The growth of natural refrigerants such as ammonia and CO2 in industrial and commercial facilities, and the regulatory restrictions that accompany their use will be a central topic of discussion in technical papers to be presented at this year’s IIAR Annual Conference in San Diego.

Rajan Rajendran of Emerson Climate Technologies will provide a summary of the variety of refrigerant options, both natural and synthetic, and what the future holds for ammonia and CO2 .

Since the Montreal Protocol went into effect in 1989, resulting in the phase-out of ozone-depleting chemicals, ammonia has remained the standard refrigerant of choice for industrial applications. Technological advancements in electronics and software have made natural refrigerant systems even more efficient.

But, Rajendran points out, synthetic refrigerants will not disappear from the landscape.

“There was a time when people thought synthetic refrigerants in nonindustrial applications would be completely wiped out, but the chemical companies have figured out how to develop very low GWP (global warming potential) fluids,” he said. “While natural refrigerants will become more important, they are not going to replace all synthetics. Synthetic refrigerants are not going to give up their territory without a fight.”

As recently as five years ago, the airconditioning and refrigeration applications were dominated by a handful of refrigerants, including ammonia in large industrial systems. Today, CO2 as a refrigerant in stationary refrigeration has grown in usage and acceptance in Europe and Australia and is making inroads in North America.

Rajendran said that CO2 will play a major role in supermarket refrigeration, especially in cold climates where the periods of trans-critical operation are limited to a few days in the year. The cascade refrigeration system will also become common, he said.

Ammonia will continue to play a dominant role in industrial refrigeration, he added. Although the future will offer more refrigerant options than ever before, Rajendran cautions against making choices that could lead to “unintended negative consequences.”

“These are not black-and-white choices,” he said. “Many people are looking at natural refrigerants as a safe bet against government regulations.”

A proposal to amend the Montreal Protocol to regulate the GWP content of all synthetic refrigerants will lead to growth in the use of ammonia and CO2 , he added.

Kurt Liebendorfer, vice president of Evapco, Inc., will address the issue of government regulations in a paper that explores the regulatory and code implications for low charge ammonia systems.

“Kurt’s paper ties in nicely with Rajan’s,” said Eric Smith, IIAR vice president and technical director. “Rajan makes the case that ammonia is a great option, and Kurt’s paper lays out the sticking points for what you have to overcome to implement an ammonia system. It gathers all the requirements from the codes, standards and regulatory agencies in one place for people to reference.”

OSHA, IIAR, ASHRAE and others have various regulations and standards related to the quantity of refrigerant in a system, along with specific actions or designs that must be followed, said Liebendorfer.

His paper identifies these regulated threshold quantities so that designers, contractors and end users can better understand the various threshold requirements. Liebendorfer calls his paper a “building block.”

“The demand for reduced ammonia charges is being driven by regulatory pressures,” he said. “So we need to know what the codes say and what the criteria are. Is some of that driven by the amount of ammonia in the system? I found that there isn’t much said that relates to charge quantity. But maybe there should be. That’s why I’m presenting this paper.”

Liebendorfer points out that the current criteria are driven solely by ammonia safety. For instance, for every pound of ammonia release through a system’s highest capacity relief valve, a water diffusion tank must hold two gallons of water, with no current threshold quantity for the diffusion tank. “If you have a lowcharge system with 500 pounds of ammonia, is that a permissible threshold?” he asked. “There probably should be more threshold quantities that allow for the relaxation of certain requirements if you have low quantity ammonia, because there is less risk.”

In researching his paper, Liebendorfer was surprised to learn that there are not regulatory exemptions or allowances when designing a lowcharge system. “This paper is a blueprint for what designers must know to meet codes and regulations. The underlying theme is they pretty much have to do the same as larger charge systems,” he said. “But maybe there should be allowances. This paper is a tool to continue the dialogue.” In related technical papers, Stefan Jensen of Scantec Refrigeration Technologies will present a case study on the operation of a cold storage facility with a direct expansion ammonia system, while John Ball, the former chief design engineer at Luke Air Conditioning, and Klaus Visser, the founding principal of KAV Consulting Pty Ltd., explore using evaporative condensing for CO2 .

“The theme in all these papers is analyzing and implementing the use of natural refrigerants in the changing landscape of our industry,” Smith said.