What Is Process Cooling?
Process cooling uses a chiller unit to draw heat away from industrial equipment. The chiller uses refrigerant designed to expand and contract more than water with temperature changes. Moving heat away from the equipment improves efficiency. With lower operating temperatures, the process equipment also lasts longer and becomes safer for employees.
Is Process Cooling the Same As Air Conditioning?
Process cooling and air conditioning have several differences, though, at their heart, both remove heat from air or liquid. In process coolers, a liquid is chilled. Often, this liquid is water or glycol, depending on the application. Unlike air conditioners, which have one function — to pull heat from the air — process coolers are more complex. Process chillers can use different fluids to reach different temperatures. These cooling units can also adapt to a variety of flow rates. Process coolers and air conditioners are not interchangeable, though industries have use for both.
Additionally, process chillers typically have separate cooling systems for the process liquid and the refrigerant. The refrigerant passes through the system and removes heat from the process liquid, which becomes chilled and returns to the equipment. Air conditioners don’t have a process liquid but use refrigerant to pull heat directly from the air and send cold air into the air-conditioned space. Understanding the difference between the two can help you understand the operation of process cooling chillers.
Refrigerants and Process Cooling Chillers
The key behind process cooling lies in its refrigerant. Manufacturers have several options available for this. But some cooling agents have substandard records for their negative impacts on the environment. At Smart Family, we use environmentally friendly R-407C or R-410A in our air-cooled chillers. R-407C and R-410A are hydrofluorocarbons (HFC), refrigerants that replace older R-22, which is being phased out. Most R-410A and R-407C cooling systems require a polyolester (POE) oil to keep the system components properly lubricated. These cooling agents are blends of other refrigerants to maximize their desirable cooling features. R-410A combines equal parts of HFC-32 and HFC-125. R-407C also includes a mixture of equal parts of HFC-32 and HFC-125, but it also adds two parts of HCF-134A(another environmentally friendly refrigerant).
We use a different environmentally friendly HFC refrigerant in our low-temperature chillers (R-404a). (The type of refrigerant used depends on the temperature needed.) Purchasers or renters of chiller units dictate their cooling needs to manufacturers, who then select the appropriate refrigerant for the situation. R-404a is best used in applications where the leaving fluid temperature is approximately 10F or below.
A Note on R-22 Refrigerant
The Environmental Protection Agency (EPA) requires phasing out of ozone-depleting substances, including R-22, by 2020. R-22 is a hydrochlorofluorocarbon (HCFC), which the EPA considers a Class II substance. All refrigerants containing this and other HCFC refrigerants will no longer be sold or imported in the United States. The same holds true for any refrigerant blends including R-22.
Though cooling units and air conditioners have long relied on HCFC, better options exist today. These HFC refrigerants do not thin the ozone layer as much as older HCFCs. Industrial process cooling does not have to harm the environment. We choose to use HFC refrigerants with lower global climate change potential in our products. They are much more environmentally friendly and not subject to phase out, making process cooling chillers from us a long-term investment. The changing refrigerant is just one innovation in the world of industrial chillers and cooling equipment. Many others exist on the horizon to meet the demands of industry. To fully understand these innovations, you first have to comprehend how process cooling chillers work.
How Does Process Cooling Work?
Process cooling chillers create a cycle that sends liquids through the system to transfer heat. A liquid draws heat from the equipment and moves into the process cooling unit. There, it exchanges heat with the refrigerant system to cool the process fluid, which lowers temperatures of the equipment.
1. The Evaporator
The process fluid’s first stop is the evaporator, which is also called a heat exchanger. Inside the heat exchanger, the fluid passes heat to the refrigerant. The refrigerant evaporates due to a decrease in pressure. As it transforms into a gaseous state from its liquid form, it becomes cold enough to chill the process fluid passing near it. The process fluid then returns where it started in a chilled state, cooling the equipment.
Evaporators have different forms. We offer brazed plate heat exchangers (BPHE) and shell and tube evaporators on our process cooling chillers. Both work to cool the process liquid by exposing it to refrigerant that absorbs the process fluid heat and turns into a gas.
- Brazed plate heat exchangers: BPHE units have the advantage of a smaller size and lower maintenance. Compared to similar shell and tube evaporators, BPHEs weigh 85 to 90 percent less. To keep these units operating at their peak, install a filter at the return water inlet. This reduces the particulate matter that could damage the heat exchanger. One of the disadvantages of this type of evaporator is that they can clog easily and are difficult to clean.
- Shell and tube evaporators: Shell and tube evaporators are highly efficient. You can raise the cooling ability of the system by 10 percent. This greater efficiency can also be used to increase the evaporator temperature, which raises the energy efficiency of the unit for saving money in the future on operating costs. Another benefit of shell and tube evaporators is that they are completely customizable. If a customer desires an all stainless steel or cupro-nickel design due to the operating conditions or fluid, it is not an issue. Although these customizations can add additional cost.
2. The Compressor
The refrigerant moves into the compressor, where it’s pressed into a high-pressure state. Changing the pressure of the refrigerant allows it to increase or decrease in temperature. Compressors use physical force to press the refrigerant down from a gas into a liquid form. The refrigerant goes to the condenser as a high-pressure gas, where air or water draws its heat away.
