Why can the efficiency of solvent recovery be improved by compression and condensation?

        In the chemical production processes, a vacuum pump is usually used to collect VOCs generated in a reactor or other form of reaction device in vacuuming method. According to Dalton's law, the partial vapor pressure of various gases in the mixed gas is equal to the percentage of the gas by volume. Taking the mixture of Dichloromethane and air as an example, the saturated vapor pressure of Dichloromethane at 20°C is 47.39KPa, and the proportion of Dichloromethane in the mixed gas is about 46.8%. Considering the insignificant change in gas pressure before and after the condenser, the temperature of the mixed gas is lowered to 0°C. The saturated vapor pressure of Dichloromethane at 0℃ is 19.2KPa, and the proportion of Dichloromethane in the mixed gas is about 18.9%.