Overall energy consumption in cooling towers

Evaporative towers require quite low energy consumption levels, mostly employed to ensure ventilation and the air circulation within the structure. These amounts are anyway drastically lower than the energy consumed by an air condenser. These consumes can be further lowered with a more a adequate design of the tower, fitting at its best the kind of installation, also leading to huge saving in big dimension plants.
Savings are clearly achieved minimizing as much as possible the ventilation, which always engenders high bills. Instead of increasing the airflow rate, in order to boost thermal transfer and efficiency it’s better to increase to thermal exchanger surface. This also allows to decrease the speed of the outlet air, thus reducing the water loss caused by drag effect and also the noise levels, another aspect that has to be evaluated when choosing this kind of thermal machine.

On the market it’s possible to find classic concrete towers for average-big plants, where the shape induces a natural air draft from the bottom to the top, providing the necessary air circulation inside the tower. This towers, as we’ve said already, require constant maintenance and water management.
In case of towers equipped with forced fans, there is often the advantageous condition of not having water in direct sunlight contact. This factor highly reduces the problem of algae growth, lowering the water treatment tasks, while the need of carry out the purge remains in order to fix the salt concentration problem.

This kind of tower is thus a cheaper solution and involving low energy consumption, offering excellent cooling efficiency. In addition it can very easily equipped with plate heat exchangers and recirculating pumps, that divide the utilities circuit from the cooled water circuit. In fact, if generally the refrigerating fluid to be cooled must be kept non-contaminated, it is also recommendable to not use water tower directly to cool production process’ utilities. That’s because it can be not completely clean, and can therefore significantly reduce the time period among maintenance operations.

Hence, in order to employ at its best the free cooling effect offered buy evaporative towers, it is suitable to insert between the process utilities and the water tower some plate heat exchangers, in fact physically separating the two circuits. This option is also preferable to the installment of an evaporative cooler, which even if is a simpler and single-piece machine, it involves severe cleaning issues when it’s necessary to remove scaling from the internal coil. While in an evaporative tower with isolated circuits from the utilities, scaling is concentrated on the exchanger, which is easy to dismantle and wash, or otherwise on the thermal transfer pack, that can be rapidly replaced.

For small and average thermal capacity modern plants, engineers are more and more prone to select package standard towers, a modular solution that allows to cover also high thermal capacities, offering a more modern installations and a series of advantages:

  • Flexibility
  • Simple maintenance
  • Reduced ROI
  • High transparency in costs evaluation
  • Quick installation
  • Construction site times near to zero (or anyway limited to the construction of the reinforced concrete tank)
  • Easier noise levels management and reduction

On the other hand, this kind of evaporative tower requires a higher power capacity installed, with a higher quantity of installed fans in substitution of a unique and bigger one. Anyway, having a higher quantity of fans installed, it’s also possible to implement a step functioning, turning some of them off and reducing to zero their power consumption based on weather conditions during the different hours through the day. And finally, a package cooling tower is also easier to dismantle in case of decommissioning, when compared to a traditional huge cooling tower with a concrete structure.

Torri consumo energia