Diesel Generator Radiator: Core Component of Cooling System

In industrial production and daily life, diesel generators play a vital role. Whether as a backup power source or as the main power supply in some remote areas, the stable operation of diesel generators is crucial. The radiator, as the core component of the cooling system of a diesel generator, directly affects the working efficiency and service life of the generator. This article will provide a detailed introduction to the working principle, structure, common problems, and maintenance methods of diesel generator radiators, helping users to better understand and use this important equipment.

When a diesel generator operates normally, it generates a large amount of heat. The high-temperature exhaust gas and heat generated by friction can increase the temperature of components such as the cylinder (head), piston, and valves. If the temperature of these parts becomes too high, it will not only affect the performance of the generator but may also lead to component damage or even safety accidents. Therefore, it is essential to keep the generator working within an appropriate temperature range.

For water-cooled diesel generators, the suitable temperature for the cylinder wall water jacket is 80-90°C. At this temperature, the cooling system plays a significant role. The main function of the cooling system is to dissipate the heat generated by the generator, ensuring that it operates within the most suitable temperature range. The radiator, as an important part of the cooling system, is responsible for transferring the heat carried by the cooling water into the atmosphere to lower the temperature of the cooling water.

A radiator consists of three main parts: the upper water tank, the core, and the lower water tank. The upper and lower water tanks are primarily used to store cooling water. The upper water tank has a fill port for adding cooling water, which is covered with a water tank cap. Hot water from the diesel generator's water jacket flows into the upper water tank through the outlet on the cylinder head, is cooled by the radiator core, and then flows into the lower water tank. It is then drawn into the water pump through the outlet pipe of the lower water tank.

The radiator core is typically constructed in two ways: tube-fin and tube-belt. The tube-fin type has many flat water pipes welded onto multiple layers of cooling fins. The advantages of this structure include a large cooling area, low air resistance, good structural rigidity, strong pressure-bearing capacity, and resistance to rupture, which is why it is widely used. However, its manufacturing process is relatively complex. The tube-belt type consists of corrugated cooling belts and flat tubes arranged alternately. The belts have slotted openings that can disrupt the air boundary layer to enhance heat transfer. Although this core type is not as rigid as the tube-fin type, it is easier to manufacture in large quantities and is becoming more popular.

The core of diesel generator radiators is mostly made of brass. Brass has good thermal conductivity and corrosion resistance, is easy to form, has sufficient strength, and is convenient for welding and repair. These characteristics make brass an ideal material for radiator cores.

In addition to brass, the water tank part of the radiator also has different material options. Generally, the material of the water tank needs to meet the following requirements: good brazing performance, easy processing and control, high thermal conductivity, corrosion resistance in the cooling medium, appropriate strength to withstand severe loads during use, low processing cost, and light weight. Currently, the most common materials for water tanks are copper and aluminum.

Copper water tanks have good thermal insulation and cooling properties, but they cool slowly and have a higher manufacturing cost. Aluminum water tanks cool quickly but are prone to oxidation. If cooling performance is the priority, a pure copper stainless steel water tank is better, but it is expensive and difficult to process. Aluminum water tanks cool quickly and have a large cooling capacity, but they are more susceptible to oxidation in high-temperature environments, which can affect cooling performance. In terms of thermal conductivity, copper water tanks are relatively better. However, in terms of cooling performance alone, aluminum water tanks cool faster than copper ones. Therefore, for most ordinary diesel generator users, aluminum water tanks are the preferred choice. Only in some high-end diesel generators would copper water tanks be considered.

To ensure the performance of the radiator and extend its service life, regular maintenance and care are essential. Good maintenance not only improves cooling efficiency but also reduces the likelihood of failures, ensuring the stable operation of the diesel generator. Here are some concise and effective maintenance and care suggestions.

To prevent and reduce the impact of impurities in the cooling water on the diesel generator, the generator is equipped with a corrosion prevention device in the cooling system. Inside the corrosion prevention device, there is a part with ion exchange resin sandwiched between magnesium plates. The function of this device is to use metallic magnesium as the source of metal ions in chemical reactions. When the cooling water flows through the interior of the corrosion prevention device, the carbonate ions in the water react with the metal ions to form magnesium carbonate, which precipitates and is filtered out in the device, thereby reducing the corrosion of the engine water jacket and other components of the cooling system by the cooling water.

