Fouling monitoring apparatus of heat exchanger and method thereof

A method for measuring a fouling resistance or a cleanliness factor of a heat-transfer surface, comprising the steps of:

• disposing a metal wire having a high resistance temperature coefficient around a heat-transfer surface;
• measuring an electrical resistance variation of the metal wire;
• measuring an average temperature of a heat-transfer surface based on the electrical resistance value of the metal wire;
• and
• computing a fouling resistance or a cleanliness factor of the heat-transfer surface.

An apparatus for monitoring scale build up on a heat transfer surface exposed to water flowing thereover which comprises:

• a housing defining an inlet and an outlet to enable water to flow therethrough,
• an inlet temperature-measuring means for measuring the temperature of water flowing into said housing,
• an outlet temperature-measuring means for measuring the temperature of water flowing out of said housing,
• a flow rate-measuring means for measuring the flow rate of water flowing through said housing,
• a fouling sensor located in said housing between said inlet and said outlet, said fouling sensor defining a heat-transfer surface and containing within said heat-transfer surface a coiled heating wire and a coiled metal wire, said coiled metal wire being located between said coiled heating wire and said heat-transfer surface,
• an electrical power supply means connected to said heating wire,
• a resistance-measuring means connected to said metal wire, and
• a data calculation means to which said inlet temperature-measuring means, said outlet temperature-measuring means, said flow rate-measuring means, said electrical power supply means and said resistance-measuring means are connected, said data calculation means computing scale built up on said heat transfer surface.