Sur le chemin de l'excellence

L’utilisation d’indices de performance pour mesurer l’activité humaine ne produit pas l’équité et la justice. Bien au contraire, cela génère une vision de pénurie qui empêche les organisations de prospérer comme elles le pourraient.



Marlène Bilodeau

Consultante en gestion des ressources humaines et en développement

organisationnel

418.692.1432

www.inspirationroyale.com

Mountain Hiking in Kerala

By: Dev Sri

Mountain Hiking is a form of walking, undertaken with the specific purpose of exploring and enjoying the scenery on the way and from the top. Anyone enjoy the good walk will also enjoy the hiking experience within the mountainous regions of Kerala. The lower attitude regions of Nilgiri Hills provide some pretty good options to enjoy a hike.

Hiking is a type of walking and while doing it one can enjoy as well as explore the scenery of the given place. Hiking can only be done in those places that have trails such as in rural or wilderness areas.

Before taking up the hiking trip it should be carefully kept in mind that the clothing should be of a fabric that provides a breather to your skin and allows your body to shed excess heat and sweat while feeling dry.

Avoid cotton cloths and for cold weather use polypropylene and for warm weather use polyester is good choice for base covering. A windproof and water resistant jacket worn loosely can be removed when you start feeling warmer after walking.

Use comfortable and right hiking shoes. One should keep different kind of shoes to face the climate changes. One should drink water before, during and after walking. All hiker should set out on a hike tour with a trail map, compass and with good idea about the route.

Mountain Hiking in Kerala

With an enormous and enthralling tourism facilities is available in Kerala, Hiking in Kerela can be a good form of recreation as well as adventure that is available in Kerela. The Eastern Kerela borders at the west of the Western Ghat’s rain shadow is the place where lies the high mountains, gorges and deep-cut valleys. It can thus be an ideal for those who are passionate about Hiking in Kerela. The popular and the most extravagant places can be the hill stations of Munnar, Palakkad, Wagamon and Idukki.

The perfect wooded Hiking trails of the place with a backdrop of the Kerala hill stations that are filled up with the fragrance of cardamom and cloves along with their thriving greenery can be ideal for Hiking in Kerala. The Hiking trail winds through the cardamom plantations, the rubber and coffee farms, and then through the misty mountain forests. Thus it will keep one wondering about the scenic beauty of the natural greenery of Kerela.

While on the way of Hiking in Kerela the tourists can feel the dry leaves chink under their foot along with listening to an assortment of the sounds of the insects and bird calls. One of the most popular places for Hiking in Kerela is Munnar. The place is well-known for its tea plantations, churches and the old British mansions. Mountain Hiking in India is famous at Kerala.

Hiking in Kerela through the jungles of Periyar Sanctuary could be a breathtaking experience. While hiking through this place one can experience the natural beauty as well as get a glimpse of the rare species of wildlife, birds and insects. From Periyar, the other destination for hiking, Munnar could be reached by a bicycle, following the mountain trail. Kerala adventure mountain hiking is popular.

About the Author

Dev Sri invites you to try adventure tours of Kerala. With Adventure Kerala, you will enjoy adventure sports like mountaineering, rapelling, rock climbing, river crossing, and a whole lot of adventure activities.

(ArticlesBase SC #333679)

Article Source: http://www.articlesbase.com/ - Mountain Hiking in Kerala

DES FLUIDES QUI FONT FROID DANS LE DOS

Chlorofluorocarbures (CFC), hydrochlorofluorocarbures (HCFC), hydrofluorocarbures (HFC), ces fluides frigorigènes font palpiter l’effet de serre. Exemple avec le R-507A, très utilisé dans le secteur des patinoires. Il possède un potentiel de réchauffement global 3 300 fois plus important que le CO2. Alors, les fuites ou les évaporations qui peuvent intervenir sur les installations, « même minimes, peuvent représenter une fraction significative du total des émissions de gaz à effet de serre pour un site donné », indique l’Ademe, dans son guide des facteurs d’émissions.

« Les fuites peuvent encore se produire, mais elles deviennent rares, défend Christian Ochem, du Syndicat national des patinoires. De plus, nous avons pour objectif de ne plus avoir de patinoires qui fonctionnent avec ces fluides chlorés. » Une belle intention qui devient, de toute façon, obligatoire cette année. L’Europe a en effet décidé d’interdire l’utilisation des hydrofluorocarbures neufs à partir du 1er janvier 2010. Ils seront tous bannis à compter de 2015. Mais alors, par quoi les remplacera-t-on dans les tuyaux de nos patinoires ? « Il y a un retour significatif à l’ammoniac », indique Christian Ochem. Ce fluide fait l’objet d’une réglementation draconienne. Il est interdit d’en utiliser plus de 150 kg par patinoire. Et heureusement. Car si l’ammoniac est beaucoup moins dangereux pour le climat, il le reste pour l’homme et l’environnement.

Mount Kilimanjaro hiking

By: James Muchina

MOUNT KILIMANJARO CLIMB

Any physically fit person can climb Mt. Kilimanjaro.. No climbing experience is necessary to get you to the top of Africa's highest mountain 5,895M (19,340FT) with its magnificent gleaming glaciers, Flora and Fauna.

Weather

Mt. Kilimanjaro can be climbed any time of the year but there are two rainy seasons - late March to mid June and November. The best months are December, January to March and July to October usually dry and minimum clouds.

8 DAYS MT. KILIMANJARO- MARANGU ROUTE

Day 1: Arrival - Arusha

Travel from Nairobi to Arusha on board a Shuttle bus or pickup from Kilimanjaro Airport – transfer to a hotel for an overnight stay

Day 2: Marangu Gate (1980m) - Mandara hut (2700m)

Hiking time: 5 hours | Distance: About 12 km's | Habitat: Montane forest



The drive from Moshi to the Kilimanjaro National Park gate, takes about 50 minutes. The journey passes through the village of Marangu, which is located on the lower slopes of the mountain. Once you reach the park gate, all hikers are requested to sign in at the Park office and make their final preparations for the climb. Porters will be seen arranging and loading their packs, containing the food, water, cooking gas as well as most of your equipment. Make sure that you have all your daypack items (containing at least drinking water, your lunch pack and extra clothing) with you as the porters ascend a lot quicker than the hikers. Our guides will be available to assist with any additional information or needs you might have. You now leave the Park gate and ascend on a cleared ridge trail through the rain forest. The forest, suffused with mist and dripping with beards of moss, is also where most of Kilimanjaro's animals are found. (An alternative and more scenic parallel forest trail, branches off to the left a few minutes after the gate. This trail follows the edge of a stream through the undergrowth and offers you the option to rejoin the main trail either, after 1½ hours hiking, or 1 hour before Mandara hut.)

Your first night stop, Mandara hut, is a group of wooden A-framed huts in a forest clearing. Each hut features 6-8 sleeping bunks with solar generated lighting. The total capacity of the camp is 60 climbers. Water is piped into the camp from springs above and there are flush toilets behind the main hut.

Lightweight Hiking - an Example

By: Steve Gillman

Is lightweight hiking and backpacking viable in cold weather? I think so. Last Fall I was in four feet of snow at 13,000 feet - in my running shoes and with just 11 pounds on my back for an overnighter. Crazy? I don't think so. Anyhow, I have been going lightweight for too many years to want to go back to a heavy pack and hiking boots.

