Document Type : Research Paper
Authors
Department of Disaster Engineering, Education and Environmental Systems, Graduate Faculty of Environment, University of Tehran, Tehran, Iran.
Abstract
Objective: In cold regions, freezing conditions and snowfall are among the most significant factors disrupting the operation of urban infrastructure and transportation systems, and they can seriously affect traffic safety and the sustainable operation of road networks. In Iran, countermeasures against these phenomena are mainly based on conventional methods such as sand spreading and chemical de-icing, which, in addition to high operational and maintenance costs, have adverse environmental impacts. Accordingly, the present study was conducted to numerically analyze the thermal performance of a hydronic heating system for snow melting on the B9 Bridge, located on Artesh Expressway in Tehran. The bridge is currently equipped with a chemical de-icing spray system, and the primary objective of this study is to investigate the feasibility of replacing the existing system with hydronic surface heating technology, with an emphasis on improving energy efficiency, enhancing infrastructure sustainability, and reducing environmental impacts under cold climatic conditions.
Method: In this study, transient thermal simulation was performed using COMSOL Multiphysics to model the heat transfer process in a hypothetical hydronic heating system. The system consists of pipes embedded beneath the bridge pavement surface, through which water flows with an inlet-to-outlet temperature range of 43 to 40 °C. The numerical model considers heat transfer through the different pavement layers, including asphalt and insulating layers, along with the dynamic behavior of fluid flow within the pipes. Simulations were conducted for two weather scenarios with ambient temperatures of −5 and −10 °C. In the second scenario, snowfall with an intensity of 30 mm/h was also incorporated to evaluate the system’s performance under critical conditions.
Results: The simulation results indicated that the hydronic heating system is capable of raising the asphalt surface temperature above the freezing point in less than 20 minutes at an ambient temperature of −10 °C. This capability enables effective melting of snowfall at an intensity of 30 mm/h and prevents freezing of the bridge surface. The energy required for one hour of full-system operation was estimated at approximately 851 kWh. Furthermore, the analysis showed that the installation of 200 fixed solar panels, each with a capacity of 700 W, could provide approximately 340 hours of annual system operation, demonstrating the high potential of using solar energy as a sustainable source to support this technology.
Conclusions: Based on the findings of this study, the implementation of hydronic heating systems on bridges and urban infrastructure in cold regions can provide an effective and sustainable solution for preventing surface freezing. Compared with conventional de-icing methods, this system offers greater operational stability, reduced dependence on chemical agents, and enhanced public safety. In addition, its potential integration with renewable energy sources can play an important role in reducing environmental impacts and contributing to the sustainable development of urban infrastructure.
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