is a little over 13.5 specific volume,
and the vapor pressure is 0.316 inches of mercury.
This concludes the second video in our series on psychrometrics,
the properties of air.
In our next video, we’ll apply this information to real-world situations.
If you would like to learn more about this subject, or Bry-Air,
visit our website at www.bryair.com , or call us toll-free at 877-4-BRYAIR.
Info 1 : Matière du test Networks
TEST ECRIT du 2 avril 2015 sur les lectures préparées
(8 points sur 40 total année)
Le test comportera :
- une partie audio (quelques extraits des fichiers étudiés, dont vous restituerez le contenu dans vos propres mots); SANS documents
- une quinzaine d’expressions à traduire d’anglais en français; SANS documents
- questions en anglais, réponses à donner en français en consultant les textes dépourvus de toute annotation de vocabulaire (+ dictionnaires explicatifs monolingues si nécessaire)
Partie de N. Baertsoen : NETWORKS
TEXTES
- Networking basics (1p. recto/verso, compilation de plusieurs sources) – schémas : voir billet du 5 mars (à consulter pour info, inutile de les imprimer)
- Introduction to How Wi-Fi works (HowStuffWorks)
- Choosing a wireless router (Computer Shopper 324, Feb 2015)
- Wireless routers (Computer Shopper 323, Jan 2015) p.97 + p. 99 non lue au cours (une question du test consistera à y rechercher des informations en rapport avec la p. 97)
- The layered approach to Internet software (Brookshear, Computer science : an overview, p. 167-170)
- Why homes could soon be wire-free (BBC Click, Apr 3rd 2013) : transcript of the video
- Gigabit Wi-Fi (The Economist, Apr 22nd 2013)
AUDITION (partie audio du test)
- Why homes could soon be wire-free (BBC Click, Apr 3rd 2013)
Partie de M. Casier : voir ses indications
màj 26/3/15 : Transcription de la vidéo (minutageYouTube)
0:32 What would you do to boost your signal ?
This week on Click we ask if the trusted Wi-Fi in our homes is up to the job anymore
and we showcase the new tech promising a lightning-fast connection.
0:43 (…)
1:12 Welcome to Click. I’m Spencer Kelly.
If you think about it, we really are living in a world of magic, aren’t we ?
Our phones, our tablets and our laptops
just talk to each other and the rest of the world
without any wires whatsoever.
And it all does seem to work quite well – up to a point.
1:30 Because the files that we want to send are getting larger
and if for example you’ve ever tried to stream a high-def movie over Wi-Fi,
well, things may have got a touch sticky.
Dan Simmons has been looking at some of the new wireless technologies in the pipeline
that may be better at handling those huge files and high data rates.
__________________
1:49 The future looks great, doesn’t it ?
Except when it does this.
(buffering circles on screen)
And if we were to travel to the time we expect to see these technologies,
about five years from now,
then this video would be in super high definition
Maybe if we were streaming this over our home Wi-Fi
we’d be watching… these buffering circles a little bit too often.
2:21 And that can happen today in the home,
even with high definition or standard definition video streaming,
regardless of how fast the connected broadband speeed into the home is.
And that’s because we are starting to ask too much of our home Wi-Fi router.
Wherever we’ve placed it in the house,
we expect it to service all of our devices at once.
2:46 Wi-Fi is no longer used just to browse the net.
We’re using it for gaming
and to stream content we’ve already downloaded to larger screens,
using technologies like HP’s TV Connect or Apple’s AirPLay,
to throw content from our phones, tablets or laptops to the big screen.
The magic all relies on Wi-Fi.
3:11 And Wi-Fi has another problem to deal with.
It uses a similar frequency to send and receive data
as many other things that we use around the home,
like all of our Bluetooth devices
or these wireless telephone handsets
– and of course our neighbours’ Wi-Fi, Bluetooth and wireless handsets.
So there’s quite a bit of interference.
3:36 So it seems that if we want to hang on to our wireless world,
we’ll need to upgrade our home Wi-Fi to something else.
No – something else.
The good news is that in recent years some of our tech has switched
from using the old 2.4GHz frequency
to jointly being able to use he less congested 5GHz frequency,
and that’s like moving up a gear
from trundling along a country road
to cruising on a motorway.
Higher frequencies make for faster data transfers,
and a new upgrade to the 5GHz service, called 802.11ac
(a name that sounds a bit like a number plate)
is starting to make its way to a range of products,
including mobile phones from HTC and Samsung.
4:28 And to reliably stream this super high definition video
(« HEVC 4K x 2K @ 3.7 Mbps »)
which has four times as many pixels as full HD,
the Wi-Fi people are about to push things even higher up the scale,
to 60 GHz.
