Reliable Cooling of Heat Exchangers

Heat exchangers are key components in refrigeration, air conditioning, process engineering, and energy technology. To ensure they operate reliably, efficiently, and quietly, proper airflow and the right fan solution are essential.
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Heat exchangers play a central role in many technical systems: they transfer heat from one medium to another. In refrigeration and air conditioning technology, in heat pumps, recoolers, condensers, evaporators, control cabinet and process cooling systems, as well as in industrial plants, heat exchangers ensure that heat is dissipated in a controlled manner or made usable.

For this process to function reliably, the air side of the heat exchanger must be precisely designed. After all, even the best heat exchanger can only perform to its full potential if it is supplied with a uniform flow of air that meets demand and has sufficient flow rate. This is exactly where modern fans, blowers, and EC drive solutions from ebm-papst come into play.

As a solutions specialist for ventilation, refrigeration, and fan technology from ebm-papst, Breuell & Hilgenfeldt assists you in selecting and designing suitable components—from individual components to system solutions, and from new construction to retrofits of existing systems.

Where are cooled or ventilated heat exchangers used?

Heat exchangers are used in a wide range of applications. Depending on the application, the requirements for airflow, pressure boost, noise level, controllability, protection rating, temperature resistance, and energy efficiency vary significantly.

● Condensers in refrigeration systems

Here, heat from the refrigerant is transferred to the ambient air. Key factors include high airflow, low noise levels, and efficient operation even when outdoor temperatures fluctuate.

● Evaporators and air coolers in cold storage rooms

In refrigeration and freezer areas, goods must be kept at a consistent temperature. Drafts, drying out, temperature fluctuations, and unnecessarily long defrost cycles should be avoided.

● Recoolers and dry coolers

In industrial processes, data centers, machinery, and energy applications, recoolers dissipate heat into the environment. The focus here is on operational reliability, energy efficiency, and part-load performance.

● Heat pumps and air conditioners

Air-to-water or air-to-air systems require fans that operate efficiently, quietly, and can be controlled. Noise levels play a particularly important role in residential and commercial settings.

● Cooling towers and adiabatic cooling systems

The key factors here are high airflow rates, robust components, and uniform airflow. In addition, humidity, corrosion protection, and ease of maintenance are important factors.

● Control cabinets, electronics, and power electronics

Compact heat exchangers and fans ensure that sensitive electronic components operate within permissible temperature ranges.

● Mechanical and Plant Engineering

Heat exchangers are used to thermally stabilize hydraulic oil, process fluids, motors, transformers, or production equipment.

Special Requirements for Cooling Heat Exchangers

Cooling heat exchangers involves more than simply moving air. In practice, the interplay of heat exchanger surface area, air flow rate, pressure drop, fan, installation configuration, control system, and environmental factors determines efficiency and operational reliability.

1. Sufficient flow rate

The air flow rate determines how much heat can be removed per unit of time. If the flow rate is too low, the temperature in the system rises. This can result in performance losses, higher condensation temperatures, derating, longer operating times, or a reduced service life of components.

However, it is important to note that more air is not automatically better. An excessively high airflow rate can waste energy, cause noise, and make the system inefficient. The goal, therefore, is to design the system to meet actual needs.

2. Pressure drop across the heat exchanger

Heat exchangers have fins, coils, protective grilles, filters, housings, or air baffles. These components create a pressure drop that the fan must overcome. The closer the fins are together, the dirtier the surface, or the more complex the airflow path, the higher the resistance.

When selecting a fan, therefore, it is important to consider not only the airflow rate but also the actual operating point, which is determined by the airflow rate and pressure increase.

3. Uniform flow

Uneven air distribution reduces the usable heat exchanger surface area. Areas with insufficient airflow can become thermally overloaded, while other areas may be flooded with air. This reduces the efficiency of the entire system.

