Performance optimization of an air source HVAC system for an internet data center building using the integrated COP method

Abstract

Internet data centers experience continuous annual cooling load compared to common buildings that experience seasonal cooling and heating loads. This study experimentally shows the effect of summer and winter seasonal optimum refrigerant charge amounts on the performance of the IDC cooling system. A methodology for determining the annual optimal refrigerant charge of the IDC cooling system using an integrated COP (ICOP) is experimentally studied at a standard indoor temperature rating of 26.7 °C, outdoor annual temperature range of −2 °C ∼ 35 °C, and varying refrigerant charge amounts. The optimum charges of 6.5 kg and 11.1 kg were found for the summer and winter conditions respectively, while the annual optimum charge using ICOP was 9.7 kg. The annual optimum refrigerant charge of the IDC cooling system using ICOP method showed 13.3% and 33.3% improvement in COP over that of the optimum charge for summer and winter conditions respectively. Alternative methods that use an outdoor temperature that yields the same COP of the IDC cooling system at the optimum summer and winter refrigerant charge amounts, and the average of the optimum summer and winter refrigerant charge amounts are also proposed to determine the annual optimum charge of the IDC cooling system.