Efficiency & Optimization of Ammonia Refrigeration Systems
Efficiency is a frequently used term to describe the operational characteristics of a refrigeration system. Other terminology can be used to describe the relative level of performance associated with ammonia refrigeration systems. You may often hear of specific terms such as:
- BHP/Ton – Brake Horsepower per Ton of Refrigeration
- kW/Ton – Kilowatt per Ton of Refrigeration
- COP – Coefficient of Performance
These descriptions can be used as a relative index to the efficiency of a refrigeration system. Ideally the desired goal is to have a lower value for BHP/Ton or kW/Ton. Conversely, a higher value is desired for the COP. The benefit of using these terms is to provide a general method for evaluating the performance or efficiency of a single component. These measurements are traditionally used for what is seen as the greatest energy users; the compressor motor(s).
It is important to be aware of other components in a refrigeration system also. In some cases, the total power input for the evaporator and condenser fan motors can exceed that of the compressor motors. Addressing a single type of component does not contribute to the overall optimization of a refrigeration system.
Ideally the desired goal is to have the system design optimized for minimal energy use. This is accomplished by utilizing the inherent equipment efficiencies and capabilities to meet all modes of operation, while maintaining temperature control. This is easily accomplished during the initial system design prior to installation of the equipment.
In the case of an existing refrigeration system, a careful examination of the installed equipment and operational requirements can also produce dramatic benefits. Re-commissioning of an ammonia refrigeration system often produces significant energy reductions by fine-tuning the control set points. This is accomplished by careful observation and study of the facility requirements and the performance aspects of the refrigeration system during the full range of operation.
In other situations positive results can be achieved by various control schemes. These may require the refrigeration system to be operated at less than the most efficient condition possible. However, in these instances the actual energy use and associate operating costs can be defined as a net reduction. While this may appear to be counter-intuitive, the savings generated are verifiable.
It is necessary to understand the electrical charges as they apply to you. Various methods are used for billing purposes based on the recorded and calculated energy use. Rate tariffs are the legal description of your energy bill and dictate how these charges are applied to your use of energy. These can include such terms as:
- Energy charges (kWh)
- Demand Charges (kW)
- Load Factor (%)
- Power Factor (%)
The operation of your facility can determine the impact these factors have on your operating costs. By reviewing the installed equipment and annual weather conditions it possible to develop an efficient ammonia refrigeration system that is optimized to meet your requirements. Other parameters such as time of use and full or part-load operation can also greatly affect the energy use and your operating costs.
Our goal is to assist you in discovering the means to allow your refrigeration system to be optimized for “minimum energy use to meet the facility requirements at the lowest possible operating cost.” The ability to sustain this performance by utilizing the various efficiency aspects of the equipment can contribute to lowering your total cost of operation.