Choosing Alternatives

What is the best retrofit blend for HCFC-22? Technicians and equipment owners are asking this question more often as we approach the next step down in the production of R-22. It sounds like a simple question, yet the answer will depend on several key factors.

There is a fundamental difference between air conditioning and refrigeration. That difference has to do with evaporator temperature. R-22 air conditioners, with evaporator temperatures between 35˚F and 50˚, will behave much differently than refrigeration systems running at 20˚ (medium temperature) or –20˚ (low temperature). Some blends will match R-22 properties in a/c and others will be better suited for lower temperature operations.

Another difference might be design capacity and run time for the intended application. Air conditioners are sized for the hottest few days of the year and will cycle considerably most of the time. A/C can tolerate lower capacity blends by simply running a little longer. Storage refrigeration applications are also sized for 18 to 20 hours run time during the day. Lower capacity blends can also be tolerated in these systems because there is allowance for longer run times. Where systems are sized to match the capacity of the load, or seem to be running all the time, blends with higher capacity will be needed to maintain equipment performance.

Smaller, self-contained refrigeration equipment or air conditioners will generally involve much less work to service or retrofit. If major components need replacement, it may often be easier to replace the entire unit, although replacement cost will also be a consideration. Blends that require component replacements or major oil changes may not be the best choice. Service of larger installations will more likely involve component replacement and planned retrofits can be more comprehensive in terms of leak repair, seal or gasket replacement, oil changes, or adjustments of controls, which opens up the choice of retrofit blend.

When doing your homework on R-22 alternative blends, don’t settle for a quick “one size fits all” solution. Depending on your application temperature, run time, and equipment size, you may find there are different answers to the question, “What should I use?”

Copenhagen Accord Doesn’t Clarify HFC Future

Even though the possible phase-down of HFCs factored into some discussions at the United Nations Framework Convention on Climate Change (UNFCCC) this past December in Copenhagen, the lack of meaningful results at the two-week international event did little to clarify those refrigerants’ future.

A scan of reports and blogs concerning the so-called Copenhagen Accord used comments like “a political statement, not a legally binding treaty,” “a climate circus,” and “clearly (falling) short of the grand scheme envisioned.”

United Kingdom Prime Minister Gordon Brown called the accord “a weak agreement” but said it was “a first step toward a new alliance to overcome the enormous challenges of climate change.” He said the Copenhagen deal requires countries to submit pledges to reduce greenhouse gas emissions by the end of January, but noted it is not a legal, binding agreement.

United States President Obama attended the conference for one day and at a plenary session said, “I’m confident that America will fulfill the commitments we have made; cutting our emissions in the range of 17 percent by 2020 and more than 80 percent by 2050, in line with final legislation.” He also said the United States would “engage in a global effort to mobilize $100 billion” annually in financing for climate-related aid to developing countries.

However, it appeared such efforts Obama was advocating were tied in with existing climate change legislative efforts within the United States, particularly Waxman-Markey, which continues to make slow progress in Congress.

“For all his usual fine words, he seemed to (be) admitting defeat on the prospects of a meaningful deal (at Copenhagen) and there were no new announcements,” said the Guardian newspaper in the United Kingdom.

In an evaluation of the Copenhagen event, Scott Barrett, professor of natural-resource economics at Columbia University said, “Failure by the U.S. Congress to pass climate legislation hindered progress in Copenhagen. What effect will Copenhagen have on the United States? It seems likely that the case for U.S. action has been harmed. Congress will not want the nation to adopt controls that are out of sync with those adopted by many other countries, especially China and India.”

Barrett was one of those following climate events who maintained the HFC aspect should not be part of broader global initiatives. “A better way to negotiate would be to break up this colossal problem (of climate change) into smaller pieces, addressing each piece using the best means appropriate.

“For example, we could negotiate a separate agreement limiting the emissions of HFCs.”

Alternatives for Commercial Refrigeration

by Joanna R. Turpin

Much of the focus lately has been about how the phaseout of HCFCs will affect air conditioning equipment; however, commercial refrigeration will also be significantly affected by the phaseout. Consider all the supermarket food cases, walk-in refrigerators/coolers/freezers, ice cream machines, beverage vending machines, and stand-alone food/beverage display cases that currently utilize R-22, and you’ll get an idea of the magnitude of that market.

The Environmental Protection Agency (EPA) has endorsed several acceptable alternatives to R-22, and some businesses have already started to transition to those refrigerants. Before any retrofit takes place, however, end users and contractors need to research which refrigerant to use, as well as how that refrigerant will affect the existing commercial refrigeration equipment. Refrigerant manufacturers weigh in on this debate by outlining the challenges end users and contractors may face during the phaseout, as well as details on the various types of alternative refrigerants currently available.

 This diagram clarifies the major differences between R-22 replacement refrigerants based on years of DuPont laboratory and field experience.

CHALLENGES AWAIT

There is no question that the HCFC phaseout will impact the commercial refrigeration market. Starting in January 2010, the HCFC consumption cap will be reduced by 58 percent from 2009 levels, significantly reducing the amount of production and imports of R-22 in the United States.

Based on EPA estimated service demand, this significant reduction in R-22 has the potential to create a 27.5-million-pound supply shortfall in 2010. This potential shortfall poses a risk to contractors and equipment owners who service and operate equipment that uses R-22, noted Joyce Wallace, North America marketing manager, DuPont Refrigerants, Wilmington, Del.

