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Ozonated Air Conditioning

Gives a complete idea about the ozonated air conditioning, development in the ozone technology and how ozone is injected in HVAC system

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Ozonated Air Conditioning

  1. 1. OZONATED AIR CONDITIONING WHAT IS OZONE? Ozone is an odd form of oxygen, a gas that normally floats around oxygen (O2). Ozone is O3, and it occurs naturally in a gaseous layer in the stratosphere, seven miles above the Earth. This high layer of ozone acts as a selective shield around the Earth. It absorbs intense ultraviolet radiation from the sun that would otherwise make life here difficult, if not downright nasty. Ozone is also found in the lower atmosphere, where it is created when certain byproducts of combustion react with sunlight. Ground ozone is a major pollutant. It contributes to smog, damages crops and forests and is dangerous to human health. WHAT IS OZONE LAYER? An Ozone layer is a layer in the earth’s atmosphere which contains 90 % of atmospheric ozone. The Ozone layer is found in the lower portion of the stratosphere from about 17 to 50 kms. above the earth’s surface. It’s thickness varies seasonly and geographically. WHY IT IS SO IMPORTANT? The ozone layer is important because - It filters harmful ultraviolet radiation as it travels from the sun to the surface of the Earth. These ultraviolet rays can harm both plant and animal life. - Adjusts the temperature of the Stratosphere.
  2. 2. OZONE FOR HVAC SYSTEMS Ozone has been successfully used in bars, smoking rooms, cocktail lounges, taverns, airport smoking areas, karaoke lounges etc., for the removal of VOCs, smell, bacteria, mould , mildew and other micro organisms from the HVAC system. Smart sensors used ensure that the ozone in the treated room does not exceed 0.03-0.05 ppm. The ASHRAE standard for ozone is 0.05 ppm. Ozone is increasingly being used in HVAC systems to improve the indoor air quality and also to improve the energy efficiency of the HVAC cooling coils. Ozone is fed in the return ducts. This ensures that there will not be any leakages in the occupied areas of the HVAC system since the return ducts are always under negative pressure. By the time the treated air passes through the AHU fan coils and return to the occupied areas via supply ducts the ozone concentration would have fallen to allowable exposure limits. AIR QUALITY, DEMAND-CONTROLLED VENTILATION The quality of the indoor airport environment is a key issue for the protection of passengers’ and staff health and well-being. The significance of well-being in buildings was first recognised in conjunction with a noted increase in symptoms and complaints associated with buildings (Sick building syndrome). 'Sick Buildings' can lead to a reduction in the productivity of individuals or even an entire staff. The injection of ozone in the return duct also enables injecting ozone at higher concentrations which are needed for VOC oxidation. Smart sensors installed in the occupied areas display the ozone concentration and cuts off the ozone generator when the set limits are reached. Advantages • Ozone generators in SS & easy to install • Easy to control ozone concentration by sensors. • Fan cooled. No cooling water required! • Compact in design combined with high efficiency • Adjustable ozone sensor (0.02 – 0.1 ppm) • Air pump for feed gas with ozone outputs in SS fittings.
