Deposition sensor based on differential heat flux measurement

In a system for detecting deposit accumulation in heat-carrying fluid vessels comprising a heat transfer reference surface, a heat transfer fouling surface, a heat transfer path between said reference surface and said fouling surface, a pair of heat flux sensors, wherein one of said sensors is connected to said reference surface and the other one of said sensors is connected to said fouling surface, a method for measuring differential heat flux across said heat transfer path, said method comprising the steps of:

• (a) providing a heating element for introducing heat flux into said heat transfer path;
• (b) transferring heat flux between said reference and fouling surfaces via said heat transfer path in response to deposit accumulation at said fouling surface;
• (c) measuring heat flux values directly from each said sensor without having to measure temperature difference between said sensors;
• (d) calculating differential heat flux data across said heat transfer path from said heat flux values;
• (e) utilizing said differential heat flux data to detect and quantify said deposit accumulation at said fouling surface;
• and
• wherein said heat flux values at said reference surface and said fouling surface both change in response to said deposit accumulation.