Global warming is currently one of the most serious environmental challenges in the world. The increase of CO2 in the atmosphere is a dominating factor to global warming .O2 / CO2 combustion technology is a new generation of clean coal power generation technology[1],it can directly capture high concentration of CO2 and make the pollutant resource ,so it is one of the most promising feasible technical to reduce CO2 emissions [2]. Compared with conventional pulverized coal combustion boiler, O2 / CO2 combustion technology can be used to produce a CO2 rich flue gas stream. So physical parameters had a very big change, such as flue gas heat capacity, motion viscosity, prandtl number and so on. Thus they affect the heat transfer characteristics [3] inside the furnace.In order to study the heat transfer characteristics of the furnace; this paper established a dynamic mathematical model for the radiation heat transfer progress of the furnace and adequate for control system design.

For comprehensive research on the dynamics of U-tube natural circulation evaporator in plant, the modular and lumped parameters method is used to establish the mathematical model of U-tube steam generator. Steam generator is divided into three parts in the model: primary water side, U-tube metal side and secondary water side. Secondary water side includes five modules. Then, the dynamic simulation experiment can be made on the basis of the simulation model. The experiment results consistent with the actual data and the adaptability and rationality of the model are verified.

Supercritical Rankine cycles using organic fluids as working fluids in converting low-grade energy to high-grade power energy are investigated in the study. The main purpose is to identify suitable working fluids which may yield high system efficiencies in a supercritical Organic Rankine Cycle (ORC) system. R123, R134a, R152a, R22, and R245fa are used for the research. Results show that: at a constant superheating of expansion outlet, system efficiency improves with the increasing of evaporation pressure for all the working fluids and supercritical ORC has a higher efficiency than sub-ORC process. Furthermore, R152a performs the best compared with other refrigerants and is suitable for SORC system.