Experimental study on reliable operation strategy for multi-split backplane cooling system in data centers

The composite air-conditioning system combined heat pipes and vapor compression, which can utilize natural cooling sources effectively, has been widely used in data centers recently. The common energy-saving strategy is to make the best use of the natural cooling sources according to outside ambient temperature. However, existing studies indicate that the cooling failure problem often occurs in the mechanical refrigeration mode due to incorrect control strategy, when the outdoor ambient temperature is lower and natural cooling capacity is insufficient. Thus, taking the multi-split backplane cooling system used in the data center as an object, the reason for the cooling failure under the condition of lower outside ambient temperature is investigated through theoretical analysis and experimental study. Results indicate that system energy consumption will decrease as condensing pressure decreases, but lower condensing pressure may cause insufficient refrigerant problems at the most unfavorable terminal. To solve the problem, a reliable operation control strategy based on variable condensing pressure is proposed and validated by experiments, and results indicate that a maximum of 12% energy consumption can be saved with the decrease of condensing pressure. Finally, the determination for condensing pressure setpoint is provided, and it is pointed out that how to determine optimal condensing pressure setpoint is worthy of further study in the consideration of energy efficiency and cooling effect meantime.