Who knows the working principle of hotel central air conditioning?

Working principle of hotel central air conditioning: refrigeration is realized by using the heat absorption when liquid vaporizes and the heat release when condensing. Liquid evaporates to form steam. When the liquid (refrigerant) is in a closed container, there is no other gas except the vapor generated by the liquid and the liquid itself, and the liquid and the vapor will reach equilibrium under a certain pressure. The steam at this time is called saturated steam, the pressure is called saturated pressure, and the temperature is called saturated temperature. When the liquid is in equilibrium, it will no longer evaporate. At this time, if a part of steam is pumped out of the container, the liquid will inevitably continue to vaporize to generate a part of steam to maintain this balance. When a liquid vaporizes, it absorbs heat, which is called latent heat of vaporization. The latent heat of vaporization comes from the cooled object, which makes the cooled object cool. In order to make this process continue, it is necessary to continuously extract steam from the container and condense it into liquid before returning to the container. If the steam extracted from the container is directly condensed into steam, the temperature of the required cooling medium is lower than the evaporation temperature of the liquid. We hope that the condensation of steam is carried out at room temperature, so it is necessary to increase the pressure of steam to the saturation pressure at room temperature.