Wallace noted that several factors could reduce the potential severity of the shortfall, including the following:

• Additional R-22 supply due to fourth-quarter inventory build throughout the supply chain and/or accelerated conversions to new equipment.

• Reduced R-22 demand due to reduced leak rates and improved service practices, and/or increased recovery, recycle, and reclaim practices.

“While there is some uncertainty around the R-22 supply and demand market dynamics, one thing that is certain is the implementation of the HCFC consumption cap as of January 2010,” said Wallace. “Given the significance of the drop-in R-22 consumption cap, having a viable refrigerant management plan that protects the equipment owner from supply interruption and the possibility of volatile shifts in R-22 pricing is an essential part of an effective business plan for commercial refrigeration.”

With the elimination of R-22 in new commercial refrigeration equipment, owners will also have to start adapting to new HFC-based equipment, stated Gus Rolotti, technical marketing director, Arkema, Inc., King of Prussia, Pa. “Most equipment owners have already completed at least a partial transition to HFC-based equipment using refrigerants such as R-404A, R-507A, and R-134a. Equipment owners also may retrofit existing systems to HFC refrigerants such as R-427A. Finally, users of existing R-22 equipment should understand that R-22 is still allowed for service of existing units through 2020.”

Gordon L. McKinney, vice president/COO, ICOR International, Inc., Indianapolis, noted that the HCFC phaseout will most likely drive up the price on mainstream refrigerants such as R-22 and other interim alternatives that contain an HCFC.

“Equipment owners will be weighing their options carefully, but my guess is that unless the economy rebounds in very short order, most equipment owners will opt to repair rather than replace. Since there are a number of non-ozone-depleting HFC replacements for R-22 now available, existing R-22-designed equipment can be maintained for many years to come.”

AVAILBLE ALTERNATIVES

The type of alternative that should be used in a system will depend greatly on the application. DuPont’s Isceon® MO99™ can be used across a wide-range of evaporator temperatures. Speaking of replacement, there are a host of different fluids that can be used instead of HCFCs, and each has performance pluses and minuses, said Chris LaPietra, marketing manager, Honeywell Genetron Refrigerants, Morristown, N.J.

“Honeywell markets several HCFC alternatives that provide benefits such as good operating performance, no need for an oil change, and no need to adjust TXV valves. Differences in equipment design dictate different solutions; for example, it may be possible to successfully retrofit a piece of equipment that has oil separation technology with an HFC/HC and retain the original mineral oil, while the same blend will not perform well in equipment with vertical suction risers. Each retrofit customer is different, so we try to aim our products at the needs of different market segments.”

Alternative refrigerants can usually be applied to existing equipment, although differing degrees of modification will be needed. LaPietra noted that equipment owners should ask the following key questions before embarking on any retrofit:

• How efficient is the retrofit refrigerant?

• What is the capacity of the retrofit refrigerant?

• Will the retrofit refrigerant require a TXV change or adjustment?

• Will the retrofit refrigerant require an oil change?

• What is the global warming potential of the retrofit fluid versus the current HCFC?

Be aware that alternative refrigerants may not have the same performance characteristics as the refrigerant currently in use, warned LaPietra.

“There is a lot of talk about R-22 retrofits that will make systems perform the same as or better than R-22. Whenever such a statement is made, contractors and end users should start asking a lot of questions of the organization making the claim. Systems that were designed and optimized for R-22 will not perform the same with a retrofit refrigerant.

“Also keep in mind that the routine ‘tuneup’ that occurs during a retrofit will help improve performance. This performance benefit, however, would occur regardless of the refrigerant and should be included as part of a routine maintenance process.”

If the equipment is designed for a HCFC, chances are that using a HFC in that same system will impact the performance since the systems are not optimized for them, noted Rolotti. “Some refrigerants will have a greater performance difference than others, so owners will need to carefully evaluate the technical information to make educated decisions. For new equipment, since it can be specially designed and optimized for the new refrigerants, the new equipment with HFCs should be able to outperform similar equipment using HCFC.”

Rolotti noted that refrigerants such as Arkema’s Forane® 427A are designed to make the retrofit work easier, but there may be a small compromise in performance. Other refrigerants, such as R-404A, R-507A for low temperature or R-134a and R-407A can also be used but will require more elaborate changeover procedures, such as changing oils or possibly replacing expansion devices, he added.

ICOR offers its NU-22B® (R-422B) as a direct replacement for R-22 in medium-temperature refrigeration or air conditioning applications. “NU-22B is a non-ozone-depleting, nontoxic, nonflammable HFC and carries an A1 ASHRAE [American Society of Heating, Refrigerating, and Air-Conditioning Engineers] safety classification,” said McKinney.

“Since NU-22B’s operating characteristics closely resemble those of R-22, there are no major system modifications required. And unlike most HFCs, NU-22B is designed to work with standard mineral oil and therefore does not require a full or partial POE oil change.”

Another product from ICOR, One Shot®C (R-422C), is a non-ozone-depleting, nontoxic, non-flammable HFC designed for use as a direct replacement for R-502. McKinney stated that this replacement does not require any system modifications or oil changes.

“One Shot can also be used to replace R-22 in low-temperature refrigeration applications with only minor retrofit procedures required.”

