Refrigeration engineers and service contractors need to understand the difference between bubble point (when a substance starts boiling) and dew point (when a substance finishes boiling) because high-glide refrigerants do not boil at a constant temperature. If refrigeration professionals do not know these terms or use them incorrectly, equipment will be inefficient and possibly be damaged. Let’s glide into this discussion about high-glide refrigerants.
Refrigerant Glide
Water boils at a consistent temperature. When you set a pot of water to boil, the water will boil at the same temperature whether the pot holds 1 cup of water or 2 cups of water. Even as the water evaporates, the remaining water boils at the same temperature. This is because the only substance being boiled is water.
Many refrigerants also have a consistent boiling point, whether they are natural refrigerants or synthetic refrigerants. But high-glide refrigerants do not boil at a consistent temperature. A high-glide refrigerant may start boiling at 18°F, but as it boils into a gas, the boiling point “glides” up to 28°F. Why does this happen? High-glide refrigerants are a blend of different refrigerants, and these refrigerants separate when they are brought to boiling. Since each refrigerant boils at different temperatures, they will evaporate into a gas at different points, which changes the composition and concentration of the remaining liquid refrigerant. This causes the boiling point to “glide.”
Let’s consider a high-glide refrigerant that is composed equally of three different refrigerants, and each boil at different temperatures; for example, 18°F, 23°F, and 28°F.
- Below 18°F, the composition is completely liquid and not boiling.
- At 18°F, the first refrigerant boils away. This changes the composition and concentration of the refrigerant blend, and the remaining refrigerants will boil at a higher temperature.
- At 23°F, the next refrigerant in the composition boils away, changing the composition and concentration again.
- At 28°F, the final refrigerant boils away. The entire refrigerant blend evaporates into a gas, and the boiling point “glides” up to 28°F.
Bubble, Mid, & Dew Point
For refrigerants without a glide, it is simpler to design a system because the refrigerant boils at the same temperature throughout the operation. But with high-glide refrigerants, the equipment could be designed for either when the refrigerant starts to boil (evaporate), when it has partially boiled, or when it has fully evaporated.
Refrigeration engineers and service contractors need to be familiar with the terms bubble point, mid point, and dew point.
- Bubble point: Liquid refrigerant starts to boil at this pressure and temperature in the evaporator.
- Mid point: Half of the liquid refrigerant has boiled away to a gas.
- Dew point: The last of the liquid refrigerant boils away.
To remember these terms, think about how a liquid bubbles as it boils or how dew forms in the morning when water vapor condenses.
The terms bubble point and dew point need to be understood and applied when discussing high-glide refrigerants. If the equipment does not specify bubble or dew point, the contractor could operate it incorrectly. Bubble point and dew point can be very different, as seen in the previous example (18°F versus 28°F). Warning: If there is ambiguity about whether equipment was designed for dew point, mid point, or bubble point, ask the equipment manufacturer. Do not make assumptions and risk damaging the equipment by running it incorrectly.
Consider This
There are two things worth mentioning to further our discussion. First, the terms bubble, mid, and dew point must be applied differently when talking about condensers on the high side of the refrigeration cycle. The condenser starts at the dew point as vapor refrigerant begins to condense into a liquid, and it finishes at the bubble point as the vapor refrigerant completely condenses into a liquid.
Second, there are also low-glide refrigerants. Low-glide refrigerant blends do not separate as much as high-glide refrigerants when they boil, so the bubble point and dew point are closer together. However, even a small temperature difference affects how equipment is sized and used. It is still important to know the difference between bubble point and dew point for any refrigerant that has a temperature glide.
These are just the basics about temperature glide, but hopefully you can already understand the importance of knowing the terms bubble point, mid point, and dew point.
Using High-Glide Refrigerants
High-glide refrigerants are more complex because of the glide. Why would someone want their system to use high-glide refrigerants? These blended refrigerants were developed specifically to have less of an impact on the environment. Older synthetic refrigerants had high ozone depletion potential (ODP) and high global warming potential (GWP). Refrigerant manufacturers have developed high-glide refrigerants to have low or no impact on the ozone layer and global warming. High-glide refrigerants are gaining popularity because of this, but the glide leads to some new challenges when designing and servicing a refrigeration system.
