Experimental investigation of a data server cabinet integrated with an indirect evaporative plate falling film heat exchanger: Heat transfer enhancement and cabinet-level cooling energy savings

To investigate a lower-energy cooling approach for a cabinet-scale data server system, this paper proposes and experimentally investigates an innovative cabinet-level cooling architecture that integrates a data server cabinet with an indirect evaporative plate falling film heat exchanger (PFFHE). A precision liquid film distributor capable of precisely metering water admission into the PFFHE, together with a techno-economically optimized PFFHE unit featuring a ‘mortise-tenon’ architecture, is developed. In the experiments, liquid guiding fibers are employed to improve the uniformity of liquid film distribution along the vertical wall of the PFFHE, while the energy consumption associated with liquid film transport is reduced by minimizing the water usage. This study systematically analyzes the effects of different operating conditions on the liquid film flow characteristics, cabinet internal temperature, and air-side heat transfer coefficient (HTC), and further evaluates the influence of cooling modes and rack-mounted load powers on cabinet-level cooling energy performance, including cabinet-level power usage effectiveness (PUE) within the defined experimental boundary. Two key findings are obtained. (1) Compared with standalone air cooling, the air-side HTC achieved by the air-water-liquid guiding fiber cooling mode is 5.61 times greater than that of the air cooling mode; (2) Under the ASHRAE Class A2 allowable inlet temperature constraint (≤35 °C), the supports a maximum experimentally validated rack-mounted load of 2500 W, at which a minimum cabinet-level PUE of 1.11 is achieved. These results indicate that the proposed cabinet integrated cooling architecture can enhance heat transfer and reduce non-IT cooling energy consumption within a single-cabinet laboratory prototype.