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Attempts to regulate the air conditioning (AC) and commercial refrigeration markets for the benefit of the environment are nothing new. During the past 25+ years, various legislative actions have limited the use of various refrigerants that depleted ozone or emitted greenhouse gases, both of which have been shown to contribute to global warming potential (GWP).
The most recent actions, including the EPA’s Significant New Alternatives Policy (SNAP) program and the much more recent American Innovation and Manufacturing Act (AIM), are further driving growth of low-GWP refrigerants. While this is good news for the environment, these low-GWP refrigerants are not without their own challenges. They may increase energy consumption, introduce added safety risks and require significant equipment modifications.
A history of efforts to benefit the environment
Refrigeration systems contribute to the emission of greenhouse gases when a leak occurs of a high-GWP refrigerant. The two refrigerants most commonly used in the early days of refrigeration were ammonia and carbon dioxide (CO2). Both proved to be problematic for different reasons. Ammonia is toxic and carbon dioxide requires extremely high pressures to operate in a refrigeration cycle.
As a result, both refrigerants lost popularity when Freon 12 (dichloro-diflouro-methane) hit the market. Among other benefits, Freon is extremely stable, non-toxic, and operates at moderate pressures. Unfortunately, it was also shown to have a high ozone depletion potential (ODP), which is the primary reason is has since been banned from use globally.
Numerous other refrigerants have also been banned through SNAP, which was established under the Clean Air Act to identify and evaluate substitutes for ozone-depleting substances. The EPA has since published numerous rules about what is and is not acceptable under SNAP, creating tremendous confusion in the industry. The policies established under SNAP took on greater meaning due to the AIM Act, which went into effect in 2020. The AIM Act requires the EPA to implement a phase down of the production and consumption of hydrofluorocarbons (HFC refrigerants) to reach approximately 15% of their 2011-2013 average annual levels by 2036. HFCs are of particular concern since they are classified as potent greenhouse gases that contribute to climate change.
Pros and cons of preferred low-GWP alternatives carbon dioxide (CO2) and propane (R290)
Tighter environmental legislation is opening the door for increased demand for low-GWP refrigerants.
Two of the more popular options on the market today are CO2 and propane (R290). Both have a long history in refrigeration but have recently again emerged as front-runners due to their low environmental impact. CO2 is the more commonly used for many reasons, including:
A key challenge of using CO2, however, is that it operates at a far higher pressure than other natural and synthetic refrigerants. This increases the risk of leaks which, in turn, necessitates the use of more durable, costly components and piping to handle the greater pressure and added controls and other safety features, many of which increase energy consumption due to high ambient temperatures.
As a hydrocarbon, R290 provides several equally attractive benefits, including superior thermodynamic properties and greater heat capacity. These combined characteristics allow R290 to absorb more heat at an accelerated rate, resulting in higher device energy efficiency with faster temperature recovery and lower energy consumption.
More importantly from an environmental standpoint, R290 (like all hydrocarbons) has no ozone depleting properties and a low GWP of 3. It is also compatible with materials commonly used in the construction of refrigeration and air conditioning equipment, is readily available and relatively inexpensive. It can be stored and transported in steel cylinders similar to how other common refrigerants are handled.
A major concern about R290 is that it’s highly flammable. That’s why refrigerant charge limits are in place, as well as other special safety standards when using R290.
Overcoming the challenges of CO2
The higher operating pressure of CO2 creates a few design challenges. But most of these can be overcome, albeit at a higher cost. Key are material upgrades, such as thicker-walled piping or high-strength K65 copper alloys.
Parker manufactures an array of valves, seals and controllers that are specially rated for CO2 high-pressure refrigeration systems. This includes pressure-rated electric expansion valves, ball valves with integrated pressure relief, stepper motor-driven pressure regulating valves, pulse width modulation valves that manage refrigerant flow and pressure-regulating gas cooler/flash gas bypass valves.
Steel piping is also being used in some instances for high pressure CO2 and the addition of electronic controls which can monitor and record pressures, temperatures and additional parameters. This includes pressure-rated electric expansion valves, ball valves with integrated pressure relief, stepper motor-driven pressure regulating valves, pulse width modulation valves that manage refrigerant flow and pressure-regulating gas cooler/flash gas bypass valves. The use of remote monitoring systems is growing. Not only is remote monitoring a safer option, but it is also in response to the current shortage of trained HVAC technicians, allowing companies to monitor multiple systems and locations with fewer workers.
