LAUSR

Abstract The efficiency improvement of organic Rankine cycle, which is an efficient way to recover the waste heat of internal combustion engines, is an eternal topic. The 3D construction method of thermodynamic cycle provides a possible way to construct efficient thermodynamic cycles based on zeotropic working fluid, whose core is to improve the thermodynamic performance by using different working fluids in different thermodynamic processes. Based on the 3D construction method of thermodynamic cycle, a composition adjustment organic Rankine cycle was proposed in this paper to recover the waste heat of internal combustion engines. The optimum working fluid used in trunk and branch processes were selected according to the requirements of different thermodynamic processes. The effects of key parameters were analyzed, and the optimized operation conditions and optimal performance were obtained. The results shown that the composition adjustment organic Rankine cycle performs best when using R123/toluene (0.9/0.1) in trunk process and R123/toluene (0.96/0.04), R123/toluene (0.66/0.34) in low-pressure and high-pressure branch processes, respectively. Under the optimal condition, the net output power, thermal efficiency and exergy efficiency are 50.07 kW, 10.96% and 45.79%, respectively. The irreversible losses in evaporator I and evaporator II account for 35.01% and 30.54% of the total irreversible losses in composition adjustment organic Rankine cycle respectively. This work provided an advanced power cycle for the waste heat recovery of internal combustion engines. What’s more, composition adjustment organic Rankine cycle proves the feasibility of the 3D construction method and opens up a novel way to construct efficient thermodynamic cycles.