Heading For Crestone Peak

It was September 2006. I was in the Sangre De Christo Mountains in Colorado, hiking up the trail to South Colony Lakes. I just surprised a large buck, who snorted and ran off. I started to see more patches of snow as I went higher. I poked at the frozen puddles with my walking stick.

I had hoped to climb Crestone Peak and Crestone Needle earlier in the month, but was rained out. Then it snowed heavily in the high country on September 18. I started checking the online forums to see if anyone was still climbing these "fourteeners" (mountains higher than 14,000 feet). Someone did mentioned climbing Crestone through the snow - which I didn't want to do.

However, by the 28th there had been several warm days, so maybe the snow melted. It had where I parked the car. But by the time I hiked to South Colony Lakes a few hours later, I was almost knee-deep in it. Then, up above the lakes and beyond the last of the trees, the snow was even deeper.

My shoes and socks were soaked, but the sun and the climb kept me warm. I continued because it really looked like there was bare rock up near the peaks. Eventually I adjusted my goal to just getting to Broken-Hand Pass, where I could look down into the San Luis Valley. I made it to within 100 yards.

It was so steep and the snow so deep, that I slid back at least as far as I stepped each time. Then I slipped and needed to self-arrest with my walking stick to keep from sliding down a few hundred feet. It was clear that I was under-equipped for climbing any further.

Lightweight Backpacking

Hiking down was worse (it often is). I sunk into the snow and hit my shins against rocks hidden there. I walked on top of the snow crust at times, until I suddenly broke through - which I did when I stopped to look at some bobcat tracks. At least I didn't have much weight on my back.

I had 11 pounds, to be exact. The pack itself weighed a pound or so. My down sleeping bag weighed 17 ounces, and the tarp 16 ounces. I also had food and water and dry socks. Going lightweight meant I hardly even noticed the pack - even after 13 miles of hiking.

Back down near the lakes it was time to put my lightweight hiking and backpacking skills and equipment to the test. It would be about 24 degrees Fahrenheit that night.

I found a nice grassy area where the snow had melted away. The sun was still bright and warm, so I laid out my wet socks and shoes to dry on a large log while I ate mixed nuts, wrote some notes, and then took a nap. Several deer walked by an hour later. I woke up gripping my walking stick like a weapon.

Everything was dry, so I put on my shoes and got busy. It took about 20 minutes to collect dry grass and old thistle stalks to make a thick mattress. This was for comfort as well as for insulation to keep me warm. I set a piece of plastic over this, and strung the tarp overhead. Then I laid out the sleeping bag to fluff it up.

I collected some dry wood and tinder and laid a fire, just in case I needed it later (I never did). I covered this with a few pieces of bark to keep frost, snow or rain off of it. I ate some wild currants and rose hips. I saved my corn chips for a bedtime meal. The fat would heat me up as it digested. I used my walking stick to lift the bag with the rest of the food up to a high branch where it would hang for the night.

I put on my thermal underwear, hat and gloves. I used my shoes with the backpack on top of them for a pillow. The wind started blowing, so I lowered one side of the tarp before going to sleep.

The frost was heavy and the ice was thick on the puddles in the morning, but I had managed to sleep well. I packed up, scattered the mattress materials so they wouldn't smother the plants underneath, and I ate some crackers. The sun was just rising as I hit the trail.

I probably had just 9 pounds total on my back by now. That may seem very lightweight for backpacking, but I had everything I needed. I even had a camera with me. I stopped hiking long enough to take a photo of Crestone Needle in the morning sun. I'll be on top of it this summer.

About the Author

Copyright Steve Gillman. To get the ebook "Ultralight Backpacking Secrets (And Wilderness Survival Tips)" for FREE, as well as photos, gear recommendations, and a new wilderness survival section, visit: http://www.The-Ultralight-Site.com

(ArticlesBase SC #156812)

Article Source: http://www.articlesbase.com/ - Lightweight Hiking - an Example

Ice arena, skating rink design

Refrigeration System Design Considerations

The primary purpose of a recreational ice refrigeration system is to safely and efficiently provide a high quality sheet of ice under all normal operating conditions.

There are many styles of refrigeration systems and each of these systems serve a useful purpose for a particular application and none of them are equally suited for all applications. Careful consideration must be taken to ensure that you get the system that suits your facility.

At Accent Refrigeration Systems we will work through the options with you to ensure that you are making the best long term solution for your facility. The following is a basic list discussion points that will be encountered in your journey to build a new ice facility. We can provide you with in depth information and recommendations on each point during the design process.

Basic Venue Consideration

Is the facility to be an indoor ice facility or an outdoor ice facility?

Outdoor Ice Surface

If you are planning an outdoor ice facility there are a tremendous amount of sub-base design considerations that are important to ensure the long term integrity of the concrete slab. This has to be done properly or it will almost always create long term problems.

Outdoor ice rinks by their nature can have extremely volatile load profiles, ranging from no load at all during times of cold still air to extremely high loads on warm windy days. Designing a refrigeration system becomes a balancing act between providing sufficient refrigeration capacity to accommodate high load conditions and yet keeping the installation costs within a practical budget. More often than not, a larger refrigeration system will be required for an outdoor ice arena.

Will the ice surface and refrigeration system be in a permanent location or moved each season. This decision will change the style of system that would be best for you.

It is always a good idea to install a sunscreen or roof over an outdoor ice rink to minimize the impact of the sun, rain, and snow.

Indoor Ice Surface

Most ice facilities are indoor venues and will have spectator seating ranging from none at all to professional venues with seating for over 20,000 spectators. The quantity of spectators will have a significant impact on the selection of refrigeration and ventilation equipment.

First cost

How important is the first cost of the equipment to you? What are you willing to give up to lower costs? Ice quality, energy efficiency, equipment lifecycle, safety?

With any new business venture, keeping your first cost down is very important in order to get the doors open. In an arena or curling club, your ice is your life and your refrigeration system is your life-line to that ice. It really has to be done right. We will show you how to do it right and we will show you how to spend your money in a manner that it will pay dividends for years to come.

Facility usage

Is your primary purpose going to be professional hockey, figure skating or community recreational skating? Each user group will have an optimum ice condition and a specific refrigeration requirement.

Will your facility be used year round or just seasonally? If your facility is to be used for ice sports more than 7 months of the year your will require sub-floor heating to eliminate the possibility of frost heaves.

Will you require a concrete floor for multipurpose or a sand floor for ice sports only. A concrete floor requires less ongoing maintenance.

Walking Sticks and Canes Online

By: Tony Johnny

Canes and walking sticks come in a varying degree of styles, colors and materials. Made from numerous different materials such as wood, bone or metal the possibilities are unlimited. You can find twisted walking sticks or stick carved, wooden canes and ones made from metal and other materials. Walking sticks or canes are mostly used as a walking help but can be employed for other things such as hiking or climbing steep trails or even for self defense. A nature shutter-bug might also use one to steady a camera in the wild.



You will recall a grandparent using a cane and walking sticks on walks or walks. You are less prone to falls because a walking stick or hiking pole can add stability on uneven terrain.

A walking stick or cane can be also used for self defense. A special cane called a shillelagh is sometimes made of blackthorn wood and sometimes some other hard wood and has the appearance of a natural cane. If surprised by an aggressive person or animal this can also be used for self defense. In any case a good walking stick or pole can have similar results if required while hiking or walking. If you hike or walk rather a lot chances are you actually have a walking stick or pole. It isn't that usual for folk who do lots of walking or hiking to have a walking stick handy and may regularly have many in their possession so they'll have one available when required for those long walks or walks.

