Novelty of Carbon Dioxide and Rascality of Carbon Monoxide

By: Dr.Badruddin Khan

Carbon Dioxide is a colorless, odorless, and slightly acid-tasting gas, sometimes called carbonic acid gas, the molecule of which consists of one atom of carbon joined to two atoms of oxygen (CO2). It was called “fixed air” by the Scottish chemist Joseph Black, who obtained it through the decomposition of chalk and limestone and recognized that it entered into the chemical composition of these substances. The French chemist Antoine Lavoisier proved that it is an oxide of carbon by showing that the gas obtained by the combustion of charcoal is identical in its properties with the “fixed air” obtained by Black. Carbon dioxide is about 1.5 times as dense as air. It is soluble in water, 0.9 volume of the gas dissolving in 1 volume of water at 20° C (68° F).

Carbon dioxide is produced in a variety of ways: by combustion, or oxidation, of materials containing carbon, such as coal, wood, oil, or foods; by fermentation of sugars; and by decomposition of carbonates under the influence of heat or acids. Commercially, carbon dioxide is recovered from furnace or kiln gases; from fermentation processes; from reaction of carbonates with acids; and from reaction of steam with natural gas, a step in the commercial production of ammonia. The carbon dioxide is purified by dissolving it in a concentrated solution of alkali carbonate or ethanolamine and then heating the solution with steam. The gas is evolved and is compressed into steel cylinders. The atmosphere contains carbon dioxide in variable amounts, usually 3 to 4 parts per 10,000, and has been increasing by 0.4 percent a year. It is used by green plants in the process known as photosynthesis, by which carbohydrates are manufactured.

Carbon dioxide is used in the manufacture of sodium carbonate, Na₂CO₃· OH₂O (washing soda); sodium bicarbonate, NaHCO₃ (baking soda); and basic carbonate of lead, Pb₃ (OH)₂(CO₃)₂ (white lead). Dissolved under a pressure of 2 to 5 atmospheres, carbon dioxide causes the effervescence in carbonated beverages. Carbon dioxide does not burn and does not support ordinary combustion, and because of these properties it is used for extinguishing fires. The CO₂ extinguisher is a steel cylinder filled with liquid carbon dioxide, which, when released, expands suddenly and causes so great a lowering of temperature that it solidifies into powdery “snow.” This snow volatilizes (vaporizes) on contact with the burning substance, producing a blanket of gas that cools and smothers the flame. Solid carbon dioxide, known as dry ice, is widely used as a refrigerant. Its cooling effect is almost twice that of water ice; its special advantages are that it does not melt as a liquid but turns into gas, and that it produces an inert atmosphere that reduces bacterial growth. The presence of carbon dioxide in the blood stimulates breathing. For this reason, carbon dioxide is added to oxygen or ordinary air in artificial respiration and to the gases used in anesthesia.

Carbon Monoxide is a chemical compound of carbon and oxygen with the formula CO. Carbon monoxide melts at -205°C (-337°F) and boils at -191.5°C (-312.7°F). It is a colorless, odorless gas, about 3 percent lighter than air, and is poisonous to all warm-blooded animals and to many other forms of life. When inhaled it combines with hemoglobin in the blood, preventing absorption of oxygen and resulting in asphyxiation. Carbon monoxide is formed whenever carbon or substances containing carbon are burned with an insufficient air supply. Even when the amount of air is theoretically sufficient, the reaction is not always complete, so that the combustion gases contain some free oxygen and some carbon monoxide.

An incomplete reaction is especially probable when it takes place quickly, as in an automobile engine; for this reason, automobile-exhaust gases contain harmful quantities of carbon monoxide, sometimes several percent, although antipollution devices are intended to keep the level below 1 percent. As little as 1/1000 of 1 percent of carbon monoxide in air may produce symptoms of poisoning and as little as a fraction of 1 percent may prove fatal in less than 30 min. Carbon monoxide is a major component of air pollution in urban areas. In addition to being present in automobile exhaust, carbon monoxide also occurs in cigarette smoke.

Because it is odorless, carbon monoxide is an insidious poison. It produces only mild symptoms of headache, nausea, or fatigue, followed by unconsciousness. An automobile engine running in a closed garage can make the air noxious within a few minutes; a leaking furnace flue may fill a house with unsuspected poison. Fuel gas, which may contain as much as 50 percent carbon monoxide, often has small quantities of unpleasant-smelling sulfur compounds purposely added to make leaks noticeable.

