Efficiency and Redundancy: Cooling System Pillars at Röchling Automotive


The automotive sector is one of the largest and most active markets for process cooling equipment. The extremely high standards for equipment specifications are reflected directly in the quality of their products. Thermal Care has worked with some of the industry leaders including Röchling Automotive.

Röchling required a new comprehensive cooling system for their Akron, OH facility. The forward thinking management at Röchling elected to pursue a system that was not only reliable and cost effective, but would incorporate industry leading technology for efficiency and built-in designs for redundancy. Their facility required both a cooling tower system and a chiller system. Below are the design features of each of these Thermal Care systems, and the benefits of some of the unique features are explained.

 
More Than One Cooling Water Temperature Required

One of the most critical questions when beginning a cooling system design is, “What temperature is required?” This drives the design toward either a cooling tower system using evaporative cooling for higher temperature supply, or a chiller system using mechanical refrigeration for lower temperature supply. Generally, anything at or above 80-85°F (27-29°C) can use a cooling tower system, and anything below that will require refrigeration. The temperature requirement is dictated by the processing equipment requiring cooling. Sometimes, facilities will utilize both a higher water temperature and a lower water temperature for various equipment throughout the facility. This is true for Röchling Automotive.

In cases like this, a water-cooled chiller is an excellent solution for the chilled water system.  A water-cooled chiller is the most energy efficient chiller design available.  It can utilize the cooling tower system for its condenser cooling, which eliminates the need for multiple fans for forced air cooling.  Because the cooling tower system is already required for other equipment, the additional capacity needed for the chiller’s condenser has minimal impact on the overall cost of the system.

TC Series Dual Circuit Chiller.

 
Variable Speed Turbo Water-Cooled Chiller

Röchling elected to install industry leading technology with the TC series central chiller. The chiller utilizes a variable speed, magnetic bearing Danfoss Turbocor® compressor. This design can modulate the speed of the compressor to match the demand of the system. With the magnetic bearings, there is no oil required in the compressor. This feature allows the compressor’s speed to be reduced much lower than a traditional compressor. Traditional compressor technologies require a minimum pressure differential to ensure proper oil circulation in the system. To achieve the minimum differential, the compressor’s speed can only be lowered so much. This minimum differential is no longer a factor when using a TC chiller.

It also incorporates two completely independent circuits, both refrigeration and water. For high level production facilities like Röchling’s, built-in redundancy like this is critical. Finally, the chillers use high efficiency brazed plate evaporators. With these, not only is the chiller’s efficiency optimized, but the extremely compact design helps to minimize the footprint of the chillers which frees up valuable space in the mechanical room.

 
Chilled Water Circuit Pumping System

The pumping system for the chilled water circuit also reflects Röchling’s comprehensive philosophy of energy efficiency and redundancy. It includes an all stainless steel reservoir to add volume to the system for temperature stability. The reservoir is fully insulated with industrial grade material to minimize waste energy losses through condensation.

The process pump, which supplies cooling water to the production equipment, is controlled by a variable frequency drive (VFD) based upon input from a pressure transducer.  As production machines are brought online or taken offline, the pressure in the chilled water system is altered. The pressure transducer measures this and provides input to the VFD, which responds by ramping the speed of the pump motor up or down to match the demand. The pumps in this system are configured with a dual standby pump and discharge manifold. This design allows for a standby pump to act as either the process pump or chiller recirculation pump in the event of an emergency.

Finally, the chilled water loop includes a full flow, stainless steel filter so 100% of the water circulated through the system is as clean as possible. This helps prevent any clogging or fouling in the piping and production equipment that reduces the efficiency of the system over time.

Pumping system with 3 pumps - process pump with VFD (left), dual standby pump (middle), and recirculation pump (right).

 
Closed Loop Cooling Tower System with a Plate and Frame Heat Exchanger

The second part of the facility’s process water system is the cooling tower system. It provides cooling to the chiller’s condenser but also any production equipment that can accept higher temperatures (in the 80-85°F range as mentioned above). Röchling’s cooling tower system is a specific type known as a closed loop design which includes a plate and frame heat exchanger. It isolates the water flowing through the cooling tower from the water circulating to the production equipment. While cooling towers are a cost effective and energy efficient means of cooling, they can introduce contamination into the water as well as create the potential for scale build-up in the system.

Cooling towers use evaporation to reject energy from the system. Evaporation increases dissolved solid concentrations and results in scaling. By using a plate and frame heat exchanger, which can be opened and cleaned, the closed loop design protects the production equipment from efficiency losses associated with clogging and fouling. Both the tower side and the process side of the heat exchanger include stainless steel, full flow filters for added protection.

There are multiple cooling towers in the system that stage on and off to match demand and add redundancy. The fiberglass cooling tower shells are designed to withstand constant exposure to the elements and harsh industrial environments for long lifespans. The efficient counter flow design maximizes evaporation and thus heat rejection. Counter flow refers to the direction of the water flow versus the air flow. The fans and motors are all direct drive and ready for VFD control. 

Fiberglass cooling tower with counter-flow design.

 

Cooling Tower Pumping System

The cooling tower pumping system is similar to the chilled water pumping system configuration. It also uses a VFD controlled process pump and a dual standby pump for an efficient, redundant combination. The dual standby includes a suction manifold and a discharge manifold. This allows the standby pump to draw water from either the tower side or the process side of the fully divided tank.

A fully divided tank refers to the baffle installed in the reservoir. It extends completely from top to bottom and is welded at all seams. This design removes the need for two separate tanks by housing completely separate wells within the same tank conserving floor space. Cooling tower reservoirs do not require insulation because of the operating temperatures of the system.

 
Conclusion

When reviewing the components and overall designs of these systems it is easy to see a consistent theme: efficiency and redundancy. Design decisions like these play a part in Röchling’s continued success in the market. As Röchling’s product quality is recognized in the industry and their market share continues to grow, their cooling system is ready to support the increased demands and even expand to match as needed.

 
About the Author

Tom Stone is the National Sales Manager of Industrial Markets for Thermal Care. He has been in the process cooling field for 14 years after graduating from Purdue University’s School of Mechanical Engineering. For more information visit https://www.thermalcare.com.

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