Performance enhancement of vapor recompression heat pump

The vapor recompression heat pump (VRHP) has the potentials of reducing the energy requirements of fractionating close-boiling mixtures. It improves the quality of low grade heat with the aid of heat pump to provide heat input to the reboiler. However, this technology does not utilize heat efficiently resulting in appreciable heat loss in the condenser. In this study, enhanced VRHP models were developed to reduce the heat loss and heat pump size. The strategies adopted rely on reducing the heat differential across the heat pump by utilizing external and utility streams, and process stream within the system. The thermoeconomic and environmental performances of the developed models were compared with the base case VRHP and the conventional distillation process. The results showed that the developed models yielded considerable energy savings. Considering the present trend of short process modification payback time, the use of an external process stream is recommended as the most preferred option to boost the plant performance. However, in situation where such streams are not available within the plant premises or uneconomical due to their influence in the chosen exchanger network, the utilization of process streams within the system will be a much more attractive alternative option.