Carbon monoxide is an important industrial fuel because it contains more than two-thirds of the heating value of the carbon from which it was formed. It is a constituent of water gas, producer gas, blast furnace gas, and coal gas. In smelting iron ore carbon monoxide formed from coke used in the process acts as a reducing agent, that is, it removes oxygen from the ore. Carbon monoxide combines actively with chlorine to form carbonyl chloride, or phosgene, and it combines with hydrogen, when heated in the presence of a catalyst, to form methyl alcohol. The direct combination of carbon monoxide with certain metals, forming gaseous compounds, is used in refining those metals, particularly nickel.

About the Author

Dr.Badruddin Khan teaches Chemistry in the University of Kashmir, Srinagar, India.

(ArticlesBase SC #628347)

Article Source: http://www.articlesbase.com/ - Novelty of Carbon Dioxide and Rascality of Carbon Monoxide




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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.

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

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.

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).

L' avenir des Arénas Québécois

«Des expertises sont présentement menées et nous voulons attendre de savoir quel est le problème exactement avant de tirer des conclusions quant à l'avenir de l'aréna», explique Claude Raymond, chargé de communication à l'arrondissement Villeray–St-Michel–Parc-Extension.

Les utilisateurs de l'infrastructure devront patienter jusqu'au mois de décembre avant de connaître le sort qu'on leur réserve.

«La Ville m'a parlé de trois scénarios possibles», relate Stéphane Robert, président de l'Association de hockey mineur de Villeray (AHMV), principale victime de la fermeture. «En premier lieu, les pièces défectueuses pourraient être réparées. Sinon, il pourrait y avoir un changement complet du système de réfrigération. Ou encore, l'aréna pourrait subir un changement de vocation.»

Une chose est sûre, AHMW a dû changer d'adresse et s'installer à l'aréna Howie-Morenz pour la saison à venir, ce qui entraîne de nombreuses complications (voir autre texte).

600 000$ plus tard, patinoire inutilisable

En 2003, 500 000$ avaient été investis à Jean-Rougeau pour de nombreuses rénovations au niveau du plafond, des douches, des toilettes, du recouvrement du plancher et pour changer la peinture qui s'écaillait sur les murs.

Et le système de réfrigération? Il a absorbé une portion de l'investissement de près de 100 000$ fait en 2004, alors que l'arrondissement avait changé le déshumidificateur, réparé partiellement le collecteur de saumures et remplacé les moteurs des quatre compresseurs du système de réfrigération.

Pour sa part, le maire de la Municipalité de Saint-Ambroise, monsieur Marcel Claveau, se réjouit des effets positifs de ces travaux qui favoriseront un meilleur rendement des installations, en plus de renforcer le pouvoir d'attraction de sa municipalité et de contribuer au développement économique et touristique de la région.

Une aide financière de 470 millions de dollars, provenant du FIMR et assumée à parts égales par le gouvernement du Québec et le gouvernement du Canada, est offerte aux municipalités et aux organismes non gouvernementaux du Québec. Avec la participation financière de ces municipalités et organismes, ce sont quelque 700 millions de dollars de travaux qui pourront ainsi être réalisés. Le FIMR poursuit plusieurs objectifs : améliorer les infrastructures collectives, la qualité de l'environnement ainsi que la qualité de vie des citoyens et soutenir la croissance économique à long terme.

Ce programme, qui sera en vigueur jusqu'au 31 mars 2010, est géré par le

ministère des Affaires municipales, des Régions et de l'Occupation du territoire du Québec. La responsabilité du gouvernement du Canada relative au programme a été confiée à Développement économique Canada. La population est d'ailleurs invitée à visiter, le dimanche 4 octobre 2009, de 13 h à 16 h, les nouvelles installations de l'aréna.

Varieties of Natural Refrigerants

Ammonia is a very good refrigerant and is used to a significant extent in large warehouses. Ammonia is toxic and, under certain limited conditions, flammable and even explosive. However, with its intense, pungent odor, it is a self-alarming refrigerant. Ammonia has emerged as a refrigerant for water chillers in Europe. These units are entirely self-contained, including a gastight cabinet that houses the entire unit and a water tank to dissolve any ammonia in case of a leak. These measures, to be sure, increase costs considerably.

