Optimizing industrial refrigeration: how to control this energy-intensive sector?
Food processing, cosmetics, pharmaceuticals… In several sectors, industrial cold chain is as crucial as it is costly. Dametis provides solutions to reduce costs while increasing the performance of the industrial production process.
Our experts, Sébastien Papouin, Technical Director, and Yann Balem, Project Manager, talk to you about this energy-intensive area.
Industrial cold, what is it?
Air conditioning, freezing of products, low-temperature storage… Cold is an industrial process used in all sectors.
“Cooling a closed space involves removing heat to reject it outside,” summarizes Sébastien Papouin, technical energy director at Dametis, during a technical training session at the Dametis Academy. “This results in a lowering of the temperature.” For this, a thermodynamic system is used, consisting of several elements: a compressor, an expansion valve, a condenser, and an evaporator. The latter two are heat exchangers. Industrial cold production occurs when the evaporator cools the building and with a high-temperature heat pump when the condenser heats the building. This installation can take the form of an outdoor monobloc or an indoor machinery room. This industrial cold sector, so common in industry, is also one of the most energy-intensive.
“Cold production can account for up to 60% of the electricity consumption of a site,” reminds the French Environment and Energy Management Agency (Ademe), in its guide Energy Management in Industrial Cold, published in 2017. The rise in energy prices since 2022 and global warming accentuate this share. However, concrete solutions can be implemented to reduce costs and help optimize industrial cold.
Some guidelines for industrial cold management
To reduce its energy consumption, it is imperative to adopt certain usage rules. The components of a refrigeration machine are calibrated for specific temperatures and pressures. Therefore, controlling the system is essential. For example, a plant controlled by fixed setpoints may consume more energy than necessary, explains Yann Balem. Managing such a system can be complex, as the operator will need to regularly adjust the setpoint. In practice, some systems adjust their setpoints every 3 months. Ideally, a dynamic setpoint system that automatically optimizes energy consumption would be best.
Finally, to optimize industrial refrigeration, regular maintenance is essential: cleaning the condensers, checking thermal insulation, purging non-condensables, etc.
Optimization and Investment
The refrigeration cycle can be optimized. Several values must be observed for this: those of the low and high pressure, as well as the temperature differentials at the condenser and evaporator levels. “The lower the low pressure, the more energy is consumed,” reminds Sébastien Papouin. “Well adjusted, we can achieve a 2% optimization on the compressors.”
Furthermore, to optimize industrial refrigeration, Dametis recommends using self-adaptive electronic expansion valves. This investment allows adjusting the flow rate of refrigerant in the evaporator to perfectly match the refrigeration needs. Similarly, implementing variable speed drives on air condensers allows for Floating HP regulation, leading to energy savings of up to 15%.
Another practice to adopt is regulating the distribution pumps of the refrigerant fluids. “By controlling the pumps according to the needs, we save an average of 50% of the pump consumption,” adds Sébastien Papouin.
How and why recover heat?
There are three main ways to recover the heat rejected by a refrigeration system:
- The first way is to recover heat from the compressor’s discharge superheat. When the refrigerant is compressed by the compressor, its temperature increases significantly. The most commonly used technology is the implementation of a Gas / Water heat exchanger (called a Superheater) which allows water to be heated to high temperature (up to 70°C). The superheater can recover up to 10% of the total energy rejected by the refrigeration system.
- The second way is to recover heat from the condensation of the refrigerant. The simplest way is to install a Gas / Water heat exchanger which allows the gas to condense and heat the water to medium temperature (from 30°C to 60°C depending on the characteristics of the refrigeration system). The advantage of the condenser is that you can recover up to 100% of the total energy rejected by the refrigeration system.
- The last way is to recover heat from the compressor oil. Indeed, the compressor of a refrigeration system generates heat due to the friction and mechanical work involved in the compression process. This heat is usually dissipated by the compressor oil. Recovering heat from the compressor oil allows water to be heated to high temperature (up to 70°C). This technology is very interesting for screw compressors where we can recover up to 10% of the total power rejected by the refrigeration system.
This heat recovery can be used for a variety of needs and help reduce gas or electrical consumption in the plant, “the heat is first injected into the process needs: production of hot water, heating of certain process units, heating of the auxiliary equipment of a boiler…,” explains Sébastien. Afterwards, the heat can be used to heat the premises and, if there is any left, to use the heat for innovative processes such as cold or electricity production.
Heat recovery contributes to improving the overall energy efficiency of the refrigeration system by using the heat that would otherwise be dissipated and therefore not recovered.
The entire process can reduce heating costs, improve system performance, and strongly contribute to more sustainable environmental practices.
Up to 100% of the energy rejected by the refrigeration system can be recovered. The rejected power is equal to the sum of the cooling power and the electrical power of the compressors.
A comprehensive offer for efficient refrigeration systems with low environmental impact
Furthermore, Dametis takes care of implementing a smart regulation system to achieve constantly optimal operating instructions for low pressure, fan operation in the condenser, and distribution pumps.
These optimizations can be easily identified using the EMS software MyDametis. The software also automatically detects any deviations to maintain performance over time.
Each solution is tailored to the specific challenges of industrial clients, with continuous performance improvements and systematic cost reductions.
