###### Abstract
Heat pipes play an important role in increasing the cooling efficiency of data centers. [PERSON] et al. proposed an integrated system of mechanical refrigeration and thermosiphon (ISMT) by combining two independent loops, a mechanical refrigeration loop and a thermosiphon loop, with a three-fluid heat exchanger. The experimental results show that it has sufficient cooling capacity. The EER of the thermosiphon mode reaches 10.7 and 20.8, when the indoor and outdoor temperature difference is 10 \({}^{\circ}\)C and 20 \({}^{\circ}\)C, respectively, and the AEER of the ISMT is 12.6, which is much higher than traditional air conditioners (TAC) [21]. In his publication, [PERSON] analyzes the need for data center cooling, which is constantly increasing in energy and involves high costs. A simple cooling system based on heat pipes is designed which has the potential to save energy up to 75% [22]. Another proposed system in this area is from [PERSON] and his colleagues. This system is designed for cold areas below 0 \({}^{\circ}\)C because it is based on storing ice or cold water on a heat pipe. The proposed system can be used as a pre-cooler in data centers [23]. [PERSON], [PERSON], [PERSON], and [PERSON] used a combination of heat pipe processes and a cooling cycle to compress the vapor in their research to cool the data center. This resolved certain issues that arose during data center cooling processes, such as valve life and heat exchange areas [24]. During further investigation of the cooling system based on the thermosiphon loop in the telecommunication box, an analytical model was developed by [PERSON] et al., which was subsequently tested experimentally. The designed device was tested at a maximum thermal load of 500 W and with various working fluids suitable for the space with electronic components. The cabinet space cooling system provided good results between the model and the experiment. Based on the results of the model, it was concluded that increasing the thermal efficiency of the system is possible by increasing the diameters of the pipes in the evaporating and condensing part of the heat pipe [25]. [PERSON] et al. developed a two-phase loop thermosiphon system for the B-ISDN telecommunications system and evaluated its performance both experimentally and by visualization techniques. The design of the proposed thermosiphon system was aimed to cool multichip modules (MCM) up to a heat flux of 8 W/cm\({}^{2}\). The results indicated that in the loop thermosiphon system, cooling heat flux is capable of 12 W/cm\({}^{2}\) with two condensers under the forced convection cooling of the condenser section with acetone or FC-87 as the working fluid [26]. [PERSON] and his research team introduced a cooling system using microchannel evaporators to cool processors. Increasing the diameter of the pipe in the heat pipe by 30% increased the heat flow by 10-60%. The results of the research served to improve the geometry of the designed device [27]. [PERSON] and [PERSON] proposed an ejector-assisted copper-water loop heat pipe with a flat evaporator (ELHP) for applications in electronic cooling and performed a simulation of its steady-state operation. The simulation results indicated that the ELHP can achieve a better performance than BLHP (basic loop heat pipe), which could be beneficial to the applications in electronic cooling [28]. [PERSON] investigated an advanced thermosiphon loop with an extended evaporator for the cooling of three parallel high-heat flux electronic components. The tested evaporators were made from small blocks of copper in which five vertical channels with a diameter of 1.5 mm and length of 14.6 mm were drilled. Tests were done with isobutane (R600a) at heat loads in the range of 10-90 W/cm\({}^{2}\) for each of the components with forced convection condenser cooling and with natural convection with heat loads of 10-70 W [29]. Recent years of scientific experiments in research centers have proven the versatile use of heat pipes. Scientists have used heat pipes for cooling in various areas of electronics.