Hydrocarbons are excellent refrigerants, but they are also flammable and explosive. In North America, any flammability risk is unacceptable, but some countries in Europe and elsewhere have less-stringent liability laws. Since the mid-1990s, virtually all refrigerator production in Germany has used hydrocarbons as the working fluid. Some heat pump manufacturers whose systems are installed entirely outdoors have followed suit, and some commercial installations have recently become publicly known. Nevertheless, the danger of fire remains an overriding concern. To address this challenge with safety features, the cost of a system would have to be increased by about one-third.

Carbon dioxide is a refrigerant that operates at very high pressures in a transcritical cycle for most operating conditions. Thus the refrigerant condenser of a conventional refrigeration system serves now as a cooler for supercritical fluid. Only after the expansion process is liquid carbon dioxide available to provide cooling capacity through evaporation. Because of the nature of the transcritical cycle, the efficiency of carbon dioxide is quite poor. However, this is its only disadvantage. All the other characteristics of carbon dioxide are very favorable. It is environmentally safe, has very low toxicity, and allows for extremely compact systems. The vapor pressure of CO2 is approximately seven times higher than that of R-22. Moreover, the supercritical CO2 has a higher density than subcritical fluids, so there is potential to reduce the size of hardware. There are indications that with modern materials and technologies, the weight of CO2 heat exchangers can be reduced considerably, especially for tap water heating, with essentially the same performance.

Co2 as a Refrigerant

Even though Hydrofluoro compounds (HFC) are widely used as refrigerants because of their environment friendly nature (no damage to ozone layer), CO2 is also a popular choice as refrigerant.

Some of the advantages of CO2 as a refrigerant are:

• widely available;
• high volumetric cooling capacity and heat transfer;
• no recovery or recycling required;
• non inflammable and non toxic;
• environment friendly;
• the compressors are compact in size

Some of the difficulties is using CO2 as refrigerant are: high working pressure and large pressure difference (3 to 5 times conventional refrigerants); low theoretical efficiency with normal refrigeration systems. Hence it requiresadvanced technology compressor and refrigeration system. The hoses need to be strong as well as the evaporators and gas coolers are used instead of condensers as there is no phase change of the refrigerant. They are widely used in vending machines.

One of the difficulties of CO2 as a refrigerant is its detection and level control.

Chemical sensor elements cannot reliably measure CO2 levels. Other alternate detectors include infrared sensors.

Simulation model of a low-temperature supermarket refrigeration system.

HVAC & R Research

| October 01, 2006 | Getu, Haile-Michael; Bansal, Pradeep Kumar | COPYRIGHT 2008 American Society of Heating, Refrigerating, and Air-Conditioning Engineers, Inc. This material is published under license from the publisher through the Gale Group, Farmington Hills, Michigan. All inquiries regarding rights should be directed to the Gale Group. (Hide copyright information)Copyright

This paper presents a computer simulation model of a low-temperature supermarket refrigeration system whose main components include a compressor, a display cabinet, a condenser, and a thermostatic expansion valve. The energy consumption of the system was evaluated as a function of the store relative humidity, which was measured every 16 seconds for 15 days. The model results were validated with the measurements taken from a representative in-situ supermarket in Auckland, New Zealand. The simulation results indicated that the rate of heat transfer in the evaporator was reduced by nearly 10.5 W for each 1% increase in daily average store relative humidity due to the insulating effect of the frost. The frost thickness was found to grow at 0.0354 mm for each 1% increase in the daily average store relative humidity over a 12 hour operation period between the defrost cycles. The pressure drop of the air over the evaporators increased by around 12 Pa for every 10% rise in the daily average store relative humidity.

INTRODUCTION

Supermarkets, which contain heating, cooling, and ventilation (HVAC) as well as refrigeration systems, are the most energy-consuming commercial establishments (Mei et al. 2002). According to the real measurements in the current study, the average power consumption of compressors/rack systems for both the low- and medium-temperature refrigeration systems of the supermarket amounts to roughly 20% of the total energy use. The energy consumption due to auxiliary equipment (defrosting, anti-sweat resistance heaters, display cabinet lights, and fans) and the air-conditioning system of the building are, respectively, 14% and 17%, while the remaining 49% is attributed to water, heating, and lighting systems of the establishment. Defrosting of evaporator coils is one of the most energy-consuming processes in supermarket refrigeration systems. A large amount of frost accumulation decreases the performance of the coil due to reduced rate of heat transfer and airflow. This consequently reduces the refrigerating capacity of the evaporator. Hence, frosting needs attention and should be minimized to improve the energy efficiency of the system and temperature control.

