• System configuration:

Figure 2 shows the configuration of the three heat reservoir cooling system. The main section of the solar cooling system can be divided into three flow loops: The solar collector flow loop, the ejector and cooling flow loop. The three flow loops are crossed by the same working fluid (R134a, R123). The choice of the refrigerants was subordinate to the saturation curve shape and to a certain extent to the knowledge of their thermodynamic and thermophysical properties.

The superheated vapour produced in the solar collector is sent to the ejector flow loop where the driving effect is produced. In our case, the intensity of the solar radiation has a direct influence on the vapour mass throughput of fluid at the collector exit and implies an intermittent flow (e. g. the solar collector in Tamanrasset (far south) will record a value of mass flow rate higher than in Algiers (north)). At the condenser exit the fluid flow separates into the driving massflowrate and the secondary massflowrate related each other by the entrainment ratio ra.

In Figure 3, the double Rankine cycle is illustrated in a logP-h thermodynamic diagram. It’s a combination of two basic Rankine cycles. The R123 and the R134a refrigerants have a positive — slope saturated vapor line. So we do not need important superheating compared to negative slope saturated line fluids where the isentropic expansion 1-2’ can induce vapor condensation that could affect the ejector performances.