A novel oscillating flow cycle engine with characteristics of temperature glide heat addition and no regenerator for low-grade heat utilization

Abstract

In oscillating flow cycle engines such as Stirling engines, nearly isothermal heat additions in heat exchangers will produce irreversibility losses during the heat transfer processes and the regenerator is indispensable and expensive. Thus, it reduces oscillating flow cycle engine’s economic attractions for low-grade heat utilization. In this work, three structures of one-way oscillating flow cycle engine are proposed for overcoming these problems. To assess the feasibility, one structure is chosen for analysis. Then, a one-dimensional computational fluid dynamic model considering various heat transfer and flow friction losses is developed. Based on the validated model, performance analysis is carried out. The temperature glide for heat absorption can reach up to 116 K and can be adjusted. The obtained maximum thermal efficiency is 7.79 %, 12 %, and 14.6 % respectively for low-grade heat’s inlet temperatures of 373 K, 423 K, and 473 K. Furthermore, the maximum specific work output for 1 kg/s hot water is 13.7 kW, 36.9 kW and 64.4 kW respectively at an inlet temperature of 373 K, 423 K, and 473 K, with corresponding maximum exergy efficiency of 42.8 %, 43.7 % and 41.1 % respectively. Thus, the results demonstrate that large temperature glide heat addition can be achieved, and a novel oscillating flow cycle engine without a regenerator is feasible and efficient.