Performance analysis and prediction of a modified precompression transcritical CO₂ power generation cycle

Area of Science:

• Renewable Energy Systems
• Thermodynamics
• Environmental Engineering

Background:

• Biomass energy utilization is crucial for rural carbon neutrality, particularly in Northeast China.
• Carbon dioxide (CO2) thermal cycles are suitable for biomass power generation due to high efficiency and lack of freezing issues.
• Split flow CO2 cycles offer higher efficiency but are structurally complex, unlike simpler single flow layouts.

Purpose of the Study:

• To propose a modified precompression transcritical CO2 cycle for small power plants in cold climates.
• To enhance the efficiency of biomass power generation in regions like Heilongjiang Province.
• To meet the structural simplicity requirements for power generation equipment in cold areas.

Main Methods:

• Energy analysis was conducted on traditional and modified single flow precompression transcritical CO2 cycles.
• Thermal efficiencies were calculated under specific operating conditions (5 MPa compressor inlet, 550°C turbine inlet).
• Performance was evaluated across a main compressor pressure ratio range of 4.5-5.5.

Main Results:

• The modified precompression cycle achieved an optimal efficiency of 44.86% at a pressure ratio of 5.0266.
• The traditional precompression cycle's optimal efficiency was 43.55% at a pressure ratio of 5.5.
• The modified cycle demonstrated higher efficiency than the traditional cycle at lower main compressor pressure ratios.

Conclusions:

• The proposed modified precompression transcritical CO2 cycle is more efficient than the traditional cycle for biomass power generation in cold regions.
• This modified cycle provides a viable solution for efficient and simple biomass power generation in rural Northeast China.
• The study highlights the potential of optimizing CO2 cycles for specific regional and seasonal energy needs.