地源热泵竖直地埋管换热量的计算

按照《地源热泵系统设计技术规范》中附录B提供的依据,对竖直地埋管换热器的各项热阻进行了详细计算,得出每米换热量,用于指导设计,并通过对结论的分析指出了应用《地源热泵系统设计技术规范》应注意的问题.     

地源热泵技术讲座(四)地埋管地源热泵系统

1 地埋管换热器的分析 (1)地埋管换热器的传热 地埋管地源热泵系统利用地埋管换热器与岩土体进行热交换.地埋管换热器设计是否合理,决定着系统的经济性和运行的可靠性.地埋管换热器由埋于地下的密闭循环管组构成.根据管路埋置方式不同,分为水平埋管和竖直埋管2种.水平埋管投资少、施工简单;竖直埋管占地少、换热性能稳定.竖直埋管的研究与应用远远多于水平埋管.     

西北地区地源热泵工程运用分析

结合具体工程案例,本文分析了地源热泵技术在西北地区的工程运用及设计步骤。文中详细介绍了地埋管换热器的换热特性测试系统及测试方法,并依照测试结果,设计地源热泵联合太阳能系统。通过对垂直U形地埋管换热器冬夏季取热和排热测试,分析不同换热工况下单双U管换热器换热特性,结合当地钻孔难度大以及地埋管换热器取热量小的特点,采用双U地埋管换热器。测试过程中,对不同入口温度、流量工况换热能力进行测试分析,提出在某些地区,地源热泵工程设计采用大流量,小温差的设计理念。     

地源热泵竖直埋管换热器的设计

本文论述了地源热泵竖直埋管换热器的设计方法,重点阐述了地热换热器各部分的设计要点,主要包括地热换热器设计中的类型选择、平面布置、埋管的管径与长度、埋管的连接方式、回填材料及循环液的选取等。     

中新生态城地源热泵地埋管BIM可视化应用研究

应用BIM建模软件,对中新生态城项目的地源热泵地埋管工程的设计与施工进行BIM建模,为地源热泵设计施工可视化管理提供了新方法。研究表明:BIM技术在地埋管设计施工中的应用,能够确保地源热泵工程的工程质量,具有广泛的应用价值。     

利用热管技术提高地源热泵水平埋管的换热效能

提出了把热管应用到地源热泵的水平埋管换热器中 ,用以提高换热器周围土壤的温度和稳定土壤周围的温度场 ,以减少埋管换热器的占地面积     

竖直U型埋管地源热泵技术的应用

通过工程实例详细介绍了U型埋管地源热泵技术的主要施工技术，施工工艺。阐述了竖直U型埋管地源热泵技术在我国发展的必要性和可行性。     

地源热泵岩土热物性测试简介与分析

地源热泵系统作为利用可再生能源的暖通空调技术,具有节能、环保等优点,在世界范围内被广泛使用。土壤作为地源热泵系统的冷热源,对整个系统有着至关重要的影响。不同建筑负荷特性要求系统对土壤的取放热量不同,二者的不平衡会使土壤的温度发生变化,影响整个系统的运行。对特定建筑地源热泵系统土壤的热物性测试是设计地埋管系统的重要依据。本文对热物性测试的理论依据进行了简单介绍,并对具体事例进行了分析计算,得出岩土体的导热系数等具体热物性参数,为地源热泵系统的精确设计提供了依据。     

地源热泵U型埋管数值模拟与分析

建立准确地模拟U型埋管动态过程的传热模型和数值模拟方法。给出随着深度、运行时间埋深方向,U型埋管热流量和土壤温度在深度方向的变化、U型埋管内流体温度分布。所建立的模型、数值模拟方法及提出的数值结果可以为在地源热泵系统里U型埋管的动态模拟、优化设计、优化运行及其改进提供参考。     

Performance of a spiral ground heat exchanger for heat pump application

A high-efficiency ground heat exchanger has been developed for use with ground-source heat pumps. The exchanger is made of copper tubing, shaped in the form of a spiral, which can be installed in a vertical borehole backfilled with sand. Thermal performance of a full-scale prototype indicated that this heat exchanger can achieve very high heat extraction rates if subfreezing operating temperatures are used. For most soil types cyclic freezing and thawing is not a problem; however, for the sensitive Leda clay in which the prototype tests were conducted, substantial settlement occurred after the first freeze-thaw cycle owing to initial collapse of the soil structure.     

Performance of ejector heat pumps

An ejector-compression heat pump can use low-grade thermal energy in the neighbourhood of 93.3°C (200°F) to provide space cooling and heating. This paper applies the existing ejector theory to estimate the performance of an ejector heat pump system at various operating conditions. The study includes parametric, sensitivity and off-design analyses of the heat pump performance. The performance enhancement options and desired ejector geometry are also examined. Refrigerants 11, 113 and 114 are three of the halocarbons most suitable for the ejector heat pump system. The estimated coefficients of performance for a simple ejector heat pump are 0.3 for the cooling mode and 1.3 for the heating mode at a sample operating condition in which the refrigerant (R-11) boiling temperature is 93.3°C (200°F), condensing temperature 43.3°C (110°F) and evaporating temperature 10°C (50°F). A 24 per cent performance improvement is predicted for a heat pump with two-stage ejectors and regenerative heat exchangers. The off-design performance is relatively insensitive to the evaporator temperature variations.     

