## 1 Introduction  
The main cable of suspension bridges usually consists of high-tensile galvanized steel wires, which are under severe corrosion environments due to the water and high temperature inside the cable [1, 2, 3]. Studies have shown that there are two main sources of moisture within the main cable: one is the penetration of moisture in the atmosphere and the other is the accumulation of moisture during cable section [4, 5]. The conventional anti-corrosion method is to form a protective layer on the surface of the main cable to block the penetration of moisture in the atmosphere, but it cannot solve the corrosion caused by the water trapped during cable section [6, 7]. Through studies on the mechanism of corrosion, researchers have proven that when the relative humidity (RH) is below 40%, the corrosion rate of steel is very low. When the RH is between 40% and 60%, the corrosion rate rises slowly. When the RH is higher than 60%, the corrosion rate rises sharply [8, 9, 10, 11]. Based on this principle, Japan took the lead in proposing the main cable dehumidification system and conducted various engineering explorations [12]. In the early 1990s, the main cable dehumidification system was first implemented on the Akashi Kaikyo Bridge in Japan, which injected dry air into the main cable to control the RH inside the main cable to lower than 60% [13; 14]. Figure 1b shows the layout of the cable dehumidification system [12]. It is mainly composed of a filter unit to remove impurities, a dehumidification plant to remove moisture from the air, a blower that supplies air to the main cable and an aftercooler unit to chill the dry air. Figure 1a shows the flow of air inside the main cable. Among these components, the dehumidification unit is critical because it directly determines the humidity of the dry air. In most of the existing suspension bridges, the desicant wheel dehumidification system (DWDS) based on solid desiccant adsorption is the sole dehumidification plant [7; 11]. However, DWDS are often unable to meet peak wet loads because of the severe and rapidly changing temperature and humidity in the summer. Moreover, the electric heating energy consumption of the regeneration process is high [15; 16]. In addition, there is a lack of discussion on air supply parameters in the field of main cable dehumidification, which is not conducive to the selection and performance evaluation of the dehumidification plant. Therefore, the research on dehumidification plants for main cables is of great significance. For main cable dehumidification systems, previous studies mainly focused on control and monitoring systems, air supply systems and sealing systems. [PERSON] [17] proposed that optimizing the detection and control system of the main cable dehumidification system could reduce energy consumption and improve dehumidification efficiency. [PERSON] et al. [18] designed a dehumidification system in which dry air was delivered from the center of the main cable section. It could reduce the gas flow loss during the air delivery process and improve the dehumidification efficiency of the main cable delivery. [PERSON] et al. [13] presented a corrosion monitoring system that could be embedded in the main cable of the suspension bridge and measured temperature, RH and corrosion rate at various points in the cable cross-section. [PERSON] et al. [19] proposed that the main cable dehumidification system combined with the traditional anti-corrosive system could improve the durability of the main cable. [PERSON] et al. [5] designed a sensor network to monitor the environmental conditions and corrosion activity within the main cable. In recent years, researchers conducted studies on improving the performance of dehumidification plants based on acquired running data. [PERSON] [17] indicated that the combination of dehumidification plants based on different methods to form an energy  
Figure 1: The principle of main cable dehumidification. Reprinted/adapted with permission from Ref. [12]. 2021, Elsevier.