System scheme and thermal performance of a third fluid cooled rocket engine

In this study, a novel expander rocket engine cycle that uses a third fluid as the combustor coolant and the turbine driver was discussed. A detailed system scheme with two stage cryogenic heat exchangers of the third fluid cooled (TFC) liquid rocket engine was improved. The design highlighted the phase-change heat transfer model of the regenerative cooling channels (RCC) on the basis of previous experiments. Subsequently, the state parameters distribution for the system was first proposed. In addition, the exergy analysis of cooled Rankine cycle (CRC) loop was investigated. The effects of the third fluid methane mass flow rate ((m) over dot(tf)) on the exergy efficiency of CRC loop were further analyzed. The results demonstrated that the (m) over dot)(tf) and the design geometric dimension of the RCC can well meet the thermal protection requirements of the thrust chamber. In the exergy analysis process, the exergy loss of the RCC was the largest. The exergy loss ratio of cryogenic heat exchanger I and II vary greatly due to the difference of the heat transfer performance. With the increase of the (m) over dot(tf), the exergy efficiency of CRC loop decreased slightly, while the maximum output power from the heat transferred through the thrust chamber wall (W-max) increased. The results will be benefit for a better thermal performance of the TFC engine through the optimization of the (m) over dot(tf) and subassemblies.