The best place to buy canes and walking sticks is on the internet. There are a huge quantity of online sellers that sell new canes, custom wooden canes and shillelaghs. You can frequently find the styles you are searching for on the web. Canes and walking sticks are frequently used for over just support they can join a costume or an actors outfit.

About the Author

Check out the following links to find our more about wooden canes or wooden walking sticks.

(ArticlesBase SC #1548642)

Article Source: http://www.articlesbase.com/ - Walking Sticks and Canes Online

Top Ten Views on a Trek to Everest

By: Jude Limburn Turner

Mount Everest, the highest mountain in the world, is also one of the most amazing areas of natural power and beauty on earth. As you travel up the mountain towards the Everest base camp, the sights become more poignant and awe inspiring. We count down the top ten.

10. Kathmandu

While not strictly on the route, Kathmandu is the city from which you base your Everest Trek Kathmandu urbar square is a work of ancient architectural genius, the people of the Kathmandu valley are warm and welcoming, and a brief immersion into the Nepalese way of life is as irresistible as the views from the city's highest buildings.

9. Lukla

The start of your Everest Trek proper, this small town and airport are the jump-off point for everyone trekking toward Everest and Everest Base Camp. Stepping off the plane, you look up, then up, then up, realising for the first time the scale and majesty of the mountain range you are about to take on.

8. Local wildlife and animals

Turning a corner and finding a Sherpa with his herd of yaks coming the other way is an 'interesting' experience - be sure to stand uphill as these large be-ribboned animals are somewhat unpredictable and have been know to knock Everest trekkers off the path! These lumbering beasts of burden are milk, meat, transport, heat and a myriad of other uses to the people of the Everest region. You may also come across the brilliant blue Impeyen Pheasant,
Himalayan Thar or if you are very lucky a Himalayan Red Panda.

7. The Hillary Bridge

This sturdy but rustic-looking suspension bridge was erected by Edmund Hillary's (the first man to trek and climb Everest) charity. It provides a link for everyone walking up from Lukla towards Everest Base Camp.

6. Namche Bazaar

One of the villages on the journey into the high Himalayas, Namche Bazaar is stepped across the slopes in Solukhumbu District. It seems incredible to see this expanded market clinging on the sides of the mountain, and the village has a practical use too. Used to help acclimatise walkers to the altitude, it is also important in gathering supplies for your trek to Everest base camp.

5. The peak of Amadablam.

Climb just above Namche Bazaar and you see The first real unspoiled view of the Himalayan mountain peaks on your trek to Everest. It's also at this point that the scenery becomes almost otherworldly - serene, powerful and unlike anything you have ever experienced before.

4. - Dingboche and the valley towards Chukhing.

Everest treks will usually lay over for two nights in Dingboche for acclimati sation. The view down the valley to Chukhing is not to be missed, and highlights your achievement so far. Almost two thirds of your way through the trek, and with Everest almost in sight, experiencing this sight is an accomplishment in and of itself.

3. Looking up the valley towards Pumori and Nuptse.

Similarly, the twin peaks of Pumori and Nuptse are a sight you won't forget as long as you live. "Everest's Daughter" and "West Peak" (as they are respectively known) are the gateway to Everest itself, a prelude to the final destination on your trip.

2. Views of Everest and the Khumbu glacier from Kala Pattar

If you have the time and the energy it is well worth ascending Kala Pattar, an eight-hour trek from Lobuche. Whilst Everest Base Camp may be the ultimate objective of your trek, the views are undoubtedly better from the rocky summit of Kala Pattar (5,545m) where you look across to Everest, and a host of other peaks, and down onto the vast, impressive Kuhumbu glacier where Base Camp is located in season.

1. Everest and Everest base camp

The finale to your Everest Base Camp trek. The terrifying Khumbu ice-fall obstructs views of the summit of Everest from Base Camp but the mighty mountain still makes its presence felt. In climbing season Everest Base Camp will be alive with adrenalin of mountaineering expeditions, but out of season there is little to be seen bar ice, rock and snow.
About the Author
Jude Limburn Turner is the Marketing Manager for Mountain Kingdoms, an adventure tour company who have run Everest treks for over 20 years. They now offer treks and tours worldwide, including destinations in North and South America, Europe, Africa, and Central and South East Asia.
(ArticlesBase SC #672090)
Article Source: http://www.articlesbase.com/ - Top Ten Views on a Trek to Everest

GREENHOUSE EFFECT AND ITS IMPLICATIONS

By: Tobi Nagy

What are the results of the Greenhouse Effect?

By using very sophisticated computer modeling, scientists have been able to predict what the world’s climate will be like when carbon dioxide levels have doubled.

1. Increase in world’s temperature It is thought that there will be an increase in the average global temperature by between 1.5 and 4.5 deg C . • By year 2030 an increase of 2 deg C, by 2100 an increase of 6 deg C. The warming will be greater at higher latitudes and in winter. This will lead to the melting of polar ice caps and glaciers which is already evident, in places like Greenland, the Arctic and Antarctic.


2. Changes in World’s climate The Greenhouse Effect will lead to world-wide changes in weather and climate. Some places may get more rain and storms while other places may get less. Not all changes will be bad. However, almost everywhere in the world will have changes in weather, which will have a big impact on our lives


3. Rising Sea Level It is estimated that by the year 2030, the average sea level will increase by approximately 20 centimetres. This will be due mainly to the melting of the polar ice cap, but also warming of the atmosphere will heat the upper layers of the oceans, which will expand when heated. For low lying countries in the Pacific like Tuvalu and Kiribati, and in the Indian Ocean like Maldives and other countries like Holland may altogether disappear.


4. Other impacts Other impacts could be the dieing out of some species of animals and plants, such as coastal marine environments and coral reefs. Some plants would not be able to survive temperature increases. It takes thousands of years for forests to move north or south to cooler climates. According to Joel B. Smith, co-author of an EPA report states that “such a warming over a century would require forests to move five times faster than the fastest rate recorded by paleontologists since the end of the last ice age”.

What are the primary Greenhouse gases?

They are a number of organic compounds which have more than two bonds (i.e 3 atoms). The seven major Greenhouse gases are:

1. Carbon Dioxide (CO2)


2. Ozone (O3)


3. Methane (CH4)


4. CFC’s (Freons F11 & F12)


5. Water vapour (H2O)


6. Nitrous Oxides (NOx)


7. Ethane (CH3CH3)

The EPA Drafts Legislation To Track and Report Carbon (CO2) Emissions

By: Daniel Stouffer

Mandatory carbon (CO2) emissions reporting is more important than ever as the United States works with facilities to reduce substances known to adversely affect air quality, the climate, and lead to global warming. Most of the known matter that is destroying the earth's ozone layer and contributing to global warming is derived from manmade compounds and chemicals with high global warming potential (GWP) and commonly known as greenhouse gases (GHGs).

Around the country a comprehensive initiative, which includes mandatory carbon emissions reporting has been introduced by the Environmental Protection Agency (EPA) with the intention of controlling carbon dioxide (CO2) and greenhouse gases (GHGs) that have an effect on global climate change. Unfortunately, some substances like refrigerant gases not only have high global warming potential but they also destroy the ozone layer when emitted into the atmosphere.

