START WITH EFFICIENCY

Back in 1981, the U.S. Department of Energy decided to rate the relative efficiencies of air conditioners. And, being a government agency, it gave birth to an acronym ... one that today is part and parcel to the hvacr language.
Explain to customers that "SEER" stands for seasonal energy efficiency ratio, and it's a mathematical ratio of cooling output versus electrical power input over a wide range of operating conditions.

A good example is that it's similar to miles-per-gallon ratings for automobiles. The higher the SEER rating, the more energy efficient the air conditioner.
In 1992, the National Appliance Energy Conservation Act set a minimum standard of 10.0 SEER for split-system air conditioners.

This type of information offers important facts about what a customer is considering when making a decision to buy.

CULPRIT IS THE COIL

While most homeowners believe "central air" is the unit humming outside behind the arborvitae bush, a residential, split-system, central air conditioning system is actually a lot more.

It's not only the outdoor condenser, it's also the evaporator coil mounted indoors on a furnace or air handler.

The system is engineered as just that -- a system. And perhaps the most important part of that system is the coil, which must be properly matched to the condenser.
When ARI (the Air-Conditioning and Refrigeration Institute) certifies SEER ratings, it bases its findings on systems that are operating as the manufacturer designed them.

That means, for example, that a high-efficiency outdoor unit is matched with a high-efficiency indoor coil. That way, the system is operating as it was engineered.

In actual residential installations, all too often a matched air conditioning system is not quoted because of pricing pressures. Homeowners are sometimes reluctant to pay the additional charges to replace not only an ailing outdoor condenser, but an existing indoor coil that seems to be operating just fine.
Is that opportunity knocking?

Of course, the problem of mismatched systems occurs more often in the residential replacement business than in new construction. But in 1996, the industry shipped more than 5.6 million new compressor-bearing units -and that market is 60% replacement -- illustrating the potential size of the problem.

York has capitalized on the situation with a new generation of coils that are simple for installing contractors to match up to condensers, a complete line of uncased, half-cased, fullcased, horizontal, and FlatTop(R) coils engineered to meet virtually any residential air conditioning installation.

The company is re-engineering its entire gas furnace and air handler lines to accept these new coils. The four standard widths of the furnaces and air handlers match up size-wise with the complete coil line.

To make certain everyone gets the "matching" message, the company has developed a dedicated "Residential System Selling Kit," which includes "Quick Selection Charts" and a reference manual detailing recommended system set-ups.

Also included in the kit is a proprietary computer software adaptation of the charts. Dubbed RSVP for "Residential System Verification Program," the interactive program is aimed at ensuring an efficient system. It allows installers to plug in system and application requirements to correctly match components.

With a correctly matched system, residential customers get ARI-certified, UL-approved performance; increased dependability; higher capacities; and more comfort.

REMIND CUSTOMERS THAT IT'S A SYSTEM THEY'RE BUYING

In general, the industry is doing a better job of matching up coils to condensing units, to get the a/c system's rated efficiency. But more customer education is still needed, and at the most basic levels.

YORK, Pa. -- A recent article published in York's Insight magazine reminds contractors to remind customers that it's a system they're buying when getting central air, not just an air conditioning unit.

Some tips on what to tell customers, who are certainly concerned with practical matters such as price and installation, are recommended, starting with educating them on what they're buying.

START WITH EFFICIENCY

Back in 1981, the U.S. Department of Energy decided to rate the relative efficiencies of air conditioners. And, being a government agency, it gave birth to an acronym ... one that today is part and parcel to the hvacr language.
Explain to customers that "SEER" stands for seasonal energy efficiency ratio, and it's a mathematical ratio of cooling output versus electrical power input over a wide range of operating conditions.

A good example is that it's similar to miles-per-gallon ratings for automobiles. The higher the SEER rating, the more energy efficient the air conditioner.
In 1992, the National Appliance Energy Conservation Act set a minimum standard of 10.0 SEER for split-system air conditioners.

This type of information offers important facts about what a customer is considering when making a decision to buy.

CULPRIT IS THE COIL

While most homeowners believe "central air" is the unit humming outside behind the arborvitae bush, a residential, split-system, central air conditioning system is actually a lot more.

It's not only the outdoor condenser, it's also the evaporator coil mounted indoors on a furnace or air handler.

The system is engineered as just that -- a system. And perhaps the most important part of that system is the coil, which must be properly matched to the condenser.
When ARI (the Air-Conditioning and Refrigeration Institute) certifies SEER ratings, it bases its findings on systems that are operating as the manufacturer designed them.

