Shape optimization of composite porous vapor chamber with radial grooves: A study on the minimization of maximum pressure drop

Composite porous vapor chamber (CPVC) with uniform radial grooves is a recently developed vapor chamber, exhibiting good temperature uniformity and excellent stability under high heat flux of 280 W/cm² with the thermal resistance less than 0.15 °C/W. However, the maximum pressure drop in CPVC due to liquid flow is prone to exceed the limits of capillary pressure, and the shape design of the wicks lacks scientific and objective enough criteria. This paper proposes a shape optimization method to optimize the shape of the evaporator wick in CPVC, based on the study on the minimization of the maximum pressure drop. In this method, the discrete adjoint method is utilized to efficiently analyze the sensitivities and find the most rapid descendant directions for the minima problem. The shape of the evaporator wick is updated by the polynomial-based approach based on the sensitivity information. Results indicate that the bottom contours of the wick blocks’ surfaces surrounding the circular cavity contribute the highest sensitivities. Consequently, the mesh deformations near the contours change the shape of the lateral surfaces of wick blocks from rectangular to concave trapezoidal in both Cylindrical and Cartesian coordinate systems. This reduces the maximum velocities and flow resistance in CPVC, due to the smoother structural transition from the condenser wick to the evaporator wick, thus reducing the maximum pressure drop by about 18.5% and 23.3% in Cartesian and Cylindrical coordinate systems, respectively. The proposed method may pave a more objective and scientific alternative to design the shape of the wicks in CPVC.