(« 60GHZ WirelessHD » – « UltraGig » labels on gear)
This system is called WirelessHD
and as the name suggests
it’s been specifically designed for video and gaming content.
4:53 Jim Chase (Silicon Image WirelessHD) :
– It supports full HD uncompressed video transmission
with up to 4 Gbps of data rate.
(« Designed to work in high-density environments »)
While WirelessHD is geared to streaming,
another emerging standard, WiGig, allows you to use that speed
to transfer any file – important for our future movie downloads
that are going to be huge.
5:20 But there’s a catch with using faster, higher frequencies for wireless devices :
the higher the frequency, the shorter the distance our data can travel through the air,
and our superfast highway simply runs out.
WiGig can transfer files (at) an amazing four and a half (4.5) Gbps.
Now that’s about as fast as this latest USB 3 cable.
But expect a big dropoff in that rate depending on how far the signal has to travel.
In fact it won’t go further than a few metres
when the first products come out later this year.
6:01 Well, that could still be useful within the confines of one room.
We could crack open two or three devices
and start streaming super high definition.
But come upstairs to the bedroom
and you get absolutely no signal at all.
Worse than the current Wi-Fi situation.
(« – Sorry about that. »)
6:29 So, just like the Washington bridge, our wireless devices will double up,
running two or more frequencies at the same time.
Dr Henry Samueli, Co-founder, Broadcom :
– If you look at Wi-Fi today,
it operates at 2.4GHz and 5GHz,
same dual-band solutions that we’re selling to the market today.
But I can see in the future, you’ll have tri-band solutions,
you’ll have 2.4GHz, 5GHz and 60GHz,
all sitting underneath the Wi-Fi protocol umbrella
and giving you the choices of speed versus distance in communication.
7:00 The limit on distance for the superfast Wi-Fi
means it’s likely to be used to replace cables.
This WiGig docking station is one of the first to use the tech.
Simply pop your laptop close by,
and it backs up all your files in seconds.
The direct link means there’s no need for a router,
so this setup could be used anywhere in the house.
7:25 So, might this be the end of cables altogether ?
Mazar Nekoveey, Communications Expert :
– Ultimately wireless goes through the air, so there’s no medium,
and it might not get always as stable as… with cables.
But then there’s no wire(s), and people that… like that,
and it’s magic, that’s what I think.
It’s even more interesting making everything as wireless as possible.
7:47 By this time next year
we should know whether that magic will allow our cables to finally disappear.
7:55
Info 1 : vidéo à préparer
Why homes could soon be wire-free (BBC Click, April 3, 2013)
sur YouTube (émission complète, écouter jusqu’à 7:55)
ou sur le site de l’émission Click de la BBC (une seule séquence de l’émission)
vidéo à préparer (à l’aide de la transcription) pour le 26 mars; ne consultez la transcription (passage par passage) qu’APRES avoir essayé de comprendre le reportage en écoutant, plusieurs fois si nécessaire, chaque passage (+/- 30 secondes).
C’est l’occasion de découvrir cette émission, qui existe à la radio ET à la télévision.
Click is « a weekly BBC television programme covering news and recent developments in the world of consumer technology » (Wikipedia).
Sur le site de BBC Click, clips de quelques minutes extraits de l’émission télévisée.
Les émissions télévisées complètes (30 minutes) sont disponibles sur YouTube (site non officiel !)… jusqu’en septembre 2014. Dommage que ce ne soit plus le cas, ce qui nous prive de la séquence Tech Review et de la sélection hebdomadaire (Webscape) d’applications et de sites intéressants. A tester à la TV ?
Podcast de l’émission radio (anciennement « Digital Planet »)
EM 1 : Matière du test Heat pumps + AC
TEST ECRIT du 31 mars 2015 sur les lectures préparées
(8 points sur 40 total année)
HEAT PUMPS and AIR CONDITIONING
Le test comportera :
- une partie audio (quelques courts morceaux de phrases à traduire + 2 ou 3 extraits un peu plus longs dont restituer le contenu dans vos propres mots); SANS documents
- une quinzaine d’expressions à traduire d’anglais en français; SANS documents
- un texte à trous à compléter (liste de mots fournie, plus de mots que de trous); SANS documents
- questions en anglais, réponses à donner en français en consultant les textes dépourvus de toute annotation de vocabulaire (+ dictionnaires explicatifs monolingues si nécessaire)
TEXTES
- (matière vue au Q1) Transcript of the video Evaporative cooling + The refrigerant circuit (Danfoss)
- Exercice préparatoire : texte à trous How the heat pump works (The Electricity Council) + schémas et liste de mots (3 pages); corrigé (texte complet) + suite au verso (defrost operation + COP)
- How an Air Conditioner works + What is a split system ? (Energy Saver)
- Types of Air Conditioners (Energy Saver)
- How geothermal works (Tetco Geothermal)
- Ductless, mini-split systems (Energy Saver)
- Air-to-water heat pumps – Domestic (Heat Pump Association) uniquement le verso : avec schémas
- Air-to-water and water-to-air systems (The Electricity Council)
- Metering devices (quelques §, ESCO press) + schémas Heating/Cooling cycle (Heat Pump Association)
- The heat pump four-way reversing valve (2 pages, compilation Danfoss + Heatpump-Reviews.com)
- Description of the Animation (Refrigeration Basics)
- Transcripts of the 4 videos listed below
(Vous remarquerez que j’essaye de vous familiariser avec une grande variété de sources.)
