Study on the heat transfer performance of boiling in vertical buried tube of direct expansion ground source heat pump

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.

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

Energy Conversion and Management ◽

10.1016/j.enconman.2013.09.002 ◽

2013 ◽

Vol 76 ◽

pp. 956-970 ◽

Cited By ~ 15

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

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

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.945-949.2820 ◽

2014 ◽

Vol 945-949 ◽

pp. 2820-2824 ◽

Cited By ~ 2

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.

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

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.700.231 ◽

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.

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

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.48-49.304 ◽

2011 ◽

Vol 48-49 ◽

pp. 304-307 ◽

Cited By ~ 1

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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