The thermosyphon evaporator is composed of two independent equipment: horizontal gas-liquid separator and horizontal evaporator. The horizontal gas-liquid separator is based on the horizontal evaporator and fixed on the upper part. The inlet pipe of the gas-liquid separator is connected with the outlet pipe of the evaporator, and the inlet pipe of the evaporator is connected with the outlet pipe of the gas-liquid separator.

　　After throttling, the refrigerant liquid enters from the bottom of horizontal gas-liquid separator. After the flash gas and lubricating oil are separated in the gas-liquid separator, it enters from the downcomer through a tube box at one end of horizontal evaporator. The refrigerant outside the tube is obtained through the tube wall in the heat exchange tube, and then gradually evaporates to produce bubbles, With the continuous heat exchange in the length direction of the heat exchange tube, more and more bubbles are produced in the heat exchange tube.

　　The refrigerant density at the outlet end of the heat exchange tube must be less than that at the inlet end. In addition, the height difference between the liquid level of the gas-liquid separator and the evaporator will form the circulating power of the refrigerant, and promote the refrigerant in the heat exchange tube to flow to the outlet end. When the refrigerant reaches the tube box on the right side of the evaporator, the bubble escapes from the refrigerant liquid, and then enters the gas-liquid separator from the riser.

　　When the evaporation intensity is high, the gas-liquid two-phase flow will be formed by the entrained droplets in the updraft. The refrigerant gas or gas-liquid two-phase flow completes the separation of gas and liquid in the gas-liquid separator. The liquid phase settles to the bottom of the separator and repeats the next cycle. The gas phase is sucked away by the refrigeration compressor from the steam outlet at the upper part of the other end of the horizontal gas-liquid separator. After the refrigerant liquid in the evaporation pipe evaporates, the liquid level in the gas-liquid separator drops, and the liquid supply valve is opened to supplement the refrigerant liquid in the evaporator, so as to maintain a certain liquid level of the gas-liquid separator.