The type of alternative that should be used will depend greatly on the application, as most refrigerants are not universally applicable across multiple evaporator temperatures, noted Wallace.

“One of the benefits of our newest product, Isceon® MO99™ is that it can be used across a wide range of evaporator temperatures. Isceon® MO99 is mineral oil-compatible and has R-22 pressure enthalpy characteristics, making it the lowest cost retrofit option. Extensive market feedback confirms that contractors prefer not to deal with the complexities and costs associated with POE oil as well as recent reports of plugging from partial POE alternatives.”
 
WORDS OF WISDOM

Cylinders are filled with R-410A, as the HVAC industry counts down to the January 2010 phaseout of R-22 in new equipment. (Photo courtesy of Arkema.)
The impending phaseout of R-22 will most likely raise concerns and questions among end users of commercial refrigeration equipment. Contractors can help allay their fears by providing information and suggestions on ways to cope with the new rules and regulations.

Due to the complexity of refrigeration systems and the broad variety of applications, contractors can help equipment owners carefully consider their unique situation. Rolotti noted that the first step is for end users to understand the regulations related to HCFC phaseout, and those have been detailed in numerous articles and discussions that contractors can share.

“The second step is to review the status of their existing HCFC equipment,” said Rolotti. “Factors such as the type and age of equipment will help determine which option to choose for the phaseout of R-22. The third step is for end users to discuss the situation with not only their contractor, but their equipment manufacturer, local wholesaler, and possibly a refrigerant manufacturer to receive a broad range of information to help make an informed decision. There are also many Websites, such as www.phaseoutfacts.org, that provide a broad range of information for equipment owners.”

McKinney cautions end users to weigh their options carefully. “Some HCFC alternatives have already been in use for several years now, so end users should request referrals and case studies on systems and applications similar to their own. Most importantly, end users should be sure that any system selected for conversion is in good operational condition prior to conversion. Converting a system to an alternative refrigerant will not cure any existing operational deficiencies.”

For applications with large amounts of refrigeration equipment, it is extremely important to have a comprehensive refrigerant management plan to transition away from R-22, said Wallace. This plan should focus on improved service practices including reduced leak rates; equipment replacement and retrofit; and recovery, recycle and reclaim programs.

“Contractors can help large equipment owners by doing their homework in advance, including working with select retrofit refrigerants to gain first-hand experience before the anticipated R-22 shortfall occurs. This will help them be ready to confidently recommend the best performing, lowest overall cost retrofit option, providing invaluable service to their customers for orderly and smooth transition away from R-22,” she said.

The phaseout of R-22 will no doubt cause some concern among end users of commercial refrigeration equipment, and they will be looking to their contractors to guide them through this time of transition. It’s a golden opportunity for contractors to share their wisdom and make themselves even more indispensable to their clients.

The Untypical Refrigeration System

by Dave Demma

While it might be fair to say that there is no such thing as a typical supermarket refrigeration system, there are commonalities between all systems that employ multiplex compressor racks. It is typical for the evaporator circuits in each supermarket to be combined into common saturated suction temperature (SST) groups, and connected to a multiplex compressor rack designed to operate within that specific temperature range.

It is also typical that there would be several SST groups in a supermarket. For example: medium-temperature (MT) fixtures/boxes at 15˚F and 25˚, and low-temperature (LT) fixtures/boxes at -13˚ and -23˚. It is also typical that there would be a variation of temperatures between the evaporator circuits within each suction group. The circuits connected to the 15˚ MT rack might vary in design from 15˚ for the service deli cases to 25˚ for the bakery walk-in cooler. These variations in design SST require some form of temperature control for each individual evaporator circuit.

But for the last five years, the supermarket industry has undergone a gradual shift in thinking regarding the preferred method for controlling evaporator discharge air temperature. You might call it an untypical … and more modern approach.

Mechanical evaporator pressure regulator (EPR) valves continue to have a strong following, and are still used in the majority of applications. However, the margin over the up-and-coming alternate choice — electric suction line regulators — is shrinking. As the name implies, this is a regulator that is installed in the suction line, and utilizes an electric step motor to drive the piston open or closed. Hence the name electric suction line regulator (Fig. 1).

In this story — the first of a multipart series regarding the changes taking place in supermarket refrigeration — we will look at some of those typical ways of currently doing business and what might be driving the changes that we will look at in future parts of this series.

EVAPORATOR SST

Evaporator SST is the temperature design criteria specified on the supermarket equipment legend. Maintaining a constant evaporator SST can be achieved with a mechanical EPR. It is designed to maintain a constant refrigerant pressure in the evaporator, which then maintains the constant SST. This will provide a fairly constant discharge air temperature, and has been the standard method of circuit temperature control dating back to the 1970s.

There are a few drawbacks to this method of circuit temperature control. There is no perfect correlation between SST and discharge air temperature. As the system conditions and/or the refrigeration load changes, maintaining a constant SST will result in some variation in discharge air temperature (Fig. 2).

This will not be problematic in all applications. Canned beverages and bottled water can certainly tolerate wider temperature swings without the risk of spoilage. In other applications, such as a fresh meat display, precise temperature control is essential for product integrity.

