Adiabatic Cooling (PAD System): the strategic balance between thermal efficiency and water sustainability
In industrial refrigeration plants, the moment of truth comes with the hottest weeks of summer. When the outdoor temperature exceeds 35 °C, gas coolers, condensers and dry coolers enter a critical operating zone: the available thermal difference shrinks, exchange loses effectiveness and the condensing temperature tends to rise.
In transcritical CO₂ systems this translates into a higher high-side pressure. In traditional cycles it means more compressor work and a reduced COP.
It is not only a thermodynamic issue. The rise in condensing temperature entails higher electrical power absorption, greater mechanical stress and a worsening of efficiency precisely in the hours when the cooling load and the cost of energy peak.
A dry system, by its nature, can cool the fluid only down to a temperature close to that of the outdoor air. When this margin thins out, increasing the fan speed becomes a partial remedy, often energy-inefficient.
The question, then, is not to replace dry technology, but to ensure its stability and efficiency even in the harshest conditions. Adiabatic cooling with PAD System was created with this objective: to keep the summer operating point under control without introducing the management complexity of an evaporative tower.
The technical principle: how the PAD System works
Adiabatic cooling exploits a simple principle: water evaporation removes heat from the air, reducing the temperature down to the wet-bulb value.
In the PAD System, the air passes through a humidified honeycomb pack before hitting the coil of the gas cooler, condenser or dry cooler. During the passage, part of the water evaporates and lowers the inlet flow’s temperature. In typical summer conditions, such as 35 °C with 40% relative humidity, the reduction can reach 8–12 K, depending on the panel’s saturation efficiency.
This thermal margin directly changes the plant’s operating point. In traditional cycles the condensing temperature is reduced; in transcritical CO₂ systems the high-side pressure is lowered. The compressor therefore operates with a lower compression ratio, the specific work decreases and the COP improves measurably.
The benefit is not only energy-related. By reducing electrical power absorption in the most critical hours, you act on the indirect component of TEWI, improving the environmental footprint without changing the plant’s architecture. Adiabatic cooling thus becomes a thermodynamic-optimisation tool that increases efficiency, widens the summer operating range and strengthens the plant’s resilience.
The difference from the spray is a design one. In misting, water is distributed directly on the exchange surface to maximise the evaporative effect. In the PAD, evaporation happens upstream: the coil stays dry and the air cooling is uniform and controlled. Two different logics, to be selected according to the environmental conditions and the plant strategy.
The structural advantages of the PAD System
Beyond the thermodynamic benefit, the PAD System introduces a radically different water management compared with traditional towers or evaporative condensers.
The system is on-demand: it activates only when a temperature threshold set in the control is exceeded. For most of the year the unit operates in fully dry mode and water use is limited to the truly critical hours. There is no permanent storage tank, no continuous blowdown cycles are needed and there is no constant 24-hour evaporation.
This approach allows a drastically lower water consumption than an evaporative tower or condenser; on an annual basis, the saving can exceed 80%, depending on the climate and the plant’s load profile. Water is no longer a continuous consumption, but a strategic resource used only when it produces a concrete energy advantage.
The same architecture brings significant benefits also in terms of hygiene and maintenance. There are no permanent storage basins and no continuous aerosol production, so water is used only during the system’s activation and is confined to the evaporative panel.
This eliminates the need for continuous chemical treatments and simplifies control procedures compared with open evaporative solutions. From a Life Cycle Costing standpoint, this means lower management costs and schedulable maintenance. Predominantly dry operation also protects the exchange coil, extending its useful life and reducing the risk of early fouling, with a consequent drastic reduction in heat exchange.
Ideal applications: where the PAD System makes the difference
Adiabatic cooling expresses its maximum potential in hot, dry climates, where the high difference between dry-bulb and wet-bulb allows significant reductions in air temperature. In these conditions it is possible to contain the rise in condensing temperature even during summer peaks, avoiding the performance decay typical of dry systems.
It is a strategic design choice in plants where operational continuity is a priority, such as data centres, refrigerated logistics platforms or in constant-load industrial processes, where even a variation of a few degrees on condensing can significantly affect consumption and system stability.
Above all, the PAD System is particularly suited to retrofits. Integrating the PAD System on new gas coolers or liquid coolers in existing plants makes it possible to increase summer dissipation capacity by up to 15–25%, depending on the climate conditions and the evaporative panel’s efficiency. This makes it possible to recover operating margin without intervening on the plant’s architecture. Designing an industrial refrigeration plant today therefore means considering all climate scenarios and ensuring stability even in extreme conditions.
At Refteco we integrate PAD or spray adiabatic solutions into gas coolers and liquid coolers according to the load profile, the installation climate and the maintenance strategy.
If your industrial cooling plant is working at its limit during summer peaks, or if the design margin has progressively narrowed, it is time to act on the dissipation point. Contact the Refteco technical team for an analysis of the real operating conditions, and to define the most efficient adiabatic configuration for your plant.
REFrigeration TEchnological COmponents
For more information