In our previous article, “Understanding Chiller Technologies”, we provided an overall picture of how a typical chilled water system works. Reading that article first is highly recommended. In this article we highlight the functions of 3 key components in a chiller system. And look at how technological advancements in their design will help you save more.
Compressor with a VFD electronic panel (P2)
The Evaporator & Compressor
The first is the Evaporator & Compressor which is the heart of the chiller system. It is responsible for removing heat from the building. To minimise losses in this heat transfer, the compressor controls the pressure exerted on a refrigerant. To get an overview of how your chiller system operates and why this process is so important, please click here.
While older compressor models have fixed output thresholds which rarely match the varying cooling requirements of a building. Newer models, with Variable Frequency Drives (VFDs) can operate at continuously varying capacities to ensure consistent temperatures, higher efficiency and reduced cooling costs.
At present, there are 3 main types of compressors available in the market.
- Reciprocating Compressor
- Rotary Compressor
- Magnetic Bearing Centrifugal Compressor
All 3 types of compressors utilize different methods to compress a refrigerant as it flows through it. The magnetic bearing centrifugal compressor uses permanent magnets to reduce friction and does not rely on oil for lubrication unlike the Reciprocating and Rotary Compressors. This results in the magnetic bearing compressor having the lowest maintenance costs. Newer versions of all 3 types combine Variable Frequency Drives (VFDs) for significant energy savings. (1)
Pumps connecting the compressor to the cooling tower (P3)
As the chiller system utilises water to transport the heat, it consumes a significant portion of its energy pumping the water around the system. New pump models have Variable Frequency Drives (VFDs) which allow the pumps to adjust the water flow based on the building’s cooling requirement. VFDs can also be retrofitted to existing pumps and are a key highlight in the energy saving technology for chillers.
Air handling Unit (P4)
Air Handling Units
Air Handling Units (AHUs) are used to regulate the temperature and humidity of areas within a building. As areas in the building can vary in their cooling needs, based on their occupancy, there is usually a significant amount of energy wasted. This occurs as a result of the mismatch between the output of the Air Handling Unit (AHU) and the cooling requirement for the area it’s servicing. Newer AHUs have the ability to sense changes to the cooling needs of an area and adjust their output accordingly.
Upgrades to all these components can result in high energy savings and be extremely cost effective due to the retrofittable nature of some of these upgrades. In addition to the energy savings these systems also reduce maintenance costs and system downtime.