  3. 3. If the oxygen (O2) content of the air is too low, the carbon dioxide (CO2) level becomes too high. This can occur in overfilled, generally also overheated zones and can produce conditions ranging from drowsiness and lack or concentration to nausea and fainting. The air purity also plays a role; smoke, dust and stale air also cause discomfort - the only solution is to introduce a source of new, fresh air. Measurement of CO2 exhaled from the occupants in airport zones provides a perfect measurement of room occupancy. Mixed-gas or "VOC" sensors (Volatile Organic Compounds) which detect oxidizable (combustible) gases, measure additional odours and bad air from dirty ventilation systems, carpets, dust, smoke, fumes etc. Elements perceived by humans as bad air. Latest combined CO2/VOC sensors combine CO2 with VOC to provide optimum room air quality measurement. The VOC values are transmitted as a maximum value (CO2 or VOC whichever is highest). These new sensors respond not only to combustible gases and vapours, but also to the humidity in the indoor air. The installation of CO2 or VOC based demand-controlled ventilation (DCV) into HVAC equipment is a proven method of protecting the air quality levels for occupants and at the same time saving huge amounts of energy, by reducing plant when not required. INDOOR AIR QUALITY (IAQ) Awareness of indoor air quality has increased substantially in recent years, and the systems that supply air to our living and working spaces are critical to the maintenance of a healthy indoor environment.. The sterilizing power of ozone is the strongest known element to be used against bacteria, micro-organisms, fungus and certain insect larvae and can therefore be used to eliminate or reduce the hazardous chemicals. The most appropriate environment for the incubation of any kind of bacteria are those places where little ventilation exists, where the temperature is warm and a certain degree of humidity prevails. In aircraft the combination of groups of people, the heating system and perspiration on bodies and in the atmosphere pave the way for the best conditions for bacteria and micro-organisms to multiply. The Air Quality Levels
  4. 4. INDOOR AIR TREATMENT Ozone in natural settings is around 0.02 ppm, but it can be as high as 0.10 ppm. At this level it is capable of keeping pathogens in check and yet at this level ozone is not harmful to higher life forms such as fish, birds, animals or man. Ozone is not causing harm to the nature. Only a prolonged exposure to very unnatural high levels of ozone may lead to discomfort, later headache and coughing, telling you to leave the space and seek better air. Energy consumption in commercial building Cooling load break up for high occupancy applications – Mall, Multiplex, IT and Software Office etc. WHY DO WE NEED FRESH AIR ? - To reduce the Volatile Organic Compounds (VOC) - To remove odours - To dilute CO2 In short fresh air is required to improve the indoor air quality. HOW DOES FRESH AIR IMPROVE INDOOR AIR QUALITY ? - The oxygen in the fresh air oxidises the VOC and odours. - The oxygen in the fresh air also dilutes the CO2 . In short , oxygen in the fresh air does the work. ENERGY CONSUMED BY FRESH AIR - 150 cfm of fresh air in Mumbai will require 1 ton of cooling load. - This will consume approx. 1 KW energy for a water cooled system or 1.3 KW of energy for an air cooled system. HOW CAN WE MINIMISE THIS ENERGY WASTAGE ? - Air quality improves dramatically. - Oxygen is thus required only to dilute the CO2. This is a much smaller requirement. - Thus fresh air can be modulated rationally down to 5 cfm or less per person. - This will reduce the overall plant capacity by up-to 25 %.
  5. 5. Saving in HVAC load due to Ozonization Saving in overall energy consumption METHODS TO ENSURE CONCENTRATION WITHIN LIMITS - Use Auto VOC Sensor and Controller. - Based on the residual VOC. - Regulate output of ozone Generator. - Use Ozone Monitor to alarm / trip Ozone Generator in the event of high concentration.
  6. 6. CONCLUSION 1. Benefit of ozone system - Dramatic reduction in build up of HC, Toxic Gases, and VOC. - Dramatic Reduction in Odor. - Near Total Elimination of Cigarette Smoke. - Depletion of Microbial Colonies (Fungi) in ducts and AHU cooling coils. Eliminates duct cleaning. - Depletion of Microbial (Fungi) Indoor. 2. Direct economic benfits of ozone systems - Capital cost savings. - Reduced size and capacity of hvac systems. - Cost of envirosafetm ozone system is often lower than savings in HVAC plant reduction. - Net result: Reduced capital cost 3. Environmental benefits - Reduced Fungi and Microbes in Ducts, Cooling Coils and Indoor. - Reduced Allergy Related Disorders. - Cleaner Indoor, Cleaner Ducts.
