Study Of The Off-design Performance Of Absorption Chiller In Distributed Energy System

Distributed energy system (DES) consists of a range of smaller-scale and modular devices designed to provide electricity, and also thermal energy, in locations close to consumers. DES is of high efficiency and environmental friendly compared with traditional separated power system, followed by the principle of energy cascade utilization. DES is an effective way to save energy and reduce emission in industrial and building area.Supported by the National Basic Research Program (973program) of China, this research have been carried out in three aspects in order to solve the problem of off-design performance degradation of DES, including mechanism study of performance degradation of absorption chiller (AC) under part-load conditions, investigation of active control strategy of AC and performance analysis of DES using active control strategy of AC. It mainly includes:(1) Mechanism study of off-design performance degradation of AC. Using energy conservation, mass conservation, phase equilibrium and heat transfer equations, the model of exhaust-fired double-effect LiBr-H2O absorption chiller under part-load conditions has been developed and the off-design performance of AC has been investigated. The phenomenon of energy level difference increase in high pressure generator due to solution temperature increase has been found and the cause of performance degradation under part-load conditions has been disclosed. It provides the theoretical support for the all-operating integration of DES.(2) Investigation of active control strategy of AC and performance analysis of DES system using active control strategy. An active control strategy of maintaining the solution concentration difference at a constant level has been proposed when the exhaust gas flow ratio is less than0.5, and the results showed that the energy level of high pressure generator is increased and the COP and refrigeration capacty are also incareased. The effect of active control strategy on the DES off-design performance has been researched and2%of fuel energy saving ratio can be enhanced. It indicated that the active control strategy of AC is an effective method for the all-operating control of DES.