Thermodynamic study on a combined heat and compressed air energy storage system with a dual-pressure organic Rankine cycle

• Compressed air energy storage (CAES) is a promising energy storage and supply technology. It has attracted attention due to its reliability, economic feasibility, longer operating lifetime and lower environmental effects compared to available storage technologies. A novel hybrid energy storage system, termed as CH-CAES-dORC, is proposed. It includes an advanced CAES, an electrical heater (EH) and a dual-pressure organic Rankine cycle (dORC). Our analysis demonstrate that integrating an dORC bottoming cycle for improving the round trip efficiency of the CH-CAES system is superior to a system relying on single-pressure ORC (sORC) system. Parametric analysis is carried out to study the effects of several key parameters on the system performance. The results indicate that the improvement of the CH-CAES round trip efficiency by means of integrating ORC bottoming cycles decreases with a higher charging pressure, and increases with a larger charge-discharge pressure ratio and a higher electrical heating temperature. The superiority of the CH-CAES-dORC, compared to the CH-CAES-sORC, is more pronounced at higher electrical heating temperature. There is always a peak round trip efficiency for the CH-CAES-dORC system with an increase in hot end temperature of low temperature evaporator under different hot end temperatures of high temperature evaporator. In other words, the dORC is a more favorable bottoming cycle for application of the CH-CAES waste heat compared with the sORC. © 2020 Elsevier Ltd

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Maskinteknik -- Energiteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Mechanical Engineering -- Energy Engineering (hsv//eng)

Nyckelord

Compressed air energy storage

Dual-pressure

Electrical heater

Organic Rankine cycle

Thermodynamics

Bottoming cycle systems

Compressed air

Electric heating

Environmental technology

Evaporators

Pressure vessels

Rankine cycle

Temperature

Waste heat

Compressed air energy storages (CAES)

Economic feasibilities

Electrical heating

Hybrid energy storage systems

Operating lifetime

Organic Rankine cycles

Parametric -analysis

Thermodynamic studies

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