Air-cooled heat exchanger: service 

Air-cooled heat exchanger: service as the basis of reliability

In our practice of servicing industrial systems, we are convinced thatair-cooled heat exchanger: serviceis not just periodic cleaning of fans, but a critical process that determines the service life of the equipment and the energy efficiency of the entire production. Ignoring routine maintenance leads to overheating of compressors, a drop in pressure in hydraulic circuits and, as a result, unplanned downtime, the cost of which often exceeds the price of an annual service contract. We have encountered situations where customers lost up to 15% of line productivity due to simple contamination of the heat exchanger lamellas, which could be detected during a routine inspection.

This article was written by engineers who have personally diagnosed more than 300 pieces of equipment in conditions ranging from the harsh winters of Siberia to the hot climate of Central Asia. Here you will not find general phrases about the “importance of prevention.” We will give specific action algorithms, analyze real cases of failures due to service errors and provide checklists that can be used tomorrow. If your goal is to reduce operating expenses (OPEX) and avoid emergency shutdowns during peak seasons, this resource will provide you with a practical guide.

Why regular maintenance affects the efficiency and service life of equipment

Contamination of the heat exchange surface is the main enemy of efficiency. During operation, the air flow carries dust, fluff, industrial fumes and oil mist. By settling on the fins of the radiator, these contaminants create an insulating layer that works like a thermos. Heat from the working medium (oil, water, refrigerant) is no longer effectively released into the atmosphere. The result is predictable: the outlet temperature rises, the automation system tries to compensate for this by increasing fan speeds or turning on additional sections, which leads to an increase in electricity consumption.

We recorded a specific case at a metallurgical plant in the Chelyabinsk region. The client complained about frequent shutdowns of the hydraulic station due to overheating. A visual inspection revealed that the heat exchanger was 70% clogged with metal shavings and dust. After a professional high pressure wash using specialized reagents, the oil temperature dropped from 68°C to 42°C at the same load. Fan energy consumption fell by 18% as the frequency converters reduced speed to nominal values. This example clearly shows:air-cooled heat exchanger: servicedirectly converted into money.

In addition to energy losses, there is a risk of mechanical destruction. Vibration resulting from uneven airflow or imbalance of impellers covered with dirt is transmitted to the collectors and tubes. Over time, this leads to fatigue cracks at the solder joints. In one of the projects in Kazakhstan, we discovered a microcrack in an aluminum collector, which arose precisely because of long-term operation in high vibration mode. Fixing the defect required shutting down the line for 4 hours and costly argon welding, although regular balancing of the fans could have prevented this situation.

It is important to understand the difference between surface cleaning and deep service. Simply blowing with compressed air often only drives dust deeper into the lamella package, creating dense plugs. This service involves chemical treatment, checking the tightness of circuits, diagnosing electric motors and measuring real thermal characteristics. Only this approach guarantees the restoration of the device’s passport parameters.

Key parameters monitored during maintenance

When carrying out work, our engineers focus on a number of critical indicators, the deviation of which indicates problems:

• Temperature delta (ΔT):The difference between the temperature of the incoming fluid and the ambient air temperature. A decrease in ΔT while maintaining the flow rate indicates contamination of the heat exchange surface.
• Air pressure difference (ΔP air):Measured before and after the fan. An increase in this parameter indicates airflow resistance due to clogged channels.
• Motor current:Exceeding the rated current may indicate mechanical jamming of the bearings or operation of the motor in abnormal mode due to overheating of the windings.
• Noise and vibration level:The appearance of new sounds or an increase in vibration acceleration on the device body often precedes the failure of the bearing assembly.

Regular monitoring of these parameters allows you to move from reactive repair (“we fix it when it breaks”) to predictive maintenance (“we change a part before it causes an accident”). This is the foundation of a modern asset management strategy.

Typical faults and methods for their elimination

Even the most reliable equipment is subject to wear and tear. Knowing typical breakdown scenarios helps to localize the problem faster. Below we look at the most common causes of failures faced by operations teams and proven methods for resolving them.

