A study on heat absorbing and vapor generating characteristics of H₂O/LiBr mixture in an evacuated tube

Highlights: • Proposed a remolded SPAR system using evacuated tube as both solar collector and solution generator. • Investigated the temperature, mass and concentration variation of the solution in evacuated tube. • Calculated the vaporization rate and equivalent refrigerating capacity per evacuated tube. • Summarized the thermal collecting efficiency and solar coefficient of performance of evacuated tube. • Calculated the total energy absorbed by the solution in evacuated tube and compared the storage density with water tank. - Abstract: It is well known that application of solar powered absorption refrigeration (SPAR) systems will save energy, especially for air conditioning during the summer. This paper presents a SPAR system where evacuated tubes act as both solar collector and solution generator simultaneously while aqueous lithium bromide (H₂O/LiBr) is used as the working fluid. In order to investigate the heat absorbing and vapor generating characteristics of lithium bromide solution in the evacuated tube, a test system was built and tested outdoors in Guangzhou in October 2015. The test results showed that lithium bromide solution in an evacuated tube can be heated up rapidly and generate vapor continuously. The vaporization rate, the solution concentration, the equivalent refrigerating capacity, the total energy absorbed by the solution, the thermal collecting efficiency and the solar coefficient of performance in theory were analyzed according to the test data. The work provides a reference for the design and simulation of SPAR systems where evacuated tubes are used as both solar collector and lithium bromide solution generator.