# Potential Study of Solar Thermal Cooling in Sub-Mediterranean Climate
## 3 GJU System Description
### System Description  
The solar heating and cooling system was installed on the rooftop of building C at the GJU campus. The solar heating system consists of 30 solar collector arrays each with five modules connected in series. Each module (model CPC1518) has 18 evacuated tube collectors with compound parabolic collector (CPC) geometry. The aperture total surface area of the solar field was 450 m\({}^{2}\) and the collectors were oriented to face the south with a tilt angle of 45\({}^{\circ}\). Figure 5 shows the solar collector field installed on the rooftop of Building C at the GJU campus. The solar field is supplying the absorption chiller with water at 85 \({}^{\circ}\)C, this amounts to 44 MWh seasonal thermal energy for the absorption chiller of 250 MWh produced by the collectors. Four heat storage tanks each with a volume of 3.5 m\({}^{3}\) were integrated to the solar heating system. One of the storage tanks is used for domestic hot water in building C and the other three hot water storage tanks were connected to the absorption chiller's generator. The solar hydraulic system is equipped with hot water pumps for each storage tank, two gas boilers (380 kW total capacity), and a dry cooler to remove excess heat. The conventional cooling system consists of two air cooled multistage compression chillers, 700 kW each (one duty/one stand-by), and one of them can also work as a heat pump which operates only if the heating load reaches beyond the capacity of the solar field and the two boilers in cold winter days when there is no or minimum solar energy gain. The evaporator of the air-cooled multistage compression chillers provides chilled water in summer at a given set value for the chilled water outlet  
Figure 4: Daily average irradiance for June 2015 in the installation site at the GJU campus. Figure 3: Daily ambient temperature at German Jordanian University (GJU) campus. temperature, this temperature is set at 9 \({}^{\circ}\)C. The used refrigerant is R134a and is cooled down in an air-cooled condenser. A 160 kW single-stage H\({}_{2}\)O-LiBr absorption chiller developed by the Technical University of Berlin was used to assist the conventional cooling system. The system was designed in a way that it does not interfere negatively with the existing compression system and operates in a way that it can be started and stopped independently from the old system. It was designed to cool a part of the airstream exiting the building down to 16 \({}^{\circ}\)C contingent on the solar energy gain. Hot water from the solar field enters the generator with a volume flow rate of 3.3 L/s. The heat sink for the condenser and the absorber is cooled with a water-stream leaving a 300-kW dry cooler with a volume flow rate of 12 L/s and temperature range between 30 to 40 \({}^{\circ}\)C. The evaporator provides chilled water with a volume flow rate varies between 3.5 to 8 L/s and temperature between 8 and 10 \({}^{\circ}\)C, depending on the generation water temperature. The major components of the absorption refrigeration system are two large containers, the low-pressure tank, and the high-pressure tank. The unit contains the four copper tube heat exchangers: evaporator, absorber, generator, and condenser. The external circuits for the chilled, cooling, and heating water were connected to the four copper tube heat exchangers. The internal sensors of the system consist of temperature and pressure sensors. The pressure in the vapor space of the three containers and the pressure in the absorber and the evaporator bottoms are measured. The temperature is measured at nine positions; this includes the reservoirs for the desorber, absorber, and evaporator, the condenser refrigerant sum of the evaporator circuit as well as all the inlets and outlets of the solution heat exchanger. The flow rate for the different circuits: solar collector field, generator, condenser, evaporator, and the compression chillers were measured via five ultrasonic flow meters.