Design Of Passive Radiative Surfaces For Energy-Efficient Base Station Cooling

Official URL: https://risc01.sabanciuniv.edu/record=b3205265

It is estimated that 65 million 5G base stations are needed worldwide due to the increasing number of internet users and IoT applications. Switching to 5G would require a denser base station network due to the higher path loss at higher frequencies to supply the required higher data rate demand per user. This would increase energy consumption for connectivity as a whole. For a vast number of base stations, it would require enormous amounts of energy to keep them at suitable operation temperature in addition to their intrinsic signal processing and propagation-related power consumption. The aim of this thesis is to investigate, design and analyze possible solutions to decrease energy consumption for cooling base stations. Natural convection cooling and passive radiative cooling are the two passive cooling solutions, which do not require any additional energy consumption, and are investigated in this thesis. It is discovered that under solar radiation for a moderate summer day, natural convection, practically applied for many base stations, is not enough to cool a small cell base station. To be able to decrease the effect of heat from solar radiation, two novel optical surfaces are designed to reflect solar radiation and radiate thermal energy to outer space. Since these surfaces are used in a wireless communication device, one of the surfaces is designed to transmit microwaves and millimeter waves, meanwhile reflecting solar radiation, and emitting thermal radiation in the atmospheric transmission window (ATW). With the titanium dioxide nanoparticles embedded in polymethyl methacrylate, 98% reflection in the solar band, and 4% reflection in ATW, along with over 98% transmission in microwave and millimeter wave frequencies, were achieved. The second optical surface is designed as multilayer thin film. With four layers of thin films and an aluminum sub-layer, 91% reflection in solar band, and 20% reflection in ATW were achieved. As a result of these studies, electronic equipment that operates with 5W can be cooled without any electric consumption.