Have questions? Contact us and ask for our Director of Regulatory Compliance & Refrigeration Technology.
We take our home refrigerators for granted. We put food into the refrigerator, and it makes the food cold. But actually, the refrigerator is not making the food cold; it is removing heat from the food. That might sound counterintuitive, so we invite you to open the door to the world of refrigeration by learning about the basics of the refrigeration cycle.
Heat Transfer & Pressure
Before we discuss the refrigeration cycle, we must briefly discuss heat transfer. Heat always transfers from warm to cold. You can see evidence of this in your beverage of choice. Your morning coffee may start hot, but as the day wears on, it gets cooler because heat transfers into the surrounding air. At lunch, your soda warms up as heat transfers from the surrounding air. This is called sensible heat transfer. You can remember this by thinking about how you can sense (feel) the change. The coffee mug feels hot as heat transfers to you; the soda can feels cold as heat transfers from you.
Heat transfer can also cause a substance to change state between solid, liquid, and gas. This is called latent heat transfer. For example, H2O can exist as a solid (ice), a liquid (water), or a gas (steam). At sea level, H2O will be water between 212°F (100°C) and 32°F (0°C). If water is heated beyond 212°F, it will evaporate into steam. If water is cooled below 32°F, it will freeze into ice. As a substance changes state, its original state will be reduced as the other state increases. For example, as ice melts, it disappears and the amount of water increases. If enough heat transfers, the substance will cease to exist in its original state. Latent heat transfer (changing state) takes more heat than sensible heat transfer (changing temperature).
Another factor is how pressure relates to temperature. Boiling points vary depending on the pressure surrounding the substance. At sea level, water boils at 212°F, but if you travel to Denver or Pikes Peak in Colorado, the atmospheric pressure is lower and the boiling point will be lower.
The Refrigeration Cycle
Your unfinished can of soda is now warm. How do you chill it again? You may think the answer is to add cold to it, but remember that heat only moves from warm to cold. It is more accurate to say that you are actually removing the heat from the soda by transferring that heat to another, colder object. This is the concept behind the refrigeration cycle.
The refrigeration cycle comes from the work of William John Macquorn Rankine, who discovered how to transfer heat away from objects that were already cool. Historically, this could be done by placing objects into an ice box. Ice works well as a refrigerant because it maintains a constant 32°F temperature. Warm product (milk, meat, etc.) transfers heat to the ice (latent heat transfer), causing the ice to melt into water. The water (full of heat) drains away, and the refrigerated space and product remain cool.
All modern refrigeration systems have four main components that work together to move heat: the evaporator, the compressor, the condenser, and the expansion device. Imagine that heat moves in a “bucket” and follow the bullet points which correspond to the figure.
- The evaporator gathers/absorbs heat from the refrigerated space into a “bucket.” The “bucket” is low-pressure, and it changes state (latent heat transfer) as it absorbs heat. Then the evaporator moves the low-pressure, heat-filled “bucket” to the compressor.
- The compressor applies pressure, which compresses the heat-filled “bucket.” The heat-filled “bucket” changes from low-pressure to high-pressure as the compressor pushes it from the colder evaporator to the warmer condenser. When pressure is added, the temperature of the “bucket” also increases.
- The condenser takes the high-pressure, heat-filled “bucket” and releases the heat from the “bucket” to the outside air (or other application). The “bucket” changes state (latent heat transfer) again as it releases heat.
- The expansion device relieves the pressure on the empty “bucket.” When pressure is reduced, the temperature also decreases. The “bucket” cools and expands on its way to the evaporator to absorb more heat again.
The downside of using ice as the “bucket” is that more ice must constantly be added as it melts away. Modern refrigeration systems needed a long-term solution. Refrigerants are the modern “bucket” because refrigerants can continually absorb and release energy without escaping the system. Refrigerants change state between a liquid to a gas. Refrigerants must be able to boil at low pressures and low temperatures to be efficient.
