Study on the comprehensive performance and control strategy of a methanol decomposition reactor for compressed air energy storage with combined heating from compression heat and solar energy

In order to further improve the exergy efficiency of the methanol decomposition reactor (MDR) for compressed air energy storage (CAES), a novel reactor with combined heating from compression heat and solar energy collection is proposed in this study. By establishing a one-dimensional transient thermodynamic model of the reactor and a detailed heat loss distribution model, the comprehensive performance of the novel reactor under off-design conditions and during dynamic processes is investigated. To ensure the stability of methanol conversion, the performance of the reactor under three different control strategies is compared. The research results indicate that, after coupling with the novel reactor, the exergy efficiency of the CAES system increases by 3.46 %, and the levelized cost of energy decreases by 6.09 $/MWh. The largest portion of exergy loss occurs during the process of converting thermal energy into chemical energy, accounting for 44.74 % and 30.36 % of the input exergy in the MDR I and MDR II stages, respectively. When the compressor input power is reduced to 90 % of its original value, methanol conversion decreases from 90.00 % to 80.90 %. The exergy efficiency demonstrates non-monotonic characteristics: an initial increase to 60.46 % followed by stabilization at 52.48 %. When the solar thermal collector temperature is reduced to 90 % of its original value, more severe performance deterioration occurs. The methanol conversion declines to 68.35 %. The exergy efficiency exhibits greater transient variation, peaking at 73.80 % before settling at 50.97 %. Considering both stability and responsiveness, the feedforward-feedback control strategy is more suitable for addressing disturbances in compressor input power and solar energy collection temperature. The parameters of the PI module in the feedforward-feedback control strategy are optimized using Integral of Time multiplied Absolute Error (ITAE) as the control objective. The optimal scheme achieves an ITAE value of 73.94 and an Integral of Squared Error (ISE) value of 0.0292, with a settling time of 67 s. The research findings provide a theoretical basis for the in-depth application of the proposed reactor in CAES systems.