Abstract: An air guide ring includes an annular air guide portion having an air duct that accommodates an impeller of an axial flow fan configured to rotate therein. The annular air guide portion has an inner side wall and an outer side wall, the air duct is enclosed by the inner side wall, and a plurality of noise reduction devices is arranged on the inner side wall of the annular air guide portion in a circumferential direction of the air guide ring The plurality of noise reduction devices is configured to reduce noise in the air duct.

Abstract: Disclosed herein are an air guide ring and an axial flow fan comprising the same. The air guide ring comprises: an annular air guide portion comprising an air duct for accommodating an impeller of the axial flow fan to rotate therein, wherein the annular air guide portion has an inner side wall and an outer side wall, and the air duct is enclosed by the inner side wall; and a plurality of noise reduction devices arranged on the inner side wall of the annular air guide portion in a circumferential direction of the air guide ring, and each of the noise reduction devices is configured to reduce noise in the air duct. According to the air guide ring in the present application, the noise reduction devices are arranged on the inner side wall of the annular air guide portion such that noise reduction can be directly performed at the portion where the noise is generated, thereby reducing the noise more quickly and efficiently.

Abstract: A system for refrigerant leakage detection includes one or more sensors configured to detect one or more parameters of a building system including a refrigerant. The system further includes one or more storage devices storing instructions thereon that, when executed by one or more processors, cause the one or more processors to receive sensor data from the one or more sensors; apply the sensor data to a long short-term memory (LSTM) model to generate predicted sensor data corresponding to the one or more sensors; receive subsequent sensor data from the one or more sensors; compare the predicted sensor data to the subsequent sensor data; determine that the building system has a refrigerant leakage based on the comparison of the predicted sensor data to the subsequent sensor data; and, responsive to determining that the building system has the refrigerant leakage, take an action to address the refrigerant leakage.

Abstract: The disclosure provides a three-way structure, including a straight tube and a branch tube perpendicular to and connected with the straight tube, is characterized in that the inner surface of the straight tube is provided with a hollow structure surrounding the straight tube. The three-way structure of the disclosure can both attenuate the noise and simplify the pipeline arrangement of the unit.