Lei Gao

Bent heat pipes in spacecraft thermal-control systems are often exposed to spatially distributed heat loads, but the combined effects of bend geometry and heat-source arrangement remain poorly quantified for aluminum-ammonia axially grooved heat pipes. Here, horizontal experiments and a three-dimensional volume-of-fluid model were used to examine single bends of 45°, 90°, and 135°, multiple-bend configurations, and four heating arrangements ranging from continuous to discrete sources. Transient and steady wall temperatures, axial temperature uniformity, thermal resistance, equivalent thermal conductivity, and the heat-transfer limit were evaluated. The numerical results were used to interpret curvature-induced secondary flow, vapor-liquid distribution, and pressure loss. The 90° single-bend pipe had the lowest measured thermal resistance at intermediate heating powers, whereas larger bend angles and repeated bends lowered the limiting heat load. Distributing the heat input also improved performance: the four-segment configuration increased the measured heat-transfer limit by approximately 21% relative to continuous heating. The two-end configuration had the lowest thermal resistance over the tested range, although its limiting heat load could not be measured because of the heater capacity. These findings quantify the trade-off between routing geometry and heat-load distribution in grooved heat pipes for spacecraft thermal control.

Thermal management is important for ensuring the safety and reliability of energy storage batteries. Conventional single-mode cooling methods fail to maintain efficiency and temperature uniformity under variable operating conditions. This study presents a phase change material (PCM)-coupled liquid-cooling strategy with an operation condition adaptive control scheme for large-capacity energy storage batteries. A battery management system numerical model with paraffin/expanded composite PCM and a parallel-channel liquid cold plate was developed. The thermal management performance of this system was comprehensively validated under different coolant flow rates, inlet temperatures, PCM melting points, and latent heats, followed by a quantitative sensitivity analysis to identify dominant influencing factors. Based on the parametric analysis, an adaptive cooling strategy was proposed: passive PCM cooling is adopted at low charge/discharge rates, while a delayed liquid-cooling activation strategy is implemented at a high rate to fully use PCM latent heat and reduce energy consumption. Results denote that this system reduces the battery surface maximum temperature by 5.1 °C and the maximum temperature difference by 2.62 °C compared with liquid cooling alone. The coolant flow rate exerts the greatest influence on both the temperature difference and the maximum temperature through the sensitivity analysis, followed by the PCM melting point, coolant temperature, and latent heat. Under the delayed cooling strategy, the total liquid-cooling runtime during continuous operation is reduced by 1720 s, with the number of cooling cycles decreasing from eight to three. This work provides an engineering-based, operation-adaptive thermal management solution that significantly enhances the temperature control effectiveness, energy efficiency, and operational safety of energy storage power stations under real-world variable working conditions.