Novel superhydrophobic microporous layers for enhanced performance and efficient water management in PEM fuel cells

Study on the dynamic and thermal performances of a reversibly used cooling tower with upward spraying

This article presents a hybrid finite-element/finite-difference approach. The approach solves the 3-D unsteady energy equation in nonisothermal fluid flow over a staggered tube bank with five tubes in the flow direction. The investigation used Reynolds numbers of 100 and 300, Prandtl number of 0.7, and pitch-to-diameter ratio of 1.5. An equilateral triangle (ET) tube pattern is considered for the staggered tube bank. The proposed hybrid method employs a 2-D Taylor-Galerkin finite-element method, and the energy equation perpendicular to the tube axis is discretized. On the other hand, the finite-difference technique discretizes the derivatives toward the tube axis. Weighting the 3-D, transient, convection-diffusion equation for a cube verifies the numerical results. The L2 norm of the error between numerical and exact solutions is also presented for three different hybrid meshes. A grid independence study for the energy equation preceded the final mesh. The outcome is found to be in acceptable concurrence ...

A Hybrid Finite-Element/Finite-Difference Scheme for Solving the 3-D Energy Equation in Transient Nonisothermal Fluid Flow over a Staggered Tube Bank

Deciphering the thermal and hydraulic performances of closed wet cooling towers with plain, oval and longitudinal fin tubes

A simplified methodology to optimize the cooling tower approach temperature control schedule in a cooling system

Thermal performance analysis of closed wet cooling towers under both unsaturated and supersaturated conditions

The thermal and hydraulic performance of plain and oval tubes closed wet cooling tower (CWCT) are investigated numerically. Computational fluid dynamics (CFD), ANSYS Fluent 12.1, is implemented for the numerical solution. Species transport without reactions is adopted to simulate the mass transfer from the air-deluge water interface to the air. Different turbulence models and near-wall treatments are used to assess which model fits the data better. The mass transfer Colburn factor j m , and friction factor f are presented and compared with experimental data. The proposed CFD model is also applied to predict the mass transfer coefficient of another CWCT and compares well with the experimental data.

Computational Analysis of Closed Wet Cooling Towers

The invention discloses a nano-coating for an unsaturated evaporation heat transfer surface. An anti-corrosion layer and a hydrophilic layer can be coated on the heat transfer surface in sequence; a heat transfer layer can be coated between the anti-corrosion layer and the hydrophilic layer; the coated heat transfer surface is irradiated with ultraviolet light for one hour, so that a contact angle between a coated surface and a water film is reduced to 0-5 degrees; the coating thickness of the anti-corrosive layer is 2-15 nanometers; the coating thickness of the hydrophilic layer is 8-35 nanometers; and ultraviolet light is used for irradiating intermittently every 2-3 days, so that the hydrophilicity of the coated surface is kept. The material characteristic of a heat exchange surface is improved, so that a spreading area on the heat transfer surface under the unit water amount of the water film is increased, distribution is more uniform, the phenomenon of 'dry spot' is avoided effectively, the scaling phenomenon of the heat transfer surface is delayed, heat and mass transfer coefficients between water and air are increased, and heat exchange performance is enhanced.

Yun-Yi Shi

Papers

Thermal performance analysis of closed wet cooling towers under both unsaturated and supersaturated conditions

Computational Analysis of Closed Wet Cooling Towers

Nano-coating for unsaturated evaporation heat transfer surface