AUDITIONS (partie audio du test)
4 vidéos :
- Heat pump basics (Goodheart-Willcox)
- How a central air conditioner works (RepairClinic)
- GeoExchange heating and cooling system
- How an evaporative cooler works (Dial Manufacturing)
màj 24/3 : PAS cette dernière vidéo (que nous n’avons pas eu le temps de regarder) – le lien sera utilisé plus tard.
(Further information about mobile swamp coolers : Air & Water video
+ have a look inside an evaporative cooler : Breezair video
– ces deux vidéos ne font pas partie de la matière du test)
EM 1 : (Heat pumps) The reversing valve(s)
Observe here how the reversing valves change the direction of refrigerant flow (click on buttons 2, 3, 4 and 5).
You might also watch this video (up to min 4:50), which shows the inside of the valve.
Info 1 : Networks
1. Les doubles page ci-dessous, extraites de HOW COMPUTERS WORK (4th edition, 1998) by Ron White (QUE), constituent une illustration métaphorique des concepts évoqués (switch + 7 OSI layers)
2. Sur le site Study.com (ex-Education Portal), une série de vidéos sur les réseaux, avec transcriptions (presque complètes) : Types of networks, Network architectures, Star, ring and bus topologies… Sur le site, les vidéos sont tronquées, mais il y a moyen de les télécharger intégralement (Firefox : Outils/Informations sur la page/Medias/sélectionner la ligne « vidéo » et Enregistrer sous…)
3. What is Wi-Fi ? (avec un accent indien à couper au couteau… mais on peut couper le son et afficher les sous-titres !)
4. Why homes could soon be wire-free (BBC Click, 3 April 2013). Vous recevrez la transcription.
+ Intel wants to eliminate PC wires by 2016 (PCWorld videos, June 4, 2014)
5. What is IPv6 ? (2009)
à suivre… (ce billet sera complété sous peu)
EM 1 : Ground source/GeoExchange heat pumps (vidéo à préparer)
1. Watch this video : GeoExchange heating and cooling system.
(vidéo à préparer pour le 10 mars; vous recevrez la transcription ce jour-là)
NB Comme le précise bien le présentateur de l’une des vidéos de Worcester-Bosch mentionnées ci-dessous, et contrairement à ce que proclame la première image de cette vidéo (« Geothermal finally explained ! »), « It must be emphasized that this is ground-source heat and NOT geothermal energy. Forget the hot springs in Iceland and all that sort of things, this is just using the sun’s rays which are stored in the ground as heat, to heat your home. »
2. You might be interested in these videos by Worcester-Bosch. They explain the various types of ground-source heat pumps and show their installation.
3. On the GeoExchange website (« a non-profit trade association promoting the manufacture, design and installation of GeoExchange® systems »), you’ll find lots of interesting information : brochures, data sheets… (« consumer resources » and « library » tabs)
_______________________________________________
màj 18 mars : Transcript
Because the earth absorbs and stores much of the energy it receives from the sun as heat,
underground temperatures remain constant at a point between 42 and 80°F year round
depending on where you are in the United States.
A GeoExchange system can use this energy source
to economically heat and cool almost any kind of building,
heat water, provide refrigeration
and perform many other kinds of applications.
0:33 A GeoExchange system is made up of three components :
a heat pump, usually located inside the building,
where it’s protected from the environment and vandalism ;
an underground heat exchanger to act as a heat sink
to store energy in the earth when cooling
and to extract energy from the earth when heating ;
and a distribution system such as air ducts
or hydronic radiant floor tubing
to provide comfort control for the building space.
1:04 The two types of heat exchangers commonly used are open loop and closed loop.
A closed loop system uses a system of continuous underground pipe loops
in which both ends of the pipe system are connected to the heat pump,
thereby forming a sealed closed loop.
Water or a mixture of water and environmentally friendly anti-freeze
circulates through the loop to transfer heat
between the heat pump and the earth.