Additionally, more consistent discharge air temperatures may be required to satisfy the requirements of regulations such as HACCP (Hazard Analysis of Critical Control Points) begins with the evaluation of a situation, to assess the possibility of consumer health hazard.

Such an evaluation depends on three factors:

1. Does the product contain contaminant-sensitive ingredients?

2. Does its manufacturing involve a controlled process step such as sufficiently high temperature, pH change, or other process that can eliminate the hazard?

3. Does its distribution chain pose any potential hazard?

In the next step, critical control points (CCPs) are identified with maximum assurance. These are the locations in the processing plant where failure to prevent contamination can be detected through instruments such as recording thermometers.

Multiplex compressor racks are typically controlled by a central processor, commonly referred to as an energy management system (EMS). Amongst its many functions is the ability to control pressure and temperature parameters in the supermarket. It will monitor the evaporator discharge air temperature of each system, and might even have a provision to cycle off a liquid solenoid valve to provide a safety against a low-fixture temperature.

The EMS is capable of providing a control signal in response to a fixture discharge air temperature that has strayed outside of its set-point parameter. While this can be used to generate an alarm for monitoring purposes, the EPR set point cannot be changed with a simple control signal. A setting change of that nature would require an on site technician to make the adjustment.

Herein is the limitation of the mechanical EPR. While it does provide a fairly consistent discharge air temperature by maintaining a constant SST, it cannot be modulated by the EMS when the discharge air temperature strays outside of the design set-point parameter. The inability of the EMS to control the EPR can certainly cause the discharge air temperature to rise above or fall below the design set point.

While the main focus of temperature control is to ensure that the refrigerated product does not suffer a loss of integrity, or prematurely spoil, there is another aspect of display case and/or walk-in box temperature control that should not be overlooked: It is never necessary for the discharge air temperature to fall below the design set point. More importantly, when the discharge air temperature does fall below its set point, it is accomplished by an unnecessary expenditure of energy. 

PULLDOWN AFTER DEFROST

Figure 2. As the system conditions and/or the refrigeration load changes, maintaining a constant SST will result in some variation in discharge air temperature.

Every refrigeration circuit in the supermarket will undergo one or more defrost cycles per day. Regardless of the defrosting method employed (off cycle, electric, gas), the product temperature will be well above its design temperature set point upon termination of the defrost cycle. The evaporator will be under its highest load condition at the very moment the defrost cycle terminates.

EPR will immediately open to 100 percent of its stroke, quickly reducing the evaporator pressure. Once the circuit pressure has been reduced to the EPR set point, the valve will start to throttle in an effort to maintain constant pressure — its design function.

This will happen well before the discharge air temperature has reduced to the design set point. The reason is because the EPR maintains a constant pressure in the evaporator, and only indirectly maintains a relatively constant discharge air temperature. The EPR does not sense discharge air temperature and therefore can do nothing to respond and provide a quicker pull-down after defrost. It can prematurely throttle after the defrost termination in an effort to maintain its control parameter evaporator pressure.

SETTING THE STAGE

All this is setting the stage for increasing use of electric suction line regulators — and that will be the focus of the next installment in this series.

The Basic Refrigeration Cycle

Mechanical refrigeration is accomplished by continuously circulating, evaporating, and condensing a fixed supply of refrigerant in a closed system. Evaporation occurs at a low temperature and low pressure while condensation occurs at a high temperature and high pressure. Thus, it is possible to transfer heat from an area of low temperature (i.e., refrigerator cabinet) to an area of high temperature (i.e., kitchen).

Referring to the illustration below, beginning the cycle at the evaporator inlet (1), the low-pressure liquid expands, absorbs heat, and evaporates, changing to a low-pressure gas at the evaporator outlet (2).

The compressor (4) pumps this gas from the evaporator through the accumulator (3), increases its pressure, and discharges the high-pressure gas to the condenser (5). The accumulator is designed to protect the compressor by preventing slugs of liquid refrigerant from passing directly into the compressor. An accumulator should be included on all systems subjected to varying load conditions or frequent compressor cycling. In the condenser, heat is removed from the gas, which then condenses and becomes a high-pressure liquid. In some systems, this high-pressure liquid drains from the condenser into a liquid storage or receiver tank (6). On other systems, both the receiver and the liquid line valve (7) are omitted.

A heat exchanger (8) between the liquid line and the suction line is also an optional item, which may or may not be included in a given system design.

Illustration of the basic refrigeration cycle.

Between the condenser and the evaporator an expansion device (10) is located. Immediately preceding this device is a liquid line strainer/drier (9), which prevents plugging of the valve or tube by retaining scale, dirt, and moisture. The flow of refrigerant into the evaporator is controlled by the pressure differential across the expansion device or, in the case of a thermal expansion valve, by the degree of superheat of the suction gas. Thus, the thermal expansion valve shown requires a sensor bulb located at the evaporator outlet. In any case, the flow of refrigerant into the evaporator normally increases as the evaporator load increases.

As the high-pressure liquid refrigerant enters the evaporator, it is subjected to a much lower pressure due to the suction of the compressor and the pressure drop across the expansion device. Thus, the refrigerant tends to expand and evaporate. In order to evaporate, the liquid must absorb heat from the air passing over the evaporator.

Eventually, the desired air temperature is reached and the thermostat or cold control (11) will break the electrical circuit to the compressor motor and stop the compressor.

