Improving Cooling Tower Energy Efficiency

cooling-tower-energy-efficiency

An HVAC, or Heating, Cooling and Air Conditioning unit's operation is one of the most essential factors to think about when running industrial, commercial or residential property applications. As such, it is of utmost importance improving cooling tower energy efficiency in terms of both power and water, and in knowing what the advantage and disadvantages are when using different types of cooling towers. Discover how to improve the efficiency of a cooling tower when downtime and running the HVAC unit at a high cost isn't an option.

Cooling Tower Motors and Pumps

A cooling tower's motor is specifically manufactured to endure the rigors of either an industrial or a commercial application. The driving equipment behind electric motors (fans and pumps) operate at a steady, constant speed, and are usually handled by a mechanical throttling such as pump valves or louver slats. These control the water, the airflow speed and the airflow volume.

Though these control methods optimize cooling tower settings indoors, the motor continues to run at full-load rate and at full speed even when tasked to do less work. This in turn lowers overall efficiency and wastes a lot of energy.

This wastage has been addressed with improvement in terms of noise reduction, overall operating efficiency, reliability and system safety, all with the introduction of newer drive technology and motors used in cooling tower applications.

There are 2 methods to control the motor current during start-up: Variable Frequency Drive, or VFD, and the Reduced Voltage Soft Starter, or RVSS.

Cooling Tower Frequency Drives

Advances in Variable Frequency Drives make load control more efficient even when the operating load varies. A VFD's primary purpose in a cooling tower setup is to save on operating costs and energy, and has been proven to be effective by running the motors in variable torque loads.

Here are its advantages:

Reduce Starting Torque

The torque required to start up an electric motor is significantly greater than the torque needed to maintain a motor at full speed. This great surge in power can cause malfunctions in the motor and other equipment in your cooling tower.

VFDs divert the stress away from insulation, which in turn increases the motor's lifespan. HVAC variable torque technology includes low speed stability settings with minimum oscillation, motors operating with decreased noise and low-speed torque implementation. There's a significantly more efficient power factor, lower maintenance costs and the equipment lasts longer.

A Variable Frequency Drive can also be used for adjusting running speed and comes with soft start options. The primary expense of setting up a VFD may be more expensive, but over time the lower utility rates in kW per hour and total kW required more than recoup the initial costs.

Benefits:

  • Reduce starting torque
  • Modulation of Hertz
  • Improve Motor performance
  • Reduce Full load amp
  • Increase the Life span
  • Reduce power consumption
  • Reduce energy cost
  • Annual savings

Disadvantages:

  • Expensive

Cooling Tower Soft Starters

Soft Starters operate on the fact that starting torque can be low during startup due to a lower motor voltage. They are also much less expensive to buy than the VFDs.

Here are its advantages:

Smooth Torque Control. It manages the cooling tower motor to steadily accelerate, reducing potential wear and tear to the cooling tower and all the connected devices.

Less Maintenance. Soft starters control power surges during startups, extending the motor's life and therefore needing less maintenance.

Adjustable Acceleration Time. This is especially useful for applications that need one equipment doing multiple functions. Soft starters allow you to control the rate and acceleration time from the outside, usually at the push of a button.

Energy Saver. Minimizing torque during motor start-up is key to reducing utility costs down the line. A soft starter can recoup the energy costs in just a few months' time.

Space Saver. Soft starters are significantly smaller than VFDs; applications that require only the control of start-up can utilize it and gain invaluable space for other necessary equipment.

Benefits:

  • Reduce starting torque
  • Increase motor life span
  • Reduce power consumption
  • Reduce energy cost
  • Annual savings
  • Affordable

Disadvantages:

  • No modulation
  • No Programing
  • No amp reduction