Applied Mechanics and Materials Vols. 361-363

Abstract: Green energy system for the old building retrofitting for energy efficiency upgrade was proposed in this paper, which was composed by solar radiant panels, energy storage, multi-source heat pump and low temperature difference energy supplier. This building energy system can make efficient use of solar energy, sky radiation and natural energy, through the radiant panel installed as the building envelop or on the roof. Two types of the proposed energy system were applied for building refurbishing and their performances were comprehensively studied. It is shown that the building energy consumption annually is less than 30kWh/m² and the indoor temperature is over 18°C in winter and under 26°C in summer, fully meeting the comfort temperature requirements.

Abstract: The power supply of large number of sensors in the Internet of Things is the bottleneck technology of intelligent building. Piezoelectric energy harvesting is introduced as it is a perfect way to solve the problem. The vibration energies in intelligent building are analyzed and concluded with two important common characters. The five difficulties for the application of piezoelectric energy harvesting technology in intelligent building are introduced and solved. The module topology of energy harvester for sensor net in intelligent building application is presented.

Abstract: This paper reports the investigation results of the possibilities for using pure and mixed refrigerants as working fluids to replace R22 for the DX-SAHP systems. Firstly, pure refrigerants are compared in terms of COP, discharge temperature and mass flow rate. Comparison results show that R290 is the most promising alternative to R22. Secondly, two kinds of mixed refrigerants are investigated as well. It indicated that the mixed refrigerant R290/R22 with more R290 performs better than the others in terms of COP. Meanwhile, the mixed refrigerants produce relatively low discharge temperatures and proper mass flow rates can be created due to appropriate mixture in suitable mass proportion. Further investigation indicates that R290 and R290/R22 show better system performance with relatively high superheating temperatures.

Abstract: A large number of nontraditional rural houses were built in 1980s in Zhejiang province. These houses often fail to meet the modern needs of local villagers. In this paper, one such house was reconstructed, using some green-construction technologies and the lowest cost, and the least construction criteria, in order to obtain the best appearance and the best energy-saving effect. Furthermore, the rural house was evaluated using simulations to examine performance on energy consumption, ventilation, and natural lighting. The annual energy consumption of the reconstructed house is 66.6 KWh/m² and the energy-saving rate is 56.23%. Wind velocity of the main activity area ranges from 0.3 to 1 m/s, and the illumination values are above 55 lx, which all meet the requirements of the Chinese Green Building Standards.

Abstract: Policies for energy saving and carbon dioxide emission reduction have enouraged the use of efficient technologies in building thermal conditioning, like geothermal source heat pumps [. Most of the thermal models used to simulate the performance of vertical ground heat exchangers do not consider the effect of outer weather conditions, except for the setting of the initial ground temperature [. This paper shows a study to assess the effect of outer weather conditions on the outlet fluid temperature, especially during the upper part of the exchanger. Different depths for typical configurations of ground heat exchangers have been analysed. Detailed simulations have been developed for a full year of performance using a commercial finite volume computational fluid dynamics (CFD) code (©ANSYS-CFX). Outer weather conditions have been set by using synthetic hourly weather data and considering all of the heat transfer phenomena involved. Errors in outlet fluid temperature and surface borehole temperature have been estimated for the whole year of simulation.

Abstract: The Solar Decathlon Competition on zero energy solar house was held in Europe in 2010 (SDE2010, Madrid). Sustainability is added as a major contest with special emphasis on reducing long term environmental impacts and costs. The life cycle oriented concepts of the entry projects are reviewed and analyzed. First, to avoid the increase of embodied energy due to extreme pursue for PV productivity, smart combination of technical solutions was stressed, including passive strategies, local and natural materials, and improving the efficiency of the solar system with innovative design. Second, modular design is an important way to improve spatial adaptability, the recycling of building components and the reduction of cost and impacts for transportation and construction. Finally, quantitative LCA & LCC methods to optimize and evaluate the projects were introduced. A comparative study shows that there is a trade-off between the initial and long term impacts, and between the impacts and the costs.

Abstract: Up to now, developed absorption refrigeration units with a great power from 30 to 6000 kW were not usable for smaller objects but only for the industrial buildings and the objects of a major character. The development of the sorption cooler with low-power (2-20kW) is a modern subject of research. One of the possibilities of alternative energy production is to use the Sun as an inexhaustible source of energy to power absorption unit. The research is based on an experimental device (absorption units with a performance of 10kW) developed at the STU in Bratislava (currently inputs and outputs of cold sources are being measured). Outputs in this paper are processed so that they connect the entire scheme of the solar absorption cooling system (i.e. the relationship between the solar systems hot and cold storage and the absorption unit).

Abstract: The tidal stream kinetic energy can be abstracted by the horizontal axial turbine, and most concentrate closing to seaside, where the tidal stream turbine must work near the free surface. The interaction between wave surface and the turbine will affect the turbine performance. In this work, the performance of tidal stream turbine working beneath the free surface was simulated, and the wave was discussed. The results indicated that the turbine depth Fr number is the main factor that affects wave induced by the turbine. As the turbine depth Fr number is less than 1.0, the wave is not apparent, and as the Fr number increased, the wave height rose. By the analysis of turbine performance, it is discovered that the wave will influence turbine efficiency, but the relationship between wave height and turbine efficiency is not regular.

Abstract: With the rapid development of human society, the construction industry is booming. How to reduce the building's impact on the environment has become a common problem of the concerns of the community. In recent years, the green building is growing up. As a key part of green building, the composite wall insulation system has attracted the attention of many researchers. This paper presents some recent advances in the experimental and numerical analysis of the thermal conductivity of composite wall, and is expected to serve as a reference for future research and development of green building.

Abstract: In this paper the software DeST was adopted as simulation tool for hourly dynamic simulation analysis for the summer cooling energy consumption of different interior and outer structure systems. Then the software Fluent was adopted for dynamic simulation analysis by seconds for the enclosure structures surface temperature and heat flow within 10~14 days. The results show that in hot summer and cold winter zone the energy-saving rate is less than 5% when only outer wall is in exterior insulation and intermittent use energy characteristics, but if the outer and interior walls are all in the external thermal insulation, the energy-saving rate will be greatly improved; Under the condition of unsteady, wall temperature fluctuation is far less than the outdoor environment temperature and the range of maximum and minimum temperature is only 2 ~ 3 °C,besides the range will be smaller only to 0.5 °C or so if using external thermal insulation; Finally the air conditioning energy consumption differences with Different retaining structures mainly reflected as the size of heat flux on the interior surface of the wall. Base on the intermittent and loculose energy use characteristics in hot summer and cold winter zone the heat flux dissipated on interior wall are the main part.