Solar assisted thermal storage system for free heating applications in moderate climates: A case study

Abstract

This paper presents a numerical investigation of the performance enhancement of a phase change material (PCM) based heat exchanger combined with a solar air heater (SAH) for free heating applications during the night-time in moderate climates. For this purpose, a lattice channel heat exchanger is considered in which the air passes through its internal channels while the space between the channels is filled with a paraffin named RT25HC as the phase change material. Numerical simulations are performed based on the experimental data available for the climate condition of northern part of Iran. The effect of air channels density (90 × 90–100 × 100–110 × 110–120 × 120) on the storage performance is investigated using both energy and exergy analysis. Results are analyzed for different design temperatures varied between 293 K and 298 K. It is observed that for the investigated conditions, variation of different parameters exhibits nonlinear behavior with an extremum point at 110 × 110 air channels number. Accordingly, the heat storage with 110 × 110 number of air channels shows the best performance based on five indicators namely power consumption (4.75 kWh), SAH efficiency (44.11%), storage efficiency (97.25%), exergy efficiency (46.85%) and coefficient of performance (values depends on the design temperature).