That means, for example, that a high-efficiency outdoor unit is matched with a high-efficiency indoor coil. That way, the system is operating as it was engineered.

In actual residential installations, all too often a matched air conditioning system is not quoted because of pricing pressures. Homeowners are sometimes reluctant to pay the additional charges to replace not only an ailing outdoor condenser, but an existing indoor coil that seems to be operating just fine.
Is that opportunity knocking?

Of course, the problem of mismatched systems occurs more often in the residential replacement business than in new construction. But in 1996, the industry shipped more than 5.6 million new compressor-bearing units -and that market is 60% replacement -- illustrating the potential size of the problem.

York has capitalized on the situation with a new generation of coils that are simple for installing contractors to match up to condensers, a complete line of uncased, half-cased, fullcased, horizontal, and FlatTop(R) coils engineered to meet virtually any residential air conditioning installation.

The company is re-engineering its entire gas furnace and air handler lines to accept these new coils. The four standard widths of the furnaces and air handlers match up size-wise with the complete coil line.

To make certain everyone gets the "matching" message, the company has developed a dedicated "Residential System Selling Kit," which includes "Quick Selection Charts" and a reference manual detailing recommended system set-ups.

Also included in the kit is a proprietary computer software adaptation of the charts. Dubbed RSVP for "Residential System Verification Program," the interactive program is aimed at ensuring an efficient system. It allows installers to plug in system and application requirements to correctly match components.

With a correctly matched system, residential customers get ARI-certified, UL-approved performance; increased dependability; higher capacities; and more comfort.

Don't get caught in a heat wave

You know those hazy, hot, and humid days are coming; they do every year. You cannot stop them, but you can plan ahead to keep as cool as possible.
It is not just a matter of comfort. Prolonged exposure to the heat can kill you. To help protect your health, the Medical Society of the State of New York offers these tips, adapted from the New York City Office of Emergency Management:
• To help prevent dehydration, always keep a supply of water on hand.
• Help keep your home cool by installing window shades or awnings to block out the sun.
• If you have air conditioning, make sure that it works properly before the heat wave rolls in.
• If you do not have air-conditioning, keep your windows open when possible so that fresh air may flow through your home. Also identify an air-conditioned location, such as a shopping mall, library, or home of a friend or relative where you can go to find relief from the heat.
• Have a plan with your neighbors to check in on each other during a heat wave, particularly if you or your neighbors are elderly, have young children, or have special needs.
This information is provided by the Medical Society of the State of New York. For more health-related information and referrals to physicians in your community, contact your local county medical society.

TROUBLE AHEAD FOR ALL TYPES OF A/C

1. Problems With New Non-CFC Equipment. The CFC phaseout is occurring so quickly that manufacturers have not had sufficient time to improve the quality and reliability of the cooling equipment--for autos, homes, and businesses-- designed to use the new non-CFC refrigerants. In effect, a multi-billion dollar field test of experimental equipment is being conducted at public expense. Already, some of the new systems have developed problems. Only time will tell how well this new generation of cooling equipment stands up to actual use.
2. Refrigerant Cross-Contamination. There are about 20 new refrigerants competing to replace the small number of CFCs that dominated the market prior to the phaseout. Again, because the CFC phaseout is occurring so quickly, industry has not had the chance to learn which substitutes are best for each application, leading to a confusing proliferation. Charging a system with the wrong refrigerant, which can cause serious damage, is occurring more frequently than ever. In addition, the law now requires servicemen to recover refrigerants during repairs, anti store them for later use (in the past, servicemen usually vented refrigerant to the atmosphere, but this is now illegal). Although each refrigerant is supposed to be kept separate during this procedure, unintentional mixing of refrigerants is common. Subsequent use of these unwanted refrigerant mixtures can shorten the life of equipment. Refrigerant cross-contamination has already been detected in most types of equipment, and the problem will likely worsen before any solutions are found.
3. Additional Phaseout Requirements. The ozone depletion issue has spawned its own bureaucracy, and, like all bureaucracies, this one wants to stay in business as long as possible. But now that it has achieved its primary objective--the rapid phaseout of CFCs--it needs new reasons to justify its continued existence. Not surprisingly, they are finding environmental problems with other refrigerants. HFC-134a, the most common substitute, is being targeted as a contributor to global warming, and some have called for its eventual phaseout. If this happens, those who had to replace CFC equipment with an HFC-134a system may have to go through another costly change. In addition, hydrochlorofluorocarbons (HCFCs), a class of compounds similar to CFCs that are commonly used in residential air-conditioners and other applications, may also be in jeopardy. As the law now stands, HCFCs will be available for at least 15 more years; thus the impact on HCFC equipment is not as immediate as that for CFC systems. However, earlier research indicating that HCFCs have a very minor role in ozone depletion is now being called into question, and efforts are under way to accelerate the HCFC phaseout. If this is achieved, the owners of the nation's 43 million residential air-conditioners will be severely affected.

