A State-Space Model for Dynamic Simulation of a Single-Effect LiBr/H₂O Absorption Chiller

Abstract

A simplified transient dynamic model for a single-effect absorption refrigeration chiller using LiBr/H2O as the working pair is developed in this paper. The model contains a series of sub-models presenting the components composing the chiller. The development of the sub-models of the four main components (i.e. generator, condenser, evaporator, and absorber), where the solution or refrigerant goes through phase change with complex heat and mass transfer progress, is based on the conservation of mass and energy, by means of dynamic modeling approaches. The throttling devices, solution pump, and solution heat exchanger (SHE) adopt quasi-steady models because their thermal inertia is much smaller compared with the main components. The system model proposed in this study is finally simplified and expressed in the form of state space matrix, which enhances the model portability and computational efficiency. Two approaches are carried out to verify the model accuracy at the end of the paper, static comparison between the steady simulation results and the design parameters under the on-design condition, the dynamic comparison between the simulation results and experimental data under the same inputs. Both comparison results show the model accuracy.

Keywords

• Absorption chiller
• dynamic model
• heat transfer
• simulation