O.4.6.4 Cycle Simulation and Prototyping of Single-Effect Double-Lift Absorption Chiller
A large amount of waste heat is exhausted in the industrial and commercial field. In particular, low temperature heat such as that below 80~90°C is not utilized enough, and the limitation of lowest release temperature also places a limit on the useful heat quantity that can be obtained from low temperature heat sources. The single-effect double-lift absorption chiller is driven by hot water around 95°C and utilizes it until under a 55°C outlet temperature. Therefore, it is expected to recover unused low temperature waste heat, and to utilize district hot water for cooling uses in the summer. In this study, a cycle simulation model of this chiller is developed and the basic characteristics are examined. This model includes a two-step evaporator and absorber construction that is used in current high efficiency absorption chillers. We estimated the performance of the two-step evaporator and absorber, the enhancement of the solution heat exchangers, and the method of circulating hot water and cooling water, using a simulation based on the model. We also manufactured a prototype machine that is driven in both single-effect double-lift operation and normal double-lift operation. As a result of a single-effect double-lift test, heat of around 90°C hot water is put in this cycle and used until below 55°C, and chilled water is cooled at 7°C. The normal double-lift operation is also conducted. In this mode, 60°C hot water is used until 56°C and 7°C chilled water is produced with cooling water of 30°C. From a comparison between simulation and experimental results, the simulation program was found to have enough function and accuracy to predict the behaviour of the SEDL absorption cooling cycle.