Compressors are sold in many different forms. The names of each compressor type come from the mechanism used to press the refrigerant down. Our process cooling chillers have both screw and scroll compressor options.
- Screw Compressor: In a screw compressor, the refrigerant passes along a moving screw or two. The turning of the screw compresses the gas into a higher pressure. Our process cooling chillers with screw compressors have gas-cooled motors, for better operation and an integral lubricating system. These compressors have a very wide operating temperature range.
- Scroll Compressor: Inside a scroll compressor is one scroll inside another. The refrigerant passes through the space between them. This space gets progressively smaller, which compresses the refrigerant and raises its pressure. We offer scroll compressors in some of our chillers. These chiller designs have at least two compressors and are low-noise, high-efficiency models. While scroll compressors are extremely efficient, be wary not to use tandem scroll compressor set-ups. These have the ability to be service issue.
3. The Condenser
Condensers restore the refrigerant back to a liquid state from its gaseous form. For this to happen, the high-pressure gas must release its heat. Condensers typically use air or water to absorb the heat from the refrigerant. The refrigerant moves through the condenser inside coils made of material used for conducting heat. Air or water passes next to the refrigerant, pulling away heat. Once the heat leaves the gaseous refrigerant, it condenses down into a liquid state. From the condenser, it returns to the evaporator to cool the process liquid.
- Water-Cooled: Condensers that use water to remove heat from the refrigerant need a separate water source. Water-cooled condensers have greater efficiency than air-cooled condensers, but the need for a separate water tower may off-set this advantage, especially in areas with sub-freezing temperatures.
- Air-Cooled: Air-cooled condensers pass ambient air over coils filled with the refrigerant. Our air-cooled systems use copper tube coils for better heat transfer. We also offer variable-speed fans to adjust to the needed airflow during cooler or warmer days. And if your plant is near a coastal region, we offer copper-copper coils (copper tubes & fins) or standard coils with a corrosion resistant coating for added protection.
What Applications Require Process Cooling?
Process cooling has applications in multiple industries. In fact, the uses are as varied as the options available for custom-designed chillers. Despite the numerous uses, all share the need to remove heat from a process.
Plating through electrolysis and aluminum anodizing both require extremely high temperatures. To protect the equipment and workers, manufacturers use process cooling to draw away excessive heat. If the plating bath is not the correct temperature, the final result suffers, especially with zinc and chrome plating. Process cooling chillers optimize the bath temperature for the plating process to create the perfect product.
To size the right chiller for metal plating and aluminum anodizing, find the BTUs of the heat load and divide that by 12,000. The heat load is equal to the volts multiplied by the rectifier amps multiplied by 3.412.
Cooling Load = (volts x amps x 3.412)/12,000
Some people purchasing process coolers for metal plating reduce the calculated BTUs to save money or to account for system losses. Factors beyond your control may affect any predicted losses. To avoid underestimating, use the calculated BTUs for plating and anodizing.
The plastics industry requires process cooling for thermoforming, extrusion and molding. The thermoforming process heats a large sheet of plastic to a specific temperature to mold it to the desired shape. Extrusion creates long pieces of plastic by pushing the melted plastic through an extruder. Molding uses a variety of molds which hold the melted plastic in the desired shape. Temperature control is vital for all these processes. That’s where process cooling comes into play. In some instances, such as extrusion, the process cooler will require additional equipment such as a filter for the cooling liquid or a secondary heat exchanger.
3. Printing Industry
Stand next to a copy machine for any amount of time, and you’ll recognize the heat generated by printing. The printing industry needs to get rid of the heat from the printers to speed the process. Rollers and printers may need process chillers to keep them cool during operation and increase efficiency.
4. Food Processing
Food production and storage both require careful temperature control. Process coolers can maintain low temperatures needed for effectively chilling ingredients or creating the cool environments to store products.
5. Pharmaceutical Industry
Manufacturing drugs often requires regulating temperatures during the process to get the formulas correct. Additionally, some drugs must be stored at low temperatures after manufacturing. Process coolers can help with these functions and many others in the pharmaceutical industry.
Large equipment used in the medical industry can easily overheat with use. MRIs, PET scanners and CAT scanners all create large amounts of heat during regular use. If this heat does not get pulled away with a process cooler, the high temperatures could affect the accuracy of the test results.
The above applications are just some of the uses for process chillers. But any industry that requires lower temperatures to make its equipment operate more efficiently can benefit from a process cooler.
What Are Some of the Main Challenges of Process Cooling?
Process cooling is not foolproof. Some challenges exist with current systems. But innovations in the chiller industry hope to overcome some of the current problems to make process cooling more efficient and effective in the future.
1. Climate and Cooling Towers
When temperatures outside drop, the need for a process chiller does not necessarily go away. The water in cooling towers can freeze if you do not take precautions. Always have a heat load for the water tower in freezing weather, and never run the water tower unattended when temperatures drop below freezing. To reduce the chance of freezing while maintaining the most economical mode, keep the temperature at 45 degrees F or higher and use the highest available water flow rate. Moving water is less likely to freeze than still water. Shut off the cooling fans to prevent moving cold air over the water and chilling it even more.
