With the increasing demand for energy and growing environmental concerns, research on the performance and dynamic control strategies of chillers is vital for energy conservation and emission reduction. This work presents a seventh-order nonlinear moving boundary model with an all-mode switchable scheme for evaporators and condensers of vapour compression cycles. The proposed model, encompassing six modes, introduces a robust switching scheme that supports adjacent-mode and cross-mode transitions. Key advancements include a refined void fraction derivative model, addressing prior simplifications, and heat transfer coefficient modelling for louvred tube-fin and microchannel heat exchangers, extending applicability beyond round-tube designs. A dynamic simulation of a chiller system, validated against integral calculations, demonstrated high accuracy with simulation errors below 0.9 % and mass and energy variations of 0.15 % and 0.27 % over 24 h. A refrigerant charge model identified 0.02995 kg as optimal for maximising COP and cooling capacity under varying conditions. Steady-state and dynamic analyses showed that increased compressor speed enhances cooling performance by boosting flow rates and temperature differentials, while air velocity improves condenser efficiency and system COP. The dynamic response exhibited rapid pressure fluctuations with slower temperature changes due to external variations or heat exchanger efficiency. These findings underline the model's reliability and practical relevance.

The dynamic study of the Supercritical Carbon Dioxide (SCO2) Brayton cycle has received extensive attention from the industry in recent years. While various dynamic operating conditions occur intermittently within the system, some commonly used control methods are unable to adapt effectively to those situations. In this study, a dynamic model of the SCO2 Brayton cycle coupled with a printed circuit heat exchanger with embedded PCM, a storage tank, and a proportional-integral-derivative (PID) controller was developed and validated with the model, and then the control effects of the various control models were compared in terms of their control effectiveness under three typical variable operating conditions (periodic temperature fluctuation, load reduction and recovery, and reduced flow rate). In addition, the stability assessment of the SCO2 Brayton cycle was modeled. Compared to the basic SCO2 Brayton cycle, the PCM-PCHE reduces the amplitude of the total efficiency fluctuations by 44.8 %, and the integrated layout covering the printed circuit heat exchanger with embedded PCM, storage tank, and PID controller shows the best stability. Controlling the extraction ratio with a PID controller contributes more to the stability of the SCO2 Brayton cycle than controlling the condensate flow rate with a PID controller. In contrast, the printed circuit heat exchanger with an embedded PCM contributes more to the stability of the SCO2 Brayton cycle concerning the storage tank. Overall, the total control layout reduced the instability by about 40 % compared to the initial recompression layout, indicating that the PCM, storage tank, and PID controller greatly improved the stability of the SCO2 Brayton cycle.