Flooded air cooled screw chiller adopts high efficiency semi-hermetic twin-roter screw compressor, high efficiency evaporator and high efficiency inverted in-coil heat exchanger, through the EXV control technology, the unit operates efficiently within its working range, even in energy-saving mode. The unit adopts R134a environmentally friendly refrigerant. The products are designed for large and medium-sized commercial, civil, and industrial buildings. They are also well-suited for areas with heavy anti-corrosion requirements, offering a wide rage of applicability.