Energy efficiency in Industrial refrigeration. Part 1: Key technologies for a sustainable industry

Energy efficiency in industrial refrigeration has become a strategic cornerstone within the cold chain industry. Faced with rising electricity costs, regulatory pressure towards decarbonisation, and the need to maintain competitiveness, companies must rethink how they design and operate their refrigeration systems. In this context, refrigeration technologies such as indirect systems with secondary fluids, the use of natural refrigerants, heat recovery, and advanced digitalisation are emerging as key solutions to optimise energy consumption and deliver added value to production processes.

Installations using secondary fluids: towards greater energy efficiency

Indirect refrigeration systems — those in which the primary refrigerant cools a secondary fluid (water, glycol, or other solutions) — offer significant advantages over traditional direct-expansion systems:

    1. Safety and Sustainability

Firstly, the charge of the primary refrigerant (NH₃ or hydrocarbons) is confined to a controlled plant room, drastically reducing the risk of leaks in working or storage areas.

This configuration also facilitates regulatory compliance and lowers costs associated with inspections and additional safety measures.

    2. Scalability and Modularity

Indirect systems allow refrigeration capacity to be implemented progressively: industries can start with part of the installation and expand it as production or storage demands grow.

This translates into lower initial investment (CAPEX) and avoids oversizing, which would otherwise penalise system efficiency.

    3. Leak Reduction and Simplified Maintenance

By minimising the length of piping containing the primary refrigerant, the risk of leaks is significantly reduced and operation and maintenance tasks are simplified.

   4. Integration Flexibility

A single secondary circuit can feed cold rooms, blast freezers or air-conditioning systems, enabling energy synergies and optimised management of the available cooling capacity.

   5. Energy Efficiency

Although there is a slight performance loss due to the additional heat transfer stage, this is offset by:

• Enhanced control of the installation

• Reduction of leaks (which prevents hidden efficiency losses)

• Possibility of integrating heat recovery and thermal storage

Application examples

• Agri-food industry: processing plants for fruit, meat, or dairy products, where safety and scalability are critical.

• Logistics platforms: enable a single NH₃ or R290 “cold hub” to supply multiple storage rooms and services.

• Supermarket distribution centres: greater safety for the public and easier integration with HVAC systems.

Natural Refrigerants enhancing refrigeration technologies

Regulatory and environmental developments are driving the adoption of natural refrigerants such as ammonia (NH₃), carbon dioxide (CO₂) and propane (R290), thanks to their environmental and thermodynamic benefits. These are now a fundamental part of modern refrigeration technologies aiming to reduce climate impact without compromising performance.

Advantages of Natural Refrigerants

1. Low or Zero Global Warming Potential (GWP)

   • NH₃: GWP ≈ 0

   • CO₂: GWP = 1 (reference value)

   • Hydrocarbons (R290, R600a): GWP < 5

2. High Thermodynamic Efficiency

   • NH₃ offers the best performance in industrial applications.

   • CO₂ excels in freezing applications and cold climates, particularly in cascade or booster systems.

3. Availability and Stable Cost

   • Not subject to phase-down quotas or progressive cost increases as with HFCs.

4. Compatibility with Indirect Systems

   • Allow natural refrigerants’ efficiency to be leveraged while minimising installation risks.

Challenges associated with refrigeration technologies

• Safety: NH₃ is toxic and hydrocarbons are flammable, requiring specific design and operational safety measures.

• Demanding Operating Conditions: CO₂ operates at very high pressures, necessitating specialised components and equipment.

• Personnel Training: It is essential to ensure that installers and operators are properly trained in handling these technologies.