DEM Analysis of Flow Dynamics and Thermal Performance of a Novel Indirect Particle Heat Exchanger

ABSTRACT In this study, we introduce an innovative gravity‐driven, noncontact particle heat exchanger featuring a double helix design to effectively separate heat and cold mediums, enhanced by a platform for control of particle velocity. Utilizing the discrete element method (DEM), we conducted simulations to analyze the particle flow and heat transfer dynamics within the exchanger. Our investigation focuses on the impact of various parameters, including the blade pitch, platform number, rolling friction coefficients between particles and walls, and particle size, on particle velocity, residence time, contact frequency, and overall heat transfer efficiency. Our findings reveal that optimizing the pitch of the heat exchanger plays a pivotal role in balancing mass flow rate and residence time, with medium pitches yielding the most favorable heat transfer outcomes. The particles exhibit three distinct motion patterns as they travel along the spiral blades, which results in varying distributions of residence time. The addition of a single platform notably increases the outlet temperature, leading to a significant enhancement in heating power. Despite having a heating power that is less than the optimal level, the discharge rate exceeds that of the optimal condition. Furthermore, we demonstrate that minimizing friction coefficients facilitates smoother particle flow, contributing to enhanced heat transfer. The use of smaller particles amplifies the contact area with the heat exchange surface, resulting in even more efficient heat transfer. Building upon these insights, we develop and validate a reduced‐order model that accurately simulates particle temperatures across varying heights within the heat exchanger, offering a valuable tool for indicating the fit quality.