by Eric Corzine, Product Manager, Climate Control at Rittal
As industrial processes scale, the threats and challenges of cooling the racks of automation equipment increase exponentially. Sophisticated, sensitive electronics and drives are the backbone of many industrial systems. This equipment is often placed inside enclosures to protect it from environmental influences such as temperature, moisture and contaminants like corrosive vapors and dust. If these are not prevented, electronic components will inevitably fail, eventually leading to the shut-down of entire production systems. The failure of a production system can add up to losses for an operation.
What will the future look like?
The single most important environmental factor to manage in industrial enclosures is temperature. Relative to each individual component, the heat of electronic components has increased significantly in recent years. At the same time, the density inside control cabinets has increased dramatically, resulting in a 50 – 60% increase in heat in the enclosures.
With the advent of microelectronics and new electronic components, the requirements for professional enclosure construction and heat dissipation have evolved dramatically over the last few years. Modern enclosure climate control systems must take these challenges into account, offering the best technical solution while guaranteeing optimum energy efficiency. If heat is not managed properly and the maximum permitted operating temperature is exceeded, the service life of these components is halved and the failure rate is doubled.
Trouble-free operation and functioning of production lines is heavily dependent on how the heat generated by electrical and electronic components is dissipated from the enclosure to the ambient environment. We distinguish three different types methods of heat transfer:
- Thermal radiation
- Thermal conduction
In the case of enclosures and electronic housings, we are mainly concerned with thermal conduction and convection. With thermal radiation, heat is passed from one body to another in the form of radiation energy, without a medium material, and plays a minor role here.
Whether we are dealing with heat conduction or convection depends on whether the enclosure is open (air permeable) or closed (air-tight). With an open enclosure, the heat (heat loss) can be dissipated from the enclosure by means of air circulation, i.e. thermal conduction, from inside to outside and is typically in a controlled environment such as data centers. However, if the enclosure has to remain closed due to harsher conditions, the heat can only be dissipated via the enclosure walls, i.e. through convection. Depending on the amount of heat loss of the components, these methods may not sufficiently cool the equipment and a climate control product may be required.
Identifying the proper cooling device depends upon the differences between the ambient temperature (Tu) and the desired enclosure internal temperature (Ti).
An additional factor to consider when choosing a means to cooling is the environment in which the enclosure is installed and the ingress protection (IP) rating required. Each climate product has corresponding IP ratings:
Other innovative, hybrid cooling technologies have been developed that rely upon two parallel cooling circuits working together depending on the temperature differential. An integral heat pipe dissipates heat from the enclosure when the ambient temperature is below the setpoint, providing passive cooling. Active climatization is achieved when the compressor’s cooling circuit is engaged and provides cooling via speed-controlled components for demand-based cooling. Combining the two circuits reduces temperature hysteresis and provides more precise cooling. Not only is energy consumption far less than with conventional technology, but the improved temperature stability leads to longer service life of both the components within the enclosure and the cooling unit itself.
The reliability of electrical and electronic components in an enclosure can be put at risk not only by excessively high temperatures, but also by excessively low ones. The enclosure interior must be heated, particularly to prevent moisture and protect against frost. It is also necessary to prevent condensation within the enclosure. The latest generation of enclosure heaters has been developed with the help of extensive Computational Fluid Dynamics (CFD) analyses. The positioning of the heater is of fundamental importance for even temperature distribution inside the enclosure. Placement of the heater in the floor area of the enclosure is recommended in order to achieve an optimum distribution of temperature and hence efficiency. Thanks to positive temperature coefficient (PTC) technology, power consumption is reduced at the maximum heater surface temperature. Together with a thermostat, this results in demand-oriented, energy-saving heating.
Smarter, intuitive, and more efficient designs will need to be a staple no matter what setting the enclosure is in. Designers will need to take careful consideration in the initial planning stages of projects, ensuring that the appropriate cooling technology is incorporated into designs.
CMA/Flodyne/Hydradyne is an authorized Rittal distributor in Illinois, Wisconsin, Iowa and Northern Indiana.
In addition to distribution, we design and fabricate complete engineered systems, including hydraulic power units, electrical control panels, pneumatic panels & aluminum framing. Our advanced components and system solutions are found in a wide variety of industrial applications such as wind energy, solar energy, process control and more.