Fangming Jiang

In recent years, immersion cooling has gained wide interest for thermal management of lithium-ion batteries. Usually, dielectric oils or fluorinated liquid are used as immersion coolants to avert short circuits, but they have low thermal conductivity and high cost. Although water offers superior heat-transfer performance, its poor dielectric property means it cannot be used directly as an immersion coolant. Near full-depth partial immersion (NFDPI) was proposed as a viable alternative, in which water does not contact the tabs of batteries. In this study, an NFDPI experimental system is set up, and the effects of coolant flow rate, discharge rate, and inlet–outlet configuration on thermal management performance are investigated. Since direct observation of the immersion tank’s internal flow is challenging, numerical simulations are conducted to resolve the flow field under various operating conditions. The experimental and simulated results reveal that NFDPI cooling effectively limits the module’s maximum temperature, and the module’s maximum temperature spread is mainly attributed to the cell’s vertical temperature gradient. These findings offer guidance for the practical deployment of water-based NFDPI lithium-ion battery energy storage systems.

The implementation of the heat pipe concept in sucker rods for oil pumping systems negates the requirement for an external heat source, thereby eliminating the necessity for expensive approaches such as separate heating systems. This method enhances the production rate by minimizing heat loss to the wellbore formation, facilitating direct heat transfer, and maintaining a lower viscosity of the oil. This study aims to assess stress evaluation and oil production through the utilization of a sucker rod heat pipe across lengths of 1.5, 2.0, 2.5, and 3.0 km within an oil pumping system. The assessment is conducted for the sucker rod heat pipe, for various inner to outer diameters of 15–27, 20–32, 25–37, and 30–42 mm, with a ratio of 0.550, 0.625, 0.670, and 0.710, respectively. This analysis considers polishing rod stroke lengths ranging from 2 to 4 m, pumping speeds between 3 and 9 strokes per minute, and different plunger diameters from 32 to 50 mm. A conceptual framework is established that incorporates the weight of the sucker rod heat pipe working fluid and its frictional impacts throughout an entire operational cycle. The observed relationship between the outcomes and the established oil well data highlights the efficacy of the method employed. The findings indicate a significant increase of 46.2% in extreme upstroke load as the inner and outer diameter changes from 15–27 to 30–42 mm, with a length extending from 1.5 to 3.0 km. Additionally, the diameter ratio and length of the sucker rod heat pipe is found to be directly correlated with the pumping speed and polishing rod stroke length during the stress evaluation. The production rate increases by 3.4%, 6.7%, 12.2%, and 21.7% for 1.5, 2.0, 2.5, and 3.0 km sucker rod heat pipe respectively, when the inner‐outer diameter is changed from 15–27 to 30–42 mm and by considering higher values of polishing rod stroke length, plunger diameter, and pumping speed. In addition, it is inferred that the production rate is influenced by the material's elasticity, which decreases as the length of the rod increases. The mathematical method that enables the selection of an appropriate sucker rod heat pipe for oil pumping within the permissible limits of available equipment is delineated.