深层地热能在安阳法院集中空调系统中的应用

结合工程实例,介绍了深层地热能在集中空调系统中的应用,并进行了经济性分析.     

A new contribution to the finite line-source model for geothermal boreholes

Heat transfer around vertical ground heat exchangers is a common problem for the design and simulation of ground-coupled heat pump (GCHP) systems. Most models are based on step response of the heat transfer rate, and the superposition principle allows the final solution to be in the form of the convolution of these contributions. The step response is thus a very important tool. Some authors propose numerical tabulated values while others propose analytical solutions for purely radial problem as well as axisymmetric problems. In this paper we propose a new analytical model that yields results very similar to the tabulated numerical ones proposed in the literature. Analytical modeling offers better flexibility for a parameterized design.     

The use of a double heat pipe heat exchanger system for reducing energy consumption of treating ventilation air in an operating theatre—A full year energy consumption model simulation

In two earlier papers [Y.H. Yau, Application of a heat pipe heat exchanger to dehumidification enhancement in tropical HVAC systems—a baseline performance characteristics study, International Journal of Thermal Sciences 46 (2) (2007) 164–171; Y.H. Yau, The analysis of enthalpy change with and without a heat pipe heat exchanger in a tropical air conditioning system, International Journal of Energy Research 30 (15) (2006) 1251–1263], two series of experiments were conducted under controlled conditions to establish the baseline performance characteristics of the heat pipe heat exchanger (HPHX). In the present paper, a complete empirical transient systems simulation program model is assembled to estimate the air states as well as the entire typical meteorological year energy consumption of an operating theatre located in Kuala Lumpur, Malaysia.     

Advanced compact device for the in situ determination of geothermal characteristics of soils

The in situ thermal response test provides an effective method to determine the ground thermal properties required for the design of a geothermal energy installation. This paper presents a unique compact testing device for in situ thermal response testing based on a previous, trolley-based unit. Modernisations in the presented new apparatus enable the time and cost of the test to be reduced and offer enhanced flexibility and application potential for in situ thermal response testing. The methodology adopted for the test, including the theoretical approach for the evaluation of test data, together with an outline of the design and workings of the apparatus are presented. A case study is also shown for the verification of the quality of the results.     

The influence of environmental and geometrical factors on air-ground tube heat exchanger energy efficiency

More and more efficient solutions of thermal insulation of buildings result in an increasing role of ventilation in the energy balance of buildings. This leads to a necessity for seeking unconventional heat sources, as well as development of the exhaust air heat recovery methods. The use of heat accumulating potential of the ground perfectly fits into this trend, allowing natural pre-heating and pre-cooling of the inlet air. There appears to be very limited research and published data on their thermal performance in Poland. This paper introduces a developed method of air-ground heat exchanger (AGHX) performance evaluation together with its validation and research results of conducted simulation. The AGHX model (based on a quasi 3D finite elements method) allows analysis of energy performance dependence on a wide range of parameters including AGHX geometrical configuration, mode of operation and environmental factors. The simulation results indicate that the analyzed parameters in various degrees affect the thermal efficiency of AGHX; various is also the nature of their impact. For some of them it is possible to set a value to maximize heat or cold yield (pipe diameter and placement depth, number of parallel pipes, bypass system, soil thermo-physical parameters, ground area shading and ground surface cover). In other cases, the influence of parameters has an asymptotic nature for which the maximum heating or cooling efficiency is achieved for parameter values tending to infinity (pipe length and distance between parallel pipes).     

Membrane heat exchanger in HVAC energy recovery systems, systems energy analysis

The thermal performance of an enthalpy/membrane heat exchanger is experimentally investigated. The heat exchanger utilizes a 60gsm Kraft paper as the heat and moisture transfer surface for HVAC energy recovery. The heat exchanger sensible, latent and total effectiveness have been determined through temperature and moisture content measurements. The annual energy consumption of an air conditioner coupled with an enthalpy/membrane heat exchanger is also studied and compared with a conventional air conditioning cycle using in-house modified HPRate software. The heat exchanger effectiveness are used as thermal performance indicators and incorporated in the modified software. Energy analysis showed that an air conditioning system coupled with a membrane heat exchanger consumes less energy than a conventional air conditioning system in hot and humid climates where the latent load is high. It has been shown that in humid climate a saving of up to 8% in annual energy consumption can be achieved when membrane heat exchanger is used instead of a conventional HVAC system.     

