How to Prepare for a CTI Thermal Performance Test, Plume Abatement Test, or Drift Emission Test

​​The CTI provides thermal, plume abatement, and drift performance testing programs as a service to cooling tower owners, operators, and manufacturers. For these programs, calibrated test equipment is provided by the agency that is performing the test. The CTI representative will collect the data, evaluate it to determine if CTI code requirements are met, calculate the test result, and prepare a test report.

In this blog, we will discuss the information you should know and steps you should take to prepare yourself for this type of testing, such as:

  • What is a thermal performance test?

  • What is a plume abatement test?

  • What is a drift emission test?

  • Site preparation

  • Tower configuration

  • Required information for your CTI representative

What is a Thermal Performance Test?

​​Thermal performance tests are conducted to determine the ability of a cooling tower to cool water. All operating thermal parameters are measured and compared against design specifications. These parameters include:

  • Inlet wet-bulb temperature

  • Cold water temperature

  • Hot water temperature

  • Water flow rate

  • Fan motor power

These tests may also be used to determine if a new tower will perform as expected, or to evaluate the performance of an older tower.

What is a Plume Abatement Test?

Plume abatement tests are used to evaluate the exhaust plume visibility of a cooling tower. This test incorporates all of the measurements of the thermal performance test, but is usually conducted in the colder months, while the thermal performance test is usually conducted in the warmer months.

In addition to the normal thermal performance test parameters, the tower exhaust air flow rate, exit wet-bulb temperature, and exit dry-bulb temperatures are also measured.

What is a Drift Emission Test?

Drift emissions result from water droplets that are entrained in the exhaust air stream that exits a cooling tower. These droplets are different from condensation — the drift droplets contain the same chemical makeup as the circulating water.

Drift emission tests are performed to measure the amount of chemically laden circulating water that exits the tower. This type of testing is used to/for:

  • Ensure proper tower function

  • Establish drift emission benchmarks

  • Environmental studies

Site Preparation

The test purchaser is responsible for ensuring that the cooling tower is ready to be tested. Proper site preparation will reduce the amount of time the CTI Test Representative has to spend at the testing site, which will reduce the overall cost. Normal test site preparation includes:

  • Installation of Pitot taps for water flow measurement

  • Installation of a cold water temperature tap

  • Erection of scaffolding

  • Scaffolding is usually required for safe access to elevated water flow measurement locations and for access to the fan stack exit plane

  • Electrical power

  • Operating cooling tower fans

If the tower design doesn’t allow for the installation of measurement taps, the CTI Test Representative should be contacted so alternate methods can be recommended. Arrangements should also be made for an electrician or other qualified technician to be available to take fan motor power readings as required during the test.

Tower Configuration

If the heat load and/or water flow to a multi-cell tower is below the operating limits, the number of cells in operation may be reduced prior to the test in order to meet code recommendations. The heat load and flow rates of the operating portion of the tower should meet code requirements on a per cell basis, rather than an entire tower basis. The test results of the operating portion of the tower will be considered representative of the entire tower.

Required Information for Your CTI Representative

For a thermal performance or plume abatement test, the CTI Representative will require the following information:

  • Thermal performance curves/characteristic Curve

  • Water flow measurement locations

  • Number and size of pipes

  • Tower type

  • Forced/induced draft

  • Tower manufacturer

  • Air inlet size

  • Height and number of open sides

  • Anticipated heat load

  • Nominal fan motor voltage

  • Cold water measurement location

  • Pump or cold water grid

  • Make-up and blow-down locations

For a drift emission test, the CTI Representative will require the following information:

  • Typical circulating water analysis

  • Sodium, calcium, and magnesium concentrations

  • Tower type

  • Forced/induced draft

  • Tower manufacturer

  • Water flow measurement locations

  • Number and size of pipes

  • Nominal fan motor voltage

  • Stack diameter

  • Stack height

  • Fan hub diameter

How Can CTI Assist With Your Cooling Tower Needs?

Cooling Technology Institute has published a plethora of papers about various cooling topics. CTI is also an advocate in promoting the use of environmentally responsible Evaporative Heat Transfer Systems (EHTS), cooling towers, and cooling technology for the benefit of the public. Additionally, CTI is an independent, third-party thermal performance testing to help participating manufacturers and owners/operators achieve the best performance from their cooling towers. Visit our website today for more information on cooling technologies!

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