The impact of store relative humidity on refrigerated display case performance has been studied by Howell (1993a, 1993b), Orphelin et al. (1997), and Henderson and Khattar (1999), where the possible energy savings were predicted by reducing the store relative humidity and the energy penalty realized by the air-conditioning system. Among other studies by Inlow and Groll (1996), McDowell et al. (1995), Horton (2002), and Walker and Baxter (2003) on supermarket refrigeration systems, Ge and Tassou (2000) have presented a mathematical model for direct expansion supermarket refrigeration systems using TRNSYS (2001). Their display cabinet model, however, was quite restricted and used loads only due to infiltration, conduction, convection, and radiation, and the model was validated only for medium-temperature display cabinets. The simulation and the experimental work carried out so far in the supermarket industry has mainly focused on medium-temperature refrigeration systems. Further, dynamic frosting, as a result of store relative humidity, is ignored except in the medium-temperature cabinet models of Ge and Tassou (2000). Therefore, there is a need to develop a complete simulation model for low-temperature supermarket refrigeration systems, since they are most affected by the store relative humidity. This paper, therefore, presents a numerical model to investigate the performance of in-situ low-temperature display cases as a function of store relative humidity. The model includes major components of the refrigeration system, such as compressors, display cabinets, condensers, and thermostatic expansion valves. Specific correlations were used to compute frost thickness, rate of heat transfer across the evaporators, and COP. The model results were validated against the measurements taken from an in-situ supermarket located in Auckland, New Zealand, from December 1, 2004, to January 10, 2005. The model was written in a software package called Engineering Equation Solver, or EES (2004), which has built-in properties of many refrigerants. The computer model can be used as a convenient tool to accurately calculate the energy savings of the low-temperature refrigeration systems as a function of store relative humidity.

THE LOW-TEMPERATURE SUPERMARKET REFRIGERATION SYSTEM

Supermarkets have three different types of cooling systems. The first one is the air-conditioning system, whose operating temperature is roughly 5[degrees]C, which regulates the relative humidity and temperature in the occupied store. The second one is the medium-temperature refrigeration system. It has an evaporation temperature of around -8[degrees]C and provides refrigeration for fresh food such as meats, vegetables, and dairy products. The third system has an evaporation temperature down to -40[degrees]C and is called the low-temperature refrigeration system. Nowadays, there are various types of refrigeration systems, such as direct expansion/multiplex, secondary-loop, distributed, and cascade refrigeration systems. However, the direct expansion refrigeration system is the most commonly employed configuration in most supermarkets for providing refrigeration to display cabinets located in the store.

The low-temperature direct expansion refrigeration system under consideration (see Figure 1) consists of display cabinets/freezer rooms of varying geometry, multiple compressors, air-cooled condensers, thermostatic expansion valves (type DANFOSS TUA/TUAE), and evaporator pressure regulating valves (EPRVs). The function of EPRVs, as presented by Tahir and Bansal (2005), is to keep the evaporating temperatures of the respective display cabinet/freezer room at the required levels. The pressure and temperature at the suction manifold of the compressors are also determined by these valves. The dotted line enclosure shown in Figure 1 contains the evaporator assemblies, including drain points for condensate collections during defrost periods. These components in the enclosure are located within the bottom parts of the display cabinets and on the walls of the freezer rooms.

The low-temperature refrigeration system (Figure 1) consists of three major circuits that feed refrigerant R-404A to three sections of the supermarket, such as frozen food cabinets, fish/meat cabinets, and freezer rooms. The geometrical parameters and the operating temperatures of each type of cabinet and freezer room are given in Table 1.

DEVELOPMENT OF SIMULATION MODEL

The development of the simulation model for a low-temperature supermarket refrigeration system, which includes major components such as compressors, display cabinets, condensers, and thermostatic expansion valves, is discussed in the following sections.

Compressor Model

Multiple compressors (rack) in a supermarket refrigeration system are mostly of the semi-hermetic reciprocating type. If the compressor performance data are known, the compressor model may be developed based on the philosophy presented by Popovic and Shapiro (1995). Their model requires inputs such as refrigerant inlet state, outlet refrigerant pressure, clearance volume, polytropic exponents for specific refrigerants, and motor speed to calculate refrigerant mass flow rate and refrigerant.