The screw chiller uses a shell and tube evaporator and a condenser, which affects the performance of the evaporator and the condenser. The following factors are roughly as follows:
1. Homogenizer and inner end cap type line: The reasonable structure of the liquid equalizer can maximize the distribution of the evaporator inlet refrigerant between the heat exchange tubes and alleviate the phenomenon of gas-liquid separation. The inner cap profile line converted in different processes should be as smooth as possible to reduce the resistance, avoid gas-liquid separation, and distribute the refrigerant evenly between the heat exchanger tubes in the next process.
2, heat exchange tube: the reasonable distribution of the number of heat transfer tubes in different processes, the structure and length of the heat transfer tube have a greater impact on its performance. It is possible to optimize the distribution ratio of the number of heat exchange tubes between different processes, so as to obtain a better ratio of heat exchange effect. It is also possible to select a corrugated inner finned tube with higher performance, which not only enhances the heat exchange on the fluorine side, but also enhances the heat exchange on the water side.
3. The water in the water between the baffle and the shell: although the heat transfer coefficient on the water side is larger than that on the fluorine side, if the water phenomenon occurs between the baffle and the shell, the water is seriously affected. Side heat exchange. In order to reduce the adverse effects of string water, in addition to taking measures on the baffle structure, the water velocity on the shell side can be optimized to obtain a relatively reasonable water velocity, such as 1.2 to 2.0 m/s.
4. Mass flow rate in the tube: It can be found from the relationship between evaporation and heat transfer in the tube that the evaporation in the tube is obviously affected by the mass flow rate of the refrigerant in the tube; and the mass flow rate of the refrigerant is gradually reduced along the length direction of the evaporation heat exchange tube. As a result, the refrigerant evaporation heat release coefficient gradually decreases along the length of the heat exchange tube, and the heat release coefficient of the latter process is much lower than that of the previous process. Therefore, the refrigerant flow rate of different ranges is calculated and optimized to obtain evaporation. A reasonable range of refrigerant flow with a high heat transfer coefficient.
