A Comparative Study on the Thermal Performance of Copper and Stainless-Steel Heat Pipes

Abstract

Heat pipes are highly efficient passive thermal devices that exploit phase-change mechanisms —evaporation and condensation of a working fluid—to transport heat with minimal temperature drop. This study presents an experimental and computational investigation of a 204 mm copper–water heat pipe equipped with a stainless-steel mesh wick for small-scale thermal management. Steady-state temperature distribution, thermal resistance, heat-transfer rate, phase-change characterization, structural deformation, and stress distribution were evaluated under controlled laboratory conditions. ANSYS steady-state thermal simulations were performed to reproduce the measured temperature distribution as a conduction-only, single-phase representation of the solid wall; the model does not resolve two-phase vapor–liquid transport within the wick. A material comparison between copper and stainless steel 304 (SS304) was conducted under identical geometric and boundary conditions with only the wall thermal conductivity varied; all the SS304 results were analytical/numerical estimates and were not independently validated by experiments (see Limitations). The copper heat pipe achieved a conduction-based heat-transfer rate of 31.15 W (analytically derived from the measured evaporator–condenser temperature difference), a thermal resistance of 1.605 K/W, and a minimum vapor mass flow rate of 1.35 × 10⁻⁵ kg/s. In contrast, the SS304 equivalent yielded 1.17 W and 42.4 K/W, demonstrating the severe impact of low wall conductivity on heat-pipe performance under this scaling approach. The ANSYS contours were consistent with smooth heat spreading in copper and a steep gradient in SS304, with the simulated copper ΔT (≈ 43 K) within 14% of the measured value (50 K; see Section 4.6.1). These findings are consistent with the superiority of copper–water systems for compact, high-performance thermal management under the tested conditions.