Unlike in most parts of Europe, it was another hot summer in the US. E&T looks at the state of air-conditioning engineering in the States and elsewhere in the world.
Summer in the US north-east may bring to mind rugged men sailing through the Cape, tanned cherubs building sandcastles or soft-shell crabs plucked fresh from the sea. But for those of us living here, the images belie a far less glamorous reality – the wretched heat and humidity.
In May, a heatwave hit southeastern Connecticut, causing many to worry that this could be a harbinger of yet another, perhaps even more dreadful, summer. The problem was much more acute for anyone struggling through the season without a proper air conditioner. I was one of those people.
But as temperatures soared above 39°C and the humidity was who-knows-what, the urgency to buy one of these energy-gobblers became increasingly clear. Yet, whether to relent – and thereby further damage the environment (and my electricity bill!) – was still indeterminate, especially since we Americans have a long way to go before our air conditioners become 100 per cent environmentally-friendly.
The late Willis Carrier, engineer and inventor of the first half of the 20th century, is a sort of ‘patron saint’ of the US coolant business. He started a modest engineering firm with a handful of partners, one which grew into a multi-city international business based out of Connecticut.
At the age of 25, Carrier had the first patent on a type of air conditioner that would presage the modern age of cooling. His design was tailor-made for a stuffy lithography plant in Brooklyn, New York, where the humid conditions ruined the pictures at the site. From there, he gained world renown, in part from his appearance at the 1939 World’s Fair, where his “igloo” drew rapt attention.
A lot has happened since 1939. Today’s machines would shock Carrier and his ilk, whose version of an air conditioner is reminiscent of the early computers that used to occupy a whole room.
No longer the mammoth machines of yore, today’s models are sleeker, more cost- and energy-efficient, and manufactured by companies that have mandates for controlling greenhouse gas emissions.
Vendors tout new – or new versions of old – technologies such as thermal cooling, which operates on a load-reduction premise.
Cooling methods from vendors in the space, such as Ice Energy and Trane, are hoping this changes the way Americans think of their coolers.
Trane has installed numerous “thermal storage” units in financial buildings such as Credit Suisse and Morgan Stanley in Manhattan.
Ice Energy, based in Windsor, Colorado, has monopolised restaurants, fitness centres, manufacturing plants and automobile dealerships. It promotes a hybrid cooling technology that integrates with standard AC units.
Ramachandran Narayanamurthy, director of research and innovation for the company, draws a distinction between what Ice Energy does and standard methods of air conditioning.
Ice storage air conditioning, he says, provides both energy and environmental benefits plus comfort. “The main reason you have air conditioning is to be comfortable, but the downside is that it drives power consumption when we have the least amount of power available on the electric grid.”
His method is to run the compressor and all the power-consuming elements overnight, storing the cooling that would normally be delivered into a building in the form of ice. He claims that this can cut power consumption by 95 per cent.
Todd Coulard, manager of the Energy Services division of Trane, says that with thermal storage and its subsequent lessening of energy consumption during the day, there is far less strain on an electric grid.
“If you look at air conditioning as a whole, I think it’s almost 30 per cent of the energy consumption of a building.” In the US, there are three such grids, with the Eastern grid being the oldest, and the one that has repeatedly failed in New York over the past few years.
Energy consultant Adam Hinge, a member of the American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. (ASHRA), concurs on thermal storage’s benefits. He says that, in the past decade or two, there has been a decided trend toward the use of thermal storage over traditional cooling methods.
This is, in part, because “as air conditioning loads grow, and the saturation of air conditioning goes into a whole lot more buildings, it’s having a fairly big effect on utility peak summer demands”.
But whether new twists, like thermal storage, solve old problems remains to be seen. Clearly, a block of ice won’t reverse the type of strain air conditioners have been putting on the environment since they gained widespread American popularity in the 1950s.
That said, America has been much more keen on protecting the environment than is sometimes given due.
Today, technology is furthering green efforts with a US Environmental Protection Agency mandate that by January 2010, ozone-depleting hydrochlorofluorocarbon-refrigerants will be greatly reduced.
Carrier was one of the leaders in this effort, but the other players are following suit. For example, Emerson Network Power – Liebert is phasing out its refrigerant R22 to the more environmentally-friendly refrigerant R407C in its cooling equipment.
Says Engineer Alan Goerke, a sales manager with Emerson: “R22 will no longer be available on new equipment industry- wide in 2010. We are also promoting more efficient cooling systems to save energy by cooling the heat load closer to the source with a liquid instead of air; since liquid is a more efficient heat transfer medium than air.”
