Numerical Simulation and Analysis of Tank-mounted Asphalt Heating Utilizing Trough Solar Collectors

Parabolic trough solar collectors heating bulk asphalt can effectively reduce fossil fuel consumption, achieving low-emission asphalt heating production. This aligns with the international “dual carbon” requirements and marks an important practice in the utilization of solar energy for industrial heat in China. This paper studies the bulk asphalt heated by thermal oil, establishes a three-dimensional model of thermal oil heated asphalt, and constructs an experimental system using parabolic trough solar collectors to heat bulk asphalt. Through experimental tests and comparison at the same temperature measurement points on the tank, the accuracy of the model is verified. Furthermore, the heating process of bulk asphalt is simulated using three-dimensional transient heat transfer for different thermal oil flow rates. The results show that with an inlet speed of thermal oil at $2.0 \mathrm{~m} \cdot \mathrm{~s}^{-1}$ and a simulated heating duration of 3.8 hours, increasing the flow rate of thermal oil from $1.5 \mathrm{~m} \cdot \mathrm{~s}^{-1}$ to $3.0 \mathrm{~m} \cdot \mathrm{~s}^{-1}$ raises the heat transfer coefficient (K) from 96.661 W $\cdot \mathrm{m}^{-2} \cdot \mathrm{~K}^{-1}$ to $126.659 \mathrm{~W} \cdot \mathrm{~m}^{-2} \cdot \mathrm{~K}^{-1}$, the Nusselt number (Nu) from 85.706 to 118.293, and the pressure drop ($\Delta \mathbf{P}$) from 12636.38 Pa to $\mathbf{7 5 6 8 6. 2 1} \mathrm{Pa}$. This indicates the feasibility of using parabolic trough solar collectors for heating asphalt. Increasing the flow rate of thermal oil can enhance heat transfer efficiency and reduce heating time. However, a higher flow rate also means higher pump energy consumption, which necessitates a balance between pump energy and heating time in practical applications.