# Enhancement of Heat Dissipation from the Hydraulic System Using a Finned Adaptive Heat Exchanger
## 1 Introduction  
Hydraulic systems are one of the main parts of stationary and mobile machines and aggregates used in the engineering, building and agricultural industries [1]. Hydraulic circuits are used in assembly procedures, 3D printers, paper mills, and metal processing [2, 3]. The systems are equipped with a sophisticated control mechanism to perform one or more precision operations to improve the quality of the output product or the quality of the process. Hydraulic oils are used to transfer energy in hydraulic equipment or systems. A closed hydraulic circuit, in which an incompressible fluid flows, generates sufficient working force via a pressure pump, e.g., for the purpose of lifting heavy loads [4]. Its advantages include the relative simplicity of its mechanisms, and its positioning accuracy with high efficiency and high strength. Precision control valves are also integrated in the hydraulic circuits to control the supply and flow of hydraulic fluid [5]. To keep the hydraulic fluid (oil) in the required temperature range, oil coolers are fitted to the assemblies [6]. Viscosity and pressure are important parameters of hydraulic oil (engine or gear oil), and these depend on the actual temperature of the oil, which must be continuously cooled [7]. Maintenance of the oil at operating temperature has a positive impact on hydraulic system and oil lifecycles, reduced maintenance and repair costs, lower downtime, and higher efficiency [8]. In addition to the use of oil coolers, overheating problems in the hydraulic system can be prevented by increasing the volume of the hydrauliccartridge, which can cause neglect of the generated temperature. However, such a solution is not suitable for every case, as increasing the volume of the hydraulic tank is usually not possible in terms of space parameters. If so, it is important to choose a suitable position, shape and a suitable size of the connecting metal pipes and hoses because of the direct influence on the temperature of the oil on the circuit. Oil coolers are also an important part of high-performance internal combustion engines. The oil absorbs the heat generated by the movement of the piston inside the cylinder (friction) and dissipates it through the piping and cooler to the surrounding environment. As with hydraulic oil, engine oil performs a few functions, some of which are specific to individual engine parts. These functions include, in addition to heat dissipation, the reduction of friction, wear, detergency, sealing of critical areas, ability to separate water, and many other functions essential for proper engine operation [9]. There are currently two basic methods of cooling oil coolers that allow the accumulated heat energy to be dissipated into a secondary medium, usually air or liquid [10; 11]. Air-cooled systems dissipate heat through the air flow. In this case, the onslaught of cold air cools the hot walls of the radiator core. This design brings with it easy maintenance which ensures low operating costs during operation. The main disadvantage of the above embodiment is that the cooling capacity may be significantly affected when the ambient temperature changes. In contrast, water-cooled systems use hot and cold media separated by a wall to dissipate heat. Changes in air temperature have a negligible effect on the cooling capacity, ensuring higher cooling efficiency. The cooler consists of a series of finned tubes through which the hot medium flows [12; 13]. The coolant absorbs heat from the oil and transfers it away from the radiator, where it is released into the atmosphere. Externally finned heat exchangers are mostly used to transfer heat from the hot working medium to the ambient air. Improving heat dissipation using finned surfaces has been the subject of research in several published scientific papers. In general, by increasing the heat exchange surface, a more intensive heat transfer from the heated surface to the surrounding air can be achieved [14; 15].