| Solar absorption-subcooled compression hybrid refrigeration system is an efficient and economical solar cooling unit for high-rise buildings.Affected by changes in solar radiation and cooling load,the system is often operated under variable conditions.The lumped parameter method is a commonly used method for modeling variable operating conditions.However,due to the large number of components in the composite system,the corresponding variable operating conditions model has low computational efficiency and difficulty in convergence.Although the black box method can be used to model the system variable working conditions,it can improve the calculation efficiency,but it cannot accurately describe the coupling characteristics of the absorption subsystem and the compression subsystem.On the other hand,the current research involving solar absorption-supercooling compression composite refrigeration system is mainly theoretical analysis,lacking research on the experimental data of the unit's operating performance.Therefore,in this paper,the characteristic equation method and the lumped parameter method are used to model the absorption subsystem and the compression subsystem,respectively,and the two models are coupled to establish the unit variable operating mode model,which not only significantly improves the calculation efficiency,but also accurately reflects the two subsystems.Interrelation of working characteristics.In addition,a solar absorption-supercooled compression composite refrigeration system test prototype was developed,and an experimental platform was built to conduct experimental research on the characteristics of variable operating conditions and operating characteristics under various meteorological conditions.The research results indicate that when the hot water temperature increases by 35 °C,the absorption subsystem COP increases by 11.5%.When the compressor speed decreases by 80%,the absorption subsystem COP decreases by 19.58% and the compression subsystem COP increases by 40.8%.When the cooling water flow drops by 80%,the COP of the compression subsystem decreases by 32.44%.In the system operating characteristics experiment under various meteorological conditions,it was found that because the absorption capacity of the absorption subsystem is used in the subcooled compression subsystem,the temperature of the chilled water outlet exceeds 22 °C,so the absorption subsystem can be lowered by a temperature greater than 60 °C.Taste can be driven.Moreover,the maximum instantaneous cooling capacity and COP of the absorption subsystem are 4 k W and 0.69,respectively.In addition,on sunny days,partly cloudy and cloudy days,the daily average solar SCOP of the absorption subsystem is 0.21,0.2 and 0.13,respectively.Subsequently,this paper establishes a off-design working model of the hybrid refrigeration system,by coupling the characteristic equation of the absorption subsystem and the lumped parameter model of the compression subsystem.The model shortens the calculation time,simplifies the calculation steps,and accurately describes the thermal coupling relationship between the absorption subsystem and the compression subsystem.Regarding the experiment of off-design operating conditions,when the hot water temperature increased by 20 °C,the heat load of the generator and the cooling capacity of the absorption system increased by 35.75% and 51.50%,respectively.The COP of the hybrid system increased by 20.94%.When the flow of chilled water and cooling water increased by 33.3% and 66.7%,the COP of the hybrid system increased by 13.83% and 8.91%.The research results of this paper are helpful to understand the actual operating performance of the system,and provide data support for the improvement and operation optimization of the solar absorption-subcooled compression hybrid refrigeration system. |
PDF Full Text Request