Corrosion is one of the main causes of potential failures in radiators. This is because air in the water can accelerate corrosion. Therefore, it is important to regularly check for leaks in the pipe joints and periodically add water from the top of the radiator to expel air, maintaining an "air-free" system. The radiator should not be partially filled or drained, as this can accelerate corrosion. For generators that are not in use, the water should be completely drained or fully filled. If possible, use distilled water or naturally soft water and add an appropriate amount of rust inhibitor. It is important to note that the coolant in the radiator is usually hot and under pressure. The radiator should not be cleaned or pipes removed when it is still hot, nor should work be performed on the radiator or the fan cover be opened when the diesel generator's fan is in operation.

In dusty or dirty environments, the gaps in the radiator may become clogged with debris, insects, and other materials, which can affect the efficiency of the radiator. For these light deposits, regular cleaning with low-pressure hot water and detergent can be effective. Spray the steam or water from the front of the radiator towards the fan. Spraying in the opposite direction will only force the dirt into the center. When using this method, cover the diesel engine and alternator with cloth. If stubborn deposits cannot be removed by the above method, the radiator can be removed and soaked in hot alkaline water for about 20 minutes, followed by a rinse with hot water.

The main damage to radiators is leakage. The causes of leakage include the following: during operation, fan blades may break or tilt, damaging the radiator pipes; the radiator may be loosely mounted on the frame, causing damage due to vibration during operation; in winter, the radiator pipes may freeze and crack if water is left inside; and impurities in the cooling water may form scale inside the radiator pipes, leading to corrosion and rupture of the pipe walls.

Leak inspection is generally carried out after the radiator has been cleaned. The following methods can be used:

Compressed Air Test: Block the inlet and outlet of the radiator, and install a fitting on the overflow pipe or drain plug to inject compressed air at a pressure of 0.15-0.3 kgf/square centimeter. Place the radiator in a water tank. If bubbles emerge, that indicates a leak.

Water Fill Test: Block the inlet and outlet of the radiator, fill it with water through the fill port, and observe for leaks. To make it easier to detect fine cracks, apply some pressure to the radiator or give it a slight vibration, and then carefully observe. Water will seep out from the leak.

Radiator repair is usually done by soldering. Before welding, clean the oil and dirt from the welding area, scrape off a new metal layer with a scraper, heat it appropriately, dip the soldering iron into zinc oxide solution, and then apply solder. After soldering, smooth the seam, and wash the surrounding zinc oxide with hot water to prevent corrosion.

For the repair of the upper and lower water chambers, if the leak is not too large, it can be directly soldered. If the leak is significant, use purple copper sheet for patching. When patching, first coat one side of the copper sheet and the leak area with solder, place the sheet over the leak, and heat it from the outside with a soldering iron to melt the solder and secure the patch.

For the repair of radiator pipes, if the outer layer of the pipe has a small crack, remove a few cooling fins near the pipe with a needle-nose pliers and directly solder the crack. If the crack is large or if a middle layer pipe is leaking, different methods such as clamping, plugging, splicing, or replacing the pipe should be used according to the specific situation. However, the number of clamped or plugged pipes should not exceed 10% of the total number of pipes to avoid affecting the cooling efficiency of the radiator.

The radiator is an indispensable and important component of the cooling system of a diesel generator. By transferring the heat carried by the cooling water into the atmosphere, it ensures that the generator operates within an appropriate temperature range. The structure of the radiator includes the upper water tank, core, and lower water tank, with the core typically constructed in tube-fin or tube-belt styles. Brass is a commonly used material for the radiator core, while the water tank part can be made of copper, aluminum, or other materials. To ensure the performance and extend the service life of the radiator, users need to pay attention to maintenance and care, including taking anti-corrosion measures, preventing corrosion, regularly cleaning the radiator, and promptly inspecting and repairing leaks. Only in this way can the stable operation of the diesel generator be ensured, providing reliable power support for users.