Experimental investigation on the geometric structure with perforated baffle for thermal stratification of the water tank

When the performance test is carried out for a water-cooled chiller, a thermostatic water tank, as an indispensable part of the testing apparatus, takes the main responsibility for the waterside working condition. In this paper, a single energy-saving thermostatic water tank is proposed to treat chilled water and cooling water drained out of water-cooled chiller and supply chilled water and cooling water at the required temperature with stable performance. The water tank works with inside and outside water flow circuit simultaneously. The inside water flow circuit takes place within three districts in the water tank divided by two baffle configurations. The outside circuit includes the water tank, a cabinet fan coil and an air-cooled chiller. Experiments are operated to obtain and analyze temperature distribution in water tank with 5 arrangements of baffle configurations to find the optimal model. Using this optimal water tank model, notched baffles are altered into baffles at 6 perforation rates from 15% to 100% respectively for further experimental analysis. Thereby the most favorable perforation rate is found. Experimental results show that the further optimized water tank provides water at design temperature stably using baffle configurations arranged in model 5 with perforation rate from 25% to 50% under 4 representative working conditions. Performance of the water tank is evaluated by the spatial temperature uniformity coefficient proposed in the paper. Evaluation results verify the reliability of the optimal water tank and determine the perforation rate to the range from 25% to 60%.