The U.S. The Environmental Protection Agency (EPA), working in cooperation with many international governments, reiterate a common message related to the dangers of carbon emissions. CO2 and its unrestricted use will only lead to more environmental damage therefor more regulations will continue to limit carbon emissions in the future. A measuring, managing, and mitigating greenhouse gas emission places the foundation for future carbon emissions trading schemes within the United States. The European Union has worked on carbon emissions reductions as part of The Kyoto Protocol for a number of years. At a meeting planned in late 2009, global leaders in the fight against climate change will rework and redefine the next set of rules to follow The Kyoto Protocol. The U.S. under leadership form President Obama plan to be active participants.

As part of the draft greenhouse gas (GHG) regulations, any organization that uses refrigerant gases or other regulated substances would be required to comply with mandatory carbon emissions reporting. In addition to refrigerant gases, the following 6 chemical compounds all factor into a comprehensive carbon accounting. The Kyoto Protocol establishes legally binding commitments for the reduction of four greenhouse gases; carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), sulphur hexafluoride (SF6), and two groups of refrigerant gases; CFCs and PFCs.)

Refrigerant gases are known to affect the atmosphere and contribute to global warming. Numerous gases are listed in the EPA regulations including nitrous oxide, methane, carbon dioxide, hydrofluorocarbons, perfluorocarbons, nitrogen trifluoride, and ethers. Refrigerant gases, such as hydrofluorocarbons (CFCs), must be managed, tracked, and reported under the existing Montreal Protocol. There is some cross-over between the different regulations that restrict harmful emissions. The good news is any CO2 related tracking will further enhance emissions management practices already in place across an organization.

The EPA's mandatory carbon emissions reporting plan comes into effect in 2010. Companies must file a first report in 2011 covering the previous year. These requirements cover those facilities with HVAC systems, refrigeration and AC systems, companies that make industrial chemicals, as well as fossil fuels, engines and automobiles. Many industrial chemicals harm the environment by destroying the ozone layer or enhance global warming. The following chemicals, such as refrigerant gases, lead to harmful effects on the environment: chlorofluorocarbons, hydrofluorocarbons, halons, methyl chloroform, chlorine, fluorine, bromine and carbon tetrachloride amongst others.

The U.S. Clean Air Act, in addition to the mandatory emissions reporting by amounts, calls for the facilities and municipalities alike to monitor and track and subsequently report harmful substances, such as refrigerant gases that are in common use. Organizations that either cannot comply or choose to not follow the environmental regulations will be fined by the EPA. On top of regulatory fines, companies may experience a financial loss when they are required to buy carbon credits to meet the cap requirements.

Organizations can comply with CO2 emissions management regulations and reporting in a couple of ways. Monitoring and tracking can be handled manually and the reports completed by hand. However this approach can be very time-consuming and error-prone, and many will opt to use a software program or a web-based application to automatically handle the monitoring and tracking requirements of greenhouse gases (GHGs). Automation helps to ensure that reports are accurate and timely. Service automation or CMMS systems can lead the way to effective company operations. It is more efficient to maintain assets at optimal working conditions and collect relevant carbon related emissions data across distributed enterprises or systems.

Mandatory carbon emissions reporting will definitely lower this country's greenhouse gas emissions. The government has said that 13,000 facilities are responsible for between 85 and 90% of the harmful substances in the air.

The United States, through the implementation of a mandatory carbon emissions reporting program, ensure that businesses will reduce their carbon footprint and will help to mitigate adverse climate changes in the years ahead. This initiative is being repeated at various locations worldwide with the aim of addressing climate change head on - in as straightforward of a manner with immediate financial incentives to drive rapid and economy wide adoption of carbon reduction and market-based trading.

About the Author

To learn more effective refrigerant management tactics and the tools that support them, you can contact Daniel Stouffer, the Product Manager for Refrigerant Tracker. This web-based software makes it easy to monitor, manage, and report refrigerant gas usage. Stay in compliance with refrigerant management regulations. Visit Verisae's http://www.Refrigerant-Tracker.com

(ArticlesBase SC #836612)

Article Source: http://www.articlesbase.com/ - The EPA Drafts Legislation To Track and Report Carbon (CO2) Emissions

La réfrigération dans les supermarchés, sources importantes de GES

L’exploitation des supermarchés engendre des

émissions importantes de gaz à effet de serre (GES).

Les deux sources importantes d’émissions de GES

sont : les fuites de réfrigérants de synthèse et la

consommation d’énergie. Au Canada, la plupart des

systèmes de réfrigération des supermarchés sont

des systèmes à détente directe (DX) qui utilisent

des quantités importantes de réfrigérant de synthèse

(environ 1000 à 1500 kg de HCFC ou HFC par

magasin). Le réfrigérant circule sous pression, de la

salle mécanique aux comptoirs réfrigérés, et ce, dans

des kilomètres de conduits comprenant des centaines

de joints. Ces systèmes sont à l’origine d’importantes

fuites de réfrigérant (entre 10 et 30% de la charge par

an) qui sont de puissants gaz à effet de serre (GES).

Les systèmes de réfrigération au CO 2

comme alternative

Les systèmes de réfrigération au CO2 sont une

alternative très performante sur le plan environnemental

par rapport aux systèmes de réfrigération que l’on

retrouve habituellement dans les supermarchés au

Canada :

• Le CO2 est un produit naturel et non toxique

et peu coûteux. Son effet sur le climat est de

1500 à 4000 fois moins important que celui des

réfrigérants de synthèse habituellement utilisés.

• Le CO2 permet la conception de systèmes plus

compacts.

La réfrigération basse température constitue une

application particulièrement intéressante pour le CO2

qui peut être utilisé autant comme fluide secondaire

pour distribuer le froid que comme réfrigérant primaire.

L’application comme réfrigérant primaire est moins

répandue, car elle posait plus de défis technologiques

et économiques. Depuis 10 ans, cependant, les

appareils conçus spécialement pour utiliser le CO2

comme réfrigérant primaire deviennent beaucoup plus

compétitifs au niveau des coûts et il existe aujourd’hui

des fournisseurs canadiens d’équipements et de

pièces mécaniques.

Bien que de plus en plus répandue en Europe,

l’utilisation du CO2 dans les systèmes de réfrigération

au Canada est encore une pratique peu connue et

très peu utilisée. On compte depuis 2008, quelques

installations utilisant le CO2 comme fluide secondaire,

mais Sobeys Quebec inc. fait figure de pionnier pour

l’utilisation du CO2 comme réfrigérant primaire.

Description du supermarché

IGA est une chaîne d’épiciers que l’on retrouve

principalement au Québec et qui appartient à Sobeys,

le deuxième plus important marchand d’alimentation

au Canada. Le supermarché IGA à St-Félix de Valois

qui a ouvert ses portes en mai 2009, occupe une

superficie totale de 3000 m2. La surface de vente de

2500 m2 offre 190 m de comptoirs réfrigérés et 88 m

de comptoirs pour les surgelés.

Description du système de réfrigération

Le système de réfrigération installé au IGA de St-

Félix de Valois est un système en cascade HFC/CO2

à trois niveaux de compression et de température :

Basse Température (BT), Moyenne température (MT)

et Haute Température (HT).

• Le niveau BT utilise le CO2 comme réfrigérant qui

circule de la salle mécanique aux congélateurs

et comptoirs de surgelés à une température de

-30 °C.

• Le niveau MT utilise un réfrigérant de la famille

des HFC, le R507A, pour refroidir une boucle de

fluide secondaire (solution de propylène glycol) qui

alimente les réfrigérateurs et comptoirs de produits

réfrigérés à -7 °C, et qui refroidit le condenseur du

niveau BT.

