Abstract: The model of the water-mass-to-collector-area ratio (WMCAR) of a flat-plate solar water heating system has been built based on the energy output model of the solar collector. The results show that the calculation values of the WMCAR model are highly consistent with the experimental values and their relative errors do not exceed 10%. The WMCARs of the flat-plate solar collector integrated with large-tilt-angle (70o-90o) into the south façades of the high-rise buildings in five climatic regions including 133 cities in China have been calculated and analyzed. For convenient use in practice, parameter relationships between the values of WMCARs and the main meteorological data have been analyzed by using the linear polynomial regression technique. The regression equations and regression coefficients in summer months and winter months have been given in this paper.
Abstract: Based on the view that it’s not suitable for all areas to exploit shallow geothermal energy, this paper proposes in the large framwork of suitability regionalization, specific project has to be evaluated in detail. The paper discusses the cost-benefit evaluation mechanism, geological conditions and geological environment veto mechanism of shallow geothermal energy exploitation, which can be used as evaluation mechanism for feasibility of shallow geothermal energy exploiture project.
Abstract: This article introduces the working principle of the recovery fresh air heat pump units,and analyzes the applications system which units apply in air-conditioning heat recovery system.By using the principle of regression analysis of mathematical statistics,the article measured data for statistical analysis.The regression equation is established, the established regression equation has a high prediction accuracy.
Abstract: The cascaded multilevel inverter may be the best topology to satisfy continuously increasing capacity and scale of grid-connected photovoltaic generation system due to its modularized circuit layout and sufficiently high operating voltage without devices in series. The operating principle of the cascaded multilevel inverter is presented. The control strategy of carrier phase shift PWM is proposed and discussed in detail. A grid-connected photovoltaic (PV) generation system based on a seven level cascaded inverter is provided. Simulation model of a seven level cascaded inverter with phase shifted PWM is built in Simulink environment and simulation results verify that the cascaded multilevel inverter can output high level voltage without devices in series, reduce harmonics, and output high quality waveforms.
Abstract: Using the series connected method, the space silicon solar cell are connected into the solar cell array. Based on the theoretical analysis, output characteristics and I-Vcurve of the solar cell array under condensing and no-condensing light intensity are tested by experimental methods. The results showed that the surface temperature of the solar cell under the essentially same conditions, the energy flux density of the solar cell surface is greater, the greater the maximum output power is. Under the condensing light intensity, the maximum output power is 21.50W.
Abstract: The imbalance in cold and heat load in large public buildings located in a cooling-dominated areas is apparent. To explore the effect of a cumulative cold and heat load ratio (CCHLR) on the performance parameters of the hybrid ground-source heat pump system (HGSHPS) of large public buildings, this study selects a Wuhan office building as the simulation object. When this model is considered as the prototype, five other building models whose CCHLR interval is relatively uniform can be developed. The full-year dynamic loads of the six models were calculated with Designer’s Simulation Toolkits. The 20-year simulation of the six HGSHPS models was conducted with TRNSYS. Then, the performance parameters of the HGSHPS model under different CCHLR values were studied and compared. These parameters included the average soil temperature, exiting fluid temperature (ExFT) of the ground heat exchanger (GHE), average energy efficiency ratio, and specific energy consumption (the electrical energy required to obtain per kilowatt cooling or heating capacity) of the heat pump system. Simulation results indicated that with the increase in CCHLR, the average soil temperature rapidly increases, the ExFT of the GHE increases to a value that is considerably higher than the suggested standard, and the specific energy consumption of the system increases.
Abstract: As large scale integration of wind power generation into grid, the fluctuation of wind power must be stabilized with fast response complementary power source such as gas and oil power generation. However entire power system is dominated by thermal power plant in China, moreover the proportion of heating units is more and more high. Therefore, expanding the peak regulating capacity of heating units to take in wind power on a large-scale is an inevitable choice. This research proposed the heat load and wind power forecast approach, meanwhile, the analysis strategy of forecasting uncertainty is also be put forward. Then, a thermal electricity combined (TEC) operation technology, which based on making the best use of the heat transfer and thermal storage characteristics of heating network and electric heating, is proposed in this paper to enhance the utilization of wind power. Final, a practical system block diagram is proposed for practical application.
Abstract: The unsteady wake effect of upstream wind turbine on the aerodynamic performance of downstream wind turbine is investigated using CFD simulations in this paper with two two-dimensional models of H-type wind turbine of three same blades. Dynamic grids based on the inertial coordinate system are employed and the SST turbulence model is used for turbulence modeling. The wind speed is 5.07 m/s and the tip speed ratio is 2.15. The distance between upstream and downstream wind turbine is 5D, 7D, 9D, 11D, 13D, 15D and 17D (D denotes the diameter of the wind turbine). The power coefficient of upstream and downstream wind turbine is comparative analyzed. The variation of the tangential force coefficient of single blade with azimuth and the velocity distribution of different locations of the wind turbine wake are discussed in detail with the distance between upstream and downstream wind turbine of 7D and 15D. In addition, two-dimensional unsteady viscous flow field through velocity contours in one circle is presented.
Abstract: The high resolution offshore wind speeds retrieval from SAR image is of great signification in the field of offshore wind energy estimation. In this paper, one operational method for offshore wind speeds retrieval from SAR image is conducted. Taking one scene ENVISAT ASAR image as a case study, the offshore wind speeds is operational retrieved combing with the NCEP/QSCAT blended sea surface wind directions. The retrieved wind speeds are compared with those from both the NCEP/QSCAT blended sea surface wind speeds and daily averaged Quick Scatter meter sea surface wind speeds. The results show that they are in good agreement. The root mean square errors of wind speed are 1.9 m/s and 1.6 m/s respectively, which show that the operational method for offshore wind speeds retrieval from SAR is available and give the orientation of SAR offshore sea surface wind energy business application in the future.