Effect of Geometrical Parameters on the Thermal Performance of Ammonia-Based Trapezoidal-Shaped Axial Grooved Heat Pipe

Abstract

Abstract Liquid–vapor interfacial shear stresses, contact angle, and thin-film resistance are incorporated in the present numerical model of the axial grooved heat pipe (AGHP). Experiments are performed to validate the numerical model, which predicts maximum heat transportation capacity (Qmax) within 2.5% error. Further, a parametric study is performed using maximum heat transportation capacity (Qmax) and total thermal resistance (Rtotal) as an objective function and geometrical parameters of groove (i.e., height of grooves (hg), number of grooves (N), and groove inclination angle (2υ)) as variables. From the numerical results, it is observed that number of grooves (N) and groove inclination angle (2υ) are inversely proportional to Rtotal as desired. Therefore, an increase in N and 2υ results into reduction in Rtotal. However, an increment in hg increases Rtotal due to liquid layer resistance into the grooves. Study is aimed to determine such a combination of variable which can maximize Qmax and minimize Rtotal. For ammonia based AGHP of 10.5 mm ID, 12.7 mm OD, and 1 m length, the best combination is determined as hg = 1.3 mm, N = 28 and 2υ = 76 deg, which gives Qmax and Rtotal as 109 W and 0.093 K/W, respectively.