High-glide refrigerants have a unique effect on a refrigeration system.
Have questions? Contact us and ask for our Director of Regulatory Compliance & Refrigeration Technology.
Maybe you already know that high-glide refrigerants are mixtures of multiple refrigerants. Maybe you already know that the boiling point glides up as a high-glide refrigerant boils away, unlike traditional refrigerants. And maybe you can see that this complicates how refrigeration equipment is designed and operated.
But maybe this world of high-glide refrigerants is new to you. Or perhaps you are finding it difficult to explain these concepts to others. Zero Zone has developed a white paper that teaches the basics of refrigeration and shows the challenges with high-glide refrigerants.
High-glide refrigerants are gaining popularity because of their reduced GWP compared to non-glide refrigerants. We hope our observations help you operate your equipment more efficiently. Once you know the best practices for using high-glide refrigerants, you will find they are a great solution.
Have questions? Contact us and ask for our Director of Regulatory Compliance & Refrigeration Technology.
The original Reveal Merchandiser® is a versatile open multi-deck that retailers use for all medium temp applications, and they tell us they love it. How can it get any better than that? Well, they said, “Give us Reveal cases that maximize the freshness of red meat and produce.” We loved their request, and we answered it! Meet the 4-deck Reveal™ MX (meat exclusive) and the 3-deck Reveal™ PX (produce exclusive) display cases!
Fresh meat and fresh produce naturally look appealing to shoppers. The bright red meat and colorful vegetables are eye catching, so we developed our display cases to enhance their visual appeal. We designed our newest cases for maximum product freshness with a sleek, clean exterior and a spacious interior with excellent packout. The Zero Zone ChillBrite® LED lighting puts those products in their best light with bright, even illumination.
In true Zero Zone fashion, we give you ways to customize the MX and PX cases to your needs. Choose between two case heights (75″ or 80″ for MX; 80″ or 82” for PX), two sill heights (low or medium), optional windowed ends, and optional glass fronts. These options allow you to choose the case configuration that is right for you.
Give yourself the competitive edge and keep your shoppers coming back for more. Choose the Reveal Merchandiser® MX or PX!
Visit the Reveal Merchandiser® page to learn more.
Retailers like you need low-charge refrigeration solutions to meet regulations and minimize risks, but you have struggled to find a reasonable low-charge option for your medium to large store. Zero Zone has the answer: the new Zero Zone LCCU ETP (Liquid-Cooled Condensing Unit Electronic Technology Package).
The LCCU ETP is a total package from Zero Zone that includes a condensing unit, controller, pump skid, and Hybrid™ display cases. It starts with a low-charge condensing unit, which runs on R-448A and uses a DC compressor and electronic expansion valve (EEV). Behind this condensing unit is a controller that acts as the brain behind this energy-efficient system. The controller optimizes operation, monitors performance continuously, and maintains consistent product temperature. The refrigerant is cooled by a glycol/water loop that is pumped by a Zero Zone pump skid. This system cools a Zero Zone Hybrid™ display case that elegantly showcases your merchandiser to your shoppers. The LCCU ETP is a seamless alternative to a high-charge rack system.
The LCCU ETP also has advantages over a traditional ACCU (Air-Cooled Condensing Unit). It has a low profile because the condensing unit is shorter than a traditional ACCU, allowing for a shorter shroud to hide the condensing unit on top of the display case. The condensing unit is also insulated and enclosed, resulting in a quieter option than an ACCU. Lastly, the condensing unit releases heat to the glycol/water loop instead of adding heat into the store like an ACCU.
Partnering with Zero Zone means you are getting durable and dependable equipment and superior customer service. Contact the responsive company™ today to learn about this new low-charge solution for your entire store.
Learn more on our Hybrid™ Display Case page!
