Dynamic performance of solar powered vapor absorption cooling system in dhahran — Saudi Arabia

This paper presents development of a dynamic model of a 3 TR single-effect absorption cooling cycle that employs LiBr-water as an absorbent/refrigerant pair coupled with solar collectors. Due to the frequently changeable cooling load, and the freckle nature of the solar radiation which indirectly provides the heat input; the system performance is highly transient. Even if, the input power from the solar field is controlled, there will be an unsteady period that precede the steady operation period of the cooling system. Throughout this transient period, most parameters keep fluctuating and do not stabilize at particular values, and some of them may go away from their allowed ranges in a manner that affects the system performance severely. This phenomena is considered as a prime motivation and fundamental concern of this study. The dynamic model is based on mass, energy balances and heat transfer equations while taking into account the dynamic response of the cycle. The results indicate that it takes an average of fourteen minutes before most parameters stabilize at their operating values and the dynamic terms almost diminish in what could be considered steady-state period. In addition, the performance of a solar absorption system was investigated under meteorological conditions of Dhahran - Saudi Arabia for a representative summer day. The results indicated that; a 60 m
²
of evacuated tube solar collectors is needed to meet the 3 TR cooling load without auxiliary heating during the period 8:00 a.m. to 3:00 p.m. an auxiliary heating is required outside this period to meet the cooling load. The developed dynamic model is able to predict the transient performance of a 3 TR single-effect LiBr-Water solar absorption cooling system which in turn helps in designing appropriate integrated systems for various sustainable applications.