Hybrid Solar Thermal Self-Regulating Power Generation System

For wide use of a power plant utilizing solar energy, improvement of its economics is important. Both the economics and characteristics of a CO2-capturing solar thermal hybrid power generation system are evaluated in this paper. Since a relatively low temperature steam of 220 °C is produced by using solar thermal energy and is utilized as the working fluid of a gas turbine, the solar collector can attain high heat collecting efficiency. The net fuel-to-electricity conversion efficiency of the hybrid system is estimated to be higher than 60% on the lower-heating-value- basis. It has been estimated that the gross income and the period of depreciation of the proposed system are 34.8 × 105 yen/year and 8.89 years, respectively, and that the system is economically feasible, under the assumptions of a solar collector area of 10 ha, a maximum net power output of 4 MW, and a heat storage capacity of 2000 m3. The amount of fuel saving and reduction of CO2 emission of our system, compared to a conventional natural gas firing plant, are also estimated in the paper. © 1999 Scripta Technica, Electr Eng Jpn, 126(4): 21–29, 1999

For wide-use of a power plant utilizing solar energy, the improvement of its economics is important. Both economics and characteristics of a CO2-capturing solar thermal hybrid power generation system have been evaluated in this paper. Since relatively low temperature steam of 220°C is produced by using solar thermal energy and is utilized as the working fluid of a gas turbine, the solar collector can attain high heat collecting efficiency. The net fuel-to-electricity conversion efficiency of the hybrid system was estimated to be higher than 60% on lower heating value basis. It has been estimated that the gross income and the period of depreciation of the proposed system are 34.8×105 yen/year and 8.89 years, respectively, and that the system is economically feasible, when the system is assumed to have the solar collector area of 10 ha, the maximum net power output of 4 MW and the heat storage capacity of 2000m3. The amount of the fuel saving and the reduction of CO2 emission of this system, compared to a conventional natural gas firing plant, have also been estimated in the paper.

A solar thermal storage power generation system based on lunar in-situ resources utilization: modeling and analysis

Solar thermal power generation is an important way to solve the future power demand, and some countries have entered the commercial application stage. According to the heat source temperatures provided by different solar thermal collector systems, different thermodynamic cycle modes of power generation systems were proposed so that the appropriate thermal cycle modes and working mediums at different heat source temperatures were obtained. The results show that, under a low-temperature heat source, in an organic Rankine cycle with R600 as the working medium, the cycle efficiency is 13.40% when the temperature of the turbine inlet is 100°C and the pressure is 1.5 MPa; the cycle thermal efficiency is 12.00% when the temperature of turbine inlet is 90°C. Under the conditions of medium temperature heat source, in the Rankine cycle with regenerative heat and R141b as a working medium, the efficiency is about 26.59% when the temperature of the turbine inlet is 220°C and the pressure is 3.0 MPa. Under the conditions of a high-temperature heat source, in the reheat extraction steam Rankine cycle, the theoretical cycle efficiency can reach 34.32% when the temperature of the turbine inlet is 380°C, the pressure is 8 MPa, and the condensation temperature is 41.5°C. The studies can provide a fundamental basis for the design of solar thermal power generation systems with different heat source conditions.

Harmonic response analysis of a large dish solar thermal power generation system with wind-induced vibration

This paper proposes a novel solar thermal power generation system that employs a proton conducting reversible solid oxide fuel cell (RSOFC-H) and a hybrid photovoltaic thermal module. The photovoltaic thermal module supplies electrical power to the solid oxide fuel cell (SOFC) while operating in electrolysis mode. The stored fuel (Hydrogen), generated by electrolysis mode is utilised to generate power in fuel cell mode. Electrochemical modelling and analysis of RSOFC-H is presented in this paper. The working condition of the system is: as a solid oxide steam electrolyser (SOSE) mode during the day time and solid oxide fuel cell (SOFC) mode during night time. Performance analysis of RSOFC-H has been conducted under varying operating and design parameters, such as current density and cell temperature. In SOSE mode of operation, efficiency has been observed to be almost constant with the variation of current density and it is obtained to be 78.31%. During SOFC mode of operation, maximum efficiency obtained is to be 64.62% at cell temperature of 873K and current density of 500A/m2.

