Abstract
Waste heat recovery technologies holds great potential for cleaner production by improving energy efficiency, reducing energy usage and emissions of carbon dioxide. Mechanical heat pumps, absorption heat pumps and absorption heat transformers are attractive available technologies to upgrade low grade waste heat for energy conservation and sustainable development. However, there are few guidelines for the integration of proper heat pumps in industrial processes. Moreover, since heat upgraded by different heat pumps require energy of several types or grades (e.g. work, high or medium pressure steam), the coefficient of performance (COP) is not suitable to evaluate heat upgrading technologies. In this work, a novel criterion is proposed for the selection of heat pumps in industrial processes. The criterion (i.e. the coefficient of performance in exergy per total annual cost) measures the available energy performance of each type of heat pumps and includes economic impacts (i.e. economic investments). In addition, a systematic methodology for the integration of different heat pumps in an industrial process has been developed. It relies on Pinch Analysis of a given heat exchanger network. The process models of mechanical heat pumps, absorption heat pumps and absorption heat transformers are developed using Aspen Plus, and then proper heat sources and heat sinks are selected from the given streams for different heat pumps. Finally, an economic evaluation is performed according to the proposed novel criterion, calculated total annualized cost and payback time. The paper can provide a reference to choose a suitable waste heat recovery system for industrial processes.
