CO₂ Refrigeration Solution

CO₂ Refrigeration Heat Recovery Solution for Supermarkets

In modern supermarket refrigeration, heat should not be treated as waste. By integrating a dedicated heat recovery stage ahead of the gas cooler, part of the high-temperature CO₂ discharge energy can be transferred to water and reused for cleaning, sanitation, and store hot water demand. The result is a smarter refrigeration system with better energy utilization, lower operating cost, and reduced carbon emissions.

System Illustration and Real Installation

The diagram below shows the basic concept of a supermarket CO₂ heat recovery system. The real installation photo demonstrates how heat recovery is implemented in practice, where the exchanger is integrated into the plant room and connected to the water circuit.

System concept: high-pressure CO₂ refrigerant first passes through the heat recovery stage, then the remaining heat is rejected through the gas cooler.

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How the Heat Recovery Principle Works

In a transcritical or high-pressure CO₂ supermarket refrigeration system, the compressor rack discharges refrigerant at elevated temperature and pressure. This discharge gas contains valuable thermal energy. Instead of rejecting all of that energy directly to ambient air, part of it can be recovered by a dedicated heat recovery exchanger.

On the refrigerant side, the hot CO₂ gives up a portion of its heat before entering the gas cooler. On the water side, cold make-up water or return water absorbs that heat and is sent to a storage tank or directly to store hot water use points. This recovered energy can support floor cleaning, sanitary washing, utility water heating, and other daily store operations.

Compressor Discharge CO₂ leaves the rack at high pressure and high temperature.

Heat Recovery Exchanger Thermal energy is transferred from CO₂ to the water circuit.

Hot Water Generation Heated water is stored or used for cleaning and service demand.

Gas Cooler Backup Remaining heat is still rejected when water demand is lower than available heat.

Important engineering point: the gas cooler should still be retained in most supermarket CO₂ systems. Heat recovery demand changes throughout the day, while refrigeration duty continues to operate. The gas cooler ensures stable system operation whenever recovered heat cannot fully absorb the available discharge energy.

Main Functions of a CO₂ Heat Recovery System

Recover useful thermal energy Transform compressor discharge heat into usable hot water rather than rejecting it entirely to the environment.

Reduce water heating cost Lower dependence on electric heaters, boilers, or other separate hot water generation equipment.

Improve total system efficiency Use the same refrigeration energy input for both cooling and water heating, improving the overall energy balance of the store.

Typical use points in supermarkets

Cleaning water for floors and service areas
Sanitary hot water for maintenance and washdown
Back-of-house utility hot water
General store water heating support

Why Ultra High Pressure PHE Matters in CO₂ Applications

CO₂ systems operate at substantially higher pressures than many conventional refrigeration systems. This makes the heat recovery exchanger one of the most critical components in the entire solution. It must combine compact size, strong mechanical integrity, reliable brazed construction, and efficient heat transfer under demanding pressure conditions.

For this reason, the heat recovery stage is not just any water heat exchanger. It requires a unit engineered specifically for high-pressure CO₂ service.

HEXNOVAS product involved in this solution

The core product in this application is the HEXNOVAS Ultra High Pressure Brazed Plate Heat Exchanger. It is designed for compact installation, efficient thermal transfer, and reliable performance in high-pressure CO₂ refrigeration circuits.

Application role Used as the heat recovery exchanger between hot CO₂ refrigerant and the water circuit.

Key advantage Compact, efficient, and more suitable for modern supermarket machine rooms where installation space is limited.

System benefit Supports stable, repeatable hot water generation while keeping the refrigeration loop integrated and clean.

Why the Gas Cooler Is Still Required

A common question is whether the gas cooler can be removed once a heat recovery exchanger is added. In most real supermarket installations, the answer is no. The reason is simple: hot water demand does not always match the amount of heat generated by the refrigeration system.

During low hot water demand periods, the heat recovery exchanger can only absorb part of the available thermal energy. The gas cooler remains necessary to reject the balance and keep the CO₂ system operating safely and efficiently. A practical design is therefore a heat recovery priority arrangement, where usable heat is recovered first and surplus heat is discharged afterward.

Solution Summary

A supermarket CO₂ heat recovery system is a practical way to turn refrigeration waste heat into real operational value. By combining a compressor rack, a retained gas cooler, a storage water circuit, and a dedicated Ultra High Pressure Brazed Plate Heat Exchanger, the system delivers both refrigeration performance and hot water generation in one integrated solution.

For projects where efficiency, sustainability, and compact design all matter, HEXNOVAS provides the right product platform for high-pressure CO₂ heat recovery duty.