Investigation on thermal radiation property of near- and super-critical water in the pressure range of 20–25 MPa based on line-by-line method

With the rapid development of supercritical water gasification (SCWG) technology, investigation on thermal radiation property of water up to critical state (22.1 MPa, 647 K) is becoming important for precisely analyzing thermo-chemical process in this engineering. This paper explores radiative absorption coefficients κ_η of water under thermodynamic states of (20−25) MPa and (773–1273) K based on line-by-line (LBL) calculations. The results are validated against experimental data and molecular dynamic (MD) simulation values. It is shown that near- and super-critical water (NSCW) has five major radiation bands within spectral range of (1−50) μm. Compared to atmospheric water vapor (0.1 MPa), NSCW holds unique spectral characteristics, including dramatically smoothed spectrum, enormous absorption coefficient, and redshift or blueshift on spectral peak positions. Based on calculation results, a gray-band model for NSCW is proposed to solve problems of radiative heat transfer in SCWG engineering.