Performance of an autonomous solar powered absorption air conditioning system

Abstract

The demand for air conditioning is increasing due to changing architectural trends and increased standards of living and indoor comfort conditions. Coupled to this, refrigerants used in conventional refrigeration systems have detrimental effects on the environment. As a result, there is an urgent need to implement environmentally cleaner ways of satisfying this air-conditioning demand. Absorption cooling systems have shown great potential to do so. In this study, system performance data for an autonomous solar heating and cooling system installed at the Vodafone Site System Innovation Centre, at the Vodacom Campus in Midrand was collected and analysed. The system comprises a 116 m2 vacuum tube collector array, a 6.5 m3 hot water storage tank, a 35 kW LiBr-Water absorption chiller, 1 m3 of cold water storage, a dry cooler for the chiller, and two underground thermal stores to pre-cool the supply air to the building and the dry cooler respectively. System performance data was collected from the beginning of December 2011 to the end of January 2012 and used to estimate the system long term performance. The chiller has an average coefficient of performance (COP) of 0.51 whilst the solar COP has an average value of 0.24. The total installation cost is R2 822 436.89, with an annuity of R225 949.75 and a cost per kWh of R28.88.