As the second highest energy consuming component of your refrigeration system, condensers are also one of the most critical elements. Knowing how to optimize your condenser can increase operational performance while reducing energy usage and maintenance costs.
These six factors can improve your condenser’s performance:
- Freeze protection — In cold climates, if water remains in a condenser and it is exposed to the elements, it can freeze. Freeze protection consists of one or more 10-15 kW water heating elements in each condenser. Remote sump tanks are often installed to prevent recirculating drain water from freezing. When switching from wet to dry operation using an evaporative condenser, a remote sump tank can also eliminate the need to drain water from the basin.
- Water treatment — Water within a condenser must be treated to avoid scale buildup and bacterial growth as we discussed in last month’s blog post on water treatment (will provide link when it posts). This typically involves adding chemicals to a remote sump tank, which is the easiest to maintain in one central location. Tubing can be utilized to route the chemicals to individual condensers if necessary. Condensers must remove water at a rate proportional to the evaporated water to limit the concentration of dissolved solids and other chemicals. Correct water treatment may lower the required rate of water drainage, minimizing the chemicals drained.
- Hybrid wet / dry coils — These products reduce the need to use water to wet the coils during cooler months. This results in water conservation, reduced pump power and the need for chemical drainage, which all lead to increased efficiency.
- Air-cooled condensers — While rare in large refrigeration systems, these are an option to eliminate the requirement for water in evaporative condensers. Air-cooled condensers have higher horsepower fans and run higher discharge pressure, but do not use water. These condensers do require more power usage, but the water savings may offset the additional energy costs.
- VFDs — Adding variable frequency drives (VFDs) to condenser fans has several advantages and will give better condensing pressure control, which can smooth system operation. VFDs are used to lower off-peak fan power usage. Condensers need to be sized for peak loads, meaning for all loads except for a few peak conditions when they are oversized. Reducing the fan speed to match the capacity will give considerable horsepower savings. As fan speed drops, power consumption drops by the cube of fan speed (50 percent fan speed = 12.5 percent fan power).
- Purging of non-condensable gasses —Any gas, such as nitrogen or air, that won’t condense at the required temperature reduces the refrigerant concentration and partial pressure, as well as the effectiveness of the condenser coil. Total head pressure must then be increased to maintain a given refrigerant condensing temperature, creating more work for compressors. Equipment that pulls vapor from condensers to collect non-condensable gasses can be purged to safely remove these gasses from the system.
If you’d like to learn more ways to improve your condenser’s performance, email me at firstname.lastname@example.org.