Uniform airflow helps prevent hot spots, improve heat transfer, and reduce noise. Key factors include:
  • Location and Number of Fans
  • Distance between the fan and the heat exchanger
  • Inflow and Outflow Ratios
  • Housing Geometry
  • Protective grilles, nozzles, diffusers, and air-handling measures
  • Preventing Short-Circuit Currents and Recirculation

4. Energy Efficiency in Full-Load and Part-Load Operation

Many heat exchangers rarely operate continuously at their design point. The outdoor temperature, process load, cooling capacity, and operating hours are constantly changing. That is why part-load operation is particularly important. Modern EC fans from ebm-papst can be continuously adjusted. This allows the airflow to be tailored to actual demand. This reduces energy consumption, lowers operating costs, and enables quieter system operation.

5. Noise generation

Fans on heat exchangers are often located in sensitive environments: on roofs, on building facades, in industrial areas, in supermarkets, in mechanical rooms, or near workplaces and living areas. For this reason, low noise levels are an important design factor.

Noise is caused not only by the fan itself, but also by unfavorable installation conditions, high flow velocities, vortices, protective grilles, housing edges, or resonance. Selecting the right fan and ensuring proper aerodynamic integration can significantly reduce noise.

6. Outdoor Installation, Moisture, and Corrosion

Condensers, recoolers, heat pump outdoor units, and cooling towers are frequently exposed to the elements, rain, snow, UV radiation, moisture, temperature fluctuations, and contamination. In coastal regions, industrial environments, or areas with aggressive atmospheres, corrosion is an additional concern. This requires robust fans with appropriate protection ratings, materials, coatings, and motor designs.

7. Contamination, Cleaning, and Maintenance

Finned heat exchangers can become contaminated by dust, pollen, grease, leaves, insects, or process particles. This increases pressure drop and impairs heat transfer. The fan solution should therefore be easy to maintain and facilitate simple cleaning.

In applications where hygiene is critical—such as food refrigeration—smooth surfaces, easy access, and designs that are easy to clean are particularly important.

8. Condensation, Ice Formation, and Defrost Cycles

Condensate, frost, and ice can form on evaporators and air coolers. This affects airflow and increases pressure loss. At the same time, goods in the cold storage room must not dry out and should be kept at as uniform a temperature as possible.

The fan solution must therefore be compatible with the defrosting system, the temperature control, and the desired air distribution.

9. Operational Safety and Redundancy

In many applications, the cooling system must not fail. Examples include process plants, data centers, refrigeration systems in the food retail industry, battery storage systems, transformers, and machine cooling systems. In these cases, multiple fans, intelligent control, and condition monitoring can increase availability.

Instead of a single large fan, a solution using several smaller fans may be preferable in certain applications. This improves air distribution and, if necessary, allows the system to continue operating even if a single fan fails.

10. Installation Space and Retrofit Capability

In existing systems, available space is often limited. When replacing old fans, it is important to consider dimensions, mounting points, electrical connections, controls, airflow, and noise levels.

A well-planned retrofit can increase energy efficiency, improve controllability, ensure the availability of replacement parts, and make the system more future-proof—without having to replace the entire heat exchanger.

What types of fans are suitable for heat exchangers?

The right fan solution depends heavily on the application, airflow path, pressure drop, and installation conditions.

Axial fans

Axial fans move air in an axial direction and are particularly well-suited for high airflow rates with relatively low to moderate pressure increases. They are frequently used in condensers, evaporators, recoolers, heat pumps, dry coolers, and cooling towers.

Advantages:
  • high flow rate
  • compact design
  • well-suited for heat exchanger surfaces
  • efficient air delivery
  • A wide range of sizes and models
  • Very low noise levels, depending on the model

Centrifugal fans

Radial fans discharge air radially from the impeller and are particularly suitable when higher pressure losses must be overcome. They are used, for example, in ventilation units, air-handling units, filter systems, duct systems, or compact units with higher flow resistance.