Corrosion and destruction of the heat exchange surface

An aggressive environment is the scourge of industrial enterprises. Chemical fumes, salt spray (in coastal areas) or high humidity cause corrosion of aluminum and copper. In our practice, there was a case at an oil refinery where sulfur compounds in the air ate through the protective coating of the lamellas over two years. This led to multiple fistulas and coolant leaks.

Solution:Standard devices are not suitable for such conditions. It is required to apply a hydrophilic coating with anti-corrosion protection (for example, epoxy coating) at the production stage. If the device is already installed, it is necessary to carry out an annual inspection of the thickness of the metal and the condition of the coating. If pockets of corrosion are detected, local restoration with special compounds or replacement of sections is applied. Ignoring this stage leads to complete failure of the device in 3-5 years instead of the required 15-20.

Fan group failures

Fans are the most moving element of the system. The main problems here are related to rolling bearings and electric motors. Overheating of the windings due to poor ventilation of the motor itself (the casing grille is often clogged) leads to an interturn short circuit. Bearings suffer from moisture and lack of lubrication.

Solution:We recommend fans rated IP55 or higher with lifetime lubricated or re-greaseable bearings. During service, thermography of electric motors is required to identify hot spots. Replacement of bearings must be carried out strictly according to the manufacturer's regulations, using torque wrenches to control the pressing force. Incorrect installation of a new bearing reduces its life by 40-50%.

Depressurization of connections and collectors

Cyclic loads (heating and cooling) cause thermal expansion and contraction of materials. Over time, this weakens solder joints and threaded fittings. Vibration also promotes self-unscrewing of fasteners.

Solution:Regular pressure testing of the circuit with nitrogen or a hydraulic test allows you to identify micro-leaks before they become visible to the eye. The use of ultrasonic leak detectors increases the diagnostic efficiency significantly. All threaded connections must be tightened with controlled tightening torque. To prevent vibration unwinding, it is recommended to use thread lockers or spring washers.

Remember: eliminating the consequences of an accident is always more expensive than preventing it. The cost of an emergency team visit, delivery of spare parts and production downtime can be 10 times higher than the cost of scheduled maintenance. Investments in quality service pay off in one season of uninterrupted operation.

Step-by-step algorithm for professional service

For a service to be effective, it must be carried out according to strict regulations. Chaotic actions “according to the situation” do not guarantee results. Below is a step-by-step algorithm that our specialists use when carrying out full maintenance.

1. Preparing and locking out equipment (LOTO).
   Before starting any work, it is necessary to completely de-energize the device and install locking locks on the input machines (Lockout/Tagout procedure). This eliminates accidental starting of fans, which is the main cause of injury. It is also necessary to shut off the shut-off valves on the coolant supply and discharge lines, relieve the pressure in the circuit and drain the residual liquid into a special container. Ignoring this step is unacceptable and violates labor safety regulations.
2. Pre-dry cleaning.
   Use compressed air or industrial vacuum cleaners to remove the main layer of dry dust, lint and large debris. The air flow should be directed against the operating direction of the fan (from the inside to the outside) to dislodge dirt from the channels. The air pressure should not exceed 6 bar, so as not to deform the thin lamellas. At this stage, up to 60% of contaminants are removed.
3. Chemical washing and disinfection.
   Applying a special alkaline or acidic detergent (depending on the type of contamination) to the surface of the heat exchanger. The reagent is left for 10-15 minutes to dissolve oil films and mineral deposits. Then the flush is carried out with water under a pressure of 80-100 bar. It is important to use fan nozzles and keep the nozzle at a 45 degree angle to avoid damaging the fins. For devices operating in the food industry, a disinfection stage is required using approved means.
4. Diagnostics of mechanical and electrical components.
   Checking belt tension (if applicable), bearing condition (by ear and with a vibration meter), integrity of fan blades. Measuring the insulation resistance of electric motor windings with a megohmmeter. Check contacts in the control cabinet for burning or oxidation. All identified defects are recorded in a defect list with recommendations for replacement or repair.
5. Functional testing and delivery.
   After assembly and removal of locks, a test run is performed. Operating currents, power consumption, noise and vibration levels are measured. Temperature readings at the coolant inlet and outlet are taken at steady state. The data is entered into the equipment passport and is compared with the factory specifications. Only after confirmation of compliance of all parameters is the device considered to have passed the service.

