This study constructed a parameter analysis for improving the energy performance of air-cooled water chillers by altering the angle configuration of the condenser coils. The mathematical models for energy and exergy analyses of the individual components and overall system of air-cooled water chillers are presented. This study investigated the potential enhancement of performance efficiency in air-cooled chillers and the energy conversion efficiency of each component, in order to determine how the angle configuration of condenser coils influences chiller performance. This study found that the overall performance of an air-cooled chiller could be improved by approximately 3.4%, and the total irreversibility could be reduced by approximately 2.7%. With each 1% increase in average wind speed over the condenser coils, the overall performance of an air-cooled chiller was found to be enhanced by approximately 0.43%, and its total irreversibility was reduced by approximately 0.35%. The results of this study can be effectively applied to air-cooled condenser units, and can provide an important basis of reference for developing and enhancing the energy efficiency of air-cooled chillers. Keywords

Wind energy is one of the most popular and economic renewable energy generations. According to the statistics, there is about 3GW wind energy power potentially in Taiwan. If the gridconnected wind turbine generator is subjected to the network faults, the induced electromagnetic torque (E/M torque) leads to torsional torque stresses on turbine mechanism, namely high/low speed shafts and blades. This project employs a single induction machine-infinite system of middle voltage level containing a fixed-speed wind turbine, in order to investigate the wind turbine torque behaviors owing to the most onerous line fault, i.e., threephase-to-ground fault. From the simulation results, it is found that such a disturbance may pose a major threat on the high speed shaft instead of the low speed shaft or blades.

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