• Le niveau HT utilise un réfrigérant de la famille

des HFC, le R407C pour refroidir le condenseur

du niveau MT par l’intermédiaire d’une boucle de

propylène glycol.

Le système en cascade répond à des charges de

réfrigération de 80 kW pour les surgelés et 293 kW

pour les produits réfrigérés. La charge totale de

réfrigérants de synthèse de 125 kg est confinée à la

salle mécanique. Elle représente 10 % de la charge

utilisée dans les systèmes conventionnels à détente

directe (DX) que l’on retrouve dans la plus part des

supermarchés.

Le dégivrage des comptoirs MT est assuré par la

recirculation du propylène glycol pour une partie des

comptoirs, sans apport d’énergie supplémentaire. La

durée du cycle de dégivrage MT est limitée par une

température de consigne du propylène glycol.

Le dégivrage des comptoirs BT est assuré par les gaz

de refoulement des compresseurs au CO2. Pour la

durée du dégivrage, la température de condensation

du système BT est élevée légèrement au-dessus de

0 °C alors qu’elle est de -7 °C normalement.

Ces deux méthodes de dégivrage sont très innovatrices,

plus particulièrement le dégivrage au CO2 des comptoirs

basse température.

Récupération et valorisation

de la chaleur

Le niveau HT du système de réfrigération produit l’effet

pompe à chaleur en valorisant la chaleur rejetée par

l’ensemble du système pour combler entièrement ou

en partie les besoins de chauffage du bâtiment. Au

total, c’est l’équivalent de 419 kW de chaleur qui est

récupéré et distribué aux applications suivantes :

• récupérateur de chaleur de l’unité de ventilation

de toit de 175 kW

• deux unités de chauffage totalisant 110 kW qui

desservent l’entrepôt et le quai de réception

• deux unités de chauffage totalisant 134 kW qui

desservent l’entrée et la section des caisses.

Un refroidisseur de fluide rejette à l’extérieur du

supermarché le surplus de chaleur du système de

réfrigération.

La réfrigération dans les supermarchés, sources importantes de GES

L’exploitation des supermarchés engendre des

émissions importantes de gaz à effet de serre (GES).

Les deux sources importantes d’émissions de GES

sont : les fuites de réfrigérants de synthèse et la

consommation d’énergie. Au Canada, la plupart des

systèmes de réfrigération des supermarchés sont

des systèmes à détente directe (DX) qui utilisent

des quantités importantes de réfrigérant de synthèse

(environ 1000 à 1500 kg de HCFC ou HFC par

magasin). Le réfrigérant circule sous pression, de la

salle mécanique aux comptoirs réfrigérés, et ce, dans

des kilomètres de conduits comprenant des centaines

de joints. Ces systèmes sont à l’origine d’importantes

fuites de réfrigérant (entre 10 et 30% de la charge par

an) qui sont de puissants gaz à effet de serre (GES).

Les systèmes de réfrigération au CO 2

comme alternative

Les systèmes de réfrigération au CO2 sont une

alternative très performante sur le plan environnemental

par rapport aux systèmes de réfrigération que l’on

retrouve habituellement dans les supermarchés au

Canada :

• Le CO2 est un produit naturel et non toxique

et peu coûteux. Son effet sur le climat est de

1500 à 4000 fois moins important que celui des

réfrigérants de synthèse habituellement utilisés.

• Le CO2 permet la conception de systèmes plus

compacts.

La réfrigération basse température constitue une

application particulièrement intéressante pour le CO2

qui peut être utilisé autant comme fluide secondaire

pour distribuer le froid que comme réfrigérant primaire.

L’application comme réfrigérant primaire est moins

répandue, car elle posait plus de défis technologiques

et économiques. Depuis 10 ans, cependant, les

appareils conçus spécialement pour utiliser le CO2

comme réfrigérant primaire deviennent beaucoup plus

compétitifs au niveau des coûts et il existe aujourd’hui

des fournisseurs canadiens d’équipements et de

pièces mécaniques.

Bien que de plus en plus répandue en Europe,

l’utilisation du CO2 dans les systèmes de réfrigération

au Canada est encore une pratique peu connue et

très peu utilisée. On compte depuis 2008, quelques

installations utilisant le CO2 comme fluide secondaire,

mais Sobeys Quebec inc. fait figure de pionnier pour

l’utilisation du CO2 comme réfrigérant primaire.

Description du supermarché

IGA est une chaîne d’épiciers que l’on retrouve

principalement au Québec et qui appartient à Sobeys,

le deuxième plus important marchand d’alimentation

au Canada. Le supermarché IGA à St-Félix de Valois

qui a ouvert ses portes en mai 2009, occupe une

superficie totale de 3000 m2. La surface de vente de

2500 m2 offre 190 m de comptoirs réfrigérés et 88 m

de comptoirs pour les surgelés.

Description du système de réfrigération

Le système de réfrigération installé au IGA de St-

Félix de Valois est un système en cascade HFC/CO2

à trois niveaux de compression et de température :

Basse Température (BT), Moyenne température (MT)

et Haute Température (HT).

• Le niveau BT utilise le CO2 comme réfrigérant qui

circule de la salle mécanique aux congélateurs

et comptoirs de surgelés à une température de

-30 °C.

• Le niveau MT utilise un réfrigérant de la famille

des HFC, le R507A, pour refroidir une boucle de

fluide secondaire (solution de propylène glycol) qui

alimente les réfrigérateurs et comptoirs de produits

réfrigérés à -7 °C, et qui refroidit le condenseur du

niveau BT.

• Le niveau HT utilise un réfrigérant de la famille

des HFC, le R407C pour refroidir le condenseur

du niveau MT par l’intermédiaire d’une boucle de

propylène glycol.

Le système en cascade répond à des charges de

réfrigération de 80 kW pour les surgelés et 293 kW

pour les produits réfrigérés. La charge totale de

réfrigérants de synthèse de 125 kg est confinée à la

salle mécanique. Elle représente 10 % de la charge

utilisée dans les systèmes conventionnels à détente

directe (DX) que l’on retrouve dans la plus part des

supermarchés.

Le dégivrage des comptoirs MT est assuré par la

recirculation du propylène glycol pour une partie des

comptoirs, sans apport d’énergie supplémentaire. La

durée du cycle de dégivrage MT est limitée par une

température de consigne du propylène glycol.

Le dégivrage des comptoirs BT est assuré par les gaz

de refoulement des compresseurs au CO2. Pour la

durée du dégivrage, la température de condensation

du système BT est élevée légèrement au-dessus de

0 °C alors qu’elle est de -7 °C normalement.

Ces deux méthodes de dégivrage sont très innovatrices,

plus particulièrement le dégivrage au CO2 des comptoirs

basse température.

Récupération et valorisation

de la chaleur

Le niveau HT du système de réfrigération produit l’effet

pompe à chaleur en valorisant la chaleur rejetée par

l’ensemble du système pour combler entièrement ou

en partie les besoins de chauffage du bâtiment. Au

total, c’est l’équivalent de 419 kW de chaleur qui est

récupéré et distribué aux applications suivantes :

• récupérateur de chaleur de l’unité de ventilation

de toit de 175 kW

• deux unités de chauffage totalisant 110 kW qui

desservent l’entrepôt et le quai de réception

• deux unités de chauffage totalisant 134 kW qui

desservent l’entrée et la section des caisses.