Study on dynamic model and dynamic characteristics of Delingha 50 MW trough solar field

Dual-helix weighting-driven 4D-CES: A new framework for multi-objective optimization of CO2 mixtures solar thermal power generation systems

A generalized Nusselt number correlation for nanofluids, and look-up diagrams to select a heat transfer fluid for medium temperature solar thermal applications

The charge and discharge process of heat transfer fluid in the solar thermal power generation system was simulated. A thermal cycle test repeated between high temperature and low temperature was put on prepared Bi-Pb-Sn-Cd low-melting-point alloy. The thermal physical performance tests were put on the alloy samples which experimented with 200, 400 and 800 times thermal cycle test respectively. The test results show that the specific heat capacity of alloy sample declines slowly and the thermal conductivity increases slowly. The phase change temperature of alloy increases slightly and latent heat decreases slightly with the thermal cycle continuing.

Aiming at the problems of high cost and low efficiency of solar thermal power generation system, CMOPSO classical optimization algorithm is used to analyze the multi-objective optimization of its economic performance. Firstly, a multi-objective optimization model of total generating capacity, normalized KWH cost and total investment of the power station is established under the constraint condition of load deficit rate. Secondly, two optimization algorithms CMOPSO are used to optimize and analyze the non-inferior solution sets of the solar thermal power station with the capacity of 10MW and 50MW respectively. Finally, taking some parameters of the solar thermal power demonstration project under construction in western China, the results can be seen to be consistent with the actual and have a certain engineering reference value.

Simulation of the parabolic trough solar energy generation system with Organic Rankine Cycle

As the effect of the global warming is becoming noticeable, the importance for environmental sustainability has been raised. Parabolic trough solar thermal collector system, which is one of the solutions to reduce the carbon dioxide emission, is a mature technology for electricity generation. Malaysia is a tropical country with long daytime, which makes suitable for solar thermal applications with parabolic trough solar thermal collectors. However, the high humidity causes the solar radiation to fluctuate. In order to simulate the solar thermal collectors’ performance at an early design stage of solar thermal power generation systems, fast still accurate transient thermal performance prediction methodis required. Although multiple transient thermal simulation methodologies exist, they are not suited especially at an early design stage where quick but reasonably accurate thermal performance prediction is needed because of their long calculation time. In this paper, a transient thermal prediction method is developed to predict exit temperature of parabolic trough collectors under fluctuating solar radiation. The method is governed by simple summation operations and requires much less calculating time than the existing numerical methods. If the radiation heat loss at the parabolic trough collector tube surface is small, the working fluid temperature rise may be approximated as proportional to the receiving heat flux. The fluctuating solar radiation is considered as a series of heat flux pulses applied for a short period of time. The time dependent solar collector exit temperature is approximated by superimposing the exit temperature rise caused by each heat flux pulse. To demonstrate the capabilities of the proposed methodology, the solar collector exit temperature for one-day operation is predicted. The predicted solar collector exit temperature captures the trend of a finite element analysis result well. Still, the largest temperature difference is 38.8K and accuracy is not satisfactory. Currently, the accuracy of the proposed method is being improved. At the same time, its capabilities are being expanded.

Solar thermal power generation system equipped with molten salt thermal storage offers continuous operation at a rated power independent of the variation of insolation. A gas turbine cycle for solar applications is studied which works in a moderate temperature range (600–850K) where molten salt stays as liquid stably. It is found that a closed cycle with super-critical state of carbon dioxide as a working fluid is a promising candidate for solar application. The cycle featured in smaller compressor work would achieve high cycle efficiency if cycle configuration and operation conditions are chosen properly. The temperature effectiveness of a regenerative heat exchanger is shown to govern the efficiency. Under the condition of 98% temperature effectiveness, the regenerative cycle with pre- and inter-cooling provides cycle efficiency of as much as 47%. A novel heat exchanger design to realize such a high temperature effectiveness is also presented.

Nocturnal reverse flow in water-in-glass evacuated tube solar water heaters