As the temperature of the air through the evaporator rises, the thermostat or cold control remakes the electrical circuit. The compressor starts, and the cycle continues.

In addition to the accumulator, a compressor crankcase heater (12) is included on many systems. This heater prevents accumulation of refrigerant in the compressor crankcase during the non-operating periods and prevents liquid slugging or oil pumpout on startup.

Additional protection to the compressor and system is afforded by a high- and low-pressure cutout (13). This control is set to stop the compressor in the event that the system pressures rise above or fall below the design operating range.

Other controls not indicated on the basic cycle which may be part of a system include: evaporator pressure regulators, hot gas bypass regulators, electric solenoid valves, suction pressure regulators, condenser pressure regulators, low-side or high-side float refrigerant controllers, oil separators, etc.

It is extremely important to analyze completely every system and understand the intended function of each component before attempting to determine the cause of a malfunction or failure.

Air Conditioning and Refrigeration History

But the engineering principle on which it is based, mechanical refrigeration, has had even more far-reaching effects, through both refrigeration itself and its close cousin, air conditioning. Taken together, these cooling technologies have altered some of our most fundamental patterns of living. Our daily chores are different. What we eat and how we prepare food have both changed. The kinds of buildings we live and work in and even where we choose to live across the whole length and breadth of the United States all changed as a result of 20th-century expertise at keeping things cool.

Look back for a moment to the world before the widespread use of refrigeration and air conditioning—a world that was still very much present well into the first decades of the 20th century. Only fresh foods that could be grown locally were available, and they had to be purchased and used on a daily basis. Meat was bought during the daily trip to the butcher's; the milkman made his rounds every morning. If you could afford weekly deliveries of ice blocks—harvested in the winter from frozen northern lakes—you could keep some perishable foods around for 2 or 3 days in an icebox. As for the nonexistence of air conditioning, it made summers in southern cities—and many northern ones—insufferable. The nation's capital was a virtual ghost town in the summer months. As late as the 1940s, the 60-story Woolworth Building and other skyscrapers in New York City were equipped with window awnings on every floor to keep direct sunlight from raising temperatures even higher than they already were. Inside the skyscrapers, ceiling and table fans kept the humid air from open windows at least moving around. Throughout the country, homes were built with natural cooling in mind. Ceilings were high, porches were deep and shaded, and windows were placed to take every possible advantage of cross-ventilation.

By the end of the century all that had changed. Fresh foods of all kinds were available just about anywhere in the country all year round—and what wasn't available fresh could be had in convenient frozen form, ready to pop into the microwave. The milkman was all but gone and forgotten, and the butcher now did his work behind a counter at the supermarket. Indeed, many families concentrated the entire week's food shopping into one trip to the market, stocking the refrigerator with perishables that would last a week or more. And on the air-conditioning side of the equation, just about every form of indoor space—office buildings, factories, hospitals, and homes—was climate-controlled and comfortable throughout the year, come heat wave or humidity. New homes looked quite different, with lower rooflines and ceilings, porches that were more for ornament than practicality, and architectural features such as large plate glass picture windows and sliding glass doors. Office buildings got a new look as well, with literally acres of glass stretching from street level to the skyscraping upper floors. Perhaps most significant of all, as a result of air conditioning, people started moving south, reversing a northward demographic trend that had continued through the first half of the century. Since 1940 the nation's fastest-growing states have been in the Southeast and the Southwest, regions that could not have supported large metropolitan communities before air conditioning made the summers tolerable

Mechanical refrigeration, whether for refrigeration itself or for air conditioning, relies on a closed system in which a refrigerant—basically a compound of elements with a low boiling point—circulates through sets of coils that absorb and dissipate heat as the refrigerant is alternately compressed and allowed to expand. In a refrigerator the circulating refrigerant draws heat from the interior of the refrigerator, leaving it cool; in an air conditioner, coils containing refrigerant perform a similar function by drawing heat and moisture from room air.

This may sound simple, but it took the pioneering genius of a number of engineers and inventors to work out the basic principles of cooling and humidity control. Their efforts resulted in air conditioning systems that not only were a real benefit to the average person by the middle of the 20th century but also made possible technologies in fields ranging from medical and scientific research to space travel.

Prominent among air-conditioning pioneers was Willis Haviland Carrier. In 1902, Carrier, a recent graduate of Cornell University's School of Engineering, was working for the Buffalo Forge Company on heating and cooling systems. According to Carrier, one foggy night while waiting on a train platform in Pittsburgh he had a sudden insight into a problem he had been puzzling over for a while—the complex relationship between air temperature, humidity, and dew point. He realized that air could be dried by saturating it with chilled water to induce condensation. After a number of experimental air conditioning installations, he patented Dew Point Control in 1907, a device that, for the first time, allowed for the precise control of temperature and humidity necessary for sophisticated industrial processes. Carrier's early air conditioner was put to use right away by a Brooklyn printer who could not produce a good color image because fluctuations of heat and humidity in his plant kept altering the paper's dimensions and misaligning the colored inks. Carrier's system, which had the cooling power of 108,000 pounds of ice a day, solved the problem. That same principle today makes possible the billion-dollar facilities required to produce the microcircuits that are the backbone of the computer industry. Air conditioners were soon being used in a variety of industrial venues. The term itself was coined in 1906 by a man named Stuart Cramer, who had applied for a patent for a device that would add humidity to the air in his textile mill, reducing static electricity and making the textile fibers easier to work with. Air-conditioning systems also benefited a host of other businesses, enumerated by Carrier himself: "lithography, the manufacture of candy, bread, high explosives and photographic films, and the drying and preparing of delicate hygroscopic materials such as macaroni and tobacco." At the same time, it did not go unnoticed that workers in these air-conditioned environments were more productive, with significantly lower absentee rates. Comfort cooling, as it became known, might just be a profitable commodity in itself.

