Performance experiment of all fresh air-handling unit with high sub-cooling degree and year-round exergy analysis

In this article, an all fresh air-handling unit with high sub-cooling degree is presented. In this unit, refrigerant flows through the high-pressure liquid receiver before it goes through the sub-cooler so as to ensure sufficient sub-cooling degree. Based on the experimental comparison between this unit and conventional unit, coupling relationships between condensing temperatures and sub-cooling degrees of these two units are worked out and analyzed. Experimental results and exergy analysis show that, sub-cooling degree drops with the decrease of condensing temperature, and sub-cooling degree of the designed unit is kept over 7°C when the sub-cooling degree of the conventional unit is only close to 0°C. Furthermore, a method of year-round exergy calculation is presented and applied in calculating and analyzing the year-round exergy of the all fresh air-handling unit. Calculation and analysis show that the all fresh air-handling unit designed and investigated in this article has a year-round exergy efficiency of 28.38%, which is 3.17% higher than that of the conventional unit without high sub-cooling degree.