Advantages:
  • Suitable for higher pressure drops
  • good controllability
  • Compact integration into devices
  • High efficiency with EC technology
  • Suitable for complex air ducting systems

Compact fans

Compact fans are used when heat needs to be dissipated in a specific area within a confined space. Typical applications include electronics, control cabinets, control systems, power electronics, and small heat exchanger units.

Advantages:
  • compact design
  • precise airflow
  • easy integration
  • Suitable for cooling equipment and electronics

Blowers

Blowers are suitable for applications in which specific air volumes must be moved against higher resistance. They are used, for example, in process air applications, burner systems, heating technology, and specialized machinery applications.

Advantages:
  • Significant pressure increase possible
  • defined air supply
  • Suitable for specialized system solutions
  • versatile

Modern Methods for Efficient Heat Exchanger Cooling

EC technology: tailored to needs, efficient, and adjustable

A major advance in fan technology is EC technology. EC motors are electronically commutated motors with integrated electronics. They combine high efficiency with excellent controllability.

For heat exchangers, this means:
  • Continuously variable adjustment of the airflow
  • Lower energy consumption during partial-load operation
  • less unnecessary air movement
  • Lower noise levels at reduced speed
  • Integrated protection and monitoring functions
  • Easy integration into modern control systems
  • greater transparency regarding operating conditions

EC technology can offer significant advantages, especially in systems with highly fluctuating loads. Instead of simply turning fans on and off, their speed can be precisely adjusted based on temperature, pressure, process load, or outdoor temperature.

Speed control instead of on/off operation

A major advance in fan technology is EC technology. EC motors are electronically commutated motors with integrated electronics. They combine high efficiency with excellent controllability.

For heat exchangers, this means:
  • Condensing pressure
  • Refrigerant temperature
  • Fluid Temperature
  • Air outlet temperature
  • Ambient temperature
  • Process or machine load
  • Differential pressure at the heat exchanger
EC technology can offer significant advantages, especially in systems with highly fluctuating loads. Instead of simply turning fans on and off, their speed can be precisely adjusted based on temperature, pressure, process load, or outdoor temperature.

Optimized Aerodynamics

It is not just the motor, but also the aerodynamics that determine efficiency and noise levels. The impeller, blade geometry, guide vanes, nozzle, diffuser, guide vane, protective grille, and housing all influence the operating point.

A good aerodynamic design can:
  • improve efficiency
  • reduce noise levels
  • increase the usable flow rate
  • Reduce Pressure Losses
  • make the flow more uniform

Multiple fans instead of a single solution

For large heat exchanger surfaces, it may be advisable to use multiple fans. This offers several advantages:

Advantages:
  • a more uniform flow over the heat exchanger surface
  • better controllability at partial load
  • greater operational reliability
  • Flexible power adjustment
  • Lower noise peaks due to reduced rotational speeds
  • easier maintenance of individual components
EC technology can offer significant advantages, especially in systems with highly fluctuating loads. Instead of simply turning fans on and off, their speed can be precisely adjusted based on temperature, pressure, process load, or outdoor temperature.

Adiabatic Support

When outdoor temperatures are high, adiabatic pre-cooling can boost the performance of air-cooled systems. In this process, the intake air is cooled by water evaporation before it flows through the heat exchanger.

However, careful planning is essential. Water quality, hygiene, corrosion protection, maintenance, control systems, and environmental conditions must all be taken into account.

