Optimizing industrial refrigeration: how to control this energy-hungry sector?

Food processing, cosmetics, pharmaceuticals… In many sectors, industrial refrigeration is as crucial as it is costly. Dametis provides solutions to reduce costs while enhancing the performance of industrial production processes.

Our experts Sébastien Papouin, Technical Director, and Yann Balem, Project Manager, tell you all about this energy-intensive pole.

What is industrial refrigeration?

Air conditioning, product deep-freezing, low-temperature preservation… Refrigeration is an industrial process used in all sectors.

“Cooling a closed space consists in removing the heat and rejecting it outside,” summarizes Sébastien Papouin, Technical Energy Manager at Dametis, during a Dametis Academy technical training session. “This lowers the temperature. This is achieved using a thermodynamic system consisting of several components: a compressor, an expansion valve, a condenser and an evaporator. The latter two are heat exchangers. Industrial refrigeration is produced when the evaporator cools the building, and high-temperature heat pumps when the condenser heats the building. This installation can be in the form of an outdoor monoblock, or an indoor machine room. This industrial cooling unit, so common in industry, is also one of the most energy-intensive.

” In some sectors, cold production can account for up to 60% of a site’s electricity consumption,” points out the French Environment and Energy Management Agency (Ademe), in its guide to energy management in industrial refrigeration. Energy management in industrial refrigerationpublished in 2017. Rising energy prices since 2022 and global warming are accentuating this share. However, there are practical solutions that can help you reduce your bills and optimize your industrial refrigeration.

A few rules of thumb for industrial refrigeration management

To reduce energy consumption, it’s imperative to adopt certain rules of use. The components of a refrigeration machine are calibrated for precise temperatures and pressures. Controlling the installation is therefore essential. If we take, for example, a plant controlled by fixed setpoints, it is possible that it will consume more than it should,” explains Yann Balem. Controlling this type of plant can be complex, because to optimize it, the operator will have to regularly modify the setpoint. In practice, we can observe installations that modify their setpoint every 3 months. Ideally, a dynamic setpoint system should automatically optimize the plant’s consumption.

Finally, to optimize industrial refrigeration, maintenance must be carried out regularly: cleaning condensers and checking thermal insulation, purging non-condensables, etc.

Optimization and investment

The refrigeration cycle can be optimized. To do this, several values need to be observed: those of low and high pressure, as well as temperature differences at the condenser and evaporator. “The lower the low pressure, the higher the consumption,” says Sébastien Papouin. “Properly adjusted, we can achieve an optimization of 2% on the compressors”.

To optimize industrial refrigeration, Dametis recommends the use of self-adjusting electronic expansion valves. This investment makes it possible to adjust the refrigerant flow rate in the evaporator to perfectly match refrigeration requirements. Likewise, the use of variable speed control on air-cooled condensers enables floating HP regulation, generating energy savings of up to 15%.

Another reflex to adopt is the regulation of heat-transfer fluid distribution pumps. “By controlling pumps according to need, we can save an average of 50% on pump consumption,” adds Sébastien Papouin.

How and why recover heat?

There are three main ways of recovering the heat rejected by a refrigeration plant:

• The first is to recover heat from desuperheating at the compressor outlet. When refrigerant is compressed by the compressor, its temperature rises considerably. The technology most often used is the installation of a gas/water exchanger (called a Desuperheater), which heats water to a high temperature (up to 70°C). The desuperheater recovers up to 10% of the total energy rejected by the cooling system.

• The second is to recover heat from the condensation of the refrigerant. The simplest way to do this is to install a gas/water exchanger, which condenses the gas and heats medium-temperature water (from 30°C to 60°C, depending on the characteristics of the cooling system). The advantage of the condenser is that up to 100% of the total energy rejected by the cooling system can be recovered.

• The final method is to recover heat from the compressor oil. The compressor in a refrigeration system generates heat due to the friction and mechanical work involved in the compression process. This heat is generally dissipated by the compressor oil. Compressor oil recovery enables high-temperature water (up to 70°C) to be reheated. This technology is particularly interesting for screw compressors, where we can recover up to 10% of the total power rejected by the cooling system.

This heat recovery can be used for a multitude of purposes, helping to reduce the plant’s gas or electricity consumption. “First of all, the heat is injected into process requirements: production of domestic hot water, heating of certain process bricks, heating of boiler room auxiliaries, etc.,” Sébastien explains. Afterwards, we can heat the premises and, if there’s any left over, use the heat for innovative processes such as refrigeration or electricity production.

Heat recovery helps to improve the overallenergy efficiency of the refrigeration system by using heat that would otherwise be dissipated and therefore not recovered.

Together, these processes can reduce heating costs, improve plant performance and make a major contribution to more environmentally sustainable practices.

Up to 100% of the energy rejected by the chiller can be recovered. The rejected power is equal to the sum of the cooling power and the compressors’ electrical power.

A complete offering for high-performance, low-impact refrigeration systems

Dametis carries out projects from design to completion. Our experts have the ability to dimension the cooling installation to the exact needs of the process in order to optimize your industrial cooling management. For example, Dametis helped alginate producers install a new cold production system where 100% of the heat is recovered in the process.

Dametis then takes care of setting up a smart regulation to obtain consistently optimal operating setpoints for low pressure, condenser fan operation and distribution pumps.

These optimizations can be identified at a glance using the EMS MyDametis software. The software also automatically detects drifts to maintain performance over time.

Each solution is tailored to the specific needs of the industrial customer, with continuous performance improvement and systematic cost reduction.