The cold and hot fluid inlet and outlet temperature and ΔP of the fluids across the heat exchangers are very significant in determination of the health of that heat exchanger. In condensers ΔP is shown as vacuum. Any increase in ΔP or decrease in vacuum is an indication of fouling or decrease in flow rate of the fluid.

Increase in ΔP for hot fluid when the inlet hot fluid P remains same, across a heat exchanger could be due to fouling on the heat-exchanging surface exposed to the hot fluid. The same applies to CW side. An increase of ΔP with an increase in inlet P is very much possible.

In condensers the decrease in vacuum could be due to fouling on heat-exchanging surface on both or either side. Most probably it will be due to fouling of heat-exchanger surface on CW side. In condensers the decrease in vacuum could also be due to leakage from the heat-exchanging surface or from the surface exposed to atmosphere.

It is important to know the design pressure on both sides (hot & cold). The high-pressure fluid may ingress in low-pressure fluid. Normally the hot fluid pressure is higher than cold fluid pressure.

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Introduction | Combined heat transfer process | Heat transfer in cooling tower | Variables affecting performance of CT heat transfer | Heat transfer within cooling system (heat exchanger) | Types of heat exchanger | Basic design procedure and theory | Designing a test heat exchanger | Log Mean Temperature difference | L.M.T.D. Correction factors | Overall heat transfer coefficient | Elaborated method for calculating U values | Effect of scale formation | Condensation of steam | Condenser, where the hot fluid temperature varies | Significance of pressure | Significance of flow rate | Methods of checking steam condenser performance | Common conversion factors