On March 1, the International Institute of Ammonia Refrigeration (IIAR) moved its new CO2 safety standard to public review. Titled the “Safety Standard for Closed-Circuit Carbon Dioxide Refrigeration Systems,” the standard will be open for public review until April 15. John Collins, Industrial Sales Manager for Zero Zone, Inc. and chairman of the IIAR CO2 Task Group, presented the new standard at a panel and at the closing forum for the 2019 IIAR Natural Refrigeration Conference & Expo.
CO2 continues to gain momentum across the refrigeration industry with thousands of CO2 systems operating worldwide. However, the industry lacks a definitive, detailed standard to guide engineers and contractors. As a standards developer accredited by the American National Standards Institute (ANSI), IIAR is equipped and positioned to fill this need for natural refrigerants. Many members of the CO2 Task Group have contributed to other safety standards. They also partnered with the North American Sustainable Refrigeration Council (NASRC) as they branch into regulations for commercial refrigeration.
The CO2 Task Group and the NASRC have developed the standard to cover the full life cycle of a CO2 refrigeration system, including design, installation, startup, inspection, testing, and maintenance. The standard establishes minimum requirements for a safe system, defining baseline requirements for the proper application of CO2 refrigeration.
After April 15, the CO2 Task Group will sort through the public comments, respond to them, and revise the standard as necessary. Speaking from experience with the process, Collins says it is common to have additional public reviews, whether of the whole safety standard or excerpts of it. After that, the standard will be evaluated, voted on, and submitted for approval. After approval, it will be published as an ANSI standard, which will become a resource for commercial and industrial CO2 systems.
Collins has served as the chairman of the IIAR CO2 Task Group since the project formally began in 2016. He has also served on the IIAR CO2 committee, the standards committee, and as a board member.
Collins describes the work as “gratifying” because they can see the interest across the industry. “Now is an exciting time for CO2 refrigeration. New and old contractors want to gain experience with working on CO2 systems,” he explained. This CO2 safety standard will provide the necessary guidance.
When making your New Year’s resolution, you possibly resolved to save more and spend less. How can retailers like you continue to save money in 2019?
Every grocery store requires thousands of kilowatt-hours (kWh) of electricity per year to operate. This electricity covers refrigeration, ventilation, lighting, cooking, heating and cooling, and office. But the overwhelming majority of electricity goes to refrigeration equipment that runs whether the store is open or not. This makes refrigeration an obvious target for energy and cost savings.
Through some simple investigation and adjustments, you could benefit from energy savings. Check out some steps our product managers and engineering team recommend to get the most out of your commercial refrigeration equipment.
Evaluate Energy Consumption
First, collect data about the energy that your refrigeration equipment uses by referring to the component specification sheets. You should verify that the equipment is operating at the specified temperatures. If not, the controls could be set too cold, which wastes energy, or there could be a performance issue such as an iced coil or low refrigerant charge. If you notice equipment is not operating correctly, contact your refrigeration contractor.
You can also contact your utility company. Ask if they can perform an energy audit to compare your energy usage to similar businesses that use refrigeration equipment. They may even suggest ways to improve the efficiency of your equipment.
In addition to checking your refrigeration equipment, look at your HVAC system settings. Refrigerated display cases are designed to operate in ambient temperatures of 75°F and 55% relative humidity (defined by ASHRAE). Ensuring that your HVAC equipment maintains good store conditions will reduce refrigeration equipment energy consumption, and it is more cost effective to have the HVAC equipment cooling the store instead of having the display cases dehumidifying it.
Install Energy-Saving Features
There are many features available that are designed to reduce energy usage and provide cost savings down the road.
- Motion sensors, which turn display case lights off when no shoppers are around, have a relatively quick payoff.
- Anti-fog coating is a clear film on doors that prevents fog buildup and helps shoppers see products. Over time, this leads to energy savings because the case does not get opened unnecessarily, which means less energy is consumed to cool the case.
- Most display cases come with standard anti-sweat heaters that limit door sweating in humid conditions, but they can run too aggressively in cooler, drier stores. Consider ordering your next display case with an anti-sweat controller, which cycles the heaters off when there is less humidity in the air, thereby saving energy.