Can't sleep? Here's all you need to know to get all the rest you need.

Ahhh, the bliss of sinking into your comfortable bed after a long, exhausting day--now this is the stuff dreams are made of. But while we all know the golden rule to getting enough sleep--turning in for at least seven to nine hours a night--not all of us are following it.

We polled more than a thousand ESSENCE readers and found that a majority of you (53 percent) get six hours of rest or less at night. That means you're missing out on sleep's benefits: the chance to decrease your risk of high blood pressure, weight gain, depression and more. The good news is that no matter what your sleep style or pattern is, we've got an easy fix. Here's your A-Z guide to gaining more restful nights (and happier mornings).
8 Secrets to Sleeping Like a Baby

The scent of lavender. The cozy feel of a duvet. Getting sleepy just thinking about them? That's because setting the scene for a good night's rest counts for more than you think. "The right atmosphere can make it easier not only to fall asleep, but also to stay asleep throughout the night," says Amy R. Wolfson, Ph.D., author of The Woman's Book of Sleep: A Complete Resource Guide (New Harbinger Publications). To make your surroundings more rest-ready:

1. PULL THE PLUG ON ELECTRONICS. Thanks to the light and noise they emit, computer screens and televisions stimulate your internal clock and can keep you wired well into the night. Shut them off, and resist the urge to snuggle up with your BlackBerry or PDA that's just as stimulating--at least 30 minutes before lights out.
2. COOL DOWN. Your body temperature naturally drops two to three degrees as it gets ready for rest. To help bring on the z's, let in some cool night air, or turn up your AC to keep the room temperature at 60 to 65 degrees. Researchers say this range matches what's happening deep inside the body and helps promote sleep better than warmer temperatures.
3. BREATHE IN RELAXATION. Studies show a connection between the nose and memory, which means you can train your brain to think of sleep with the whiff of a relaxing bedtime scent of your choice. For all-night aromatherapy, use a linen spray or your favorite body lotion in calming scents like lavender and chamomile.
4. BLACK OUT. Your brain associates light with being awake, so even a small amount from your window or the LED display on your alarm clock can push back your sleep time. Use dark shades on windows, keep your clock out of view, or use an eye mask to help shut out rays.
5. DO SOME SOUNDPROOFING. A carpet or rug can absorb environmental noise while you sleep. If that doesn't agree with your decor, hang heavy drapes on the windows for a similar effect.
6. GET CALM WITH COLOR. Experts who create the cocoonlike rooms you find at most day spas suggest that warm, earthy colors like taupe or moss green can induce the sense of relaxation that keeps you going back. To re-create the spa experience at home, skip bright, bold hues for your bedroom.

7. LIGHTEN UP. Going under the covers this time of year can cause you to overheat and wake up sweaty during the night. The same goes for heavy pajamas in fabrics like flannel. You'll want to strip down and listen up, for now, with more breathable cotton sheets and pj's.
8. DO WHAT FEELS GOOD. Makers of memory foam mattress pads may claim they ease an aching back, but the jury's still out on their real medicinal benefits. Whatever pillows, pads or covers you use to create your sleep-tight sanctuary, experts say only one thing matters: comfort.

Better Sleep in a Bottle

Is the quick fix of an over-the-counter sleep aid what you need? Here's how to tell

PICTURE THIS: You've been lying in bed for more than an hour, full of frustration and unable to do a single thing to doze off. If that's enough to make you want to try an over-the-counter (OTC) sleep aid, then you're not alone. Nearly one-third (29 percent) of readers polled said they have tried an OTC product designed to help them fall asleep. But think twice before you hit the drugstore aisle to find a product. It's one thing to use an OTC drug when work demands or a sick child have you suddenly unable to rest well at night. But, doctors say, anything beyond two weeks of missed sleep, and you should skip the OTCs and see a sleep specialist for an evaluation.

It's not the pills themselves that are a problem. "Most of the drugs you'll find really just give you the sleep-inducing side effect of an allergy medication," says David Rapoport, M.D., director of the Sleep Medicine Program at the New York University School of Medicine. The real concern with using these drugs is that a much more serious condition that could threaten your health, such as insomnia or sleep apnea, can go undiagnosed. (For those disorders, you may need to try behavioral therapy or a prescription drug as your first course of treatment.)

