Performance analysis and parametric evaluation of a PCM-integrated air conditioning system for peak load management

• PCM tank enhances peak cooling load by up to 42% in daily operation. • RT8 achieves highest system COP among tested PCMs under transient mode. • Design parameters significantly influence PCM charge–discharge behavior. Air conditioning (AC) systems are among the largest energy consumers in buildings, and their peak demand aggravates pressure on power grids. This study develops a transient simulation model of a vapor-compression cooling system integrated with a phase change material (PCM) storage tank. The objective is to examine how PCM type, pipe number, and flow conditions influence load shifting and overall system efficiency under different climatic conditions. Validation of the model is based on our previous work, ensuring reliability of the simulation framework. The results demonstrate that PCM integration increases cooling delivery during peak demand by up to 42%, while improving discharge COP by 7–18% depending on the operating conditions. Among the investigated PCMs, RT8 provided the most balanced performance, achieving a higher melting fraction and overall COP compared to water, oleic acid, and SP224A. Increasing pipe length enhanced stored energy up to 20.8 kWh, but reduced system COP by around 3–5%, while increasing the number of pipes improved melting fraction but decreased effective storage volume. Parametric analysis further revealed that raising the refrigerant mass flow rate significantly improved melting fraction and discharge cooling capacity, but at the expense of a 39% reduction in COP during charging. Conversely, increasing the water flow rate in the discharge loop enhanced PCM energy extraction by 5.4% with a modest rise in COP. Climatic analysis across Tehran, Bushehr, and Ahvaz confirmed that system efficiency is strongly dependent on ambient temperature.