Overcoming the challenges of R290
With the high flammability of R290, refrigerator manufacturers need to make the necessary system design changes to align with applicable UL and ASHRAE standards that include charge limits, marking requirements and ventilation requirements. System charges of up to 150 grams are currently allowed for most R290 applications, though a few are even lower. Proposed and under-revision UL safety standards seek to raise this limit as high as 500 grams for open refrigeration appliances, and 300 grams for closed appliances. While some systems or applications would remain with more restrictive charges, these increases promise to open R290 to many more applications and enable new applications.
To address flammability concerns, Parker manufactures innovative filter driers and thermostatic expansion valves (TEVs) that are designed to minimize the amount of refrigeration system charge when using flammable refrigerants.that are designed to minimize the amount of refrigeration system charge when using flammable refrigerants.
In addition, some system manufacturers use a sealed design that seals off the spark inside by isolating the R290 from the electrical switch assembly. This type of design reduces the potential for explosion by stopping the gas from entering the electrical switch compartment.
Another option is to fit the leak detection and control systems such that, when activated, it will pump down the propane charge into a liquid receiver and then shut off the electrical supply. If the compressor is enclosed, a ventilation fan must be installed and activated by the leak detection system to remove any gas that might leak from the compressor into the enclosure.
Preparing for an uncertain future
Despite the ongoing changes and obstacles presented by various environmental regulations in the U.S. and abroad, the good news is that the necessary product and material innovations are already available to help engineers overcome the design challenges presented by low-GWP refrigerants, such as CO2 and R290.
This article was contributed by Parker Sporlan Division.
Additional helpful content:
25 Jun 2021
The COVID pandemic impacted the way many industries do business, and the HVAC industry is no exception. Ongoing concerns regarding infection risk and indoor air quality have prompted an unprecedented demand for filters with a Minimum Efficiency Reporting Value (MERV) value of 13, commonly known as MERV 13 filters, as well as those with even higher MERV ratings. As part of its COVID response, ASHRAE recommends increasing outside air within buildings as much as possible, as well as upgrading air filters to a minimum MERV 13 efficiency rating.
The rush to upgrade to high MERV filters, however, opens the door to a practical discussion about whether that is the best action in all cases. The reality is that using the wrong filter for the wrong application in the wrong place can substantially limit HVAC systems’ efficiency. The result is that air quality will suffer, and the system will consume more power than it should to function.
Is MERV 13 really the best choice for your HVAC system?
A MERV rating is determined by the filter’s particle-size removal efficiency. The higher the number, the higher the filter efficiency. Before considering ratings, however, it’s important to determine the purpose of the filter.
If the primary purpose is to keep heating and air conditioning systems clean and block contaminants from interfering with the operation of key components, you likely don’t need as high a MERV rating. If the primary objective is to protect breathing air quality, then a higher MERV rating might make sense.
An option worth considering in some applications is the use of a multi-filter system that includes final filters and pre-filters. A less expensive, lower MERV-rated filter, functioning as a pre-filter, can trap dirt and large particles before the air reaches the final filters downstream which then remove the small particles. Multi-filter systems can extend the life of the more expensive final filters, creating overall cost savings.
When choosing a filter, it’s also important to consider the conditioned space’s activities and the types and sizes of particles those activities generate. Contaminants of greatest concern need to be evaluated to determine the level of filtration efficiency required for that contaminant’s size (measured in micrometers/microns). Once a full list of contaminants of concern has been identified, you can use the ANSI/ASHRAE Standard 52.2-2017 to select the proper filter with the appropriate MERV.
Additional considerations when choosing a filter
Of course, particle-capture efficiency matters. But there are also other filter characteristics that should be considered when determining the best filter for a specific application. Cost is always a consideration and should include the purchase price, as well as service life and maintenance requirements. The filter’s resistance to airflow also is a key consideration, as it is proportional to the energy consumed by the filter. Energy expenditures can account for about 81% of an air filtration system’s annual operating costs, while its purchase price and maintenance can account for about 18.5%.
Other considerations include the design and materials used in filters. Some designs are easier to install, seal better, and don’t absorb moisture or shed. Pleated filters, which are commonly made with a blend of cotton and polyester or synthetic media, provide a larger filter-surface area than panel filters. Most pleated filters are MERV 6 to 13. Depending on the filter, capture efficiencies for particles in the 3 to 10-micron range can be 35% to 90%.
