Environment – key factor when choosing chiller
- Aug 29, 2017-
When choosing proper water chiller for application, many factors should be taken into consideration, such as how much cooling capacity need for processing equipment, in what environment chiller operated, types of process fluid and flow & pressure.
Today, let us talk about equipment, that is the ambient temperature. An air-cooled chiller’s ability to dissipate heat is affected by the ambient temperature. This is because the refrigeration system uses the ambient air/refrigerant temperature gradient to induce heat transfer for the condensation process. A rising ambient air temperature decreases the temperature differential (ΔT) and, subsequently, reduces the total heat transfer.
If the chiller uses a liquid-cooled condenser, high ambient temperatures can still have negative effects on key components such as the compressor, pump and electronics. These components generate heat during operation, and elevated temperatures will shorten their lifetime. As a guideline, the typical maximum ambient temperature for non-exterior rated chillers is 104°F (40°C).
Spatial Constraints. Adequate air circulation space around the chiller — typically specified in the user manual — is important to maintain the proper ambient air temperature. Without proper airflow, re-circulation of the resulting insufficient air volume rapidly heats that air. This decreases chiller performance and potentially can damage the chiller.
Electrical Supply. Based on region, electric power frequency is either 50 or 60 Hz. At 60 Hz operation, motor speed (rpm) is approximately 20 percent higher, delivering more power to the compressor, pump and fan. This factor is demonstrated by the performance curves in figure 2. The dashed lines represent 50 Hz and the solid represents 60 Hz.
The available frequency in the country of operation as well as the electrical input rating of the chiller (voltage, frequency and number of phases) must be known to correctly size a chiller.