Solar Collector with FMHPA

Description

This project simulates a solar collector equipped with flat micro-heat pipe arrays (FMHPA) using ANSYS Fluent, a renewable energy technology that captures solar heat and transports it via an internal working fluid rather than through direct fluid heating alone. The collector sits inside a parabolic computational zone representing the surrounding air environment, and its structure is layered: an outer cylindrical glass surface absorbs solar radiation, an air gap beneath it channels that captured heat inward, and rows of micro-scale, square-cross-section pipes carry the working fluid that ultimately delivers the heat out of the system. The working fluid picks up heat and vaporizes in the initial section, the evaporation zone, then travels to the far end of the collector where it meets a heat exchanger airflow, loses its heat, and condenses again in the condensation zone. The 3D geometry, spanning the outdoor environment, glass layers, air gap, and FMHPA pipes, is built in Design Modeler and meshed in ANSYS Meshing with a structured grid of 153,680 cells.

Methodology

Turbulence is resolved with the standard k-epsilon model using Menter-Lechner near-wall treatment, and the energy equation is active throughout. Solar heating is captured through the Solar Ray Tracing radiation model, with both direct and diffuse irradiation computed via the solar calculator based on the collector's geographic coordinates, orientation, and the specified date and time of the simulated exposure. The simulation is unsteady and pressure-based, with gravity included at standard acceleration. The working fluid enters through a mass flow inlet at 0.01088 kg/s and 126.2°C, and exits through a pressure outlet at 0 Pa gauge, with both boundaries participating in solar ray tracing; inner walls are coupled and opaque, while outer walls are set to zero heat flux and also opaque. Pressure-velocity coupling uses the Coupled scheme, with second-order discretization for pressure, momentum, and energy, and first-order upwind for the turbulence quantities, initialized using the hybrid method.

Analysis

The resulting 2D and 3D temperature, pressure, and velocity contours trace the working fluid's thermal cycle through the collector: temperature rises in the evaporation zone as the fluid absorbs heat transmitted through the glass layer and air gap from solar radiation, then falls in the condensation zone as that same fluid gives up its heat to the external heat exchanger airflow. This temperature progression confirms the collector is successfully transporting solar heat from the absorbing outer layer into a usable thermal output at the condensation end,