On the evaluation of design parameters effects on the heat transfer efficiency of energy piles

In this paper a methodology for comparative evaluation of design alternatives of cast-in-place energy piles (EPs) is presented. The methodology proposes the comparison to be based on the difference between the temperature of fluid in the pipes and the temperature at the axis of the pile, under a constant heat injection rate in a homogeneous infinite concrete - ground solid, for a period that the thermal influence between all the pipes has been developed, while the conductive heat transfer along the pile is not significant. It is proved that the temperature at the axis of an EP does not depend on the number of the pipes, thus behaving as a reference temperature at a given time for an EP of a given diameter. The difference between the mean fluid temperature in the pipes and the temperature at the axis of the pile is analysed in four components. It is proved that only one of these components depends on time, and it is common in all EPs of the same diameter, the other three depending on the basic design parameters of the EPs, i.e. the number of pipes, the type and dimensions of pipes and the heat/flow characteristics in the pipes. EPs with different design parameters can be compared, the comparison based on the, easily calculated, constant in time temperature difference between the fluid and the axis of the pile.     

Development of an elliptical fitting algorithm to improve change detection capabilities with applications for deformation monitoring in circular tunnels and shafts

Terrestrial laser scanning, also known as Light Detection and Ranging (LiDAR) is an emerging technology that has many proven uses in the geotechnical engineering community including rockmass characterization, discontinuity measurement and landslide monitoring. One of the newer applications of LiDAR scanning is deformation monitoring and change detection. In tunnels, deformation is traditionally measured using a series of five or more control points installed around the diameter of the tunnel with measurements recorded at regular time intervals. LiDAR provides the ability to obtain a more complete characterization of the tunnel surface, allowing for determination of the mechanism and magnitude of tunnel deformation, as the entire surface of the tunnel is being modeled rather than a fixed set of points. This paper discusses terrestrial LiDAR scanning for deformation mapping of a surface and for cross-sectional closure measurements within an active tunnel using an elliptical fit to data for profile analysis. The methods were found to be accurate to within a few millimeters when measuring 58 mm of diametric difference over an 18.3 m diameter circular profile, even when some sections of the data were removed from the analysis.     

Energy and exergy analysis of a ground-coupled heat pump system with two horizontal ground heat exchangers

In this paper we investigate of energetic and exergetic efficiencies of ground-coupled heat pump (GCHP) system as a function of depth trenches for heating season. The horizontal ground heat exchangers (HGHEs) were used and it were buried with in 1 m (HGHE1) and 2 m (HGHE2) depth trenches. The energy efficiency of GCHP systems are obtained to 2.5 and 2.8, respectively, while the exergetic efficiencies of the overall system are found to be 53.1% and 56.3%, respectively, for HGHE1 and HGHE2. The irreversibility of HGHE2 is less than of the HGHE1 as about 2.0%. The results show that the energetic and exergetic efficiencies of the system increase when increasing the heat source (ground) temperature for heating season. And the end of this study, we deal with the effects of varying reference environment temperature on the exergy efficiencies of HGHE1 and HGHE2. The results show that increasing reference environment temperature decreases the exergy efficiency in both HGHE1 and HGHE2.     

地热供热系统调峰负荷的确定方法

介绍了直接式和间接式地热供热系统调峰负荷的理论计算方法。重点分析了间接式地热供热系统调峰负荷随环境温度的变化,以及所受末端散热器设计、地热水与循环水换热器设计运行参数的影响。     

不同回填材料下地埋管换热器性能的实验研究

实验研究了原土(粉细砂)和中粗砂回填条件下双U形地埋管换热器的传热性能,获得了换热量随管内流体平均温度的实测变化曲线。结果表明,换热量与流体平均温度之间呈线性变化规律,在地埋换热器工作温度范围内,中粗砂回填时的换热量比粉细砂回填时高约10%(取热工况)和6%(排热工况)。建议在选择回填材料时,应在考虑其对地埋管换热器传热特性影响的基础上,进一步考虑其经济性。     

地热换热器U型埋管的传热模型及热阻计算

讨论了地源热泵地热换热器竖直U型埋管钻孔内的二维稳态传热模型。基于钻孔内的温度场的二维解析解，得出钻孔热阻表达式。分析了影响钻孔热阻的几个相关因素，通过与一维简化模型得到的钻孔热阻相比较，认为采用二维模型可以为工程设计提供更准确可靠的热阻数据。     

Investigation of response of metro tunnels due to adjacent large excavation and protective measures in soft soils

