Heat pumps in industrial processes - an optimization methodology

Journal article, 1990

The optimal integration of heat pumps in industrial processes has not yet been fully understood. In this paper an optimization methodology and a method which uses the composite curves as a guideline to the correct choice of heat pump type are outlined. The selection is done by matching the shape of the composite curves against the specific characteristics of several heat pump types. Furthermore, a methodology for the optimization of the most important parameters in a heat pump system is presented. In the optimization methodology the annual cost is minimized by varying heat source and heat sink temperatures, the heat pump size and the stream or streams to be utilized as heat source and heat sink. To reveal the potential for electrically driven compression heat pumps two different examples were studied with the methodology. The first example had close composite curves and was thought to be a poor heat pump candidate. The second one had open composite curves and was thought to be a promising example. The results showed that for both examples, heat pump installations were advantageous under good economic conditions for the heat pump, i.e. low electricity price, high fuel price and low investment costs. Also reasonable payback periods were achieved. With more unfavourable conditions the payback period increased, and in extreme cases a heat pump was no longer a better alternative than pure heat exchange. This decline in potential for heat pumping was much less in the example with open composite curves than in the example with closed ones. However, the conclusion to be drawn is that there exists today a potential for heat pumps in industrial processes.