A semicircular trough solar collector for air-conditioning system using a single effect NH3–H2O absorption chiller

This paper reports on the feasibility of a non-tracking semi-circular trough (SCT) solar thermal collector to operate a 17.6 kW single effect NH3–H2O absorption chiller. The SCT solar collector module employs a novel direct metal-to-water contact resulting in an increased heat transfer to the working fluid. This is the first cooling system of its kind that integrates SCT collectors with NH3–H2O absorption chiller and requires a significantly smaller number of collector tubes compared to a non-concentrating collector in order to attain an optimum operating temperature of ≥100 C. In a sequence of experiments, the efficiency of the SCT collector has been measured in both clear and cloudy conditions. It is concluded that this collector is capable of providing thermal power to drive absorption cooling systems in both clear and cloudy conditions. A record −3.3 C was achieved when the chiller reached an operating temperature of 120 C. The average coefficient of performance of the absorption chiller was measured to be 0.42. The SCT collector’s simple design makes it a highly attractive candidate for solar thermal applications including solar heating, cooling and food processing. The collector is currently in the process of commercialization in Thailand.