2. Particulate Matter in the Cooling Liquid
Some processes, such as plastics extrusion, can contaminate the cooling liquid with particulate matter. The particles can clog the system and render the process cooler less effective. To avoid this problem, use a filter for the process liquid. The filter should remove any particles from the cooling liquid before it moves into the heat exchanger. Alternatively, use a second heat exchanger to cool the process liquid.
3. Water Use for Water-Cooled Process Chillers
In drought-prone areas, water restrictions are common. Industrial water use also comes under these restrictions, which may make using water-cooled process coolers difficult. A glass manufacturer in Texas uses 107 million gallons of water annually. But by reusing wastewater for cooling towers and in other non-potable applications, the plant cut their water use by 27.5 million gallons. Rather than relying on fresh water, reclaimed wastewater in water-cooled chillers could help reduce the environmental impact these units have.
4. Bacteria in Water Towers
Testing for and eliminating bacteria from the water in a cooling tower can lengthen the life of the chiller. Without testing, bacteria can produce slime that clogs the workings of the system, increasing the need for more frequent repairs. Another concern is Legionella bacteria, which can cause disease in humans who breathe in the aerosolized bacteria.
Testing for bacteria and treating it prevents spreading diseases to people. Compared to the standard testing method of using dip slides, stainless steel mesh biofilm is more accurate at finding Legionella and other bacteria. Using this method on a Colorado HVAC cooling tower, researchers found bacteria where standard testing came negative. Using more accurate testing allows for better bacteria control, which protects the chiller equipment and people.
Despite these challenges, process cooling remains a reliable source for removing heat from equipment during manufacturing and storage. Addressing these challenges has led many companies to embrace the current trends in process cooling.
What Are Some Current Trends in Process Cooling?
As other industries evolve, so does process cooling. Several trends are keeping process cooling relevant today and innovative for the future. Here are just some of the current trends in process cooling.
1. Cold Plates
Overheating in electronic components poses a real threat as technology gets faster and produces more heat in the process. Cold plates allow for liquid cooling of electronic parts. Though the technology has existed since the 1960s Apollo program, applications today have become smaller and more advanced. Using liquid cooling through cold plates allows for more direct, better cooling of electronics with lower flow rates than with air cooling. This tiny use of process cooling allows industrial motors and controls to use insulated-gate bipolar transistors (IGBTs) without overheating.
2. New Refrigerants
Though older CFCs and HCFCs are no longer allowed in chiller units, even the current standard for an environmentally conscious refrigerant, HFC, is not a perfect solution. HFC refrigerants can still cause ozone depletion, though not to the degree of older refrigerants. And some HFC refrigerants, like R134A that we use, have one-third the global climate change potential of other HFCs like R404A.
Process chiller manufacturers and chemists continue to work toward finding equally efficient refrigerants that will cause no environmental problems. Natural cooling agents in the testing phase include carbon dioxide, ammonia and hydrocarbons. Combustibility and achieving appropriate pressure levels remain two of the many challenges chemists must overcome before these natural refrigerants become mainstream.
Explosion-proof electronics for use in hazardous areas will become more popular in the future as the manufacturing industry expands. We already construct explosion-proof chillers for several well-known companies such as Exxon, Dow and Chevron. These chillers cool equipment while adhering to the strict guidelines set for explosion-proof equipment. Because explosion-proof chillers are so specific to the space where they are installed, we customize our XP chillers by building them from the ground up unlike some of our contemporaries who modify standard units.
4. Innovating Ways to Protect Against Bacteria
Bacteria in water towers remains a problem for process chiller owners. But innovations could solve this concern by integrating antibacterial material in the design of the tower. A closed tower blocks out sunlight, which prevents the growth of algae. Because Legionella bacteria eat algae, stopping algae can inhibit the growth of the bacteria by depriving it of food. Additionally, AccuSheild in the tower material will block bacterial growth. Keeping the water moving also slows the growth of bacteria. These traits combined aim to stop the growth of potentially lethal Legionella bacteria in the water tower. If embraced by all water-cooled process chiller users, this innovation could prevent Legionnaires’ disease outbreaks that have been too common in recent years.
5. Improving Efficiency
The efficiency of a process chiller is based on the system remaining intact. A refrigerant leakage decreases the cooling capability of the system. Continuously monitoring for leakage can prevent problems by alerting maintenance when a fault occurs. Additionally, the system may require adjustments to run as efficiently as possible, even if the ambient temperature changes drastically. Monitoring flow rates and operation are currently essential and new ways to watch these values will become important in the future.
Smart Family of Cooling Products Can Fulfill Your Process Cooling Needs
Multiple industries need process cooling, and Smart Family industrial cooling products have the features you need to meet the needs of your industry. Our chillers range in size from one ton to more than 300 tons in cooling capacity, and we can customize scroll chillers between 10 and 220 tons. We even have low-temperature chillers that reach negative 40 degrees F. For more information about our process cooling chillers, contact us today. We’d love to help you find the perfect process cooling chiller for your business.