Carrier and others set out to explore the potential. In 1915 he and several partners formed the Carrier Engineering Corporation, which they dedicated to improving the technology of air conditioning. Among the key innovations was a more efficient centrifugal (as opposed to piston-driven) compressor, which Carrier used in the air conditioners he installed in Detroit's J. L. Hudson Department Store in 1924, the first department store so equipped. Office buildings soon followed.  


Even as Willis Carrier was pioneering innovations in industrial air conditioners, a number of others were doing the same for comfort cooling. Beginning in 1899, consulting engineer Alfred Wolff designed a number of cooling systems, including prominent installations at the New York Stock Exchange, the Hanover National Bank, and the New York Metropolitan Museum of Art. The public was exposed to air conditioning en masse at the St. Louis World's Fair in 1904, where they enjoyed the air-conditioned Missouri State Building. Dozens of movie theaters were comfort cooled after 1917, the result of innovations in theater air conditioning by Fred Wittenmeier and L. Logan Lewis, with marquees proclaiming "It's 20 degrees cooler inside." Frigidaire engineers introduced a room cooler in 1929, and they, along with other companies such as Kelvinator, General Electric, and York, pioneered fully air-conditioned homes soon after.

Refrigerators did not represent quite as much of a revolution. Many people at the turn of the century were at least familiar with the concept of a cool space for storing food—the icebox. But true mechanical refrigeration—involving that closed system of circulating refrigerant driven by a compressor—didn't come along in any kind of practical form until 1913. In that year a man named Fred Wolf invented a household refrigerator that ran on electricity (some earlier mechanical refrigerators had run on steam-driven compressors that were so bulky they had to be housed in a separate room). He called it the Domelre, for Domestic Electric Refrigerator, and sold it for $900. It was a quick hit but was still basically an adaptation of the existing icebox, designed to be mounted on top of it. Two years later Alfred Mellowes introduced the first self-contained mechanical refrigerator, which was marketed by the Guardian Refrigerator Company. Mellowes had the right idea, but Guardian didn't make what it could of it. In 2 years the company produced a mere 40 machines.

Into the breach stepped one of the giants of the automotive industry, William Durant, president of General Motors. Realizing the potential of Guardian's product, he bought the company in 1918, renamed it Frigidaire, and put some of GM's best engineering and manufacturing minds to work on mass production. A few years later Frigidaire also bought the Domelre patent and began churning out units, introducing improvements with virtually each new production run.

Other companies, chief among them Kelvinator and General Electric, added their own improvements in a quest for a share of this obviously lucrative new market. By 1923 Kelvinator, which had introduced the first refrigerator with automatic temperature control, held 80 percent of market share, but Frigidaire regained the top in part by cutting the price of its units in half—from $1,000 in 1920 to $500 in 1925. General Electric ended up as industry leader for many years with its Monitor Top model—named because its top—mounted compressor resembled the turret of the Civil War ship-and with innovations such as dual temperature control, which enabled the combining of separate refrigerator and freezer compartments into one unit. 


Market forces and other concerns continued to drive innovations. Led by Thomas Midgley, chemical engineers at Frigidaire solved the dangerous problem of toxic, flammable refrigerants—which had been known to leak, with fatal consequences—by synthesizing the world's first chlorofluorocarbon, to which they gave the trademarked name Freon. It was the perfect refrigerant, so safe that at a demonstration before the American Chemical Society in 1930 Midgley inhaled a lungful of the stuff and then used it to blow out a candle. In the late 1980s, however, chlorofluorocarbons were found to be contributing to the destruction of Earth's protective ozone layer. Production of these chemicals was phased out and the search for a replacement began.

At about the same time Frigidaire was introducing Freon it also turned its attention to the other side of the mechanical refrigeration business: air conditioning. Comfort cooling for the home had been hampered by the fact that air conditioners tended to be bulky affairs that had been designed specifically for large-scale applications such as factories, theaters, and the like. In 1928 Carrier introduced the "Weathermaker," the first practical home air conditioner, but because the company's main business was still commercial, it was slow to turn to the smaller-scale designs that residential applications required. Frigidaire, on the other hand, was ready to apply the same expertise in engineering and manufacturing that had allowed it to mass produce—literally by the millions—the low-cost, small-sized refrigerators that were already a fixture in most American homes. In 1929 the company introduced the first commercially successful "room cooler," and a familiar list of challengers—Kelvinator, GE, and this time Carrier—quickly took up the gauntlet. Window units came first, then central whole-house systems. Without leaving home, Americans could now escape everything from the worst humid summers of the Northeast and Midwest to the year-round thermometer-busting highs of the South and desert Southwest.

