Experimental study and simulation of the compressed CO2 hydrate cool storage system

This study employed tetrabutylammonium bromide (TBAB) as a thermodynamic additive to enhance the cool storage performance of carbon dioxide hydrate. The formation characteristics and cool storage properties of the hydrate were investigated under different charging pressures (2.4–3.0 MPa) and TBAB concentrations (5–20 wt%). Furthermore, the effects of compressor rotational speed, inlet water temperature, and inlet water mass flow rate of the gas cooler on the cool storage performance were studied using simulation software. The experimental results indicated that higher charging pressures led to better cool storage performance. As the TBAB concentration increased, the cool storage performance first improved and then declined. The optimal cool storage performance within the investigated range was achieved at a TBAB concentration of 15 wt% and a charging pressure of 3.0 MPa, with the maximum total cool storage capacity (6256.25 kJ), fastest average cool storage rate (2.49 kW), and highest COP (2.50). The simulation results showed that higher compressor rotational speed, lower inlet water temperatures, and faster inlet water mass flow rates of the gas cooler improved the cool storage performance. The optimal cool storage performance within the investigated range was achieved at the compressor rotational speed of 1600 rpm, the inlet water temperature of 20 °C, and the inlet water mass flow rate of 0.9 kg·s −1 , resulted in the highest COP (3.17), the fastest average cool storage rate (3.70 kW), and the lowest compressor power consumption (1.17 kW). The study demonstrated that TBAB significantly enhanced the performance of compression-type CO₂ hydrate cool storage systems.