3D asymmetric loop thermosyphon under radial rotation: A novel method for enhanced heat transfer in grinding

Symmetrical radial-rotating thermosyphons (SLTs) have been investigated as a means to enhance heat transfer during grinding, thereby preventing workpiece burns and improving overall process efficiency. These LTs feature channels with a uniform diameter, yet previous research has shown significant limitations under conditions of high centrifugal acceleration, which negatively impacts their heat transfer capability. Specifically, SLTs with uniform diameter channels experience flow stratification due to high centrifugal forces, causing a reduction in oscillatory motion and leading to reduced heat transfer efficiency. To address such limitations, a novel 3D asymmetric loop thermosyphon (ALT) with two different channel diameters is proposed. This asymmetric configuration induces an additional pressure difference, which appears to counteract the adverse effects of centrifugal forces, thereby sustaining oscillatory motion and enhancing heat transfer especially at higher rotational speeds. The thermal performance of the ALT is evaluated in terms of thermal resistance, temperature uniformity, and heat dissipation efficiency under a wide range of centrifugal accelerations and heat fluxes. Compared to SLT, at accelerations of 18g, 73.5g, and 165g, the novel ALT demonstrates a reduction in thermal resistance of 31 %, 43 %, and 44 %, respectively. The temperature uniformity is also improved compared to SLT by 37 %. Results also showed that the ALT works as an Oscillating Heat Pipe when the acceleration remains under 1.12g. These results indicate that the ALT effectively improves heat transfer performance by maintaining oscillatory motion and enhancing temperature uniformity, ultimately offering superior adaptability for high-speed grinding applications, ensuring more stable thermal management, reducing workpiece burns, and minimizing grinding wheel wear.