1:33 In some installations, the pipes of a closed loop system
can be placed in a horizontal trench
dug below the frost line.
The number of pipes in each trench
and the number of trenches needed
will vary depending on the size of the GeoExchange system being installed
and the type of soil found in the area.
1:53 To minimize trenching,
Slinky (™) coils – spring-like coils of polyethylene pipe –
can often be used to increase the pipes’ surface area
and thus the heat-exchange per foot of trench.
Another way to increase the heat-exchange rate of a closed loop system
is to take advantage of the naturally higher heat-transfer capability of water over soil or rock.
If a stream, river or pond of sufficient size is available
coils of heat-exchanger pipe can be installed on or near the bottom
to form a pond loop system.
2:30 In locations where space is limited
or a large heat exchanger is required,
the pipes of a closed loop GeoExchange system can be installed vertically
in wells drilled into the earth.
As with the horizontal and pond loop systems,
the number of loops and the depth of the wells needed in a vertical closed loop system
are determined by the size of the building,
system demands,
the ground temperature
and other variables.
2:59 Since it’s not necessary for the heat exchanger to be connected to the rest of the system above ground
whichever type is installed can be placed within existing landscaping :
under sidewalks, driveways and parking lots
or even beneath the building itself.
In an open loop system, on the other hand,
ground water from an aquifer is pumped through one well
and passes through the heat pump
where heat is added to or extracted from it.
The water is then discharged back to an aquifer
or harnessed for other water management uses.
Because the system’s water supply and discharge are not connected underground,
the loop is open. (3:42)
EM1 : Air-source (air-to-air and air-to-water) heat pumps
1. Watch this illustration
Air-to-air heat pumps : central/distributed vs ductless, mini-split
(source : http://fr.slideshare.net/fortunatmueller/be-2014-heat-pump-and-pv – slides 33 to 37: Types of heat pumps)
Further information here (Energy Saver) : on air-source systems in general; on ductless, mini-split systems.
2. Lots of interesting information on Worcester-Bosch heat pumps website, e.g.
– Renewable technologies brochure, with descriptions of various types of systems
– Installation instructions and user instructions for air-to-air heat pumps
(downloadable here)
– a video showing the installation of an underfloor heating system (air-to-water)
3. On This Old House (a website devoted to home improvement), videos on
– how to position a mini-duct air conditioning system : all parts are shown very clearly.
– how to install a mini-split air conditioner
You can find many videos on YouTube showing the installation of heat pumps. Enter the name of a well-known manufacturer, such as Daikin, Sanyo, Honeywell, Trane…
Info 2 : Répartition des points Q2 + consignes
Points TJ Q2
– points TJ audio non attribués au Q1 = 3,5 : 2 tests les 21 et 28/4
(extraits à synthétiser, gap-filling et/ou réponse en français à des questions sur le contenu d’extraits réécoutés)
– points TJ audio Q2 = 3,5 : 2 prestations individuelles Tech News (calendrier : voir billet du 22/2)
présenter en anglais le contenu d’un des « segments », en s’aidant éventuellement de quelques mots-clés
! noter au tableau les mots de vocabulaire spécifique dont les autres étudiants auront besoin pour prendre leurs notes
(les points obtenus compteront double : 1x pour l’audition, 1x pour les présentations)
– points TJ lecture Q2 = 2,5 : test récapitulatif écrit le 31/03
répondre en français à des questions sur le contenu des 14 bulletins (7 x Click + 7 x WTU), en s’aidant des notes prises en anglais pendant les présentations, complétées individuellement d’après réécoute et/ou liens donnés sur les deux sites
– points TJ présentations Q2 = 2,5 : 2 prestations individuelles Tech News (cf. plus haut) + 1 présentation par groupe (le 19/5) du travail de Labo réseaux
Examen oral Q2 : mêmes consignes que pour le Q1 (cf. billets du 29/10 et du 3/11)
y compris Google doc des choix individuels; varier sujets et sources, ne pas reprendre de sujets traités dans le dossier du Q1
Amendement : longueur minimum du dossier de lectures Q2 = 50 000 signes (et non 75 000 comme initialement prévu)
Dates de remise des dossiers: cf. calendrier
Attention : dossier/liste des auditions incomplet(-ète), envoyé(e)/remis(e) en retard ou non envoyé(e)/remis(e) = PAS d’examen oral (0). Idem si vous n’avez pas vos fichiers mp3 sur clef USB le jour de l’examen.
Remarque sur le choix des fichiers audio : vous pouvez reprendre des Tech News déjà présentés, jusqu’à concurrence de 5 minutes sur les 20 à préparer.