Retrofitting Existing Systems

Many existing systems still use older AC fans or unregulated solutions. Retrofitting to modern EC fans may be a good idea if:

  • to reduce energy consumption
  • the system is too loud
  • Spare parts are hard to come by
  • to improve controllability
  • frequent outages occur
  • Statutory efficiency requirements must be taken into account
  • the system is to be adapted to new operating conditions

Breuell & Hilgenfeldt assists you in evaluating existing systems and selecting suitable replacement solutions.

ebm-papst Solutions for Heat Exchanger Applications

ebm-papst offers a broad portfolio of fans, motors, blowers, and electronic solutions for air handling and refrigeration technology. The following product lines are particularly relevant for heat exchanger applications:

AxiBlade – High Efficiency and Quiet Operation for Ventilation, HVAC, and Refrigeration Systems

AxiBlade axial fans were developed for demanding applications in air conditioning and refrigeration technology. The modular design enables high efficiency and excellent noise levels across a range of operating conditions. Typical applications include condensers, recoolers, heat pumps, adiabatic cooling systems, evaporators, and cooling towers.

Axial fans with integrated diffuser

An integrated diffuser can help reduce flow losses and improve efficiency. This is particularly relevant for heat pumps, air conditioners, and condensers, where high airflow, a compact design, and low noise levels must all be combined.

AxiCool – Fans for Evaporators and Air Coolers

The AxiCool series is specifically designed for evaporators and air coolers. It is suitable for commercial and industrial cooling applications, such as in cold storage rooms, warehouses, food processing facilities, and logistics. Depending on the application, either suction or discharge installation configurations can be implemented.
The following are particularly relevant:
  • even air distribution
  • Energy-efficient EC models
  • hygienic design
  • easy to clean
  • High operational reliability in cooling environments

EC medium-pressure axial fans

When large volumes of air need to be moved against moderate pressure losses, EC medium-pressure axial fans are a suitable solution. They are suitable, for example, for cooling towers, large recoolers, or industrial heat exchanger applications.

Radial Fans and FanGrid Solutions

For applications with higher pressure losses or more complex airflow patterns, centrifugal fans may be the right choice. In ventilation units, air-handling units, filter sections, or ducted systems, they enable efficient and easily controllable airflow. FanGrid configurations with multiple fans can offer additional advantages in terms of redundancy, installation space, air distribution, and maintenance.

Compact Fans for Electronics and Equipment Cooling

In small heat exchanger or electronic cooling applications, compact fans offer a reliable solution in confined spaces. They are suitable for control cabinet cooling, control systems, power electronics, and equipment manufacturing.

Planning and Design: What Data Is Important?

In order to select the right fan for a heat exchanger, the relevant operating data should be known. The more precisely the requirements are described, the easier it is to find a suitable solution.

Important information includes:
  • Desired cooling capacity
  • Airflow
  • Pressure drop across the heat exchanger
  • Media and Media Temperatures
  • Ambient temperature
  • Permissible air outlet temperature
  • Installation configuration: suction or pressure
  • Available installation depth and mounting points
  • Power Supply
  • desired arrangement
  • Communication Interfaces
  • Acoustic Requirements
  • Protection Class
  • Temperature range
  • Moisture and Corrosion Exposure
  • Hygiene and Cleaning Requirements
  • Operating Hours and Load Profile
  • Redundancy Requirements
  • Service and Maintenance Guidelines
  • Requirements for Spare Parts Availability and Retrofits
Breuell & Hilgenfeldt helps you evaluate these requirements and determine the appropriate fan solution based on them.

Common Mistakes in Heat Exchanger Cooling

In practice, similar problems arise time and again. Many of them can be avoided through careful selection and design.
Mistake 1: Focusing Only on Airflow
Ein Ventilator muss zum tatsächlichen Betriebspunkt passen. Volumenstrom ohne Druckverlustangabe reicht für eine seriöse Auslegung nicht aus.
Mistake 2: Not Taking the Installation Situation Into Account
A fan that performs well on an open test bench may perform significantly worse in an unfavorable housing. Inflow, outflow, protective grilles, wall clearances, and recirculation must all be taken into account.
Mistake 3: Underestimating Partial-Load Operation
Many systems do not operate at full load most of the time. For this reason, part-load performance is often more critical than the maximum operating point.
Mistake 4: Not Considering the Sound Until the End
Acoustic problems are often difficult to correct retroactively. Therefore, acoustic optimization should be part of the planning process from the very beginning.
Mistake 5: Neglecting Cleaning and Maintenance
When heat exchangers become fouled, pressure loss increases and performance decreases. Therefore, ease of cleaning and maintenance are important design criteria.
Mistake 6: Retrofitting Without a System-Wide Perspective

When replacing old fans, it is not enough to simply compare their size and connected load. The key factor is whether the new solution is compatible with the overall system in terms of aerodynamics, electrical characteristics, and control technology.