Compliance with this sequence guarantees an integrated approach. Skipping any step, such as chemical washing after dry cleaning, leaves hidden contaminants that will continue to reduce the efficiency of the system.

Seasonal features of operation in different climatic zones

Russia and the CIS countries are characterized by a huge variety of climatic conditions. What works in Krasnodar may turn out to be ineffective or even dangerous in Yakutia. The service of heat exchangers must take these factors into account.

Winter operation and frost protection

The main threat in winter is freezing of the coolant inside the pipes. The ice expands and tears apart the metal, causing catastrophic damage. In our practice, there was a case when, due to the failure of the temperature sensor and the fans stopping, the water in the device froze overnight. The repair required the replacement of three sections and a week's downtime of the workshop.

Recommendations:
For the winter period, it is necessary to use devices with an air recirculation function or blinds to regulate the flow. It is mandatory to use antifreeze liquids (glycol solutions) with a concentration calculated for the minimum temperature of the region with a margin of 5-7°C. The automation system must have frost protection: when the return temperature drops below the set value, the fans stop and the pumps continue to operate. Regularly checking the glycol concentration with a refractometer is a mandatory procedure in the fall.

Summer operation and combating overheating

In summer, the main task is to maximize heat transfer. High ambient temperatures reduce the temperature delta, forcing the system to operate at its limit. During this period, dust and poplar fluff clog the devices at a record speed.

Recommendations:
Increase the frequency of cleaning in summer to once a month for very dusty industries. Check the operation of all fan stages and the correct settings of the frequency converters. Make sure that there are free air suction areas around the device (at least 1.5 times the fan diameter from walls or other obstacles). Installing sun visors can reduce the intake air temperature by 3-5°C, which will significantly improve efficiency.

Transitional seasons (spring/autumn)

This is the time of greatest temperature differences between day and night. Automation must respond quickly to changes. In the spring, it is important to carry out complete conservation after winter: check the condition of the antifreeze, remove insulating mats (if used), and carry out general cleaning after the winter period.

Adapting the service to the climate is not just a recommendation, but a necessity. There are no universal solutions, and trying to use one regulation for the entire country will either lead to accidents or overspending of resources.

Modernization vs Repair: economic justification

Often the chief engineer is faced with the question: should he repair the old device or replace it with a new one? Or perhaps modernize the existing one? The correct answer depends on the technical condition and economic calculations.

RepairIt is advisable if the housing and main heat exchange sections are in good condition, and the problem is localized in attached equipment (fans, motors, control cabinets). Replacing worn-out components allows you to extend the life of the device for another 5-7 years at a cost of 20-30% of the cost of a new one.

Modernization- this is the golden mean. Often older devices are equipped with inefficient axial fans of the previous generation and a relay control circuit. Replacing them with modern electronically controlled EC fans and installing frequency converters can increase energy efficiency by 30-40%. It is also possible to replace old copper-aluminum sections with more compact and efficient aluminum blocks with improved fin geometry. Such projects pay for themselves in 1.5-2 years only due to energy savings.

Replacementnecessary if the degree of corrosion of the heat exchange surface exceeds 30%, if there are multiple leaks in the tubes, or if the required thermal output has increased significantly due to expansion of production. The new models are more compact, quieter and meet modern environmental standards.

When making a decision, use the TCO (Total Cost of Ownership) formula: consider not only the purchase or repair price, but also the costs of electricity, maintenance and possible losses from downtime in the future. Often, cheap repairs turn out to be the most expensive solution in the long run.

Choosing a reliable partner: equipment quality as the foundation of service

The effectiveness of any service measure directly depends on the initial quality of the equipment. Even the most careful care cannot indefinitely compensate for design flaws or low corrosion resistance of materials. This is why it is critical to pay attention to certification and the alloys used when selecting a supplier or planning an upgrade.

A striking example of an approach that places reliability and durability at the forefront is the companyWuxi Kaisheng Electric Power and Petrochemical Equipment Co., Ltd.. Specializing in the development and production of complex heat transfer equipment for the energy and petrochemical industries, the company offers solutions that initially minimize the risks of future breakdowns. Their products, including air coolers, titanium shell-and-tube heat exchangers and ASME high-pressure units, are made from premium materials: 316 stainless steel, C46400 marine brass, copper-nickel alloys and N06625 nickel alloys.

