An efficiency booster for energy conversion in natural circulation loops

• Low driving power conversion efficiency of natural circulation loops is proved.
• The low conversion efficiency leads to low heat transfer capacity of such loops.
• An efficiency booster is designed with turbine to increase the efficiency.
• Performance of the proposed booster has been numerically simulated.
• The booster drastically enhances heat transfer capacity of such loops.

In this paper, the capacity of a natural circulation loop for transferring heat from a heat source to a heat sink has been analyzed. It is concluded that the capacity of the natural circulation loop depends on the conversion efficiency of the thermal energy from the heat source to the driving force for the circulation of the flow. The low conversion efficiency leading to weak driving force in such loops has been demonstrated analytically and validated through simulation results. This issue has resulted in a low heat transfer capacity in the circulation loop. To increase the heat transfer capacity, one has to improve this efficiency. To meet such a need, a novel efficiency booster has been developed in this paper. The booster essentially increases the flow driving force and hence significantly improves the overall heat transfer capacity. Design and analysis of this booster have been performed in detail. The performance has been examined through extensive computer simulations. It is concluded that the booster can indeed drastically improve the heat transfer capacity of the natural circulation loop.