Enhancing energy saving and carbon footprint reduction using PCM-based heat exchanger: a COMSOL simulation approach

• Detailed study, previous work, future possibility of a heat exchanger to fulfill energy demand. • Modeling and study of novel geometry of heat exchanger using COMSOL Multiphysics • Energy storage analysis by varying geometry and boundary conditions. • Analysis of the optimum thickness of the inner copper tube. • Techno-Economic Analysis and Carbon Mitigation. The increasing energy consumption and greenhouse gas emissions are negatively affecting the environment, among which thermal comfort accounts for more than 40% of the total consumption in residential buildings. In this study, the energy storage capacity of the heat exchanger was enhanced by integrating a phase change material (PCM) (n-octadecane) for thermal energy storage. To this end, this study focuses on leveraging the high latent heat and appropriate melting point of n-octadecane for effective phase-change applications.. The geometry of the heat exchanger was also optimized to improve the liquid fraction and energy storage capacity. A COMSOL Multiphysics-based simulation model was employed to investigate and optimize the heat exchanger’s performance. The results show improved energy efficiency compared to traditional methods. For instance, a single PCM capsule (25 mm × 30 mm × 1,000 mm) can achieve an annual CO 2 emission reduction of 13.53 kg. Furthermore, scaling up to an array of 60 PCM tubes (each 2.55 m long) are used in the heat exchanger leads to annual energy savings of 2,074.68 kWh, corresponding to reduction in CO 2 , SO 2 , and NO emissions of 2,070.53 kg, 16.68 kg and 4.42 kg, respectively. Economic analysis indicates the project's feasibility, with a net present value of US$5.91 and a payback period of 3.75 years for a solar chimney integrated with PCM. In conclusion, heat exchangers based on n-octadecane PCM demonstrate significant potential as an efficient and reliable solution for thermal energy storage in building applications, contributing to a reduced carbon footprint.