Такой выбор материалов обусловлен жесткими требованиями отраслей, где работает оборудование: нефтепереработка, химическая промышленность, опреснение морской воды и судостроение. Продукция ООО «Уси Кайшэн», сертифицированная по международным стандартам PED и ASME, отличается исключительной устойчивостью к высоким давлениям, температурам и агрессивным средам. Использование трубных пучков из специальных сплавов и высококачественных трубных решеток (из стали 321, латуни C46400 и др.) гарантирует, что теплообменный аппарат сохранит свою эффективность на протяжении десятилетий, а интервалы между серьезными ремонтами будут максимально увеличены. Инвестируя в такое оборудование, предприятие закладывает прочный фундамент для своей сервисной стратегии, снижая совокупную стоимость владения (TCO) и обеспечивая стабильность технологических процессов по всему миру.

Frequently Asked Questions

Как часто нужно проводить чистку теплообменника?

Частота зависит от условий эксплуатации. Для чистых помещений (например, сборочные цеха электроники) достаточно одного раза в год. Для металлургии, деревообработки или цементных производств интервал сокращается до 1-3 месяцев. Главный индикатор — рост температуры обратной линии или увеличение перепада давления воздуха. Если вы видите эти признаки, чистка требуется немедленно, независимо от графика.

Можно ли мыть теплообменник водой под высоким давлением?

Да, можно, но с ограничениями. Давление не должно превышать 100-120 бар, а струя должна направляться строго перпендикулярно или под небольшим углом к ламелям. Использование парогенераторов или слишком горячей воды (>60°C) для алюминиевых теплообменников не рекомендуется, так как это может повредить клеевые соединения или вызвать деформацию тонкого металла. Всегда используйте специальные моющие средства для удаления жировых пленок, одна вода их не смоет.

Что делать, если аппарат шумит больше обычного?

Повышенный шум обычно указывает на дисбаланс вентилятора (налипание грязи, поломка лопасти), износ подшипников или резонанс конструкции. Сначала проведите визуальный осмотр лопастей и очистите их. Если шум сохраняется, проверьте подшипники методом прослушивания или виброанализа. Затяните все крепежные соединения рамы и опор. Игнорирование шума приведет к разрушению посадочных мест подшипников и выходу двигателя из строя.

Какой антифриз лучше использовать для зимней работы?

Оптимальным выбором являются водные растворы пропиленгликоля (для пищевой промышленности) или этиленгликоля (для технических задач) с пакетом антикоррозийных присадок. Концентрация должна обеспечивать точку кристаллизации на 5-7°C ниже минимальной ожидаемой температуры в регионе. Не используйте автомобильные тосолы, так как содержащиеся в них силикаты могут выпадать в осадок и забивать тонкие каналы теплообменника, снижая эффективность теплопередачи.

Conclusion and next steps

Надежная работа системы охлаждения — это залог стабильности всего технологического процесса.Теплообменный аппарат воздушного охлаждения: сервискоторого выполняется профессионально и своевременно, становится активом, приносящим прибыль, а не источником постоянных проблем и затрат. Мы рассмотрели ключевые аспекты обслуживания: от методов очистки до стратегий модернизации и сезонной адаптации, а также важность выбора качественного оборудования от таких производителей, как ООО «Уси Кайшэн».

Не ждите, пока оборудование откажет в самый неподходящий момент. Профилактика всегда дешевле ремонта. Оцените текущее состояние ваших теплообменников, сверьтесь с нашими чек-листами и запланируйте проведение ТО до наступления пиковых нагрузок.

Если у вас возникли вопросы по подбору запчастей, необходимости модернизации или вы хотите заказать выезд нашей сервисной бригады для диагностики, свяжитесь с нами сегодня. Наши инженеры готовы предложить индивидуальные решения, которые продлят жизнь вашему оборудованию и сэкономят бюджет предприятия.

Для получения подробной консультации или расчета стоимости услуг перейдите на страницуконтактов сервисной службыили ознакомьтесь с нашим каталогомзапасных частей для промышленных холодильных систем.