For the past several years, many of the leaders in this area, such as HVAC behemoth Carrier, have shown a steady improvement.
This does not mean, though, that the newfangled air conditioners will reverse the damage already done: they still have an enormous way to go before they become truly energy efficient.
According to Engineer Fred Keller, a former Carrier consultant, there are many reasons why modern air conditioning still contributes to the carbon footprint.
“The new refrigerants we selected to replace the ozone-depleting ones are now a concern because they are global warming compounds,” says Keller.
These would be R-134a chillers and Puron R-410A-based residential products which do not contain chlorine and thus do not contribute to damaging the Ozone Layer, Keller points out.
He adds that “about 5 to 10 per cent of the total carbon emissions for the life of that air conditioner are due to the refrigerant. The other 90 to 95 per cent are due to the energy that the refrigerant will consume”.
Bruce Wollenberg, an engineering professor at the University of Minnesota, says a niggling problem is that designers have yet to manufacture a truly efficient air conditioner.
Over the past 20 years, there has been a push for more energy-efficient refrigerators, furnaces and air conditioners, Wollenberg points out. And yet, “We really have not begun to attack motors. Motors consume the largest part of the electrical use simply because every household has so many and they are what’s driving the industry”.
Consistent research has been done to make air conditioners more efficient, but it has not been concentrated enough. “The motors are rather inefficient; and the trouble is that making them efficient runs the cost up,” Wollenberg says.
By efficiency, he means that a fan, for example, will at best only use about 60 per cent of its cooling capacity – the rest is lost through the inefficiency of its motor. That is obvious, when one simply touches the back of the unit, Wollenberg points out. A similar problem is still occurring with other appliances, including air conditioners.
In the summer, this is particularly perplexing for air conditioning engineers.
Wollenberg’s students are most interested in what they can do to curb carbon emissions through their future designs.
Yet, carbon emissions are an entirely different matter from increasing the air conditioner’s efficiency.
As Keller put it: “There’s a lot of uncertainty as we look forward 15 to 20 years as to exactly what technologies we will be using in our air conditioners.”
In 1960, The Carrier Centrifugal Refrigeration Compressor, built in 1922, was donated to the Smithsonian Institute’s National Museum of American History in Washington, DC. The compressor truly presaged the age of air conditioning in America.
At the time, visionary Willis Carrier – the father of modern air conditioning in America – took technology developed in the US Civil War and fine-tuned the design.His system compressed refrigerant gas through centrifugal force created by fast-spinning rotors. This reciprocal compression caused the refrigerant to act on pistons inside cylinders – much like an automobile would.
Fred Keller, a long-time engineer with Carrier’s Indianapolis centre and now a consultant, says that this design was used for a tile factory in Upstate New York where they needed to control the humidity inside a lithography plant.
Keller says: “The development of the centrifugal compressor was a major achievement that started the air conditioning industry.”
Following the introduction of the compressor, systems were designed specifically for homes, whereas formerly it was mainly commercial properties such as movie theaters and large office buildings that had them.
Before this, Keller, points out, “places like movie theaters and department stores almost had to close down during the summertime because the temperature and humidity were just so stifling.”
The Smithsonian’s David Shayt in the institution’s Division of Work & Industry, which has oversight for the installation (currently in storage), says that the early-model refrigerator was used from the 1920s to the 1950s in the lithography department of Onondaga Pottery Company, Syracuse, New York.
“This pioneering machine was displayed in the Refrigeration Section of the Hall of Power Machinery in the Smithsonian’s new National Museum of History and Technology from 1964 to 2002,” says Shayt. “The Carrier now resides in one of our reference areas awaiting future uses.”
The 1891 Tampa Bay Hotel in Florida is now a museum, but back in the day, this National Historic Landmark was something else: screen legend Sarah Bernhardt sipped mint juleps on its expansive Georgian porch, while Teddy Roosevelt and other high-ranking officials strategised during the Spanish American War.
Why was this hotel so remarkable? Apart from its impressive architecture and location, builder Henry Plant had connected modern railroads to Tampa, which promoted growth in the region. Today, Plant’s passion for the railroad is evidenced by the beams in the hotel – which came from old railroad tracks.
Another draw, though, was the relatively cool temperature – an important factor during the hot, sticky summers. The Tampa Bay Hotel was designed to support nature’s air conditioner – the refreshing sea breezes. Sally Shifke, a museum representative, says that the mahogany-aligned windows have a brass chain that supports the cross-ventilation.