Also contact your refrigeration manufacturer. They may be able to offer other features to reduce energy consumption.
Schedule Routine Maintenance
It pays to be proactive and schedule regular maintenance for your refrigeration equipment. Instead of waiting for an issue to happen, you should schedule regular visits from your refrigeration contractor to keep the equipment running efficiently and catch component failures early.
General cleaning and maintenance is important for efficient case operation. You should clean doors and windowed ends so people can see product. Regularly clean lint and dust accumulation off of condenser coils and discharge air grills. On a monthly basis, ensure gaskets are not torn, doors are at ideal tension, and all fans are operating.
- To check gaskets, simply place a dollar bill in the door track. If the dollar slides out with little to no resistance, it’s time to have the seals replaced or adjusted.
- To check ideal door tension, open the door and observe how well it closes. A properly tensioned door will close itself gently and not swing open. If the door does not close or swings open, the case will not operate optimally.
- There are two ways to check fan operation. One way is to put your hand near the discharge air grills. If all fans are working, the airflow will be the same from door to door. If less air is coming out, a fan may not be working. However, the most effective way to check fan operation is to unload product, take out the cover, and visually confirm that the fan is working. Do not put your hand into the fan, even if it appears to not be operating.
With so many steps available for reducing your refrigeration energy consumption, it is wise to develop a plan. Even if the budget does not allow for a full equipment overhaul, you may be able to update your cases department-by-department. That allows you to stay within budget, and your New Year’s resolution will be off to a good start!
How should retailers use open multi-decks and reach-in display cases to best showcase products? We asked Mike Floersch—owner of Ray’s Apple Market in Seneca, KS—and Marc Robért III—general manager of Robért Fresh Market in New Orleans, LA—to provide some insight about their merchandising strategies.
Open Multi-Decks
Both retailers selected the Reveal Merchandiser® open multi-deck for displaying produce, citing the natural appeal of fresh fruits and vegetables being enhanced in open cases. “I did not want to put produce behind doors. I’ve been in the business 50-some years, and I felt like it presented itself well,” Floersch said.
Robért Fresh Market uses a 54-foot run of Reveal Merchandiser® cases as its big “showstopper” that shoppers see first when they enter the store. Robért Fresh Market also uses the Reveal Merchandiser® for fresh meat. “That bright red meat color really pops, and it’s all about ‘eye appeal is buy appeal,’” Robért explained. He also emphasized that products are more accessible to customers in open cases.
Reach-In Display Cases
Both retailers also chose reach-in display cases—the Crystal Merchandiser® and Highlight Merchandiser®—for other refrigerated products, such as dairy, deli, and frozen foods. The key to Zero Zone reach-in merchandisers is the CoolView® doors. The door rails and mullions have a sleek, narrow design, maximizing display area and providing excellent visibility.
Zero Zone reach-in cases perform exceptionally well for stores in humid regions like New Orleans. To prevent condensation from forming, CoolView® doors include heaters in the doors, door rails, mullions, and sills. Robért has been pleased. “With our high humidity environment, I have found that [Zero Zone] has been a perfect match and that we’ve had zero issues with sweating and humidity issues coming onto our product.”
Floersch admitted that he “was a little nervous about putting things behind doors, but I’m so glad I have.” His shoppers have told him that they appreciate the warmer environment. “A lot of stores you go into, it’s cold, and it’s because of all the open cases.” His shoppers welcome this change.
A Solution for You… Whatever the Case May Be
Whether you prefer open multi-decks, reach-in display cases, or both, Zero Zone offers a solution for your entire store. Robért says that the combination of reach-in and open cases from Zero Zone “brought the décor and the feel of the whole store together.” Floersch shared that he has experienced a 25% drop in kilowatts, which results in great cost savings each month. In the end, getting the total package from Zero Zone was the right solution.
As 2018 comes to a close, everyone has their own story to tell. At the Zero Zone Systems Division in Ramsey, MN, our story focuses on our community and our industry. We are proud to be the City of Ramsey 2018 Business of the Year. When asked about what it takes to be business of the year, Vice President and General Manager Rick Steer promptly points to the Zero Zone employees. “They represent the company and build our relationship with our customers and our community.”