Opponents of OTCs add that these drugs won't actually improve the quality of your sleep and can even lose their effect if you use them for too long. Not to mention, if they linger in your system, you might be left groggy and still unable to function optimally in the morning.

If you find yourself resorting to OTC medication on a regular basis, stop using it and rule out a more serious condition by consulting your doctor. In the meantime, opt for herbal soothers like valerian root extract or chamomile tea.

A new technology could mean the end of air pollution from fossil-fuel power-generating facilities.

In the early industrial world, people could burn all the coal, oil or gas they wanted with no regulatory consequences. It the goal was power without concern for the world's health, the Industrial Revolution approach would work just fine: a big box, burn the coal, make the power.

As we progress through the electronic and biotech eras, the world's population desires an air quality environment closer to the pre-Industrial Revolution condition. With that in mind, a team at ThermoEnergy, along with support from the Department Of Energy and EPA, have created a patented process called TIPS: ThermoEnergy Integrated Power System, designed to enable existing power plants to burn fossil fuels with virtually no air emissions.

With many groups searching for solutions to pollution, the team at ThermoEnergy recognized that traditional pollution control techniques had been perfected and a different physical process was needed for zero air emissions from the combustion of fossil fuels.

"The initial direction we went in was different" says Alex Fassbender, inventor of the TIPS process. "We observed that the capture of CO₂ in a useful form changes the thermodynamic endpoint of combustion-fueled power generation. The capture of CO₂ in a useful form requires a compression step at some point. Rather than combust fossil fuel and then use capital and parasitic power to clean up particles, acid gases, mercury and CO₂ sequentially, TIPS integrates all of these functions into a system that simultaneously recovers the heat of vaporization from both the entrained and produced water from fossil fuel combustion.

"TIPS pays the capital and parasitic power costs up-front by separating the air. The CO₂ capture compression step is performed during the air separation process. When we implement TIPS as envisioned, we have a power plant with no air emissions and facilities that can clean up their own solid and liquid wastes. The ash becomes a product, the acids are recovered and the water cleaned. By controlling all of the emissions, the regulatory risk from a combustion standpoint is also controlled."

Necessity strikes again

The TIPS process works by elevating the pressure at which combustion and exhaust gas cleanup occurs. The elevated pressure increases the temperature at which steam condenses into water to a temperature significantly above the ambient temperature of the cooling water used at power plants. This elevated pressure also raises the temperature at which CO₂ will condense into a liquid to a temperature above the ambient temperature used at most power plants.

The combustion exhaust gases are cooled with hot water, a portion of which becomes steam. Once cooled, particles are removed by steam hydroscrubbing or nucleate condensation. The cleaned exhaust gases are further cooled and the nucleate condensation process repeats as the CO₂ is condensed into a liquid. Volatile mercury compounds and acid gases such as NO_x or SO_x condense at pressure and temperature regimes between water and CO₂, and are removed as the CO₂ condenses.

Brian Rustia, senior program manager for Civil Engineering Research Foundation, which has a contract with EPA to look at environmental technology, sees TIPS as a promising technology.

"Coal is an abundant resource but its power generating technology is a hundred years old" Rustia says. "To switch to a system like this that will meet all air standards and create a resource makes sense and is a great alternative."

TIPS came about in the midst of an existing expertise in hydrothermal technologies. Fassbender previously invented a dual shell pressure balanced reactor and had been working in the area of pressurized systems for some time. When asked to look into energy production, Fassbender noticed that many of his peers were looking at super critical water oxidation (SCWO), which uses an enclosed pressurized system and offered the potential for different physical processes and unit operations.

"The more we looked at it, the more challenging it became from an engineering standpoint;' Fassbender says. "When you traverse the critical point of water, the pressure is quite high. Then the properties of water change radically and dissolved solids can cause a lot of problems."

Fassbender then asked himself, what if, rather than super critical water, we used super critical CO₂?

"Basically, it all fell out from there" Fassbender says. "We did the math, put some balances and flows together and looked at the equipment required. It was all pretty much do-able."

So far, everyone Fassbender's team has talked to believes it can be done. Each individual piece of process equipment either in or similar to those in the TIPS process has been built and operated at industrial scale. Large pressure vessels in the oil refining and chemical industries handle both higher temperatures and pressures.

Of course, TIPS is going up against technology that has billions of dollars of development over generations to get to the current state of development and, according to Fassbender, this is not where it needs to be.