There are also extended-surface filters that are made with synthetic, fiberglass or cellulose/glass-fiber media. These include bag or pocket, rigid-cell, aluminum-separator and V-bank filters. Pocket filters provide an even greater filter surface area than pleated filters to provide maximum efficiency with the lowest pressure drop and longest life. They typically have MERV ratings of 11 to 15.
Other factors that can affect efficiency
Even a filter with the highest MERV rating can’t achieve high-quality air if some of the air is not going through the filter. Gaps around high-efficiency filters or filter housings can decrease filter performance. They occur when filter media are not sealed properly in the filter frame, when filters are not gasketed properly in filter racks, or when air-handler doors and duct systems are not sealed properly.
For a 1-mm gap, bypass flows can increase to 25% to 35% of the total airflow. The percentage increases based on the filter’s efficiency because air naturally flows through areas with the least resistance. Since higher efficiency filters have a greater resistance to airflow, bypass air has a larger effect. This, in turn, reduces the efficiency rating. For a 1-mm gap, for instance, a MERV 15 filter will perform only as well as a MERV 14 filter. A 10-mm gap, in contrast, causes a MERV 15 filter to perform as a MERV 8 filter. That’s why building operators and maintenance personnel should perform regular field inspections to ensure filter seals and gaskets are installed properly.
To combat gap problems, Parker created its QuadSEAL® HVAC filters with proprietary E-Pleat® media technology. The molded polyurethane frame incorporates a QuadSEAL integrated gasket on all four sides and can flex without damage. Since the media pack is 100% bonded into the foamed frame, bypass is eliminated as is the need for additional sealants or adhesives.
Challenges with MERV 13 filters (and what can be done)
If it were just a matter of choosing the filter that produced the best air quality, the decision would be simple. Everyone would install filters with the highest MERV ratings they could find. Unfortunately, it’s not quite so simple. The challenge facing engineers, building owners and maintenance personnel tasked with specifying and installing filters is that more efficient filters cause higher pressure drops because the smaller pores create more resistance to air flow.
Not only are higher efficiency filters less energy efficient (causing increased energy consumption by the fan), but your air handling unit simply may not have enough capacity to function with a high-efficiency filter. The reality is that most commercial HVAC systems today can only handle MERV 8 filter or MERV 9 filter types.
So, what are your options?
When COVID hit, suddenly industries that, for years, had functioned well with filters with MERV ratings of 8, 10 or 11, were scrambling for MERV 13, 14 and 16 filters. The reality, though, is that there are filter options even more efficient than MERV 16 filters.
High Efficiency Particulate Air (HEPA) and Ultra-Low Particulate Air (ULPA) filters are designed to trap the smallest airborne particles and contaminants. HEPA filters have a minimum efficiency of 99.97% at 0.3 microns, whereas ULPA filters have an efficiency rating of 99.999% at 0.12 microns or higher. This does not mean that ULPA filters are better than HEPA filters when taking air flow and other variables into account. In fact, HEPA filters cost less, have a lower resistance to air flow and offer a longer service life than ULPA filters.
Parker offers a complete line of HEPA and ULPA standalone and pre-filters for removing particles and contaminants with efficiencies up to 99.9995%. They also are designed to reduce energy consumption and operating costs.
So why doesn’t everyone simply switch to a HEPA or ULPA filter since they represent the gold standard in air quality? Because most commercial and industrial HVAC systems on the market today simply aren’t compatible with them. Since they are so efficient, HEPA and ULPA filters cause a higher pressure drop than filters with lower MERV ratings.
The best option today for using HEPA and ULPA filters is as part of stand-alone systems. Many school districts are looking at options for installing portable air filtration systems with HEPA filters in each classroom to augment their central air filtration systems. HEPA and ULPA filters are also frequently found in critical medical applications and cleanrooms.Newer innovations offer superior efficiency while overcoming problems with air flow
Parker’s approach to balancing the need for efficiency with minimum pressure drops has been the development of its LoadTECH® filter that utilize Parker’s proprietary E-pleat® technology. This patented design molds filtration media into a series of pre-formed channels that direct the air smoothly through the filter, allowing for even loading, minimum resistance and complete media utilization. The previously mentioned QuadSEAL® filters offer a similar benefit of improving efficiency without restricting air flow. The advanced media used in these filters also resists tearing, damage, moisture and microbial growth, leading to a long filter life and the need for fewer filter changeouts.