Un refroidisseur de fluide rejette à l’extérieur du

supermarché le surplus de chaleur du système de

réfrigération.

California Global Warming Solutions Act (ab 32): an Introduction to Refrigerant Gas Management

By: Daniel Stouffer

How to stay ahead and address the early action requirements for Stationary Equipment Refrigerant Management to be included in updates to AB 32.

The California Global Warming Solutions Act (AB 32), first passed in 2006 with additional early actions taking effect in 2010, is a broad and comprehensive directive with the goal of reducing greenhouse gasses (GHGs) by approximately 25% by the year 2020. This objective of the early action stems from increases in carbon equivalent emissions in California since 1990. The intent of the legislation to reduce greenhouse gasses to their 1990 levels, thereby reversing 16 years of pollution in less than 14 years.

As part of the California Global Warming Solutions Act (AB 32) the Air Resources Board (ARB) has approved an early action measure to reduce high-global warming potential (GWP) greenhouse gas (GHGs) emissions by establishing new legislation and defining requirements related to improved monitoring of AC/HVAC systems, enforcement of regulations, reporting of refrigerant usage, and recovery, recycling, or destruction of high-GWP refrigerant gases.

The greenhouse gasses (GHGs) as defined by the California's AB 32 are identical to those gasses identified in the Kyoto Protocol. These gases are already being regulated, monitored, and managed by many other countries around the World. In addition to carbon dioxide (CO2), which is the most widely known GHG, the following gasses are also defined as GHGs with high global warming potential (GWP) carbon equivalent emissions by the AB 32 legislation:

* Methane (CH4): a byproduct of waste decomposition, and natural geological phenomena; the majority of methane is derived from natural gas drilling.

* Nitrous Oxide (N2O): a pollutant created by industrial processes, motor vehicle exhaust, and industrial air pollutants reacting with the atmosphere; like methane, nitrous oxide can also be a product of waste decomposition in nature and agriculture.

* Sulfur Hexafluoride (SF6): a gas used for various electrical applications, including gas insulated switchgear. Sulfur Hexafluoride is also used for experimental applications.

* Perfluorocarbons (PFCs) and Hydrochlorofluorocarbons (HCFCs): a collection of commonly used refrigerant and aerosol gasses with a wide variety of other commercial applications. CFCs and HCFCs are considered Ozone Depleting Substances (ODSs), as defined in title VI of the US Clean Air Act (Section 608).

The California EPA's Air Resources Board (CARB) has developed a complex and highly detailed system of greenhouse gas management for refrigerant gasses, known as the Stationary Equipment Refrigerant Management Program, and stricter standards for new or existing refrigeration systems installation and ongoing maintenance. According to CARB this strategy includes careful monitoring of potential refrigerant gas leaks, improved record keeping and certification of personnel as well as specifications for PFC and HCFC recovery equipment.

The proposed Stationary Equipment Refrigerant Management Program, which integrates two AB 32 early action measures, addresses the detailed monitoring and management of the PFCs and HCFCs noted above and includes tracking requirements for new and existing commercial and industrial refrigeration systems. Likely to be implemented by January, 2010, is the monitoring and management of high global warming potential (GWP) refrigerants in large systems in the range of 2,000 pounds of refrigerant gas.

CARB is charged with the monitoring GHGs and high GWP gasses, as well and the eventual development and enforcement of specific and quantitative new regulations covering Refrigeration Video which refrigerant management with the tracking, reporting, cylinder management, and gas recovery for stationary refrigerant and air conditioning (AC) systems all becoming key integral parts.

The CARB proposal could also involve fines for mismanagement of refrigerant record keeping, intentional venting of systems, and the inability to regularly submit the required refrigerant usage reports. The California Air Resources Board (CARB) is an extension of the EPA and works to monitor and enforce the US Clean Air Act. Section 608 of the Air Act regulates refrigerant gas usage, leaks, recovery, and annual reporting.

The overall intent of CARB's strategy is to monitor and reduce the introduction of man-made GHGs and high GWP gasses into the atmosphere, as called for in the California Global Warming Solutions ACT (AB 32) in effect since 2006 with tighter controls, monitoring, and overall regulations becoming enforceable by early 2010.

Refrigerant gas monitoring, tracking, and management are important business planning considerations. Just like organizations manage assets, like a delivery truck, the consequences the release of high GWP gases, such as refrigerant gases, must be consider. Refrigerants cost money, harm the ozone and environment, and are subject to mandatory carbon emissions reporting. As organizations with AC/HVAC systems containing refrigerant gas of 50 pounds or more will soon find out, the effective monitoring, management of data, and systematic reporting of refrigerant usage will be key to business success in our emerging carbon economy.



About the Author

To learn more effective refrigerant management tactics and the tools that support them, you can contact Daniel Stouffer, the Product Manager for Refrigerant Tracker. This web-based software makes it easy to monitor, manage, and report refrigerant gas usage. Stay in compliance with refrigerant management regulations. Visit Verisae's http://www.Refrigerant-Tracker.com

(ArticlesBase SC #734799)

Article Source: http://www.articlesbase.com/ - California Global Warming Solutions Act (ab 32): an Introduction to Refrigerant Gas Management

Les conditions au sommet de l’Everest

Plus on monte en altitude, plus la température sur l'Everest est extrême. Malgré l’utilisation d’équipements modernes, l’homme doit puiser au plus profond de ses ressources physiques et mentales. La température au sommet de l’Everest descend parfois sous les moins 50 degrés Celsius. Le vent représente cependant le plus grand danger. À 110 kilomètres/heure et plus, le vent augmente l’impression de froid et réduit la visibilité en soulevant la neige, rendant l’escalade très périlleuse.

Pour franchir avec succès la dernière étape de l’escalade de l’Everest, Mario Dutil souligne que les grimpeurs doivent pouvoir compter sur au moins 4 à 5 jours de temps clair avant d’atteindre le sommet.

Une des questions les plus fréquemment posées lors des conférences de Mario Dutil touche le niveau d’oxygène en montagne. Le public est toujours surpris d’apprendre que, contrairement à ce que l’on croit généralement, le pourcentage d'oxygène dans l'air est à peu près équivalent à celui du niveau de la mer, soit 23%.

Alors, pourquoi, lui demande-t-on, les grimpeurs peinent-ils à respirer, s’épuisent-ils aussi rapidement et ont-ils besoin de masque à oxygène? Mario Dutil explique que plus on s'éloigne du niveau de la mer, plus la pression atmosphérique diminue, moins il y a d'air à respirer et, donc, moins d'oxygène. En plus du manque d’air, il faut composer avec une diminution des quantités d’azote, d'argon et d’autres gaz que l’on retrouve dans l'air.

Bien que les proportions de gaz dans l'air changent peu, une bouffée d'air enverra moins d'oxygène dans le système sanguin. C’est ce qui explique que le grimpeur soit à bout de souffle.

Au sommet de l'Everest, le montant d’oxygène représente le tiers de celui du niveau de la mer. Imaginez un coureur qui ne prendrait une bouffée d’air qu’au bout de 3 foulées plutôt qu’à chaque foulée.

Si on prive une cellule nerveuse d'oxygène pendant 3 minutes, elle meurt ! Mais cette baisse de pression a d'autres conséquences : elle joue sur le cœur, le foie, les reins, la respiration.

En haute altitude, de nombreux changements physiologiques surviennent. Ces changements, précise Mario Dutil, sont causés par le manque d’oxygène. À 1,500 mètres, on doit déjà s’ajuster et modifier sa respiration. La fréquence et la profondeur du mouvement respiratoire augmentent. La fréquence cardiaque s’accélère et la tension artérielle est plus élevée.



