Applied Mechanics and Materials Vols. 253-255

Abstract: Under the circumstances of the increasing energy consumption of buildings, the development and application of building energy efficiency technology have attracted the attention of many people. As one of the important building energy efficiency technologies, roof greening has played a positive role in building a low-carbon and energy-saving society. This paper analyzes the technological characteristics and the formation methods of the roof greening system. It also expounds on the role of roof greening in building energy conservation.

Abstract: The present frequency domain method of calculating wave power may not be accurate enough for calculating the incident wave power of a specific site, which is primary measurement for evaluating the efficiency of wave energy converters (WECs) and an alternative measure, the time domain method, is proposed. Three sites including two nearshore sites and one deepwater site at Chengshantou sea area were selected, and a sample wave parameters data set was obtained from wave model SWASH to demonstrate the application of these two methods. A comparison of the results of each method was also performed and two influential parameters used in calculation were analyzed. The results show that frequency domain method is very likely to overestimate the wave power at both deepwater and nearshore site. The time domain method proposed in this paper is believed to be more superior in calculating the incident wave power during a short term.

Abstract: The continuous advance of the policy about ‘Energy saving and emission reduction’, along with the continuous development of information technology, control technology, which bring profitable conditions for the monitoring and control over the building (here mainly refers to the large building of government, commercial or industrial user). In particular, a interaction and monitoring system is proposed, which is used to monitor the parameters about energy consumption of energy consumption system or equipment inside the building, in addition the information about the running of the energy consumption system or equipment. At the same time, the relevant units of the energy consumption system or equipment is controlled by the interaction and monitoring system. The interaction and monitoring system for energy saving in building consists of the node for energy saving and monitoring, wireless sensor network (hereinafter referred to as WSN), the platform for energy saving and monitoring, making up the three-layer structure of the interaction and monitoring system inside the building. The node for energy saving and monitoring is a wireless sensor actually, which plays the role as collecting data and controlling. Along with the other nodes for energy saving and monitoring, as well as the nodes acting as repeater, router, coordinator, all nodes inside the building compose the WSN. The node acting as the repeater is of great significance for the transmission of data, especially when some nodes for energy saving and monitoring is located in underground building and some other places where the signal of WSN is blocked, as well as the places far away from the neighbor nodes of WSN. The coordinator is located on the platform for energy saving and monitoring, meanwhile the function of gateway is integrated in the node acting as the coordinator. This node converge the data of the WSN, and transfers the data to the server of the platform for energy saving and monitoring.

Abstract: Saving energy is one of the basic national policies, and energy efficiency in building is the important part of energy conservation work. It is of great significance to develop this work permanently. Discusses the definition of energy efficiency in building, introduces the concept of the life cycle, and sets up the life cycle cost estimation model. Through the analysis of energy saving building, comes to an important conclusion. Although the initial investment of energy saving building increases, the whole life cycle cost is obviously lower than general building. With the increasing of the discount rate and the extension of life cycle, the effect is more outstanding.

Abstract: Since the 90's of last century, energy conservation project of civil architecture has been started in China. Till now, civil builings’ energy consumption, especially public buildings is still serious, which is caused by many factors and the duty mechanism is one of the most important factors. The paper analyzed the prerequisites to launch the duty mechanism, those who should take the responsibility to launch the duty mechanism, responsibility system of the duty mechanism and how to realize the duty mechanism.

Abstract: Lighting energy shares a large portion of building energy. Although lighting control system is deployed in the building, it has limited effects on reducing lighting energy use without the help of occupancy sensors. We use PC’s power save mode as an occupancy sensor in office buildings that are not equipped with occupancy sensors. When each PC goes to power save mode, it means that there is no one in that area, that is, no occupancy. If we make mapping relation between the lights and the PC’s, we can figure out when the light should be turned on and off from the state of PC’s power save mode. This scheme can contribute to reduction of lighting energy use in buildings that has lighting control system but has no occupancy sensors. The estimated results show the positive effect on reduction of the lighting energy use.

Abstract: Building Energy Management System (BEMS) can save energy and minimize the impact on the environment due to energy efficiency technologies and systems. The most important things of Building Energy Management are the monitoring of indoor environment in a building by various sensors and the measurement of energy consumption in a building by various meters. We need to arrange sensors and meters automatically, and develop an automatic sensor and meter arrangement system being usable in any kinds of wired or wireless network. In this paper, we propose an automatic sensor and meter arrangement system for building energy management and explain each component operation of an automatic sensor and meter arrangement system for building energy management, a sensor arrangement simulator and a meter arrangement simulator.

Abstract: High purity hydrogen generated by hydrolysis of sodium borohydride can be used as the fuel of PEM fuel cell and other portable device. As its high hydrogen storage capacity, controllable reaction and mild condition, hydrogen generation by catalytic hydrolysis of chemical hydride, such as sodium borohydride, has been the major focus of researches. On the threshold of the controllable of hydrogen generated by hydrolysis of sodium borohydride, the catalyst for hydrolysis of hydrogen generation (HG) is studied. First, applying chemical plating, Ru/Ni foam catalyst was prepared; then, continuous flow reactor method was used to generate hydrogen. Varied parameters, such as concentrations of NaBH4 and NaOH, flow rate of NaBH4 solution and quantity of catalyst, were inspected in this research. It was found that, the NaBH4 and NaOH concentration at 20wt% and 3wt%, fuel feed to 4 g/min, hydrogen yield of 1.72 L/min, the hydrogen production efficiency as high as 91.2%. The present hydrogen generator was integrated with a 100W PEMFC and the optimum performance of the integrated system was studied. The hydrogen produced from NaBH4 has high purity and humidity; therefore, it can be directly used as the fuel for PEMFCs, which in general require humidified hydrogen. It is found that for cell voltage above 0.6V, the performance of cell using NaBH4 hydrogen is 103.45W, versus 99.9W with cylinder hydrogen.

Abstract: An increase in exergy efficiency of flat plate solar collector leads to a considerable improvement in collector’s performance. Different parameters influence the performance of collector. In this paper, Sequential Quadratic Programming (SQP) and Genetic Algorithm (GA) have been employed for optimizing exergy efficiency of the flat plate solar collector. Absorber plate area and mass flow rate of inlet water have been considered as optimization’s variables. The results show the possibility to reach higher exergy efficiency with lower absorber area and consequently lower price. Also it is obvious that SQP method performs optimization process with higher convergence speed but lower accuracy than GA.

Abstract: In present research we propose a nonlinear solving method to obtain the optimum tilt angle for solar panels. For this purpose, solar radiation on tilted panels are estimated by applying anisotropic model in Maple and the maximum is obtained by solving parametric nonlinear equations with Sequential Quadratic Programming (SQP) algorithm. Comparing its results with prevalent calculation proved this method faster and more efficient. The used model is validated by comparing results with measured data on a 45o-tilted surface in Tehran, Iran. Results showed solar radiation on a tilted surface increases 32% by monthly adjustments, in comparison with a fixed horizontal surface.