"If clean coal were a solved problem, natural gas would probably not account for 90 percent of all new power plants being built," he adds. "We'll do a lot more optimization, but we don't believe we have to invent a whole new technology to make this work.

Birth of a process

TIPS' first step is to separate the air and pressurize the system--then combust. Although there is a parasitic power loss to separate the air and pressurize the system, the flipside is all the down-stream side (cleanup) is prepaid for. Everything is a lot easier.

"We use different physics" Fassbender explains. "The physics of the condensing heat exchanger is not reduced if there is a small number of particles. If you have a filter system, you get diminished returns. With TIPS, the small number of particles doesn't matter." CANMET has demonstrated essentially complete removal of particles using this technique at atmospheric pressure.

An example of a basic application for TIPS is a coal-fired boiler that has some pretreatment and aftertreatment, and no emissions. The two main products that will result from the process are CO₂ in a form that's useful, a reasonably pure liquid and of course, electricity.

"We see it appropriate for the retrofit market," Fassbender says. "We could probably build much of the TIPS plant onsite while the existing plant is still running."

An example of a TIPS retrofit: For existing coal-fired plants, the only modifications required are the addition of an air separation plant and replacing the combustion boiler and exhaust train--the remaining portions of the plant would still be usable.

Since the process does condense water, there is less penalty for wet fuel. This means wet coal and even municipal solid waste can recover the latent heat of vaporization of both the entrained and produced water. When a wet fuel is burned, part of the energy has to go into vaporizing the water, which usually goes up the stack. Coal doesn't have much hydrogen or produce much water but municipal solid waste produces water in gaseous form. TIPS will recover the heat of vaporization of that water, according to Fassbender.

"Recent studies in the last five years showed that CO₂ sticks to coal better than methane," Fassbender says. "You can actually push CO₂ down into the coal seams and you can displace the methane. The use of CO₂ for enhanced oil recovery is well known. If one has a large stream of very cheap CO₂ in a useful form, pressurized to the point where one can inject it into the ground, it is possible to sequester a large amount of CO₂ on coal seams and generate coal-bed methane in collection wells."

Using CO₂ to saturate the coal seam will reduce the amount of methane in the atmosphere in the vent the coal is mined. Less methane gets into the atmosphere and no CO₂ since the liquid CO₂ is directly used and not emitted into the atmosphere. With the amount of CO₂ this system would produce, CO₂ could quickly become a low-cost commodity.

Rustia agrees that switching to clean technology should be a no-brainer.

"Even if TIPS were more expensive than existing technology, the benefits might make people change their minds because it creates a commodity" adds Rustia. "Not to mention that it is a dean technology. Who wants to be downstream of a coal plant with all that pollution?"

Fassbender agrees that the CO₂ commodity will be an incentive.

"The technology exists to change the way a lot of things are done if one uses CO₂ as a solvent instead of water," Fassbender adds. "There are a lot of smart people out there working on uses for CO₂ and with a technique like TIPS, vast quantities would be produced. Even if the CO₂ still winds up in the atmosphere, a CO₂ solvent system will displace other pollutants."

Currently, ThermoEnergy is working to get funding to develop several different computer models of the technology in action. The model should be well under-way in a year.

"The first model we do will be an overall process model," Fassbender says. "With a process-model software, we will answer a lot of `what ifs,' this coal vs. that coal, if the coal was wet, etc., and see what this does to flow and equipment so we could do some preliminary sizing. Based on this, we can go out and get preliminary bids on equipment and estimate cost. Second, is to do a computational fluid dynamics model CFD, of combustion at pressure. After that, we're ready to go into testing and design."

ThermoEnergy plans to participate in a TIPS testing program through the Environmental Technology Evaluation Centers, a non-profit organization partially funded by EPA once the pilot plant is implemented. Optimism is high for all parties.

The feeling of having invented what may be a key solution to power-generating emission pollution does have its human rewards also.

"I feel, when I talk to another scientist who has an open mind, it's surprising how positive the responses have been," Fassbender explains. "Elation comes from constituency acceptance and that we might be on the track to contributing to the future solutions to providing energy to our economy with minimal consequences to the environment."

About humudufiers. Continue....

ISOTHERMAL HUMIDIFIERS

Utilizing a constant temperature, isothermal humidifiers use thermal energy to generate steam, which is introduced into the supply-air stream or directly into a space.

Isothermal humidifiers can be classified into one of two groups, based on the pressure of the vapor or steam and the method of steam generation and injection:

• Boiling-water-vapor injection, which inject a vapor at atmospheric pressure into an air stream.

