In many facilities, chiller and condenser systems are the largest energy consuming component of the plant. Operating a chiller at its peak performance saves energy, as well as maintenance costs, and can keep the facility’s loads properly maintained. Chiller performance varies significantly with operating conditions, and any opportunity to improve efficiency and extended equipment life is greatly desired by any facility manager. One major indicator of chiller performance is the historical values of the chiller approach temperatures. These temperatures show the heat transfer efficiency and can be a precursor to a potential issue in the system. With proper, routine monitoring of approach temperatures, the chiller’s operating life and operating efficiency are greatly increased.
Condenser approach temperature is simply defined as the difference between the condenser liquid refrigerant temperature and the outlet condenser water temperature. The closer these temperatures are to each other, the more efficient the heat transfer. Similarly, the evaporator approach temperature is the difference between the evaporator refrigerant temperature and the leaving chilled water temperature. Most later model chillers provide the approach temperatures on the chiller control panel or remotely accessible.
Approach temperatures should be routinely monitored to ensure that the system is running at the maximum efficiency. Reaching maximum chiller efficiency occurs when the facility is producing the greatest tonnage at the lowest kilowatt usage. This typically equates to running at 70 to 75 percent, along with the lowest entering condenser water temperature (ECWT). High chiller approach temperatures usually mean reduced heat transfer, increased energy consumptions, and a reduction in refrigeration capacity. High approach temperatures should be investigated as they are usually an indication of a severe problem:
- Fouled/Contaminated tubes (biofilm, scale, sludge, corrosion, etc.)
- Non-condensable gases present (Air in the refrigerant)
- Low refrigerant charge or altogether loss of charge
- Incorrect cooling tower operation
- Irregular water flow to chiller
It’s critical to keep approach temperatures at an operable level. This requires effective water treatment systems that help protect equipment and manage costs. Ensuring these temperatures are ideal leads to great efficiencies with less power consumption. Protecting the cooling water system also eliminates many maintenance costs. Use recirculating systems, closed loops, once through systems, as well as solid water treatment. Maintaining a good protective program allows for optimized operations.
There are many ways to keep chiller temperatures at the normal rate like daily logging for operating history and baselines, increasing tube cleanliness, and effective condenser water treatment. Chem-Aqua is a leader in chiller optimization using custom water treatment solutions. They specialize in custom designed water treatment programs for boiler, cooling, and process water systems. These reliable and durable systems help their customers to minimize their energy, water, and maintenance costs while ensuring safe and reliable operation of these critical systems. Contact Chem-Aqua today to learn more about their products to improve chiller efficiencies and how to save money by keeping condensation systems running efficiently.