Design and operating performance analysis of an innovative hybrid cooling unit for absorption refrigeration

Abstract

Solar driven air-conditioning by absorption refrigeration is a technology, that has the potential to significantly decrease the worldwide electricity consumption. For such a device, a cooling unit is needed to release heat to the ambient. For this thesis, a small-scale cooling unit was designed and analyzed. Its main part is a finned heat exchanger, which was repeatedly sprayed with water to increase the cooling capacity. The water distribution could be observed through the transparent canal walls.<br />The experiments were conducted in a climatic chamber to simulate various ambient conditions. The experiments showed a significantly higher cooling capacity when the spray water was used: Depending on the ambient conditions, the cooling capacity increased by a factor of 1.6 to 3.6 (while the fan power was kept constant). Even though pressure losses and electricity consumption also increased, the wet operation is recommended.<br />Two heat exchangers with slightly different geometries were analyzed, but no clear preference can be given. The choice depends on the characteristics of the system in use, which will differ from the prototype setup. Although the cooling unit fully meets the requirements of the considered absorption refrigerator, other heat exchanger geometries could be analyzed in the test rig to find an even better solution.