This is the type of innovation Entertainment Engineering loves to report on. It’s interesting and inventive and can be used across multiple industries. Cooling is important, particularly during certain times of the year when cooling becomes necessary for industrial manufacturing processes, machine and cabinet cooling, IT computer centers, control rooms, offices, and more. Cooling plays an important role in controlling energy costs and complying with energy efficiency regulations. It can also eliminate costly losses due to damaged IT equipment, machines, or food spoilage—and creates a safe place for people to work.

Most refrigeration systems rely on traditional refrigerants like fluorinated gases (F-gases), ammonia, or propane. However, these conventional refrigerants pose threats to the environment, safety, and human health. F-gases contribute to ozone depletion and global warming while ammonia is toxic and propane inflammable. Therefore, there has been a widespread search for safe, clean, sustainable, and affordable refrigerants.

When a KNF customer developed their design to use water as a refrigerant, one of the key components they incorporated was a KNF pump. The cooling system relies on pure water, also called R718, to be used. This solution is the first and only water-based chiller in the world to be mass-produced. The core of the technology is that water, as highly energy driven refrigerant, works in a closed circuit where it is continuously evaporated, compressed, and condensed. The inherent system requires a constant and precise vacuum.

The main advantages lie in the technology's outstanding efficiency and sustainability. It enables electricity savings of up to 80 percent compared to current conventional cooling systems and generates almost zero CO2 emissions. Because it uses only water, the technology poses no risk to humans or the environment. Filling the system, service, and maintenance, including the recycling is simple and there is no need to lean on safety regulations like the ones used for traditional refrigerants.

Water can be used as a refrigerant thanks to a precise and constant vacuum in the system, which needs to be maintained during all operations. Only under the right vacuum does water undergo the changes of state at temperatures required for using water as a refrigerant. This creates high demands on the vacuum pump. It needs to operate in areas between 10 and 100 mbar abs. and in temperature ranges from 5 °C to 45 °C. In addition, the pump must operate oil-free and reliably over long periods without maintenance.

A small footprint and a general high robustness are vital, and the pumps must be able to cope with the challenging steam environment in the chiller. Therefore, diaphragm pump technology is ideal for the task and ultimately led to a collaboration between the system’s manufacturer and KNF, the leader in diaphragm pump technology. 

The final pump used in the system is based on the KNF N 813.3 series, tailored to the specific customer application. For a higher rotational speed, the motor has been digitally parametrized. This is possible because the brushless DC motor is an in-house developed component, allowing KNF to make advanced digital adjustments. On the suction side, the pump was fitted with a head plate with permanently open gas ballast, a filter, and a nozzle. The gas ballast helps remove condensate from the pump, ensuring ideal performance.

Despite its powerful performance and the high motor rotation speed, the vacuum pump operates very quietly and with low vibration. This opens the possibility to use the chiller in residential buildings and in manufacturing processes where low-noise operation is important. This example illustrates how the quality of one component like a pump can have a major effect on the entire system and its applicability for different areas. It also shows that customizing a pump collaboratively can lead to solutions that would otherwise not have been possible.

For more information: 

KNF

Pump N 813

*Pump image courtesy of KNF. Other images are from Depositphotos.com.