Au niveau de la mer, le taux d’oxygène saturé dans le sang est de 98%. Il diminue à 89% à 3,000 mètres. Au sommet de l’Everest, il a chuté à 40%. À moins de s’acclimater efficacement, explique Mario Dutil, les grimpeurs s’exposent au mal des montagnes et mettent leur vie en danger. Les risques d’œdème cérébral et pulmonaire sont bien réels.

Pour éviter le mal des montagnes, il faut y aller par étapes, escalader graduellement, résister à l’envie d’aller trop haut, trop vite. Dès que les symptômes du mal des montagnes apparaissent, Mario Dutil conseille aux grimpeurs de ralentir et de laisser le temps à leur corps de s’acclimater. Ils peuvent même devoir redescendre plus bas afin de permettre au corps de produire suffisamment de globules rouges.

Il va sans dire que les bombonnes d'oxygène facilitent l’acclimatation, surtout si on se retrouve à une altitude de 8,000 mètres.

Par Jean-Philippe Perreti Ultimatum Media

Le Nouvel Hôtel accueille les fans de la F1!

Le retour de la Formule 1 à Montréal est la concrétisation de nos efforts soutenus et de notre détermination. Il s’agit d’une entente gagnant-gagnant qui respecte nos conditions ainsi que la capacité de payer des contribuables et qui amènera une stabilité pour les cinq prochaines années. Je suis très heureux que notre métropole récupère cette étape incontournable de la Formule 1 pour les amateurs de partout dans le monde et qui représente une opportunité exceptionnelle pour son rayonnement international», a déclaré pour sa part le maire de Montréal, Gérald Tremblay.
Compte tenu des retombées fort appréciables qu’il génère pour les membres de notre association, Tourisme Montréal est heureux de contribuer au retour du plus important événement touristique du Canada. De plus, la télédiffusion du Grand Prix à l’échelle mondiale représente une vitrine exceptionnelle pour la destination et contribue à la promotion touristique de Montréal », a conclu Charles Lapointe, président-directeur général de Tourisme Montréal.

Groupe Hôtelier Tidan

Pour un séjour longue durée, pourquoi ne pas choisir le confort d'un de nos condos ? Chaque studio comprend un très grand lit et une cuisinette toute équipée ; certaines unités sont même dotées d'une machine à laver et d'un sèche-linge. Profitez de nos tarifs spéciaux pour les séjours de 30 jours et plus !

Carbon Dioxide Could Replace Global-Warming Refrigerant

ScienceDaily (July 4, 2000) — WEST LAFAYETTE, Ind. – Researchers are making progress in perfecting automotive and portable air-conditioning systems that use environmentally friendly carbon dioxide as a refrigerant instead of conventional, synthetic global-warming and ozone-depleting chemicals.

It was the refrigerant of choice during the early 20th century but was later replaced with manmade chemicals. Now carbon dioxide may be on the verge of a comeback, thanks to technological advances that include the manufacture of extremely thin yet strong aluminum tubing.

Engineers will discuss their most recent findings from July 25 to 28, during the Gustav Lorentzen Conference on Natural Working Fluids, one of three international air-conditioning and refrigeration conferences to be held concurrently at Purdue University. Unlike the two other conferences, the biannual Gustav Lorentzen Conference, which is being held for the first time in the United States, focuses on natural refrigerants that are thought to be less harmful to the environment than synthetic chemical compounds.

"The Gustav Lorentzen Conference focuses on substances like carbon dioxide, ammonia, hydrocarbons, air and water, which are all naturally occurring in the biosphere," says James Braun, an associate professor of mechanical engineering at Purdue who heads the organizing committee for all three conferences. "Most of the existing refrigerants are manmade."

Purdue engineers will present several papers detailing new findings about carbon dioxide as a refrigerant, including:

• Creation of the first computer model that accurately simulates the performance of carbon-dioxide-based air conditioners. The model could be used by engineers to design air conditioners that use carbon dioxide as a refrigerant. A paper about the model will be presented on July 26 during a special session sponsored by the U.S. Army in which researchers from several universities will present new findings.

• The design of a portable carbon-dioxide-based air conditioner that works as well as conventional military "environmental control units." Thousands of the units, which now use environmentally harmful refrigerants, are currently in operation. The carbon dioxide unit was designed using the new computer model. A prototype has been built by Purdue engineers and is being tested.

• The development of a mathematical "correlation," a tool that will enable engineers to design heat exchangers – the radiator-like devices that release heat to the environment after it has been absorbed during cooling – for future carbon dioxide-based systems. The mathematical correlation developed at Purdue, which will be published in a popular engineering handbook, enables engineers to determine how large a heat exchanger needs to be to provide cooling for a given area.

• The development of a new method enabling engineers to predict the effects of lubricating oils on the changing pressure inside carbon dioxide-based air conditioners. Understanding the drop in pressure caused by the oil, which mixes with the refrigerant and lubricates the compressor, is vital to predicting how well an air conditioner will perform.

Although carbon dioxide is a global-warming gas, conventional refrigerants called hydrofluorocarbons cause about 1,400 times more global warming than the same quantity of carbon dioxide. Meanwhile, the tiny quantities of carbon dioxide that would be released from air conditioners would be insignificant, compared to the huge amounts produced from burning fossil fuels for energy and transportation, says Eckhard Groll, an associate professor of mechanical engineering at Purdue.

Carbon dioxide is promising for systems that must be small and light-weight, such as automotive or portable air conditioners. Various factors, including the high operating pressure required for carbon-dioxide systems, enable the refrigerant to flow through small-diameter tubing, which allows engineers to design more compact air conditioners.

More stringent environmental regulations now require that refrigerants removed during the maintenance and repair of air conditioners be captured with special equipment, instead of being released into the atmosphere as they have been in the past. The new "recovery" equipment is expensive and will require more training to operate, important considerations for the U.S. Army and Air Force, which together use about 40,000 portable field air conditioners. The units, which could be likened to large residential window-unit air conditioners, are hauled into the field for a variety of purposes, such as cooling troops and electronic equipment.

Freon

"Freon" is a trade name for a family of haloalkane refrigerants manufactured by DuPont and other companies. These refrigerants were commonly used due to their superior stability and safety properties: they were not flammable nor obviously toxic as were the fluids they replaced, such as sulfur dioxide. Unfortunately, these chlorine-bearing refrigerants reach the upper atmosphere when they escape. In the stratosphere, CFCs break up due to UV-radiation, releasing their chlorine atoms. These chlorine atoms act as catalysts in the breakdown of ozone, which does severe damage to the ozone layer that shields the Earth's surface from the Sun's strong UV radiation. The chlorine will remain active as a catalyst until and unless it binds with another particle, forming a stable molecule. CFC refrigerants in common but receding usage include R-11 and R-12. Newer refrigerants that have reduced ozone depletion effect include HCFCs (R-22, used in most homes today) and HFCs (R-134a, used in most cars) have replaced most CFC use. HCFCs in turn are being phased out under the Montreal Protocol and replaced by hydrofluorocarbons (HFCs), such as R-410A, which lack chlorine. However, CFCs, HCFCs, and HFCs all have large global warming potential.

Newer refrigerants are currently the subject of research, such as supercritical carbon dioxide, known as R-744.[4] These have similar efficiencies compared to existing CFC and HFC based compounds, and have many orders of magnitude lower global warming potential.