“The chain on the window and the way the windows opened is something that I think was part of the period,” Shifke says. While most of the museum is air-conditioned these days, the few non-air conditioned rooms are still cooler than outdoors, by about 10°C. Shifke points out that shade produced by the surrounding oak trees could also contribute to the temperature disparity.
The need to cool buildings is obviously not new. Everyone from Romans to Medieval Egyptians, Iranians, Chinese and Brits played a role in developing what would become the air conditioner.
Ancient Romans cooled down via circulated water from an aqueduct, while in China, members of the Song Dynasty used water-powered fan wheels and circulating jet stream water from fountains.
In Iran, then Persia, cisterns and wind towers helped cool buildings in a similar fashion to that used in Victorian Tampa Bay, Florida, catching wind and channeling airflows over a cistern and through a cooling tower. When cistern water evaporated, this cooled air in the building.
In the early 1800s, Michael Faraday compressed and liquefied ammonia to chill air upon evaporation. This prompted Florida’s Dr John Gorrie to use compressor technology to create ice – perhaps a precursor to today’s thermal storage methods.
Into the 20th century, Stuart Cramer, a textile mill worker, coined the term ‘air conditioning’ when he patented a technology to help offset the effects of the dry air issuing from his industrial work. In the parlance of the day it was called ‘water conditioning’. Then came Willis Carrier and his revolutionary centrifugal cooler, in 1922.
Many years later, in 1987, the Montreal Protocol was signed to protect the Earth’s ozone layer, establishing international cooperation on the phase-out of ozone depleting substances including CFC refrigerants used in HVAC equipment.
In 1997, the Kyoto Agreement took it a step further, with the aim of helping reduce overall greenhouse gas emissions worldwide. The US did not sign the agreement, but many Americans remain optimistic that a new political regime will reverse this decision.
Since then, many other countries have worked on perfecting the modern air conditioner. Japanese Sanyo has been a leader introducing the split-type air conditioner in 1961 and now helping reduce CO2 emissions, purportedly by as much as 30 per cent, with its solar air conditioning system.
In Australia and New Zealand, advances are being made in the way air conditioners are installed. With units positioned above office buildings, the firm won’t have to build a chiller plant room. Daikin Australia/New Zealand, for example, offers outdoor units that extend air conditioning capacity up to 54 HP through this type of technology.
Last February, the Japan Refrigeration and Air Conditioning Industry held a convention in Tokyo, extending the country’s commitment to reducing environmental damage through refrigerants. And last April, China put on its 19th annual refrigeration exposition in Shanghai, a sign that aircon engineering continues to gain momentum.
1889: Carnegie Hall equipped with a comfort cooling system that includes racks for ice.
1889: Passenger compartments of six Mississippi River steamboats air conditioned.
1906: Willis Carrier receives a patent for ‘An Apparatus for Treating Air’, for developing a system to control heat and humidity.
Stuart Cramer coined the term “air conditioning” to refer to conditioning of the environment for product manufacturing, rather than conditioning products themselves.
The Brooklyn Bridge subway station air conditioned.
1922: Carrier’s centrifugal air conditioner was introduced, presaging the age of modern air conditioning.
1931: First air-conditioned train route, The Columbian, run on the Baltimore and Ohio railroad.
1936: United Airlines uses air conditioning in its “three-mile-a-minute” passenger planes.
1939: Willis Carrier’s “igloo,” which includes a machine that chills water to air condition. Both this display and the neighboring DuPont display at the World’s Fair in New York City, offered a glimpse into the future of modern air conditioning.
1950s: Widespread adoption of a smaller, sleeker version of the air conditioner comes into American homes. In 1952, air conditioners come into tract homes.
1990s: A push for more energy-efficient & non-Ozone depleting appliances, including solar-powered air conditioners, as reported by the IEEE.
2010: Per the Montreal Protocol of Sept. 2007, the US will reach a 75 per cent level towards phasing out ozone-depleting hydrochlorofluorocarbon refrigerants (http://www.epa.gov/ozone/strathome.html).
2030: A full phase-out for US and other developed countries will be reached, with no importation or production of HCFCs.
Source: Stay Cool! Air Conditioning America (1 May, 1999 – 2 January, 2000); National Building Museum, Washington, DC (Writer/editor Natalie Shivers; Curator, Chrysanthe B. Broikos)
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