This analysis should include an assessment of where the greatest improvements are possible, then prepare a plan of measures needed to achieve energy efficiency. In this article we present some elements relevant to making important electricity savings by properly maintaining the refrigeration systems.
1. Evaluation of the utilization parameters of the refrigeration systems
The first step in any optimization strategy for the operation of the refrigeration systems should be to evaluate the utilization parameters of the cooling system and make sure they are not adjusted for a higher load than is required.
From this point of view there are significant possibilities of reducing the load for the refrigeration system by ensuring the following aspects:
- An appropriate insulation in the refrigerator (roof, walls, floor)
- A ventilation adapted to the needs to avoid heat and humidity losses
- An appropriate conditioning and dehumidification in the cooking and charging areas to reduce heat transfer as well as moisture migration in the cold areas
- Effective handling of raw materials and products to reduce the need for cooling and storage (e.g. pre-cooling of products)
2. Minimum maintenance of refrigeration systems
When the basic performance of the refrigeration plant is set on a correct variation in proper working conditions and loads, the process of assessing the steps to improve these performance starts. This process must be done in a systematic way, because all measures have complementary effects in a refrigeration process.
Minimum maintenance of evaporators (coolers):
Decreasing by 2 degrees the evaporation temperature leads to a 5.4% increase in compressor consumption, and operation with 1 degree below the required room temperature increases the consumption by 2-3%. Decreasing electricity consumption can be achieved by:
- Checking the condition of the evaporator surface (cooler)
- Checking the power consumption of the fans
- Checking the function of the defrost function because it consumes energy
- Checking the cooling system
Annual minimum maintenance operations of compressors:
- Cleaning the suction filters
- Analysis of the quality and quantity of refrigerant oil
- Compressor vibration analysis
- Checking the quantity and quality of the refrigerant
Minimum maintenance of the capacitor:
Increasing with 0.7 bar the condensation pressure leads to an increase in compressor consumption by 6%. Decreasing electricity consumption can be achieved by:
- Check the condition of the condenser surface
- Check fan power consumption
- Checking the cooling system
3. Reducing heat and pressure losses in refrigeration systems
Improving the energy efficiency of the refrigeration plant can be mainly done by reducing or eliminating energy losses due to heat loss and pressure drops in the refrigeration system.
In many companies, losses due to heat absorption in refrigeration systems are considerable. Therefore, it is necessary to isolate all pipes, surfaces and refrigeration components. The insulation must be inspected for moisture input which may influence insulation efficiency. This is essential because, over time, insulation may lose its efficiency and absorb moisture. Check the pressure levels in the refrigeration suction pipes to identify whether valves, components or pipes need to be changed.
Heat exchangers on suction lines, intercoolers, pipes and other refrigeration lines must be insulated to avoid loss of cooling and water condensation. Otherwise, this additional heat load increases the cooling demand and power consumption of the plant.
Reducing the pressure drop is another crucial issue for refrigeration systems. Pressure drops in valves and other components, especially on the suction side, can be costly due to the impact of the pressure drop on compressor performance. A drop in the evaporation pressure at 1°C may have a 3-5% higher cost in energy consumption.
With small instructions, technical staff can play an important role in increasing the performance of refrigeration equipment. These simple precautions can save a lot of money in energy and service bills, help to avoid costly failures in peak hours and prolong the life of refrigeration units.