  7. 7. AIRCRAFT ODOR AND FUNGI CONTROL Airlines spend vast amounts of money on chemicals to disinfect aircraft. In aircraft the combination of groups of people, the heating system and perspiration on bodies and in the atmosphere pave the way for the best conditions for bacteria and micro-organisms to multiply. The application of ozone in aircraft deodorizes the environment and regenerates oxygen resulting in a completely clean environment free of bacteria, micro-organisms and odors. Portable units can be used by aircraft cleaning personnel to easily deodorize and disinfect the aircraft. The efficiency of the ozone units can easily be demonstrated especially after long international flights. AIRPORT The Dubai International Airport may be the largest ozonated HVAC system in the world with air treatment in all buildings. There are over 300 ozone sensor/controllers and many VOC sensor/controllers as well. There are many small ozone generators spread along the HVAC ductwork along with the ozone and VOC sensors. Virtually all interior spaces are treated including the freight terminal. After operation of the system for about one year, the preliminary findings were :- - Passengers and employees note a pleasing air quality without the distinct smells that are often found in busy airports. - The savings of ozone replacing carbon filters are very large. Carbon filters have high replenishment costs and occupy a lot of valuable space. - The energy savings in reducing the makeup air requirement are significant Other HVAC system maintenance costs are reduced such as less cleaning of the ducts due to virtually no mold and mildew accumulation. SANITIZING AND DEODORIZING WASHROOMS Odors and bacteria are significantly reduced by ozone in washrooms. Noxious airborne chemicals and surface bacteria cause unpleasant and harmful odors. Ozone not only deodorizes washrooms effectively, it also kills the germs than can lurk on surfaces such as taps and toilets. Ozone should be used in conjunction with normal cleaning procedures to enhance the disinfecting process. Ozone being gaseous can penetrate even into the most inaccessible places. Due to ozone being a highly unstable molecule, it will react very easily when it comes into contact with an oxidizable substance. Unused ozone reverts back to oxygen leaving no residue. The generator is economical to run, it requires no chemical consumables and maintenance is minimal. Ozone been applied on a large scale to heating, ventilating, and air conditioning (HVAC) systems. Major reasons for this surge of interest in ozone treatment of indoor air include: 1. Heightened public awareness that something can be done about indoor air quality (IAQ). 2. Increased IAQ problems due to sealed buildings and less makeup (outside) air metered into HVAC systems. 3. Increased public intolerance for smoking and the realization that many common chemicals contribute to poor IAQ. 4. New ozone generator and ozone monitor designs that make system control a reality. 5. Attractive payback economics due to savings in energy and other factors. The large majority of projects so far are for larger hospitality businesses including restaurants, showrooms, and bowling centers. These users have found that there is a high return on investment in systems which create and maintain high air quality. Many projects, often much smaller in scale, have been completed for cocktail lounges,
  8. 8. taverns, airport smoking areas, and even for advanced technology facilities for animal raising on a large commercial scale. The major objection to ozone is safety. Its concentration in public areas must be kept below harmful levels. This is accomplished by new technology ozone generation and monitoring equipment combined as a self-controlling system. There is disagreement among cognizant agencies about what are safe levels and suitable guidelines for ozone concentrations. The US FDA states a limit of .05 ppm for areas where people of all kinds congregate. Most ozonated HVAC systems with automatic controls are programmed not to exceed concentrations ranging from 0.03 to 0.05 ppm. These concentrations are below naturally occurring outdoor levels in many regions, but are just high enough to reduce VOCs significantly. Furthermore, the ozone concentrations are much higher in the supply ducts where bacteria, mold, mildew, and VOCs accumulate. For ozone injected into HVAC systems it is absolutely necessary to include ozone sensors to automatically control the ozone concentration in areas where the public congregate. THE DUBAI INTERNATIONAL AIRPORT MAY BE THE LARGEST OZONATED HVAC SYSTEM IN THE WORLD WITH AIR TREATMENT IN ALL BUILDINGS. VIRTUALLY ALL INTERIOR SPACES ARE TREATED INCLUDING THE FREIGHT TERMINAL. Dubai Airports’ conservation efforts are paying environmental and financial dividends as the organisation reported the results of 2011 energy and fuel saving initiatives that reduced CO2 emissions by 72,793 tonnes, saved 131.9 million gallons of water and achieved AED 15.9 million (US$4.33 million) in fuel savings. The ozone is injected into the central air conditioning system. The ozone generators are controlled by sensors activated by excessive VOC concentrations and turned off by excess ozone concentration sensors. Carbon dioxide sensors call for makeup air if the carbon dioxide concentration exceeds a standard set-point. The air conditioning system is large and energy- consuming because outdoor temperatures routinely exceed 40 deg C in the warmer months. All systems and components are controlled by a computerized Building Control System (BCS). The ozone monitors keep the ozone concentrations in the occupied areas to less than .05 ppm. The VOCs to be minimized by the ozone treatment include cigarette smoke, jet fuel and exhaust fumes in the makeup air, and building chemical fumes such as from paint, carpets, and cleaning chemicals. The conditioned air residence time in the passenger areas is about 15 minutes or about the half- life of the ozone in such environments. Because the ozone concentration drops about 90% from supply ducts to return ducts instead of about a 50% drop predicted by half-life, we can see that much of the ozone has reacted with VOCs. An unexpected finding was that the makeup air could be cut by 50% without compromising the carbon dioxide concentration criterion. The ozone is destroying the VOCs sufficiently to significantly reduce the makeup air without reducing the building’s air perceived quality. This translates to great energy savings because cooling the very hot makeup air requires large amounts of energy. The indicated energy saving should recover the cost of the ozone equipment in about one year.
