Experimental study on diffusion absorption refrigeration systems with low GWP refrigerants

Abstract The diffusion absorption refrigeration (DAR) cycle is driven by heat input. The DAR systems do not employ pumps or compressors; they use refrigerants, absorbents, and auxiliary gases as working fluids. In this study, experiments were conducted on refrigerants with low GWP. The refrigerants R1234ze(E) and R600a (a natural refrigerant) were used in the DAR cycles with dimethylacetamide (DMAC) and isooctane as the absorbents, respectively. To investigate the operating characteristics of refrigerants with low GWP in the DAR cycle, the evaporation temperature and generator outlet temperature of the cycle were analyzed against the concentration of the working fluid and its charge pressure. In addition, the performance of the cycle was evaluated by the bubble pump shape. Using the results, the relationship between the shape of the bubble pump and the performance of the DAR cycle was analyzed. The maximum coefficient of performance of DAR achieved using R600a/isooctane was estimated as 0.157with the tube diameter of 3.17 mm and that of R1234ze(E)/DMAC DAR was estimated as 0.134 with the tube diameter of 4.76 mm.