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The inefficient operation of cooling equipment is a significant impact factor to the high energy consumption of cooling system in data center. This study proposes an advanced model predictive control (MPC) strategy for a hybrid cooling with water storage system to improve energy efficiency and reduce the accumulation of cold storage losses. Mixed integer linear programming (MILP) in MPC strategy is used to optimize the operating parameters under free cooling, hybrid cooling, and mechanical cooling modes, further solving the problem of precise optimization for different modes. Taking Guangzhou city as an example, the equipment scheduling and the appropriate volume of cold water storage tank for MPC strategy are analyzed. The results indicate that, the emergency cold water storage tank 500 m3 only supports the efficient operation of cooling system under the maximum 60 % IT load rate, meanwhile, the optimal tank volume 1400 m3 could meet the 60–100 % IT load rate. Compared to Baseline strategy, the biggest reduction of annual energy consumption using MPC strategy would be attained by 12.19 % under free cooling mode, by 4.04 % under hybrid cooling mode, and by 22.15 % under mechanical cooling conditions at the 55 % IT load rate. Therefore, the MPC strategy proposed in this paper has important guiding significance for energy conservation and carbon reduction in global data centers. • A novel advanced MPC strategy and MILP solver is developed for hybrid cooling system of data center. • The energy consumption of MPC strategy decreases by 12.19 % under free cooling mode at 55 % IT load. • The relationship between the water tank volume and IT load rate under MPC strategy is studied. [ABSTRACT FROM AUTHOR]

• PCHP is proposed to enhance energy saving in high thermal density space. • Heat transfer and energy consumption models of PCHP are established. • The effects of padding thickness, ambient temperature, relative humidity, and air flow rate on the performance of PCHP are investigated. • Cooling capacity and EER of PCHP are investigated compared with CHP, providing design guide for heat pipe system in application. • The annual free cooling time of PCHP was analyzed in five typical climates in China. High thermal density space consumes massive energy, and cooling device accounts for large percentage of total consumption. To cut down energy consumption of cooling device, PCHP is proposed on the basis of heat pipe and evaporation technologies. Heat transfer and energy consumption models of PCHP are developed. The effects of geometric and operational parameters on the PCHP performance, including pad thickness, ambient temperature and ambient relative humidity (RH), air flow rate, are investigated. The results show that cooling capacity increases with the increase of pad thickness and airflow rate, and it decreases with the increase of ambient temperature and RH. With the increase of thickness, energy efficiency ratio (EER) increases at the start and then decreases under RH20%-40%, while it decreases continuously under RH70%-90%. EER increases with the decrease of ambient temperature, ambient RH and air flow rate. PCHP markedly enhances annual free cooling time compared with conventional heat pipe system (CHP), and the maximal enhanced free cooling time and increasing percentage occur at Urumchi and Guangzhou Cities, respectively. [ABSTRACT FROM AUTHOR]