Oil coolers are heat exchangers that use air to cool hot fluids. Like other coolers, rust and scale will appear, mainly because the cooling water contains a lot of calcium, magnesium ions and acid carbonate, when the cooling water flows through the metal surface, carbonate will be produced; In addition, the oxygen dissolved in the cooling water will also cause the metal to rust and form rust. When it produces rust and scale, the heat transfer effect will decline, and it will block the pipe so that the heat transfer effect will lose its effect. In order to achieve the cooling effect, it is necessary to spray cooling water in the shell. And as the sediment continues to increase, it will also cause an increase in energy costs, because as long as a very thin layer of scale will increase the operating cost of the scale part of the equipment by more than 40%, so the impact of scaling on heat transmission is huge.
First, features:
1, the water-cooled oil cooler uses water as a medium and oil for heat exchange, the advantage is that the cooling effect is better, can meet the requirements of relatively low oil temperature (the oil temperature can be reduced to about 40 ° C, the disadvantage is that it must be used in the place where there is water.
2, the air-cooled oil cooler uses air as a medium and oil for heat exchange, the advantage is that the air is used as a cooling source, basically not limited to the use of places, and environmental protection, the disadvantage is that due to the impact of the ambient temperature, when the temperature is higher, the oil temperature can not be reduced to the ideal temperature (air cooling is generally difficult to reduce the oil temperature to only 5~10 ° C higher than the ambient temperature).
Core. If the checked pressure drop exceeds the allowable pressure drop, the design selection calculation needs to be re-performed until the process requirements are met.
Three, oil cooling performance
8, the water flow has two processes and four processes, the flow has a large flow (guide plate large lead) small flow (guide plate small lead), a variety of varieties, can meet various requirements.
Heat exchanger is a heat exchange device, with a low temperature substance to cool another high temperature substance, because the medium is suitable for circulation, so it determines that the cooling and the cooled substance must be a fluid form, such as water to cool high temperature compressed air, with glycol cooler hydraulic oil and so on. The main purpose of the heat exchanger under most conditions is to obtain the cooled material, so the heat exchanger is often called a cooler, and it is also used to heat another fluid with high temperature fluid, such as heating cold water with steam, at this time it is a heater, the principle of use is the same.
According to the different cooling medium, heat exchangers can be mainly divided into two categories, air cooling and water cooling, that is, wind or water to cool other substances. The advantage of air-cooled heat exchanger is that there is natural wind anywhere, and the use is relatively wide, especially in the field operation of machinery, it is difficult to obtain water, so the use of air-cooled a large number of. The disadvantage of air cooling is that the cooling effect is full, the efficiency is low, after all, it is the natural wind, which is added a fan, the cooling effect is still not comparable to water cooling.
Structurally speaking, the main air-cooled heat exchanger is plate-fin type, which is also considered as a tube type, that is, copper tubes with fins, such as the air conditioning machine is a more typical plate-fin air cooling. The principle is to conduct the heat of the hot fluid to a large surface area as much as possible, using natural wind for cooling.
1, wide heat transfer area: the heat transfer pipe of the cooler adopts the design of copper pipe thread, and its contact area is wide, so the heat transfer effect is higher than the general smooth heat transfer pipe.
2, good heat transfer: this series of copper tube is processed by direct rotary burning of copper tube, so that the heat transfer pipe is integrated, so the heat transfer is good and true, there is no welding spot falling off caused by poor heat transfer.
3, can be suitable for large flow: the number of heat transfer tube is reduced, the use of oil fluid area is increased, and can prevent the loss of pressure. It is equipped with a partition to guide the flow direction, which can produce curved flow direction, growth process and play an effective role.
4, good heat transfer tube: The use of good thermal conductivity of 99.9% pure copper, z* suitable for cooling pipe.
5, no oil leakage: because of the integrated design of the tube and the body, it can avoid the trouble of mixing water and oil, and at the same time, the air tightness test is really tight before leaving the factory, so it can achieve the purpose of leakage prevention.
6, easy assembly: the foot seat can be 360 degrees free rotation, for the body to change the direction and Angle assembly, through the foot seat can be directly welded in any position of the mother machine or oil tank, which is convenient and simple.
7, the spiral baffle guide oil into a spiral shape uniform continuous flow, to overcome the traditional baffle generated heat transfer dead Angle, high heat transfer efficiency, small pressure loss.
2. Pay attention to problems
The plate type or corrugated type should be determined according to the actual needs of the heat exchange occasion. When the flow rate is large and the pressure drop is small, the plate type with small resistance should be selected, and the plate type with large resistance should be selected. Depending on the fluid pressure and temperature, decide whether to choose detachable or brazed. When determining the plate type, it is not appropriate to select plates with too small a veneer area, so as to avoid excessive number of plates, small flow rate between plates, and low heat transfer coefficient, and pay more attention to this problem for larger heat exchangers.
The process refers to a group of parallel flow channels in the same flow direction of a medium in the plate heat exchanger, and the flow channel refers to the medium flow channel composed of two adjacent plates in the plate heat exchanger. In general, a number of flow channels are connected in parallel or in series to form different combinations of cold and hot medium channels.
The form of the process combination should be calculated according to the heat transfer and fluid resistance, and determined when the process conditions are met. Try to make the convection heat transfer coefficients in the cold and hot water channels equal or close, so as to obtain the best heat transfer effect. Because when the convection heat transfer coefficients on both sides of the heat transfer surface are equal or close to each other, the heat transfer coefficient obtains a larger value. Although the flow rate between the plates of the plate heat exchanger varies, the average flow rate is still calculated when the heat transfer and fluid resistance are calculated. Because the nozzle of the "U" shaped single process is fixed on the pressing plate, it is easy to disassemble and assemble.
In the design and selection of plate heat exchangers, there are generally certain requirements for pressure drop, so it should be calibrated
水的比热最大, 水是最好的冷却介质, 一些高温的流速大的介质只能用水冷却. 比如大型工程机械, 功率比较大的空气压缩机, 环保行业的水处理等. 水冷换热器的效率高, 冷却效果好, 劣势是造价较高, 需要用水, 对水质有一定要求.
水冷换热器的主要种类包括管壳式(列管和翅片), 板式. 不同于依靠自然风的风冷, 水冷换热器的两种介质都是人为添加和控制的, 两种介质都需要有管道来引导, 都要有封闭的空间.列管式又叫管壳式, 里面是管子都一种介质, 管子外面的壳体里走另一种介质. 翅片式是在换热管的外面增加了翅片, 大大增加了换热面积, 具有结构紧凑换热器效率高的特点. 板式换热器利用板片上的凹凸和密封圈, 形成了冷热流体交替排列, 紧紧贴合的结构, 冷热介质均匀交替排列, 板式换热器的换热效果最好.