At about the same time that both refrigeration and air conditioning were becoming significantly more commonplace, both also went mobile. In 1939 Packard introduced the first automobile air conditioner, a rather awkward affair with no independent shut-off mechanism. To turn it off, the driver had to stop the car and the engine and then open the hood and disconnect a belt connected to the air conditioning compressor. Mechanical engineers weren't long in introducing needed improvements, ultimately making air conditioning on wheels so de rigueur that even convertibles had it.

But as wonderful as cool air for summer drives was, it didn't have anywhere near the impact of the contribution of Frederick McKinley Jones, an inventor who was eventually granted more than 40 patents in the field of refrigeration and more than 60 overall. On July 12, 1940, Jones—a mechanic by training but largely self-taught—was issued a patent for a roof-mounted cooling device that would refrigerate the inside of a truck. Jones's device was soon adapted for use on trains and ships. Hand in hand with Clarence Birdseye's invention of flash freezing, Jones's refrigeration system made readily available—no matter what the season—all manner of fresh and frozen foods from every corner of the nation and, indeed, the world.

Small but incrementally significant improvements continued as the century unfolded, making refrigeration and air conditioning systems steadily more efficient and more affordable—and increasingly widespread. The range of applications has grown as well, with mechanical refrigeration playing a role in everything from medical research and computer manufacturing to space travel. Without, for example, the controlled, air-conditioned environment in spacecraft and spacesuits, humans would never have made it into space—or walked on the Moon—-even with all the other engineering hurdles overcome. But most of us don't have to go quite so far to appreciate the benefits of keeping cool. They're right there for us, each time we open the refrigerator door and reach for something cold to drink.

Air Conditioning and Refrigeration

Which of the appliances in your home would be the hardest to live without? The most frequent answer to that question in a recent survey was the refrigerator. Over the course of the 20th century, this onetime luxury became an indispensable feature of the American home, a mainstay in more than 99.5 percent of the nation's family kitchens by century's end. 

  
Air Conditioning and Refrigeration Timeline
  
Keeping cool has been a human preoccupation for millennia, but until the 20th century most efforts were ineffective. People tried everything from draping saturated mats in doorways to the installation of water-powered fans. Even Leonardo da Vinci designed and built a mechanical ventilating fan, the first of its kind. The modern system—involving the exchange of hot, moist air for cool, dry air by way of a circulating refrigerant—was first used in industrial settings. Indeed, a North Carolina textile engineer named Stuart Cramer, impressed with how the latest system of controlling the heat and humidity in his plant improved the cloth fibers, coined the term "air conditioning" in 1906. Since then comfort of cool is no longer considered a luxury but a fact of modern existence.

      1902~Comfort cooling system installed at the New York Stock Exchange

A 300-ton comfort cooling system designed by Alfred Wolff is installed at the New York Stock Exchange. Using free cooling provided by waste-steam-operated refrigeration systems, Wolff’s system functions successfully for 20 years.

      1902~First office building with an air-conditioning system installed

The Armour Building in Kansas City, Missouri, becomes the first office building to install an air-conditioning system. Each room is individually controlled with a thermostat that operates dampers in the ductwork, making it also the first office building to incorporate individual "zone" control of separate rooms.

      1904~A self-contained mechanical refrigerator is displayed at the St. Louis World's Fair

A self-contained mechanical refrigerator is displayed at the St. Louis World's Fair by Brunswick Refrigerating Co., which specializes in designing small refrigerators for residences and butcher shops. The ammonia refrigerating system is mounted on the side of a wooden icebox-type refrigerator.

Thousands of attendees at the World's Fair also experience the public debut of air conditioning in the Missouri State Building. The system uses 35,000 cubic feet of air per minute to cool a 1,000- seat auditorium, the rotunda, and various other rooms.

      1906~First office building specifically designed for air conditioning.

In Buffalo, Frank Lloyd Wright’s Larkin Administration Building is the first office building specifically designed for air conditioning. The system uses safe, nonflammable carbon dioxide as a refrigerant.

      1906~Patent filed for "dew point control" system

Willis Carrier files for a patent on his "dew point control" system. Carrier has studied the science of humidity control after designing a rudimentary air-conditioning system for a Brooklyn printing plant in 1902. This and subsequent designs allow him to devise a precise method of controlling humidity using refrigerated water sprays, thereby allowing the manufacture of air-conditioning systems to be standardized.

      1906~First air-conditioned hospital

Boston Floating Hospital becomes the first air-conditioned hospital, using a system designed by Edward Williams to maintain the hospital wards at about 70°F with a relative humidity of 50 percent. The hospital’s five wards are individually controlled by thermostats. Williams’s system features "reheat" in which cooled air is heated slightly to lower its humidity.

      1907~Air-conditioning equipment installed in dining and meeting rooms at Congress Hotel in Chicago

Air-conditioning equipment designed by Frederick Wittenmeier is installed in dining and meeting rooms at Congress Hotel in Chicago. This is one of the first systems designed by Wittenmeier for hotels and movie theaters. His firm, Kroeschell Brothers Ice Machine Company, installs hundreds of cooling plants into the 1930s.

      1914~Aircooled, electric, self-contained household refrigerating unit is marketed

Fred Wolf, Jr., markets an aircooled, electric, self-contained household refrigerating unit, the Domelre (Domestic Electric Refrigerator), in Chicago. The system is designed to be placed on top of any icebox, operating automatically using a thermostat. The first household refrigerating system to feature ice cubes, the Domelre uses air to cool the condenser, unlike other household refrigerators that need to be hooked up to water.

