Advanced Materials Research Vols. 1008-1009

Abstract: Based on a mathematic model of diesel generator mechanical centrifugal governor and the traditional PID control and fuzzy control, a fuzzy PID controller is designed so as to accomplish the self-adjustment of diesel generator mechanical governor parameters. The fuzzy PID controlling diesel generator mechanical governing system is simulated by Simulink and the simulation results suggest that the fuzzy self-adjusting PID control owns the merits of well dynamic property, strong robustness and better adaptability compared to the traditional PID control. Therefore, the performance of diesel generator rotate speed governing system is largely advanced.

Abstract: Organic Rankine Cycle (ORC) is an attractive technology solution in waste heat recovery. There is about 60% energy of fuel as waste heat is discharged to atmosphere in the diesel engine. The 15kw ORC plant had been developed using the diesel engine waste heat, which including the jacket coolant and exhaust gas. The working fluid is the R245fa, the plate type heat exchangers were used as the condenser and evaporator in the ORC systems, the twine screw expander as the working machine. The performance of condenser and evaporator had been simulated and developed using the distributed parameters calculations methods according to the effective-NTU. The ORC system and engine can stable run for a long time without frequently control acting. The ORC systems can bring 15.4 kW electric energy in the stable condition. The efficiency based on the first law of thermodynamics is 7.7%; completely generating efficiency is 6.8%.

Abstract: This paper analyzes the working principle of solar array and drive requirements and presents an efficient drive technology of brushless DC motor for solar array. The technology solves the phenomenon of step-out in stepping motor control system. Brushless DC motor mathematical model is inferred and the possibility of driving solar array by brushless DC motor are analyzed in this paper. To achieve speed feedback loop control, reversing, over-current protection function, high-efficiency motor control chip are used in the system for brushless DC motor closed-loop control. Experimental results show that the system has simple structure and it can works in the harsh environments.

Abstract: In this paper, a new method for voltage inverter feeding induction motor fault diagnosis is presented. It is based on the so-called the Lissajous curve of an auxiliary winding voltage Park components. For this purpose, time domain mathematical model of a three phase induction motor fed by an inverter and expressions of the inserted winding voltage and its Park components are presented. Simulation results curried out for non defected and defected inverter show the effectiveness of the proposed method.

Abstract: As benefit of people’s livelihood and social justice issues highlighted and large scale of china had a cold winter in 2012, winter heating problem has been put on the national research agenda in area where hot in summer and cold in winter. This paper analyzes the climate and central heating features of three typical regions include extremely cold regions, cold regions and heating transition regions. Then the economy of three typical regions and the differences across regions from the perspective of heat price has been analyzed. This paper just provides a reference to study the winter heating in area where hot in summer and cold in winter.

Abstract: Focus on the prediction of flow rates in buildings under natural ventilation, the investigation conducted a series of model rooms with cross ventilation. The impact of window-wall ratios, windows configurations as well as corresponding flow rates was investigated. The object of this investigation is to analyze characteristics of windward window opening discharge coefficient by measuring static pressure difference and the flow rate through windows. The conclusion are as follows: For large openings, the discharge coefficient of windward window opening increases as the window-wall ratio grows up; With windward window-wall ratio of 44.4% and 11.1%, the discharge coefficient of windward openings is almost irrelevant to flow rate and less affected by leeward window area; However, with windward window-wall ratio of 2.78%, the discharge coefficient increases slightly as flow rate rises, and the larger the area of leeward opening is, the smaller the discharge coefficient of windward opening becomes.

Abstract: A model of a 24-storey building (94.5m high) with air-conditioning system was developed to analyze the elevator piston effect on building airflow by dynamic mesh technique of computational fluid dynamics (CFD). The results of the pressure distribution and airflow paths show that with the upward movement of elevator cabs, due to the elevator piston effect, changes in the pressure distribution and airflow paths occur in all the building; the pressure difference across the elevator door is enlarged, which is likely to cause some security issues; but the air exfiltration rate is hardly affected.

Abstract: Virtualwind is a quantitative software which can be used to analyses fluid flow, especially within the indoor natural ventilation aspect. Most of patio-style traditional dwelling architecture in Jiangxi Province has a poor ventilation condition, such as uneven distribution of wind speed. In this research, a traditional dwelling architecture located in Panxi Village, Jingdezhen City, Jiangxi Province, is taken as an example. Through adopting Virtualwind software to simulate indoor natural ventilation, it offers potential suggestions to develop the poor ventilation condition by the results of the research.

Abstract: Vuilleumier cycle heat pump (VM) has highest efficiency among all heat driven cycle. In this paper, solar, geo-thermal and biomass energy are investigated as input thermal energy to driven VM cycle heat pump. Fuzzy comprehensive evaluation method is applied to evaluate system performances. Initial investment of the system (IS), system reliability (RS), environmental protection of system (EP), VM exergy efficiency (EE) and VM coefficient of performance (COP) are selected as main evaluation indexes. For all the three renewable input energy, system are scored good, solar driven is better than the other two.

Abstract: In gas cooler, a key component of transcritical heat pump system, CO2 is always in supercritical status. A well design gas cooler should get the full informations of supercritcal CO2 in-tube cooling heat transfer characteristic. An EES program is developed to calculate the supercritical CO2 cooling heat transfer performances based on 4 selected correlation equations. According to the results and the thermopgysical parameters of supercritical CO2, such as specific heat, density, thermal conductivity and dynamic viscosity, two region, the starting area of supercritical region and the main supercritical region, is suggested for supercritical CO2 cooling heat transfer by temperature at 80°C. In the staring area, the variations of heat transfer and other parameters are intensive, while in the main supercritical region, the variations are clined to be stable.