• Direct-injection steam jacketed (double-wall distribution tube), which introduce 5- to 10-psig steam generated in a central boiler plant or “clean-steam” generator into an air stream.

Boiling-water-vapor-injection type

Electric. At least two types of electric humidifiers are available: electrode and heating element. With both, steam is generated from a wall, floor, or ceiling location and delivered to the supply-air stream via a dispersion assembly.

An advantage of boiling-water-vaporinjection- type humidifiers is that they introduce chemical-free vapor into air streams. Disadvantages of these units include:

• Additional space needs.

• The cost of the equipment.

• Wiring and controls.

• The need for additional water because of drainage.

• The additional cost of the emergency- power system.

• Sensitivity to water impurities.

With an electrode-type unit, the use of water with a high mineral content will result in the need to replace the canisters or clean them frequently, while the use of water with a low mineral content likely will cause the unit to malfunction, as it relies on water conductivity to operate.

Because current does not pass through water in heating-element-type units, purified water may be used to improve performance and greatly reduce maintenance.

Electric humidifiers primarily are used in existing facilities, where only a few are needed. However, they also may be considered where humidification requirements are limited and energy consumption is low.

Gas-fired. Because of an inability to vent the flue or provide combustion air, the use of gas-fired humidifiers often is limited to single-story facilities, where only a limited number of units need to be installed.

Steam-to-steam. In steam-to-steam humidification, steam is delivered from the central boiler plant to a wall-, floor-, or ceiling-mounted converter, where it passes through a heat exchanger, boiling makeup water and generating steam. That steam is conveyed via vapor piping to ductwork and dispersed into the air stream.

When potable water is used, minerals and other impurities are deposited as scale inside the water tank and on the heating coil, reducing the efficiency of  the humidifier. To minimize this problem, the use of automatic flush valves and softened or deionized water is recommended.

Disadvantages of steam-to-steam humidifiers include:

• Additional space needs.

• The cost of the equipment.

• The additional costs of makeupwater and drainage piping.

• The need for additional water because of drainage.

• Water-treatment equipment. If steam is available on site, advantages of steam-to-steam humidifiers are:

• Low energy cost.

• Humidification vapor as pure as the makeup water.

Direct-injection-steam-jacketed type A direct-injection-steam-jacketed humidifier injects live steam into the air for humidification by a distribution manifold. Steam flows through the outer jacket of the distribution manifold— keeping it hot to prevent condensate formation—into a condensate separator, through a control valve, and into the inner tube of the distribution manifold. From there, it is discharged through holes into the air stream.

Clean steam. An advantage of clean steam is that it is free of boiler-treatment chemicals. Disadvantages include the need for stainless-steel steam and condensate- system piping and components and the need to treat makeup water in reverse-osmosis or deionization equipment.

Central-plant steam. Compared with other vapor and steam systems, centralplant systems with direct-injectiontype humidifiers are the best controlled and have the lowest first and operational costs. These systems, however, have a major drawback: Boiler steam carries chemicals used for corrosion control. These volatile neutralizing amines pass through the humidifiers and into air supplies. Proper maintenance and monitoring procedures must be implemented to achieve low ambient-air concentration of amines.

HUMIDIFIER SELECTION A number of considerations go into humidifier selection:

• Technologies. The specifying engineer should be thoroughly familiar with all available humidification technologies and methods and understand performance characteristics, product features, utility requirements, and proper applications.

• Codes and standards. For a given application, code may prohibit the use of a particular type of humidifier. For example, some states allow only dry-steam humidifiers in health-care facilities, while other states make exceptions for computer rooms in these buildings.

• User preferences and requirements. For example, some large users have adopted Legionella-prevention policies that allow the installation of steam humidifiers only, thus prohibiting the use of adiabatic-type humidifiers.

• Humidifier capacity. Location, project type, and outdoor and indoor conditions should be analyzed to determine the capacity of a humidifier.

• Application. The application determines the humidification process and moisture-delivery method. (See Table 1 for recommended applications.)

• Availability of central steam. If steam humidification is required, but the central steam boiler is not available, then local electrical and electronic humidifiers should be considered.

• Chemicals in central-boiler steam. Chemicals in central-boiler steam may make steam unsuitable for direct injection. In such cases, steam-to-clean-steam converters must be considered.

• Relative cost of gas and electric power. The choice of gas or electric power should be based on a life-cycle-cost analysis.

• Maintenance. The intensity of maintenance should be considered in a lifecycle- cost analysis.