Advantages of a Professionally Designed Heat Exchanger Cooling System

The right fan solution offers several advantages:

  • stable temperatures
  • greater operational reliability
  • improved energy efficiency
  • reduced operating costs
  • lower noise levels
  • longer service life of the components
  • better controllability
  • less thermal stress
  • higher system availability
  • Future-proof modernization of existing systems
  • better adaptation to new efficiency and environmental requirements
Precisely because energy prices, efficiency targets, and sustainability requirements are on the rise, it’s worth taking a closer look at the air side of the heat exchanger. There is often significant potential for optimization here.

Breuell & Hilgenfeldt: Your Solution Specialist for ebm-papst Fan Solutions

Whether it’s a new construction project, a modernization, a need for replacement parts, or a custom system solution, Breuell & Hilgenfeldt will assist you in selecting the right fans, blowers, and components from ebm-papst.

Our services include, among other things:
  • technical consulting
  • Product Selection
  • Design of Appropriate Fan Solutions
  • Support for Retrofit Projects
  • Custom and System Solutions
  • Consulting on EC Technology
  • Support for the Replacement and Modernization of Existing Systems
  • Solutions for Ventilation, Refrigeration, and Fan Technology
Drawing on our experience with ebm-papst products and applications in ventilation, refrigeration, air conditioning, and building services engineering, we will work with you to find a solution that suits your application.

Frequently Asked Questions About Heat Exchanger Cooling

This depends on the application, pressure drop, airflow, installation conditions, and noise requirements. Axial fans are ideal for many condensers, evaporators, recoolers, and heat pumps. Centrifugal fans may be a better choice for higher pressure drops or more complex airflow paths.
EC fans can be continuously variable and operate very efficiently, especially under partial load. Since many systems rarely run continuously at their design point, demand-based speed control can significantly reduce energy consumption and noise levels.
When retrofitting, the following factors must be evaluated: unit size, airflow capacity, pressure increase, noise level, electrical connections, control system, installation conditions, and safety requirements. In many cases, a simple 1:1 replacement based solely on dimensions is not sufficient.
Key factors include a suitable fan, low rotational speed during partial-load operation, aerodynamically optimized inlet and outlet conditions, appropriate protective grilles, sufficient clearances, and a low-vibration installation. EC technology can help reduce noise peaks through stepless control.
Possible causes include poor airflow, insufficient distance between the fan and the heat exchanger, recirculation, dirty fins, incorrect fan position, unsuitable protective grilles, or an inappropriate operating point.
Replacing the system may be worthwhile if it runs for long periods, consumes a lot of energy, is difficult to control, operates too loudly, or if replacement parts are no longer reliably available. A retrofit to EC technology can be economically advantageous, particularly in refrigeration, air conditioning, and process applications.

Conclusion: The right ventilation system makes the heat exchanger more efficient

Cooling heat exchangers places high demands on the fan, motor, aerodynamics, control system, and installation configuration. What matters most is not just the maximum airflow, but the optimal interaction of all components under actual operating conditions.

With modern fan solutions from ebm-papst, heat exchangers can be operated efficiently, quietly, and tailored to your needs. As a solutions specialist, Breuell & Hilgenfeldt supports you in the selection, design, and modernization of your ventilation, refrigeration, and fan systems.

Are you planning a new system, looking to replace existing fans, or wanting to make your heat exchanger cooling more efficient? Contact us. We’d be happy to advise you and work with you to find the right solution.