Papers by Keyword: System Efficiency

Abstract: Based on the EPBD 2010 directive and the mandated method of cost-optimum calculation the forthcoming national regulations require “nearly zero energy buildings” which have high energy performance, significant share of renewables in covering the low energy need and harmonizing the requirement system and the cost-optimum. Known intention of MS as well as some research reports create the impression that predominant use of biomass in the forthcoming years will be the right way to fulfil the above requirements of nearly zero energy buildings. Nevertheless a brief analysis proves that these expectations are exaggerated due to either cost problem or seasonal system efficiency whilst some “secondary” environmental problem must not be forgotten.

Abstract: The main aim of this article is to evaluate the performance of an air conditioner working with R22 and the new ternary mixture which comprises R32/R125/ R600a (0.4:0.4:0.2, by mass). The energy performance assessment of the air conditioner is made for four different condensing temperatures such as 30, 35, 40 and 45 ^°C with evaporator temperatures 22 and 25 ^°C respectively. The experimental tests are performed with secondary fluids like water and air in the condenser and in the evaporator respectively. The experimental tests are performed and comparative exergy analysis has been presented. REFPROP is utilized to find the thermodynamic properties of the mixture. The overall exergetic performance of R22 is comparatively better than that of the mixture. The performances of the individual components are also examined. The exergy destruction of compressor is larger for the mixture, followed by condenser then evaporator and ended with expansion valve. Thus to improve the performance of the system the compressor design has to be reformed.

Abstract: The large capacity storage technologies at present are reviewed, particular attention is paid to the principle and current situation of compressed air energy storage power generation. Considering the operating characteristic of non-fuel compressed air energy storage, this paper proposes a hybrid expansion system with piston expander and turbine expander in series and preliminarily analyses the expansion process. The results display that the application of hybrid expansion system can significantly enhance the efficiency of compressed air energy storage power generation and it shows a broad application prospect.

Abstract: Seawater desalination system has been established based on the ocean thermal energy conversion in this paper. Through compared finned tube heat exchanger with round tube heat exchanger obtained the fresh water output at different temperature and flow velocity of the warm and cold sea water. In this system the energy of the warm and cold sea water has been fully utilized, and so improved the economic benefits of the ocean thermal energy conversion.

Abstract: Oilfield waterflood system efficiency test set and computation analysis software can monitor real-time electric power consumption of waterflood system and optimize parameters in waterflood activity in time. This test tool adopts chip microprocessor as electric circuit for acquisition of pressure, flow rate and electricity. Wireless transmission applies Bluetooth and GPRS techniques. The computation analysis software has such functions as graphic simulation, efficiency computation, behavior diagnosis and design optimization. The filed application of this tool effectively cuts production cost and achieves the goal of energy saving.

Abstract: To achieve the operational efficiency maximization of ultrasonic motor system, this paper analyzes optimum control of the ultrasonic motor system’s efficiency including driving circuit, while the speed closed-loop control performance is ensured. Based on regulating characteristics of open-loop speed control and fuzzy control, two optimum control methods for regulating the changing step-length of driving voltage amplitude, to shorten the elapsed time of efficiency optimization process and to improve the general operational efficiency of motor system and the speed closed-loop control performance, are also analyzed. The effectiveness of the methods mentioned in this paper are reflected using experiments.

Abstract: Scalability is one of the most important indicators to for performance of cloud storage system. In this paper, firstly, we pointed out limitations of three classical scalability evaluation methods with conditions of iso-speed, iso-efficiency and iso-ratio of parallel overhead to computation, when describing scalability. Then, we proposed a new scalability evaluation model which was suitable for cloud storage environment and named as EP scalability model. The EP scalability model directly reflected the performance of cloud storage system when the system scale and storage tasks expand.

Abstract: A simple analytical approach is given to calculate the performance of parabolic mirrors for various wavelengths. Expressions are given for the efficiency of the parabolic mirror system and insertion gain. As examples, parameters for some mirrors for CuKα and MoKα radiation are calculated.