Random Heat Temperature Field Model Analysis on Buried Pipe of Ground Source Heat Pump

2011 ◽  
Vol 383-390 ◽  
pp. 6626-6631
Author(s):  
Cheng Ju Huang ◽  
Chang Sheng Guan ◽  
Kai Xia
Keyword(s):  
Heat Transfer ◽  
Temperature Field ◽  
Heat Pump ◽  
Design Theory ◽  
Transfer Model ◽  
Ground Source Heat Pump ◽  
Buried Pipe ◽  
Reliability Design ◽  
Ground Source ◽  
Temperature Field Model

The random properties on buried pipe of ground-source heat pump (GSHP) is analyzed, the equation of Kelvin one-dimensional line source of heat transfer model is discussed. The model randomness is analyzed also, and the GSHP buried pipe to random excess temperature field, space-time statistics and the correlation of features are studied. The engineering example shows that heat transfer in buried pipe has relationship with the distance from the pipe center and run time of the system, and also the heat transfer between buried pipes can not be ignored. The method in this paper has great significance for improving the reliability design theory and reducing the construction cost of GSHP buried pipe in this paper.

Analysis on Heat Transfer Energy Efficiency of U-Tube Buried Pipe under Variable Entering Water Temperature Conditions

2014 ◽  
Vol 960-961 ◽  
pp. 603-608
Author(s):  
Yu Zhou Cui
Keyword(s):  
Heat Transfer ◽  
Energy Efficiency ◽  
Water Temperature ◽  
Heat Pump ◽  
Temperature Difference ◽  
Heat Extraction ◽  
Ground Source Heat Pump ◽  
Buried Pipe ◽  
Ground Source ◽  
Heat Transfer Capacity

Taken as the carrier of heat extraction between rock-soil body and ground source heat pump systems, U-tubed pipe heat transfer efficiency was the key for ensuring the long-term and high-performance operation of ground source heat pump systems by means of improving the heat transfer effect. The efficiency coefficient, E, is defined as the ratio of the actual heat transfer capacity to the theoretically maximal heat transfer capacity from the U-tube into rock-soil body, which illustrated the effect of heat transfer ability and the variable heating or cooling loads. Aim at Variation characteristics of heat transfer coefficient of energy efficiency under the variable temperature inflow condition, decomposed into the product of the ratio of biggest buried tube heat transfer temperature difference φ and heat pump outlet water temperature difference σ. Use of u-shaped buried pipe three-dimensional heat transfer model which based on the multipole theory, the influence law of its change which caused by the construction load, buried pipe flow and the unit performance were analyzed, it can provide technical support to optimize the design of ground source heat pump system.

Intermittent Convective Heat Transfer for Ground-Source Heat Pump Design

2000 ◽  
Author(s):  
James W. Stevens
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Thermal Diffusivity ◽  
Transfer Coefficient ◽  
Convective Heat Transfer ◽  
Heat Pump ◽  
Convective Heat ◽  
Ground Source Heat Pump ◽  
Buried Pipe ◽  
Ground Source

Abstract An accurate estimate of the heat transfer from a buried pipe to the surrounding ground is essential for the design of the ground loop portion of a ground-source heat pump. Exact analytical solutions to this problem are complicated by the fact that heat pump systems rarely operate continuously. Complete numerical simulations of system designs can be carried out, but these are unwieldy and difficult to justify for initial scoping calculations, or for preliminary performance estimates. The purpose of this paper is to describe the development of simple algebraic correlations that can be used to approximate the intermittent overall heat transfer between a fluid flowing in an isolated buried pipe and the surrounding ground. The correlations described in this paper were drawn from results of a numerical finite-difference analysis of a fluid flowing intermittently in a single round pipe and exchanging heat with the surrounding ground. The two-dimensional analysis was carried out for ranges of the parameters of intermittence factor, thermal diffusivity of the ground, and convective heat transfer coefficient at the fluid-wall interface. The surrounding ground is unbounded for the purposes of the analysis. The dimensionless heat transfer can be easily related to the overall thermal resistance between the flowing fluid and the ground far from the buried pipe. It is found that the cycle average heat transfer is always lower for the intermittent case than for the continuous case, but that the average over just the active part of the cycle is always higher for any intermittent case than for the continuous case. The effect of the ground thermal diffusivity is largest when the heat transfer coefficient is large, and decreases with decreasing heat transfer coefficient. The range of heat transfer coefficients where isothermal wall conditions are approached is illustrated. Correlations for the operating average and cycle average total heat transfer are presented as functions of the thermal diffusivity, intermittence factor, and heat transfer coefficient.

