Abstract: A method to condense and liquefy vapor by introducing the vapor into a heat exchanger and bringing same into contact with a cooling body in the heat exchanger, wherein a droplet condensation promoting agent is directly added to the vapor introduced into the heat exchanger or to the heat exchanger. A droplet condensation promoting effect due to the droplet condensation promoting agent can be sufficiently manifested and condensation efficiency by droplet condensation can be improved by way of directly adding the droplet condensation promoting agent such as a film forming amine or the like to the vapor introduced into the heat exchanger or to the heat exchanger.

Abstract: A method to condense and liquefy vapor by introducing the vapor into a heat exchanger and bringing same into contact with a cooling body in the heat exchanger, wherein a droplet condensation promoting agent is directly added to the vapor introduced into the heat exchanger or to the heat exchanger. A droplet condensation promoting effect due to the droplet condensation promoting agent can be sufficiently manifested and condensation efficiency by droplet condensation can be improved by way of directly adding the droplet condensation promoting agent such as a film forming amine or the like to the vapor introduced into the heat exchanger or to the heat exchanger.