Abstract
Due to the merits of energy saving and environmental protection, the absorption chiller (AC) has attracted a lot of attention, and previous studies only concentrated on the dynamic response of the AC under a single working condition. However, the working conditions are usually variable, and the dynamic performance under different working conditions is beneficial for the adjustment of AC and the control of the whole system, of which the stabilization can be affected by the AC transient process. Therefore, the steady and dynamic models of a single-effect H2O-LiBr absorption chiller are built up, the thermal inertia and fluid storage are also taken into consideration. And the dynamic performance analyses of the AC are completed under different external parameters. Furthermore, a whole system using AC in a process plant is analyzed. As a conclusion, the time required to reach a new steady-state (relaxation time) increases when the step change of the generator inlet temperature becomes large, the cooling water inlet temperature rises, or the evaporator inlet temperature decreases. In addition, the control strategy considering the AC dynamic performance is favorable to the operation of the whole system.
Highlights
With the speed-up of urbanization, the energy consumption of air conditioning and refrigeration keeps increasing continuously [1]
Where Qc,int is the internal heat exchange rate in the condenser, kW; MCpc is the thermal capacities of the refrigerant storage and the container in the condenser, kJ/K; MCpc,con is the product of the container mass and its specific heat in the condenser, kJ/K; UAint,c is the product of the internal heat transfer coefficient and internal heat transfer area in the condenser, kW/K; Thx,c is the uniform temperature of the heat exchanger in the condenser, ◦ C
To investigate the effects of the mass and thermal storage, a step change of 10 °C for Tgin appears at time 0, and the dynamic response of the absorption chiller (AC) is observed and shown in where Qe,st is the cooling capacity on steady‐state after the dynamic process, which is obtained from the steady model, kW; Qe,ext,i is the external heat exchange rate in the evaporator at time i, which is calculated with the dynamic model, kW
Summary
With the speed-up of urbanization, the energy consumption of air conditioning and refrigeration keeps increasing continuously [1]. Evola et al [26] presented a dynamic model and its experimental verification for a single-effect absorption chiller, taking into account the thermal inertia of the heat exchangers, containers and solution storage. Previous studies [15,16,25,26,27] only concentrated on the dynamic response under a single working condition They didn’t show how long it takes to reach a new steady-state, for example, under different cooling water temperatures. This is important for the adjustment of AC and the control of the whole system, because the working conditions are usually variable. The objective of this work is to conduct dynamic performance analyses for single-effect AC under different working conditions, including different generator inlet temperatures, cooling water inlet temperatures and evaporator inlet temperatures
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