Performance Evaluation of a Vertical U-Tube Ground Heat Exchanger Using a Numerical Simulation Approach

2013 ◽  
Vol 724-725 ◽  
pp. 909-915
Author(s):  
Ping Fang Hu ◽  
Zhong Yi Yu ◽  
Fei Lei ◽  
Na Zhu ◽  
Qi Ming Sun ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Performance Evaluation ◽  
Heat Exchanger ◽  
Heat Pump ◽  
Heat Transfer Process ◽  
Working Fluid ◽  
Outlet Temperature ◽  
Ground Heat Exchanger ◽  
Ground Source Heat Pump ◽  
Ground Source

A vertical U-tube ground heat exchanger can be utilized to exchange heat with the soil in ground source heat pump systems. The outlet temperature of the working fluid through the U-tube not only accounts for heat transfer capacity of a ground heat exchanger, but also greatly affects the operational efficiency of heat pump units, which is an important characteristic parameter of heat transfer process. It is quantified by defining a thermal effectiveness coefficient. The performance evaluation is performed with a three dimensional numerical model using a finite volume technique. A dynamic simulation was conducted to analyze the thermal effectiveness as a function of soil thermal properties, backfill material properties, separation distance between the two tube legs, borehole depth and flow velocity of the working fluid. The influence of important characteristic parameters on the heat transfer performance of vertical U-tube ground heat exchangers is investigated, which may provide the references for the design of ground source heat pump systems in practice.

Ground source heat pump performance in case of high humidity soil and yearly balanced heat transfer

2013 ◽  
Vol 76 ◽  
pp. 956-970 ◽  
Author(s):  
Luigi Schibuola ◽  
Chiara Tambani ◽  
Angelo Zarrella ◽  
Massimiliano Scarpa
Keyword(s):  
Heat Transfer ◽  
Heat Pump ◽  
High Humidity ◽  
Ground Source Heat Pump ◽  
Pump Performance ◽  
Ground Source

Simulation on Ground Temperature Change of GSHP System in Severe Cold Regions

2014 ◽  
Vol 945-949 ◽  
pp. 2820-2824 ◽  
Author(s):  
Li Bai ◽  
Peng Xuan Wang
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Temperature Change ◽  
Heat Pump ◽  
Ground Heat Exchanger ◽  
Ground Source Heat Pump ◽  
Cold Regions ◽  
Ground Source ◽  
Ground Coupled Heat Pump ◽  
Operation And Management

For the case of ground-source heat pump in severe cold regions in winter, the heat transfer situation of the ground and ground heat exchanger was dynamically simulated according to the statistics of a project in Changchun to analysis the change of the ground heat, which provided references for the initial design and operation and management of the ground-coupled heat pump in severe cold regions.

Study on Engineering Construction with Three-Dimensional Heat Transfer Modeling for Double U-Tube Heat Exchangers in Ground-Source Heat Pump Systems

2013 ◽  
Vol 700 ◽  
pp. 231-234
Author(s):  
Lian Yang ◽  
Yong Hong Huang ◽  
Liu Zhang
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Pump ◽  
Heat Exchangers ◽  
Three Dimensional ◽  
Ground Source Heat Pump ◽  
Ground Source Heat Pumps ◽  
Engineering Construction ◽  
Single Hole ◽  
Ground Source

There are many ground source heat pumps in engineering construction application. However, Research on heat exchanger models of single-hole buried vertical ground source heat pump mostly focuses on single U-tube ground heat exchangers other than double U-tube ones in China currently. Compared with single U-tubes, double U-tubes have the heat transfer particularity of asymmetry. Therefore, the use of the traditional single tube models would have large error in the simulation of the actual double U-tube heat exchangers. This paper frames a three-dimensional heat transfer model for the vertical single-hole buried double u-tube heat exchanger in a ground source heat pump system. The model considers the performance of U-bube material and uses a dual coordinate system and makes the control elemental volumes superimposed.

Characteristics Analysis of Soil Temperature of Surrounding Underground Pipe of Ground Source Heat Pump when Thermal and Seepage Coupled

2011 ◽  
Vol 48-49 ◽  
pp. 304-307 ◽  
Author(s):  
Xiao Bin Zhang ◽  
Wei Bing Zhu ◽  
Si Peng Tan
Keyword(s):  
Heat Transfer ◽  
Heat Conduction ◽  
Heat Pump ◽  
Operation Mode ◽  
Ground Source Heat Pump ◽  
Geothermal Heat ◽  
Medium Theory ◽  
Ground Source ◽  
Transfer Capability ◽  
Characteristics Analysis

The heat transfer capability of the underground geothermal heat exchanger (GHE) is influenced by groundwater advection, and heat conduction and groundwater heat advection is coupled. Based on porous medium theory, the GHE’s mathematical model under coupled heat conduction and advection is established with correspond simplifications. Through numerical simulation, the performance of the GHE with groundwater advection is analyzed. The GHE’s heat transfer effect in winter in the continuous operation mode(COM) and the intermittent operation mode(IOM) is compared, furthermore the soil recovering effect in IOM is analyzed, finally the heat recovering time which the soil demands in a system running period is researched. It supplies theory support and technology accumulation for the application of ground-source heat pump (GSHP).

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