The thermodynamics of the vapor compression cycle can be analyzed on a temperature versus entropy diagram as depicted in Figure 2. At point 1 in the diagram, the circulating refrigerant enters the compressor as a saturated vapor. From point 1 to point 2, the vapor is isentropically compressed (i.e., compressed at constant entropy) and exits the compressor as a superheated vapor.

From point 2 to point 3, the superheated vapor travels through part of the condenser which removes the superheat by cooling the vapor. Between point 3 and point 4, the vapor travels through the remainder of the condenser and is condensed into a saturated liquid. The condensation process occurs at essentially constant pressure.

Between points 4 and 5, the saturated liquid refrigerant passes through the expansion valve and undergoes an abrupt decrease of pressure. That process results in the adiabatic flash evaporation and auto-refrigeration of a portion of the liquid (typically, less than half of the liquid flashes). The adiabatic flash evaporation process is isenthalpic (i.e., occurs at constant enthalpy).

Between points 5 and 1, the cold and partially vaporized refrigerant travels through the coil or tubes in the evaporator where it is totally vaporized by the warm air (from the space being refrigerated) that a fan circulates across the coil or tubes in the evaporator. The evaporator operates at essentially constant pressure. The resulting saturated refrigerant vapor returns to the compressor inlet at point 1 to complete the thermodynamic cycle.

It should be noted that the above discussion is based on the ideal vapor-compression refrigeration cycle which does not take into account real world items like frictional pressure drop in the system, slight internal irreversibility during the compression of the refrigerant vapor, or non-ideal gas behavior (if any).

Low Temperature Freezing

The low-temperature freezing (for frozen food) and the medium-temperature cold (for chilled food) secondary loops use theoretically noncorrosive and nontoxic brines with high heat capacities and low viscosities at low temperatures. They eliminate the use of refrigerants on both cold and freezing sides of the system and are separately pumped to the display cases and cold storage rooms. The display case heat exchangers were designed to use secondary fluids and, consequently, the temperature differences between the brines and the air were minimized.

As secondary fluid on the low-temperature freezing loop, an inhibited potassium formate solution with a concentration of 100%--a nontoxic product compatible with the majority of most common metals and alloys--was chosen. Some analytical studies indicate thermal and pressure drop advantages for HFE-7100 over other potassium formate solutions for low-temperature applications (below -20[degrees]C or -4[degrees]F) (IEA 2003). However, it was recently demonstrated that corrosion had been a problem associated with the use of potassium salts, particularly when galvanized materials were used in display cases. At the same time, the HFE-7100 is an unnatural global warming substance and is expensive. For future applications, a valuable deep-freeze coolant would be carbon dioxide (C[O.sub.2]). As a two-phase secondary coolant, C[O.sub.2] has no ozone degradation potential and negligible GWP. It is universally available, uses very little energy for pumping, and has low costs. In the presented system, the low-temperature secondary fluid (pure potassium formate) is circulated through the freezing secondary loops by two 37.5 hp parallel pumps. Although propylene glycol (35%) has a relatively high level of viscosity at low temperatures, it was chosen for the medium-temperature cold secondary loop. It is also circulated through the loop by two 37.5 hp pumps installed in parallel.

Two warm secondary loops reject the condensing excess heat to the outdoor air by means of remote air-cooled liquid coolers located on the roof (Figure 1). Both loops use ethylene glycol (with a concentration of 50%) as warm secondary fluid. This fluid presents certain environmental risks, but they are minimal compared to the risks associated with common refrigerant leakages.

Evaporator, Compressor & Condenser

The Evaporator

The purpose of the evaporator is to remove unwanted heat from the product, via the liquid refrigerant. The liquid

refrigerant contained within the evaporator is boiling at a low-pressure. The level of this pressure is determined by two

factors:

- The rate at which the heat is absorbed from the product to the liquid refrigerant in the evaporator

- The rate at which the low-pressure vapour is removed from the evaporator by the compressor

To enable the transfer of heat, the temperature of the liquid refrigerant must be lower than the temperature of the product

being cooled. Once transferred, the liquid refrigerant is drawn from the evaporator by the compressor via the suction line.

When leaving the evaporator coil the liquid refrigerant is in vapour form.



The Compressor

The purpose of the compressor is to draw the low-temperature, low-pressure vapour from the evaporator via the suction

line. Once drawn, the vapour is compressed. When vapour is compressed it rises in temperature. Therefore, the

compressor transforms the vapour from a low-temperature vapour to a high-temperature vapour, in turn increasing the

pressure. The vapour is then released from the compressor in to the discharge line.

The Condenser

The purpose of the condenser is to extract heat from the refrigerant to the outside air. The condenser is usually installed

on the reinforced roof of the building, which enables the transfer of heat. Fans mounted above the condenser unit are

used to draw air through the condenser coils.

The temperature of the high-pressure vapour determines the temperature at which the condensation begins. As heat has

to flow from the condenser to the air, the condensation temperature must be higher than that of the air; usually between -

12°C and -1°C. The high-pressure vapour within the condenser is then cooled to the point where it becomes a liquid

refrigerant once more, whilst retaining some heat. The liquid refrigerant then flows from the condenser in to the liquid line.

Source: http://www.europe.honeywell.com/70_refrigeration_control/EN5B-0024UK07%20R0505.pdf

Refrigerants in subcritical applications

In subcritical applications, refrigerant is metered by a capillary tube or thermostatic expansion valve, the control strategy being to inject liquid into the evaporator and maintain a given superheat entering the compressor. The metering device is selected or designed to ensure that there is complete evaporation ahead of the compressor.

Superheat is maintained to ensure that evaporator efficiency is optimal, and that liquid refrigerant does not enter the compressor. Excessive superheat may lead to overheating of the compressor.

In systems where a thermostatic expansion valve is used rather than a capillary tube, superheat is maintained by placement of a sensing bulb at the outlet of the evaporator. The modulation of the valve is then controlled by the temperature transmitted to it from the bulb and the pressure at an internal or external equalization port.

A different control strategy is needed in transcritical cycles.

A system based on the transcritical CO2 cycle uses a high pressure expansion valve (HPEV). Rather than controlling refrigerant metering from the low-pressure side of the system, modulation control comes from the high side of the system. A mechanical HPEV will control refrigerant injection into the evaporator by opening and closing based on the increase or decrease in gas cooler pressure.

In the HPEV, spring force is a closing force that acts on the top of a diaphragm. Increasing spring force throttles the valve, causing a backpressure in the gas cooler; the valve will not open until that back pressure, opposing spring force, increases to the point where it can overcome spring force and open the valve. The valve set point for the inlet pressure can be adjusted manually by compressing a spring in the valve.

Unlike a TEV, an HPEV does not control evaporator superheat. The HPEV injects refrigerant into the evaporator, but superheat is not directly controlled — instead it is indirectly regulated by system design.

The system charge, its distribution between the components, evaporator design, and the heat load, along with other external operating conditions, determines system superheat. By controlling the gas cooler pressure, the HPEV will indirectly influence system superheat, but the system must be designed so that liquid refrigerant in the evaporator outlet is not allowed to return to the compressor.

The HPEV was designed to control gas cooler pressure rather than suction line superheat as does a TEV. An HPEV, therefore, must withstand high-side CO2 pressures that can reach 1500 psia, at the same time accurately controlling gas cooler pressure. Slight capacity and energy efficiency (COP).