Advanced Materials Research Vols. 374-377

Abstract: Geothermal energy is a stable energy, stored underground and not influenced by the geographical, seasonal weather and the change of day and night. Medium-enthalpy and low-enthalpy geothermal energy are distributed in many areas of China, having a broad prospect for development. Taking water resources heat pump (WSHP) engineering in Tianqiao District as an example, medium-enthalpy and low-enthalpy geothermal energy is combined with the technology of aquifer thermal energy storage (ATES), providing cold energy in summer and warm energy in winter for the buildings. On the base of analysis of hydrogeological conditions in Tianqiao District, the temperature field of energy storage aquifers is numerically analyzed in the period of heating and cooling. The results show that the energy storage well can meet the requirement of heating and cooling conditions. The system of WSHP greatly utilizes medium-enthalpy and low-enthalpy geothermal energy, making the running costs economical.

Abstract: A hot-water and air-conditioning (HWAC) combined ground sourse heat pump(GSHP) system with horizontal ground heat exchanger self-designed and actualized was presented in this paper. The heat transfer performance for the heat exchanger of two different pipe arrangements, three layers and four layers, respectively, was compared. It showed that the heat exchange quantity per pipe length for the pipe arrangement of three layers and four layers are 18.0 W/m and 15.0 W/m. The coefficient of performance (COP) of unit and system could remain 4.8 and 4.2 as GSHP system for heating water, and the COP of heating and cooling combination are up to 8.5 and 7.5, respectively. The power consumption of hot-water in a whole year is 9.0 kwh/t. The economy and feasibility analysis on vertical and horizontal ground heat exchanger were made, which showed that the investment cost per heat exchange quantity of horizontal ground heat exchanger is 51.4% lower than that of the vertical ground heat exchanger, but the occupied area of the former is 7 times larger than the latter's.

Abstract: Life cycle assessment (LCA) has become an international recognized method to estimate the environmental impacts of a building during its life. A building’s environmental impacts can be divided into two parts－impacts in the service stage and impacts in other stages of its life cycle. Other stages comprise material acquisition stage, constructing stage and final disposal stage. In life cycle except service stage, the LCA analysis was made on a timber structure teaching building using Athena software Eco-calculator. Then the teaching building is assumed to be redesigned adopting the structure of RC-frame and steel frame respectively. And the LCA analysis was made on the two assumed buildings too. By comparing the results, the conclusion can be drawn that timber buildings have lower environmental impact indexes compared with that of RC-frame and about the same with that of steel structure. The aboard usage of the timber structure instead of RC-frame structure can result in good environment performance. In service stage, if a sensible thermal insulation scheme is also considered, a great amount of energy will be saved, and the environmental impact of a building can be made minimum.

Abstract: As a “special earth”, the water sensitivity of loess is an improtant factor influencing its mechanical characters and engineering properties. Through carrying on tests on the FSY30 non-saturated triaxial instrume, this paper shows ~ and ~ curves of the intact loess under different water contents.Then, it is found that the mechanics characteristic of Q3 loess is mainly influenced by the stress condition as well as the water content condition. In addition, the mechanics behavior of intact Q3 loess appears over-consolidated feature under low water content and low cell pressure.

Abstract: CFD simulation is a useful tool for studying. However, in reality there are often complex, unsteady air flow patterns and large geometry domain and complex boundary conditions which are very difficult to totally take into consideration in the simulations. So sometimes we made the calculation domain not the same with geometry domain and simplified the boundary conditions. In this paper, five cases were made to study the calculation domain and boundary conditions for push-pull ventilation. According to the analyses and calculations the walls with windows and door closed setting for wall boundary conditions were not correct. On that basis cracks added, and the boundary conditions were pressure-inlet, and the pressure was zero. The calculation domain was reduced, the result was some different: the tendency was the same, but the difference of specific point values was some big. The new boundaries of the reduce calculation domain were set for pressure-inlet, and the pressure was zero. Under this condition, the cracks could be simplified to wall boundary conditions.

Abstract: China's rapid urbanization makes low-carbon become the pursuit of sustainable development society. In this paper, a new district cooling and heating system named regional distributed heat pump energy bus system is introduced, which can make large scale integration of renewable energy sources or untapped energy sources be used for air-conditioning. This article briefly describes the system concept, applicability, design principles, analysis of the system topological structure and outdoor pipe network heat and pressure loss. Ultimately analyze energy bus system energy consumption compared with DHC system and water supply system by examples.

Abstract: Reasonable determination of indoor ventilation rates are the main content of residential ventilation designs, and can save consumption by air conditioners. Firstly, the energy saving potential of ventilation cooling technology in Guangzhou is analyzed in this paper. The cooling load of a residential building in Guangzhou with different air exchange rates is simulated by the DeST-h after indoor heating quantity of different rooms is set. The energy saving rate is analyzed, the functional relation between energy saving rate of ventilation and air exchange rate is obtained using the linear-regression analysis method. After a comprehensive consideration of various factors, including variation of energy efficiency, room volume, air outlet size, and that the maximum air exchange rates of different rooms are fixed.

Abstract: The Yellow River flood area mainly consisted of silt and silty clay. Water level observing holes and pore water pressure gauges were embedded in the test section. The observation results showed that: The pore water pressure of 3m and 5m grew slowly at the beginning. With the increase of ramming strike and the total ramming strike energy, the fourth hit pore water pressure mutated and then grew slowly. The pore water pressure of 7m and 9m grew slowly all the time. Because of the well point dewatering, the excess pore water pressure dissipated very soon. 70~75% of the excess pore water pressure of the first pass dissipated 3 hours after ramming strike, then the excess pore water pressure dissipated slowly. The excess pore water pressure of 3m and 5m grew significantly, so the effective reinforcing depth of dynamic compaction was 5m.

Abstract: In this paper, taking a building in Wuhan as a case, the CFD method is used to simulate the air flow field and temperature field of respiration double-skin facade,and by analysis, we know how the position and size of air inlet and air outlet can influence the thermal performance , and their area ratio2:3 is suggested with staggered arrangement. Meanwhile, according to the simulation results of the three models, we come to the conclusion that the special structures of double-skin facade can form natural convection heat transfer, take away the heat in channels and achieve the goal of energy conservation and consumption reduction.

Abstract: This paper study some types of the condensation prevention measures in the radiant cooling board. The test bench for its surface condensation's performance is designed and built. In the experiment, four different types of radiation board, which are the grooved surface, Teflon coating surface, super-hydrophobic coating surface and the grooved surface pasted by the PTFE membrane, are investigated. The visual camera is used in observing the condensation process. It is found that: though both the Teflon coating and the super-hydrophobic coating treatment all can reduce the drop fall-off diameter effectively. Further, the super-hydrophobic coating treatment also can delay the fall-off time. The radiant cooling surface, by the measure of the grooved surface pasted by the PTFE membrane, can keep dry continuously. This work may lay the foundation for the simplification of the radiation cooling air conditioning system.