The inevitable influence of large excavation in soft soils on nearby tunnels is of great concern in practice. In this paper, the influence of a nearby large excavation on existing metro tunnels of the Ningbo Metro Line 1 in sensitive soft soils is investigated and presented. Considerable displacement in the left tunnel closer to the excavation induced by the nearby excavation was revealed by field monitoring. Visible cracks and leakages were observed in left tunnel linings. Three dimensional numerical simulations are conducted to investigate the responses of the ground and left tunnel due to the adjacent excavation. The development of bending moment and displacement of the left tunnel during different construction stages of the nearby excavation is obtained. Then the interaction mechanism between the nearby excavation, surrounding soils and existing twin tunnels is investigated, which is of significance to the interpretation of the influence of the nearby excavation on the existing twin tunnels. Several protective measures for alleviating the influence of adjacent excavation on left tunnel are studied, including divided excavation, soil improvement and a cut-off wall. It is found that the left tunnel is influenced to varying degrees during different construction stages and the time effect is distinct for this large excavation in soft soils, which would be suggestive to engineers to pay more attention to the protection of adjacent tunnel during the crucial construction stages. The bending moment and displacement of the left tunnel is strongly related to the unloading effects and displacement of surrounding soils, which can be alleviated by means of proper improvement of excavation sequence. Comparatively, longitudinally divided excavation is more effective in protecting the left tunnel than soil improvement or a cut-off wall. This study is of certain reference value for protecting metro tunnels adjacent excavation in soft soils.     

利用土壤能的地下埋管新风系统的研究现状及展望

回顾了地下埋管新风系统的研究进展，介绍了地下埋管部分的换热计算，分析了影响地下埋管新风系统性能的因素，给出了工程应用实例，并针对系统存在的问题展望了今后的发展方向。     

Using buildings to harvest wind energy

Research and development by Altechnica into the applied use of wind energy suggests the novel and innovative solution of employing buildings as primary wind collectors. Buildings can be designed with the means of extracting wind energy advantageously. The roof design of a building can direct and accelerate the wind flow to turbines along the ridge. Dr Derek Taylor of Altechnica introduces the idea of a wind energy system for (new and existing) buildings that can augment solar power, work for a range of building typologies and settings, generate electricity for the building and contribute into the larger electric grid.     

Using buildings to harvest wind energy

Research and development by Altechnica into the applied use of wind energy suggests the novel and innovative solution of employing buildings as primary wind collectors. Buildings can be designed with the means of extracting wind energy advantageously. The roof design of a building can direct and accelerate the wind flow to turbines along the ridge. Dr Derek Taylor of Altechnica introduces the idea of a wind energy system for (new and existing) buildings that can augment solar power, work for a range of building typologies and settings, generate electricity for the building and contribute into the larger electric grid.     

Model experiments for examining heaving phenomenon in tunnels

In recent years, heaving has occurred in pavement slabs in some expressway tunnels, adversely affecting road comfort and tunnel stability. When the heaving displacement is limited, the repair is limited to the overlay slabs. However, in the sections where the displacements are significant, the tunnel invert needs to be reconstructed and this brings many additional problems; for example, in reconstruction, traffic needs to be restricted which brings inconvenience to the public. In this study, model experiments as well as numerical analysis using the finite differential method (Code FLAC) were carried out to establish a rational measure facing to the heaving phenomenon. Based on the results of model experiments and numerical analysis, the validity of reproducibility of the model experiments has been examined, some characteristics of heaving phenomenon have been grasped, factors for estimating the heaving phenomenon in different loading patterns have been established. All these factors have important implications for future construction practice.     

论地热能源在供暖方面的作用及影响

通过对地热能源的研究和调查,分析了地热能源在供暖方面的应用现状、作用及影响,同时总结出地热能源所具有的优势和不足,为地热能源的应用奠定了理论基础,以实现资源的节约。     

Analysis of different models to estimate energy savings related to windows in residential buildings

A Window Energy Rating System (WERS) provides a simple, approximate method to compare the energy performance of the various windows and to determine the different potential savings for the various weather conditions. The main aim of this paper is to obtain a WERS for two climatic zones in Spain.For this purpose, the heating loads and energy savings of a residential building with different types of windows were obtained by three ways. Firstly, the energy through the window was evaluated considering only the climatic conditions. Secondly, the study was performed taking into account the energy useful for the heating system considering the climate and the type of building. Finally, the different cases were simulated using TRNSYS16 and WINDOW5. This study was performed for different European climates.The WERS proposed here is based on the second method. It takes into account the U factor of the window, U factor of the frame, absortivity of the frame, solar heat gain of the glazing and infiltration.