• Water quality. The use of potable or deionized, demineralized water should be verified with the equipment manufacturer. For deionized water, corrosionresistant stainless-steel components should be specified.

• Cost of water. When water carries dissolved minerals in excess of 120 ppm, a water-treatment system should be considered. Also, the most efficient humidifier should be selected to minimize water consumption.

• Availability of compressed air. When compressed air of a required pressure and purity is available, compressedair/ water-nozzle humidifiers should be considered.

• Availability of emergency power. In applications such as health care, humidification must be on emergency power.

• Cooling effect. The cooling effect of adiabatic-type humidifiers should be considered as heating-plant capacity is determined.

EVALUATING COMPETING PRODUCTS

Only humidifiers utilizing the same humidification process (adiabatic or isothermal) can be considered in an evaluation of equivalency. Characteristics that come into play in such a comparison include:

• Performance, including capacity,  efficiency, and dispersion distance.

• Quality of the distributed mist or fog, based on the size of the droplets.

• Controls (electric or pneumatic, modulating or on/off).

• Water consumption attributed to the drainage cycle. As local, self-contained steam humidifiers produce clean steam, minerals in the incoming water are left behind, increasing the water-conductivity level. To maintain the conductivity required for proper operation, the cylinder must be drained automatically. Drained boiling hot water is tempered before leaving the humidifier and being discharged into the sewer, as required by code.

• Steam, water, and air pressure and consumption.

• Materials of the humidifier components.

• Maintenance requirements.

• Installation requirements.

• Dripping potential. Atomizing heads in pneumatic systems using only air under pressure and drawing water from non-pressurized tanks often drip  at the end of the “on” cycle, while dual pneumatic atomizing heads using air and water under pressure tend to drip on “start-up.” A system should include controls to prevent dripping. Products without a non-drip feature should not be accepted.

• Dusting potential. Potable water used in atomizing humidifiers contains soluble and insoluble minerals and impurities. When an atomized water droplet evaporates in air, it leaves behind a white dust made up of these impurities. The amount of this dust depends on the quality of the potable water. If dusting is unacceptable, water must be purified. Other types of adiabatic humidifiers, such as wetted media, do not present a dusting problem.

• Disposability or reusability of components. Engineers should specify equipment with cleanable, reusable components.

CONCLUSION

The specifying engineer must learn about all available humidification technologies and base his or her specifications on the fundamentals of humidification theory, requirements of the project, the project budget, and costs of the products and utilities involved.

I want to talk about humudufiers. Do not why )

Let's start the show now!

So. Humidification is used to improve comfort, control static electricity, and maintain relative-humidity (RH) levels. Applications include health-care facilities, computer rooms, museums, refrigeration warehouses, and food-processing plants.

As diverse as the areas they serve are humidification units themselves, utilizing various processes and methods of moisture delivery.

This article will discuss humidification processes, available technologies, and factors to consider when evaluating competing products.

HUMIDIFICATION PROCESSES

Basically, there are two processes of humidification: adiabatic and isothermal.

In the adiabatic process, the energy required for evaporation is obtained from ambient air. This process is characterized by constant enthalpy. While enthalpy remains constant, the moisture content of the air increases, and the temperature decreases.

The isothermal process, on the other hand, involves the addition of energy for the evaporation of water. Isothermal steam humidifiers increase the enthalpy of air, but do not change air temperature.

ADIABATIC HUMIDIFIERS

In adiabatic humidifiers, water can be circulated and returned to the reservoir or sprayed and not returned.

Some adiabatic humidifiers use mechanical energy to generate fog or mist of water particles. These particles absorb heat from air and evaporate. This process adds moisture to air and lowers its temperature, thus, providing a cooling effect. This effect must be considered in the determination of the heating capacity of a system.

Adiabatic humidifiers can be classified into one of two groups, based on their method of introducing water into air:

• Atomizing, which fracture water into particles 1 to 200 microns in size and discharge the particles directly into the air stream, where they evaporate.

• Evaporative, which evaporate water before introducing it into the air stream.

Atomizing type

Ultrasonic. In ultrasonic humidifiers, electronic oscillation is converted to mechanical oscillation using a piezo disk immersed in a reservoir of mineralfree water. The mechanical oscillation is directed at the surface of the water, where it creates—at very high frequencies—a fine mist of 1-micron water droplets.

Immersion-type germicidal ultraviolet (UV) lamps can be mounted inside the stainless-steel water tanks of humidifiers. The tanks drain automatically when not in operation.

