Heat Transfer Fluid Storage in the Solar Collection Loop – The Storage Volume Impact on the Work Performance of a Solar Absorption Cooling System

Implementing systems that utilize solar energy shows a great potential for preserving fossil fuels and reducing the need for electricity production. Traditionally solar energy was used for space heating and domestic hot water production. However, through the use of absorption systems, it is possible to use solar energy for cooling as well. Due to the intermittent nature of solar energy during days and its absence during nights, in order to enable continuous operation and extend the working hours of an absorption system, special attention has to be paid to the thermal energy storage. The main goal of this paper is to determine how a hot water thermal energy storage volume, placed in solar loop, impacts the work performances of an absorption cooling system and to find the optimum storage volume for given solar collector area and nominal capacity of a chiller. Numerical simulations of a hot water powered 10 kW absorption cooling system have been performed in Trnsys software, for different hot water storage volumes. The observed parameters were total working time and total energy exchanged in the evaporator of the absorption chiller. The simulation showed that the heat storage with a volume of 2.4 m3 in the solar loop reduces the effect of short term fluctuations in the solar radiations, stores the excess heat in the periods with high solar availabilities for the use in periods with low solar availabilities and prolongs the total working time of the proposed system.