热泵原理及发展和供热经济性分析

对热泵原理进行了阐述,介绍了热泵在我国的发展与应用,对热泵的技术性和热泵供热的经济性进行了分析,并与其它常用能源供热所需费用进行了综合的比较,提出了热泵技术在中国的发展前景和展望。     

地下水源热泵及其设计方法

文章介绍了地下水源热泵的优点，并提出了地下水源热泵地下水流量的设计方法及地下水流量的设计方法及地下水的处理方法。     

Experimental performance of borehole heat exchangers and grouting materials for ground source heat pumps

The system performance of a ground source heat pump (HP) system is determined by the HP characteristics itself and by the thermal interaction between the ground and its borehole heat exchanger (BHE). BHE performance is strongly influenced by the thermal properties of the ground formation, grouting material, and BHE type. Experimental investigations on different BHE types and grouting materials were carried out in Belgium. Its performances were investigated with in situ thermal response tests to determine the thermal conductivity (λ) and borehole resistance (R_b). The line‐source method was used to analyze the results, and the tests showed the viability of the method. The main goal was to determine the thermal borehole resistance of BHEs, including the effect of the grouting material. The ground thermal conductivity was measured as 2.21 W m^?1 K^?1, a high value for the low fraction of water‐saturated sand and the high clay content at the test field. The borehole resistance for a standard coaxial tube with cement–bentonite grouting varied from 0.344 to 0.162 K W^?1 m for the double U‐tube with cement–bentonite mixture (52% reduction). Grouting material based on purely a cement–bentonite mixture results in a high thermal borehole resistance. Addition of sand to the mixture leads to a better performance. The use of thermally enhanced grouts did not improve the performance significantly in comparison with only a low‐cost grouting material as sand. Potential future applications are possible in our country using a mobile testing device, such as characteristics, standardization, quality control, and certification for drilling companies and ground source HP applications, and in situ research for larger systems. Copyright © 2011 John Wiley & Sons, Ltd.     

Experimental performance evaluation of a closed‐loop vertical ground source heat pump in the heating mode using energy analysis method

An experimental study is performed to determine the performance of a ground source heat pump (GSHP) system in the heating mode in the city of Erzurum, Turkey. The GSHP system using R‐134a as refrigerant has a single U‐tube ground heat exchanger (GHE) made of polyethylene pipe with a 16 mm inside diameter. The GHE was placed in a vertical borehole with 55 m depth and 203.2 mm diameter. The average coefficients of performance (COP) of the GSHP system and heat pump in heating mode are calculated as 2.09 and 2.57, respectively. The heat extraction rate per meter of the borehole is determined as 33.60 W m^?1. Considering the current gas and electric prices in Erzurum city, the equivalent COP of the GSHP system should be 2.92 for the same energy cost comparing with natural gas. The virgin ground in Erzurum basin has high permeability and low thermal conductivity. In order to improve the thermal efficiency of GHE and thus improve COP of a GSHP in the basin, the borehole should be backfilled with sand as low‐cost backfill material and a 1 to 2 m thick surface plug of clay should be inserted. Copyright © 2007 John Wiley & Sons, Ltd.     

Metal hydride heat pumps

Heat pumps have been known for a long time, but, until the energy crisis of 1973, there were only a few studies covering them. Since that time, in addition to alternative energy sources, scientists and engineers have started studying heat pumps more earnestly. There are several kinds of heat pump and utilizations of them, but the most common one is the vapour-compression heat pump. In recent years researchers have started to study metal hydride heat pumps. The paper considers the metal hydride bed, its thermodynamics, and its utilization as a heat pump. It is also compared with conventional heat pumps. The results indicate that the metal hydride heat pump has several advantages, and its utilization in the industrial, commercial and residential fields is foreseen.     

Value of electric heat boilers and heat pumps for wind power integration

The paper analyses the economic value of using electric heat boilers and heat pumps as wind power integration measures relieving the link between the heat and power production in combined heat and power plants. Both measures have different technical and economic characteristics, making a comparison of the value of these measures relevant. A stochastic, fundamental bottom‐up model, taking the stochastic nature of wind power production explicitly into account when making dispatch decisions, is used to analyse the technical and economical performance of these measures in a North European power system covering Denmark, Finland, Germany, Norway and Sweden. Introduction of heat pumps or electric boilers is beneficial for the integration of wind power, because the curtailment of wind power production is reduced, the price of regulating power is reduced and the number of hours with very low power prices is reduced, making the wind power production more valuable. The system benefits of heat pumps and electric boilers are connected to replacing heat production on fuel oil heat boilers and combined heat and power (CHP) plants using various fuels with heat production using electricity and thereby saving fuel. The benefits of the measures depend highly on the underlying structure of heat production. The integration measures are economical, especially in systems where the marginal heat production costs before the introduction of the heat measures are high, e.g. heat production on heat boilers using fuel oil. Copyright © 2007 John Wiley & Sons, Ltd.     

Optimum arrangement and use of heat pumps in recovering waste heat

Relations are derived for the coefficient of performance of heat pump systems used to transfer heat from a low temperature heat source stream to a high temperature heat sink stream. The manner of use and operation of a number of heat pumps in such a system has been determined for the thermodynamic optimum for reversible and irreversible heat pumps.