Heat pump appropriate placement

Thus the appropriate placement of heat pumps is that they should be placed across the pinch. Note that the principle needs careful interpretation if there are utility pinches. In such circumstances, heat pump replacement above the process pinch or below it can be economic, providing that the heat pump is placed across a utility pinch. Such considerations are outside the scope of the present text. 

A refrigeration system is a heat pump in which heat is absorbed below ambient temperature. Thus the appropriate placement principle for heat pumps applies in exactly the same way as for refrigeration cycles. The appropriate placement for refrigeration cycles is that they also should be across the pinch. As with heat pumps, refrigeration cycles also can be appropriately placed across utility pinches. It is common for refrigeration cycles to be placed across a utility pinch caused by maximizing cooling water duty. 

To ensure energy saving, the position of unit operations with respect to Pinch must respect the rules of the Appropriate Placement. For example, a heat engine has to be placed either above or below the Pinch, but not across it. Distillation columns should not be placed across the Pinch. Contrary, a heat pump is optimally placed across the Pinch. This subject will be discussed in more detail in the Chapter 11. 

The improvement of design can be realised by Appropriate Placement and Plus/Minus principle. Appropriate Placement defines the optimal location of individual imits against the Pinch. It applies to heat engines, heat pumps, distillation columns, evaporators, furnaces, and to any other unit operation that can be represented in terms of heat sources and sinks. 

It should be pointed out that appropriate placement of heat pumps and heat engines should also account for the utility pinches, and not just the process pinch as stated above. However,... 

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