Advantages of ultrasonic humidifiers include:

• Lower energy consumption than with electrical steam humidifiers.

• Lower system cost than with electrical steam humidifiers.

• Additional cooling effect.

• Low-temperature humidification.

Disadvantages of ultrasonic humidifiers include manufacturer-recommended use of mineral-free, deionized, or reverse-osmosis treated water.

Ultrasonic humidifiers are well-suited for dataprocessing centers, cleanrooms for electronics and pharmaceutical manufacturing, and telecommunications centers. They also work well in the refrigerated storage of fruit and vegetables, food processing and storage, the cultivation of mushrooms, plant nurseries, orchid culturing, wine cellars, the storage of cut flowers, and other industrial applications.

Centrifugal. Centrifugal humidifiers draw water from the reservoir onto large rotating discs. Centrifugal force accelerates the water across the discs and throws it against an atomizing screen. Water is fractured into non-wetting particles of 5 to 10 microns and discharged directly into the air, where it evaporates, creating an even distribution of droplet-free mist throughout the room.

For easy maintenance and cleaning, air used by a centrifugal unit is drawn through a built-in filter, which protects working parts from dust and dirt in the air.

Advantages of centrifugal humidifiers include:

• Lower energy consumption than with electrical steam humidifiers.

• Lower system cost than with electrical steam humidifiers.

• Additional cooling effect.

• Work with reverse-osmosis or demineralized water, as well as potable water.

• Charcoal filters.

• Safety overflow or level control.

• Automatic flushing device.

Disadvantages of centrifugal humidifiers include a lack of provisions for UV and other germicidal devices that would prevent algae formation in the reservoir.

Centrifugal humidifiers work well in the lower capacity ranges (several pounds per hour) and may be used locally to store and protect perishables and raw and finished goods. Also, they are well-suited for use on a room-by-room basis in small laboratories, tobacco humidors, and greenhouses.

Compressed air/water nozzle. A pneumatic atomizing system that uses only air under pressure and draws water from open, non-pressurized tanks is called a gravity system. It is susceptible to algae and bacteria growth in the tanks. A system that uses both water and air under pressure typically is called “dual pneumatic,” as it utilizes dual pneumatic atomizing heads. Minimum water and air pressure, consumption, and droplet size vary from manufacturer to manufacturer.

Advantages of compressed-air/water-nozzle humidifiers include:

• Lower energy consumption than with electrical steam humidifiers.

• Lower system cost than with electrical steam humidifiers.

• Additional cooling effect.

• Reduced maintenance with use of reverseosmosis or demineralized water with all-stainlesssteel construction.

• Use of control cabinets.

• Fail-safe shutdown upon loss of air.

• Various control options.

• Connection to building-automation system.

Disadvantages and limitations of compressedair/ water-nozzle humidifiers include:

• The relatively high cost of oil-less compressors and water pumps.

• The energy consumed by the compressors and pumps.

• Mineral fallout, or “dusting.”

• Sensitivity to distance for proper evaporation.

• Water-quality limitations.

• Noise.

• Sensitivity to dirty, unfiltered, and oily air.

Compressed-air/water-nozzle humidifiers work well in greenhouses, cold storage, woodworking, the printing and paper industry, textile-manufacturing areas, cleanrooms, and other industrial applications in which a large amount of humidification is required.

Evaporative type

Because no droplets of water enter the air stream, minerals remain in evaporative humidifiers and must be removed periodically by cleaning, blowdown, and continuous bleed-off. On the positive side, no mineral fallout or “dusting” is experienced with this type of humidifier.

Wetted media. Among the most popular materials for evaporative cooling and humidification are specially impregnated and corrugated cellulose sheets with different bonded flute angles. This design yields a cooling/humidification pad with high evaporative efficiency, but relatively low pressure drop.

A water-distribution system allows uniform supply of water to the cooling pads to minimize dry spots.

Advantages of wetted-media humidifiers include:

• Lower energy consumption than with electrical steam humidifiers.

• Lower system cost than with electrical steam humidifiers.

• Additional cooling effect.

• No mineral carryover.

• Low scaling.

• Use of potable water.

Disadvantages of wetted-media humidifiers include:

• Potential microbial contamination from water being drawn from an open tank.

• High water consumption because of continuous bleed-off and periodic blowdown.

• Additional air-pressure drop from evaporative media being mounted in an air stream.

Air washers. Air washers pass air over a continuous film of water. Because high levels of humidification cannot be achieved with this method, it is less popular than the wetted-media approach.

Thanks for your attention. To be continued...