The decision to use a filter with a MERV 13 rating (or higher), in accordance with the latest guidance from the Centers for Disease Control (CDC) and ASHRAE, is complicated by the fact that most commercial HVAC systems cannot handle the highest efficiency-rated filters. While there are options for upgrades, redesigns that include a multi-filter system, and new technologies that balance efficiency and air flow, specifiers need to be careful that they choose the right filter after considering all the variables, including cost, maintenance requirements, operating efficiency and, of course, air quality.
This article was contributed by the Parker HVAC Filtration Division.
24 Jun 2021
For decades, futurists have been dreaming of “flying cars” that are easier and nimbler to operate than a helicopter and accessible to everyone. Today, many aerospace technologies are coming together helping numerous companies develop small passenger electric aircraft as soon as 2023.
It’s no secret that Advanced Air Mobility (AAM) is going to be a hotly contested market with legacy aircraft builders, nimble startups, and original equipment manufacturer (OEM) systems providers clarifying their vision of the future. This new market aims to transport passengers and cargo at lower altitudes through urban, suburban, and regional landscapes. Aircraft that will meet these needs will utilize more- or all-electric technologies.
According to a 2020 Roland Berger study on Urban Air Mobility (UAM), a submarket of AAM, “the passenger UAM industry will generate revenues of almost $90 billion a year, with 160,000 commercial passenger drones plying the skies.” Further, Morgan Stanley Research projects that the UAM market could grow to $1.5 trillion by 2040.
Even the most conservative forecasts indicate the AAM market has huge potential as evidenced by the hundreds of vehicles in development.
In early 2021, Air One, the world’s first airport for electric aircraft, was launched in Coventry, England by Urban Air Port, a subsidiary of sustainable tech company small (Six Miles Across London Limited) in partnership with Hyundai Motor Company, Coventry City Council, and the UK government.
As technology evolves, infrastructure is built, and the regulatory/certification requirements established, AAM vehicles will take different forms:
More-electric aircraft (MEA), which have been in production for over a decade, utilize electric power for all non-propulsive systems. The trend toward more-electric aircraft has been driven by the desire for improvements in aircraft weight, fuel efficiency, emissions, life-cycle costs, maintainability, and reliability.
Technology advancements in the areas of electric motors, motor controllers and inverters, electromechanical actuators (EMAs), and thermal management equipment are providing the building blocks that enable development of systems for more-electric aircraft.
Parker Aerospace, via its dedicated AAM systems team, offers a broad range of products and systems expertise for present-day applications as well as future-state aircraft:
Certification: where concepts meet reality
The AAM market is dynamic and changing rapidly. New ideas for platforms, infrastructure, and the technologies that make this exciting segment possible are surfacing daily.
Amid this excitement, these aircraft must be certified for their intended purpose, as do the systems and components that enable the platforms to execute their missions. Regulatory agencies such as the FAA and EASA are presently establishing the parameters under which AAM vehicles can be approved to fly.
Platform builders need to know that their partners have the engineering muscle and experience to not only design an innovative solution that meets requirements, but to also produce a solution that can be certified. This is where an experienced aerospace technology partner is crucial.
Over decades, Parker Aerospace has built thousands of certifiable components and systems for commercial and military aircraft. All Parker equipment is conceived and engineered to offer redundancy, safety, and reliability with the certification process in mind. Contributing to Parker’s track record of certification success is its state-of-the-art simulation capabilities, advanced test equipment, and thorough knowledge of global regulatory requirements.
As the market continues to ascend, Parker Aerospace and its AAM team are actively innovating to help customers take full advantage of these new and fast-changing opportunities.
To learn more about how Parker Aerospace innovation is shaping the AAM market, email the team at email@example.com.
Making the world a better place is in our DNA
As a trusted partner, Parker's team members work alongside customers to enable technology breakthroughs that change the world for the better. We help our customers and distribution partners meet the newest standards for safety or emissions, reduce power usage, improve efficiency, and move faster to optimize resources. Parker's Purpose is at the core of everything we do. Watch the introduction video with Parker's CEO Tom Williams.
This blog was contributed by Chris Frazer key account manager and UAM/eVTOL/AAM business development lead of Parker Aerospace.
15 Jun 2021