Thermal Performances of Heat Conducting Oil Steam Generator

Abstract Thermal performances of heat conducting oil steam generator in parabolic trough solar system are experimentally and numerically investigated. According to experimental results, the heat flux density of steam generator mostly increases with inlet flow velocity and temperature of water and oil, while the heat efficiency first increases and then decreases with the flow velocities of water and oil, and it approaches to maximum with optimal flow velocities of water and oil. Based on the experimental system, the boiling heat transfer process inside the circular steam generating tube is simulated by VOF model, and then associate distributions of temperature and gas content are further analyzed. According to the simulation results, the heat transfer inside steam generating tube mainly includes the regions of single phase convective heat transfer and boiling heat transfer, and boiling heat transfer plays the primary role in steam generator. During the boiling heat transfer process, the liquid water changes to steam by the heating process, and the steam bubbles gradually go into the bulk flow, so two phase flow forms with vortices between the liquid water and steam. As the water flow velocity decreases, the region with single phase convective heat transfer shortens.