Brazed plate oil cooler
All engines are oil dependent. They serve as a piston seal in the combustion chamber and provide lubrication to engine parts. The oil is heated by friction and combustion. Higher temperatures are unfavorable: they reduce the viscosity. If the temperature is high, the oil ceases to perform its function: the low viscosity causes the lubricating film to be thin and the engine parts to wear excessively. High temperatures also degrade the oil itself. The engine then does not run efficiently and has a limited service life.
Internal combustion engines cannot be used efficiently without a gearbox. Their function would be limited to one fixed gear. About 15% of the power used is lost in the gearbox and this heat must be dissipated. Otherwise the oil will deteriorate and the gearbox will get damaged. The temperature of the transmission oil should be kept below 90 °C, more preferably around 80 °C.
Hydraulic oil is used in hydraulic equipment to multiply pressure. Temperatures above 60 °C are too high and reduce oil life. Temperatures of around 80 °C should not be reached even on cooler inlets: not only it degrades the hydraulic oil but also the seals in the system. Hydraulic oil cooling should be set so that the temperature is maintained around 50 °C. Excessive cooling is also undesirable: if the temperature is too low, the hydraulic oil is thick and the machine will run slowly.
|Cooler capacity||Oil flow rate||Plate cooler type|
|10 kW||2 m3/h||SWEP B8TH|
|25 kW||5 m3/h||SWEP B10TH|
|50 kW||10 m3/h||SWEP B12|
|100 kW||20 m3/h||SWEP B35H|
|250 kW||50 m3/h||SWEP B320H|
|500 kW||100 m3/h||ARES A4A, A4M|
|1 000 kW||200 m3/h||ARES A6S, A6M|
Oil coolers are used to dissipate heat and maintain the required oil temperature. Our oil/water heat exchangers are in stainless steel AISI 316 (steel 1.4401), or AISI 304. They are corrosion-resistant and suitable as plate coolers for cooling synthetic oils. Water is usually used as the cooling medium. The plate cooler conducts both circuits (oil and cooling water) in countercurrent. That makes possible to achieve much higher cooling capacities than with air cooling. The table above shows the types of plate coolers for the given heat loads. The table serves only for rough orientation. The design must take into account the type of oil, coolant, design temperatures. Plate coolers are much more efficient than tube coolers and thus have significantly smaller dimensions.
Choosing plate coolers
We are successfully replacing heat exchangers from manufacturers such as Alfa Laval. Our customers are often surprised how efficient the installation works at a much lower acquisition cost.
Almost all brazed heat exchangers can be suitable as oil/water coolers. For cooling capacities up to 500 kW, the SWEP brazed heat exchanger tends to be more economical. For oil coolers above 500 kW, it is better to consider ARES gasketed heat exchanger. You can use an ARES online calculator for oil viscosities VG 32 and VG 46. Finally, you are always welcome to request a calculation from us.
Cleaning the plate cooler
If the oil contains solid particles, it is advisable to install a filter before entering the plate heat exchanger. For SWEP brazed heat exchangers, the mesh size of the filter should be < 1 mm, for ARES heat exchangers < 2 mm. Smaller mesh catches more dirt, but such a filter will create pressure losses and will need to be cleaned frequently. The plates of the exchanger are rough and folded due to the herringbone pattern. That brings turbulent flow and a self-cleaning ability. The greater the media flow, the greater the effect. However, higher flow results in greater pressure losses and a more powerful circulating pump may be required to overcome them.
It is usually necessary to take into account that the cooler will need to be cleaned. This can be achieved by switching it to a cleaning circuit: the heat exchanger is flushed with kerosene at a current higher and opposite than that which is normal during operation.
More thorough cleaning can be achieved after disassembling the heat exchanger. This method is only possible with gasketed heat exchangers. It is advisable to perform regular circulation of the cleaning liquid. You should disassemble the heat exchanger only if it cannot be sufficiently cleaned by circulating and the plate cooler shows a high pressure drop and does not provide the original performance. The heat exchanger plates must not be scratched: the deposits must be cleaned with a plastic brush not a steel brush.
Compact SWEP brazed heat exchangers cannot be disassembled. For most applications, however, SWEP brazed heat exchangers are more suitable. For high performance applications, ARES gasketed heat exchangers are more cost-effective. Furthermore, for gasketed heat exchangers, the output can be additionally increased by adding more plates. Before purchasing an oil cooler, it is necessary to consider several times whether it really has to be a unit which can be disassembled.