  9. 9. After operation of the system for several years, the preliminary findings were: - Passengers and employees note a pleasing air quality without the distinct smells that are often found in busy airports. - The savings of ozone replacing carbon filters are very large. Carbon filters have high replenishment costs and occupy a lot of valuable space. - The energy savings in reducing the makeup air requirement are significant. Other HVAC system maintenance costs are reduced such as less cleaning of the ducts due to virtually no mold and mildew accumulation. “We take our environmental responsibility very seriously and as we step up efforts to limit our footprint, it’s becoming increasingly clear that green business is good business,” said Dubai Airports CEO Paul Griffiths. Dubai International is an efficient global hub whose two largest airlines Emirates and Fly Dubai have young, fuel- efficient fleets featuring the latest aircraft technology. That combined with Dubai’s geocentric location that effectively reduces flying time and the number of required connecting flights limits associated emissions.
  10. 10. Aside from these efficiencies, Dubai Airports continues its aggressive campaign to conserve water and reduce power consumption across both of its airport properties. By installing energy-saving lamps and occupancy sensors, re-setting air conditioning by a mere three degrees (from 21 degrees Celsius to 24 degrees) and implementing chiller management systems Dubai Airports managed to save over 21.4 million kilowatt/hours of electricity worth AED 8.13 million ($2.21 million), equivalent to 9,993 tonnes of CO2 during 2011. At Dubai World Central, the conservation of 2.242 million kWh of electricity saved AED 1.04 million and equivalent 1,906 tonnes of CO2 during the same time frame. Water conservation efforts led to a reduction of 126.45 million gallons and savings of AED 5.06 million at Dubai International last year. At DWC water savers were introduced in all facilities, resulting in the conservation of 696,000 gallons of water worth AED 27,840. Additionally the use of treated sewage effluent water for irrigation has resulted in the saving of 4.75 million gallons of potable water worth AED 190,000. During the year under review the company also set a new standard in the region with the installation of the largest solar panel array for any airport in the Middle East. Thanks to the considerable contributions and support of long standing partner Air BP, the array consists of 92 panels of high efficiency photo-voltaic cells providing 21.6 KW capacity. Located atop the airport's Car Park B, it provides enough power to offset fully the energy consumed by the lighting and plasma displays in the airport’s historical photo exhibition. The installation has a lifespan of 25 years, and will continue to provide free, clean energy to Dubai International during its lifetime. Another successful initiative which continues to yield substantive fuel and CO2 savings is the airport’s stand hold policy which limits the number of aircraft taxiing and queuing at the runway. The intention is to absorb any delay time on the stand whilst the aircraft engines are shut down. This contributes to a fuel saving in addition to keeping the airfield free of congestion whilst providing an optimal flow to the runway. During 2011 this policy generated 530,621 minutes of reduced engine run time and saved 5.3 million gallons of fuel (or 19,332 tonnes) and reduced CO2 emissions by 60,894 tonnes. Last year Dubai International’s demand for electricity dropped by 11 MW from 80 MW to 69 MW during the Earth Hour event. “Our ultimate goal is to contribute to the development of a clean, sustainable future in which airports, aircraft and all ancillary services are carbon-neutral,” added Griffiths. “Aviation’s sustainability is of vital importance to Dubai. Currently it supports over 250,000 jobs and contributes some US$22 billion in economic activity. By 2020 that contribution will increase to 320,000 jobs and US$44 billion. As an industry we still have a long way to go to achieve our environmental goals, but each incremental step forward we take is a step in the right direction.”