      1916~Flash-freezing system for preserving food products developed

Clarence Birdseye begins experiments in quick-freezing. Birdseye develops a flash-freezing system that moves food products through a refrigerating system on conveyor belts. This causes the food to be frozen very fast, minimizing ice crystals.

      1923~Electrically refrigerated ice cream dipping cabinet is marketed

An electrically refrigerated ice cream dipping cabinet is marketed by Nizer and shortly after by Frigidaire. These cabinets use a refrigeration system to chill alcohol-based antifreeze, which surrounds ice cream cans placed in wells in the cabinet. The alcohol is later replaced by salt brine.

      1927~Gas-fired household absorption refrigerators become popular

Gas-fired household absorption refrigerators that do not require electricity are marketed to rural areas in the United States. One, the Electrolux, marketed in Sweden since 1925, becomes very popular.

      1927~First refrigerator to be mass produced with a completely sealed refrigerating system

General Electric introduces the first refrigerator to be mass produced with a completely sealed refrigerating system. Nicknamed "The Monitor Top" for its distinctive round refrigerating unit, resembling the gun turret of the Civil War ironclad ship Monitor, the refrigerator is produced over the next 10 years and is so reliable that thousands are still in use today.

      1928~Chlorofluorocarbon (CFC) refrigerants are synthesized

Chlorofluorocarbon (CFC) refrigerants are synthesized for Frigidaire by the General Motors Research Lab team of Thomas Midgley, Albert Henne, and Robert McNary. Announced publicly in 1930 and trademarked as Freon, CFCs are the first nontoxic and nonflammable refrigerating fluids, making it possible for refrigerators and air conditioners to be used with complete safety.

      1929~First room cooler goes on the market

Frigidaire markets the first room cooler. The refrigeration unit, which uses sulfur dioxide refrigerant and has a capacity of one ton (12,000 BTUH), is designed to be located outside the house or in the basement.

      1930~Smaller air-conditioning units appear on trains

With the advent of the centrifugal chiller, smaller air-conditioning units become feasible for trains. In 1930 the Baltimore & Ohio Railroad tests a unit designed by Willis Carrier on the "Martha Washington" the dining car on the Columbian, running between Washington, D.C. and New York. To test the system, the car is heated to 93°F. The heat is then turned off and the air conditioner turned on. Within 20 minutes, the temperature in the dining car is a comfortable 73°F.

      1931~"Hot- Kold" year-round central air-conditioning system for homes on the market

Frigidaire markets the "Hot- Kold" year-round central air-conditioning system for homes. During the early 1930s, a number of manufacturers design central air conditioners for homes, a market that grows slowly until the 1960s, when lower costs make it affordable for many new homes.

      1931~ A heat pump air-conditioning system in Los Angeles office building

Southern California Edison Company installs a heat pump air-conditioning system in its Los Angeles office building. Since a refrigeration system moves heat from one place to another, the same principle can be used to remove heat in summer or add heat in winter by engineering the system to be reversible.

      1932~First overnight train with air conditioning

Chesapeake & Ohio Railroad begins running the first overnight train with air conditioning, the George Washington, between New York and Washington. Four years later United Air Lines uses air conditioning in its "three miles a minute" passenger planes.

      1936~Albert Henne synthesizes refrigerant R-134a

Albert Henne, coinventor of the CFC refrigerants, synthesizes refrigerant R-134a. In the 1980s this refrigerant is hailed as the best nonozone-depleting replacement for CFCs.

      1938~A window air conditioner using Freon is marketed

A window air conditioner using Freon is marketed by Philco-York. Featuring a beautiful wood front, the Philco air conditioner can simply be plugged into an electrical outlet.

      1939~Air conditioning offered as an option in a Packard automobile

Packard Motor Car Company markets an automobile with air conditioning offered as an option for $274. The refrigeration compressor runs off the engine, and the system has no thermostat. It discharges the cooled air from the back of the car.

      1947~Mass-produced, low-cost window air conditioners become possible

Mass-produced, low-cost window air conditioners become possible as a result of innovations by engineer Henry Galson, who sets up production lines for a number of manufacturers. In 1947, 43,000 window air conditioners are sold in the United States. For the first time, many homeowners can enjoy air conditioning without having to buy a new home or renovate their heating system.

      1969~More than half of new automobiles are equipped with air conditioning

More than half of new automobiles (54 percent) are equipped with air conditioning, which is soon a necessity, not only for comfort but also for resale value.

By now, most new homes are built with central air conditioning, and window air conditioners are increasingly affordable.

      1987~Minimum energy efficiency requirements set

The National Appliance Energy Conservation Act mandates minimum energy efficiency requirements for refrigerators and freezers as well as room and central air conditioners.

      1987~The Montreal Protocol

The Montreal Protocol serves as an international agreement to begin phasing out CFC refrigerants, which are suspected of contributing to the thinning of the earth’s protective, high-altitude ozone shield.

      1992~Minimum energy efficiency standards set for commercial buildings

The U.S. Energy Policy Act mandates minimum energy efficiency standards for commercial buildings, using research and standards developed by the American Society of Heating, Refrigerating, and Air Conditioning Engineers.