Passive heating of the ground surface

Abstract

Abstract. The phenomenon of phase change is one of the most important contemporary issues of thermal engineering. In particular, this applies to all kinds of heat exchanger systems, which should achieve the highest possible efficiency while reducing investment and operating costs. Some of these systems are heat pipes or thermosyphons, which, among others, are used for the heat transfer, temperature stabilization and the regulation of heat flux density. Additionally, they are passive systems, and therefore do not require an external power supply. Heat pipes can be used to stabilize the surface temperature of roads and driveways. Large heat tubes can be applied for heating the surface of bridges and overpasses, which become icy in unfavorable climatic conditions. The paper presents research on the test facility, whose main component is a long vertical copper fin. The temperature at the base of the fin was kept constant for a given series of measurements. Heat receiving fluid was ethanol at atmospheric pressure. The measurement methodology and the results of investigations were discussed. The surface temperature distribution was measured with the infrared camera, and on this basis the local values of heat flow and the heat transfer coefficient were determined. The results were presented as boiling curves for both the fin with the smooth surface and the one covered with a metal capillary-porous structure. The results obtained are useful in the design of heat exchangers, including passive heating of the ground.

Boiling on fins with wire screen of variable effective conductivity

“…That prevents overheating that is unwanted, and also allows setting the optimum technological parameters. Therefore, exchangers of that type have gained increasing popularity [1][2][3][4].…”

Quasi-stationary phase change heat transfer on a fin

“…Such an installation may also absorb heavy heat fluxes that may be derived from fire flames [8] and constitute the passive element of fire-fighting protection. Phase change processes can be also applied in inactive road defrost [9] decreasing the exploitation costs and eliminating the dependence on mobility of traffic maintenance workers. This kind of solution brings advantages both in economic and ecologic aspects not only to the direct user.…”