Analysis of an industrial wind turbine to harness waste energy from air-conditioning chillers

Abstract

In recent decades depletion of energy resources along with global warming concern has made a need to study green renewable energy resources, one of which is to reuse waste energy in industrial applications, exhaust wind from cooling towers of large scale air-conditioner is addressed in this study to be harnessed by a small Darrieus vertical axis wind turbine (VAWT). This study in particular is analyzing the performance of the turbine under the influence of some design parameters including tip speed ratio (TSR), rotor diameter, solidity that includes number of blades and effect of laminar boundary layer separation. ANSYS FLUENT 14 has been used to simulate a 2-D VAWT with NACA0018 airfoils along with ICEM as pre-processor software to create mesh, Shear Stress Transport (SST) k-? model has been used to model the turbulent flow around the airfoils. Grid independency has been studied for cell size of 65,000 and 140,000 by the comparison of graphs for horizontal force components as a function of angle of rotation. This simulation has been validated by comparing the result with experimental work of Claessens (Claessens, 2006). Maximum power coefficient of 0.34 was obtained for 3 bladed VAWT at TSR=4 while for 6 bladed VAWT maximum amount was achieved 0.32 at lower TSR of ?=3. Power coefficient remains constant for different rotor diameter when chord length and rotor diameter ratio is constant. Performance has been observed low for laminar flow. In order to boost the efficiency in this type of flow different airfoil geometries can be investigated in further studies. Bigger number of blades causes larger effect of blockage and consequently larger torque but maximum ???? is achieved at comparatively lower value of ? as compared to 3 bladed VAWT and a great deal of torque is needed to generate the same power coefficient.