Numerical and experimental analysis of a horizontal ground-coupled heat pump system

The main objective of this work is to evaluate a heat pump system using the ground as a source of heat. A ground-coupled heat pump (GCHP) system has been installed and tested at the test room, University of Firat, Elazig, Turkey. Results obtained during experimental testing are presented and discussed here. The coefficient of performance (COP_sys) of the GCHP system is determined from the measured data. A numerical model of heat transfer in the ground was developed for determining the temperature distribution in the vicinity of the pipe. The finite difference approximation is used for numerical analysis. It is observed that the numerical results agree with the experimental results.     

土壤蓄冷与土壤耦合热泵集成系统

以平衡电网负荷、削峰填谷及利用可再生浅层地热能为基本出发点,提出了土壤蓄冷与土壤耦合热泵集成系统的新设想.该集成系统将蓄冷装置与地下埋管换热器合二为一,在夏季空调工况时,利用电力低谷时段的廉价电力,将冷量全部或部分储存到土壤中,以供白天用电高峰期空调使用;在需供冷的过渡季,系统按土壤耦合热泵系统的供冷工况运行,将系统的冷凝热排至土壤中,为冬季供暖储备热量;供暖季节,系统按土壤耦合热泵系统的供暖工况运行,土壤作为热泵系统的低位热源.介绍了该集成系统的形式、技术特点及核心研究内容,并在前期研究工作的基础上对影响集成系统运行特性、冷量损失的因素进行了较全面的总结.     

土壤耦合热泵系统地下埋管换热器传热模型的研究

在总结埋管传热理论的基础上,系统地介绍了国外关于土壤耦合热泵系统地下埋管换热器传热模型的研究进展,并给出了各传热模型的形式及其理论基础。     

Artificial neural networks and adaptive neuro-fuzzy assessments for ground-coupled heat pump system

This article present a comparison of artificial neural network (ANN) and adaptive neuro-fuzzy inference systems (ANFIS) applied for modelling a ground-coupled heat pump system (GCHP). The aim of this study is predicting system performance related to ground and air (condenser inlet and outlet) temperatures by using desired models. Performance forecasting is the precondition for the optimal design and energy-saving operation of air-conditioning systems. So obtained models will help the system designer to realize this precondition. The most suitable algorithm and neuron number in the hidden layer are found as Levenberg–Marquardt (LM) with seven neurons for ANN model whereas the most suitable membership function and number of membership functions are found as Gauss and two, respectively, for ANFIS model. The root-mean squared (RMS) value and the coefficient of variation in percent (cov) value are 0.0047 and 0.1363, respectively. The absolute fraction of variance (R²) is 0.9999 which can be considered as very promising. This paper shows the appropriateness of ANFIS for the quantitative modeling of GCHP systems.     

A techno-economic comparison of ground-coupled and air-coupled heat pump system for space cooling

This paper reports a techno-economic comparison between a ground-coupled heat pump (GCHP) system and an air-coupled heat pump (ACHP) system. The systems connected to a test room in Firat University, Elazig (38.41°N, 39.14°E), Turkey, were designed and constructed for space cooling. The performances of the GCHP and the ACHP system were experimentally determined. The experimental results were obtained from June to September in cooling season of 2004. The average cooling performance coefficients (_COPsys${\mathrm{COP}}_{\mathrm{sys}}$) of the GCHP system for horizontal ground heat exchanger (HGHE) in the different trenches, at 1 and 2 m depths, were obtained to be 3.85 and 4.26, respectively and the _COPsys${\mathrm{COP}}_{\mathrm{sys}}$ of the ACHP system was determined to be 3.17. The test results indicate that system parameters can have an important effect on performance, and that GCHP systems are economically preferable to ACHP systems for the purpose of space cooling.     

直接膨胀式土壤耦合热泵系统研究进展

介绍了DX-GCHP系统和SL-GCHP系统,分析了DX-GCHP系统的循环特点及设计时需要注意的问题,回顾和总结了DX-GCHP系统的发展现状和相关研究文献,展望了DX-GCHP系统的发展前景。     

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.     

地源热泵系统施工技术概述

介绍了竖直埋管地热换热器施工技术,特别是对地热换热器的钻孔、下管和回填的技术要点和设备等进行了详细的阐述。     

谈某工程土壤源热泵地下管路系统施工要点

简述了土壤源热泵系统的概念,结合具体工程实例,详细介绍了土壤源地源热泵地下管路系统在各个施工环节中应注意的施工技术及质量控制要点,以供类似工程参考借鉴。     

土壤源热泵系统热平衡问题的讨论

土壤源热泵具有节能与环保的特点．近年来发展迅速,但在应用中存在冷热负荷不平衡的不利因素。这种不平衡会导致热堆积。引起整个系统性能的降低。本文介绍了针对不同情况的解决方法,如冷却塔辅助散热装置,太阳能-土壤源热泵混合系统等。并提出了亟待解决的新问题。     

Development of a numerical model to predict heat exchange rates for a ground-source heat pump system

Ground-source heat pump (GSHP) systems can achieve a higher coefficient of performance than conventional air-source heat pump (ASHP) systems. For the design of a GSHP system, it is necessary to accurately predict the heat extraction and injection rates of the heat exchanger. Many models that combine ground heat conduction and heat exchangers have been proposed to predict heat extraction/injection rates from/into the ground in the research field of heating, ventilation and air-conditioning systems. However, most analysis models are inaccurate in their predictions for long periods because they are based on a thermal conduction model using a cylindrical coordinate model or an equivalent diameter model. In this paper, a numerical model that combines a heat transport model with ground water flow and a heat exchanger model with an exact shape is developed. Furthermore, a method for estimating soil properties based on ground investigations is proposed. Comparison between experimental results and numerical analysis based on the model developed above was conducted under the conditions of an experiment from 2004. The analytical results agreed well with the experimental results. Finally, the proposed model was used to predict the heat exchange rate for an actual office building in Japan.     

