High efficency integration of thermodynamic solar plant with natural gas combined cycle

Fundamentals and applications of cryogen as a thermal energy carrier: A critical assessment

“…For example, such an approach has been widely used to recover waste heat from the Brayton cycle with a combined cycle gas turbine (CCGT) technology. The approach has also been investigated for the use of low grade solar heat [12,15,23]. However, steam is not an idea working fluid for utilizing low grade heat as the critical temperature of water (374 C) is much higher than the ambient temperature and its critical pressure (22.1 MPa) is extremely high.…”

“…It is assumed that the working fluids are to be heated from ambient temperature, T a , to T h ¼ 400 C. A normalised heat, Q , is used, which is defined as the ratio of heat load at a certain temperature, T, to the total heat exchange amount during the whole process. Table 1 Comparison of specific heat, latent heat and exergy density of cryogens and some commonly used heat storage materials [9,15]. …”

“…For example, high grade heat can be generated by solar energy to produce steam at 250e300 C [12e14]. Another example is the Archimedes project, where a binary mixture of molten salts (40% KNO 3 , 60% NaNO 3 ) is used as a sensible heat storage medium, which is the world's first solar energy system integrated with a gas-fired combined cycle power plant and the working temperature ranges from 290 to 550 C [15].…”