Employees and the Community
Zero Zone and our employees are engaged throughout the Ramsey community. Zero Zone supports various events and organizations in town, including the Happy Days Festival, Safety Camp, and the Ramsey Firefighters Relief Association. Our employees also joined the local Adopt-a-Spot program by cleaning Bunker Lake Boulevard NW. We are involved in these events and programs because they are important to us and to our community. We believe it is our responsibility to give back to a city that has stood with us.
We also believe we have a responsibility to showcase the value of manufacturing jobs. Industrial Production Manager Justin Borer assists with setting the curriculum for manufacturing courses at the local high school and technical college. Zero Zone is a member of various manufacturing advocacy organizations, including the National Association of Manufacturing, the local Manufacturing Alliance, and OPTIMA. We are also a charter member of the local Manufacturing Day in Ramsey, MN, since it began in 2012.
Zero Zone and Natural Refrigeration
Not only is Zero Zone a leader in the local community, but also in the entire refrigeration industry. 2018 has been a breakthrough year in terms of natural refrigerants, particularly CO2 transcritical refrigeration. All across the country, there is ever-growing interest in greener solutions. It is the future of refrigeration, and Zero Zone is proud to be among the first to have installed CO2 transcritical systems in supermarkets and ice rinks. We are proud to partner with customers who are reducing their use of refrigerants with high global warming potential by switching to environmentally-friendly natural refrigerants like CO2.
Our employees also contribute to the refrigeration industry. Industrial Sales Manager John Collins serves as the chairman of the IIAR CO2 Task Group that writes new safety standards for CO2 refrigeration. This includes every step from design, to installation, and maintenance.
Our Commitment
What does it take to be business of the year? Zero Zone believes the answer is a combination of commitment to the refrigeration industry and to the local community. That commitment would not be possible without the employees. “Our employees have been the core of what makes Zero Zone special,” says Rick Steer. “It has been a pleasure being the City of Ramsey 2018 Business of the Year, and we look forward to many great years ahead.”
Even though they are separated by nearly 1,000 miles, Ray’s Apple Market in Seneca, KS, and Robért Fresh Market in New Orleans, LA, share a lot in common. They are both local, family-owned supermarket chains that now each have six stores across their states, and they are proud of their history in their communities.
Most importantly, they share a common mission: freshness. “We feel like that’s where we need to be the best… perishables,” says Owner Mike Floersch of Ray’s Apple Market. “You can buy groceries about anywhere today, but if we have the freshest meat, freshest produce, people will shop with [us].” Freshness is something that brick-and-mortar retail stores are particularly equipped to deliver, and each partnered with Zero Zone to accomplish this.
Fresh Produce
Marc Robért III, General Manager of Robért Fresh Market, says that “so much of produce is about the impulse, the visual, the pop of the colors, the appearance, and the appeal of the freshness.” He decided to make produce their big “showstopper.” When shoppers enter Robért Fresh Market, they are met with a 54-foot run of open Reveal Merchandiser® cases loaded with fresh produce. “The biggest thing that we focus on serving is healthy meal options that are quick and easy for [shoppers]. In our produce department, we have an enormous, growing [selection of] cut fruit and cut vegetables.”
Fresh Meat
Robért Fresh Market also uses the open Reveal Merchandiser® for fresh meats, such as beef, poultry, and pork, saying that the fresh meat colors really pop. “It’s all about eye appeal is buy appeal,” he noted.
Ray’s Apple Market sells meat in reach-in cases instead of open multi-decks. “Our product is lasting longer. We don’t see the shrink. The product behind the doors is phenomenal how it does keep longer.” Shrink can be reduced by up to 50% by switching to Zero Zone reach-in cases. Owner Mike Floersch also mentioned that shoppers perceive the meat as fresher because of the clean appearance of Zero Zone reach-in cases.
While their fresh meat strategies are different, each found that Zero Zone offered a solution that matched their goal of being fresh.