土壤蓄冷与土壤耦合热泵集成系统全年连续运行特性分析

针对上海地区的一栋办公楼,按照适用于土壤蓄冷与土壤耦合热泵集成系统的运行方式,对该系统的全年运行特性进行了模拟计算分析。结果表明,该集成系统采用的运行方式不仅有效地降低了白天高峰时段空调的用电量,而且还缓解了冬夏负荷不平衡导致的土壤温度逐年变化问题。     

地埋管地源热泵水平埋管冬夏季工况换热牲能及土壤温度场

建立了水平埋管的二维数学模型,使用边界离散、保形变换方法对模型进行求解,用VB编制了地埋管地源热泵水平埋管土壤温度场计算软件.运用模型和软件,详细模拟了冬季和夏季工况下水平埋管及其周围土壤温度场和热流分布规律.冬季水平埋管周围土壤温度纵向呈不对称单峰状分布,横向呈完全对称的单峰状分布.夏季水平埋管周围土壤温度纵向呈不对称单谷状分布,横向呈完全对称的单谷状分布.随着位置远离埋管,土壤温度变化幅度减小.埋管外表面温度分布和土壤沿与埋管同圆心的圆周上温度分布都呈正弦曲线.埋管上部各单元的热流量相对较高,下部各单元的热流量相对较低.求解了给定工况下水平埋管的单位管长换热量,并通过文献中的实验数据对算法进行了验证,误差为6.2%,模型算法具有可靠性.     

某住宅小区地源热泵系统设计分析

本文阐述了某住宅小区地源热泵系统的设计方案,空调冷热负荷的计算,即针对代表建筑用DeST软件模拟全年动态负荷,结合建筑物的特点及工程经验取得同时使用系数并确定最终空调负荷值,分析了居住类建筑集中供能系统装机容量与最终空调负荷之间的关系,总结了地源热泵系统设计过程中的思考体会。     

北京某住宅小区复合式地源热泵空调系统方案设计

该方案为由地埋管换热器和辅助冷热源组成的复合式地源热泵空调系统,采用分散设置热泵主机的水环热泵系统,以地埋管换热器作为全年冷热源主体,夏季采用湖水辅助散热,冬季采用燃气锅炉辅助加热.系统设置专门的热泵供应生活热水,一方面充分利用建筑物周围的空地设置埋管,另一方面应用辅助散热(加热)系统满足供热和制冷的高峰负荷,降低了系统的初投资,提高了系统经济性和运行的可靠性.     

Experimental study of a ground-coupled heat pump combined with thermal solar collectors

This paper presents the experimental study of a ground-coupled heat pump used in a 180 m² private residence and combined with thermal solar collectors. This process, called GEOSOL, meets domestic hot water and heating–cooling building energy needs. Solar heat is used as a priority for domestic hot water heating and when the preset water temperature is reached, excess solar energy is injected into the ground via boreholes. This system has the advantage to contribute to the balance of the ground loads, increasing the operating time of the solar collectors and preventing overheating problems. After 11 months in operation, the power extracted and injected into the ground had average values of 40.3 and 39.5 W/m, respectively. Energy injected into the ground represents 34% of the heat extracted, and the heat pump's coefficient of performance (COP) in heating mode had an average value of 3.75. In addition, the domestic hot water solar fraction had an average value higher than 60% for the first 11 months in operation.     

地埋管源热泵系统热平衡及其地域性分析

通过某公寓项目设计实例,以全年负荷计算为基础,从岩土体全年热平衡的角度分析了地埋管地源热泵系统在工程应用中的可行性及其地域性特点.     

A mathematical simulation of a solar assisted heat pump system using the ground for energy storage

A residential heating system utilizing a combination of a solar collector, a heat pump and an energy storage in the ground is described and some simulation results are presented.It is concluded that for ground heat-pump systems without a solar collector the best positioning of the heat absorbing tubes are horizontal, whereas the vertical tube configuration seems to be superior when a solar collector is included in the system.Finally it is observed that the use of a heat storage consisting of vertical tubes buried under the house appears to be a rather attractive solution.     

直接膨胀式土壤耦合热泵系统设计与施工

结合示范工程,介绍了直接膨胀式地源热泵系统的设计方法和施工要点.详细分析和讨论了系统的初投资和冬夏季运行情况.结果表明该系统运行稳定,达到了预期的效果.     

A parametric study on the exergoeconomic assessment of a vertical ground-coupled (geothermal) heat pump system

An exergoeconomic model of a vertical ground-source heat pump residential heating system presented in this study uses exergy and cost energy mass (EXCEM) methods. The data obtained from a ground-source heat pump (GSHP) residential heating system installed at the Solar Energy Institute, Ege University, Turkey, are utilized for calculations at different reference temperature values in the range 0–25 °C. The performance of the geothermal heat pump residential heating system is evaluated to indicate how exergoecomic parameter values change with system. We also undertake a parametric study to investigate how varying reference temperatures will affect the exergoeconomic analysis of the GSHP system. A correlation between the ratio of thermodynamic loss rate to capital cost and reference state temperature is developed.