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Cui P.,Jinan Key Laboratory of Renewable Energy Utilization Technologies In Buildings | Cui P.,Shandong Jianzhu University | Cui P.,Shandong Key Laboratory of Building Energy saving Technique | Li X.,Shandong Key Laboratory of Building Energy saving Technique | And 2 more authors.
Applied Energy | Year: 2011

This paper investigates the transient heat conduction around the buried spiral coils which could be applied in the ground-coupled heat pump systems with the pile foundation as a geothermal heat exchanger. A transient ring-coil heat source model is developed, and the explicit analytical solutions for the temperature response are derived by means of the Green's function theory and the image method. The influences of the coil pitch and locations are evaluated and discussed according to the solutions. In addition, comparisons between the ring-coil and cylindrical source models give that the improved finite ring-coil source model can accurately describe the heat transfer process of the pile geothermal heat exchanger (PGHE). The analytical solutions may provide a desirable and better tool for the PGHE simulation/design. © 2011 Elsevier Ltd.


Wang D.,Hong Kong Polytechnic University | Lu L.,Hong Kong Polytechnic University | Zhang W.,Hong Kong Polytechnic University | Cui P.,Jinan Key Laboratory of Renewable Energy Utilization Technologies In Buildings | Cui P.,Shandong Jianzhu University
Applied Energy | Year: 2015

The effect of groundwater flow on the heat transfer performance of pile geothermal heat exchanger (PGHE) with spiral coils was simulated by a 3-D simulation model using finite element method. Different groundwater flow conditions were taken into consideration by applying different hydraulic gradients. Based on the moving ring-coils model and simulation results, an improved analytical model is developed by introducing a key parameter of effective dimensionless velocity. The calculation results shows that the improved model can better describe the heat transfer performance of PGHE with spiral coils. Both numerical and analytical results indicated that the groundwater flow has an enhancing effect on the heat transfer performance of the PGHE with spiral coils and can accelerate the heat transfer process into stability. When the groundwater flow mean velocity equal to 6.98E-06. m/s, the amount of heat exchange is higher than 26.72% than it of non-advection situation. The improved ring-coils analytical model can be used as a reliable tool for the design of pile geothermal heat exchanger with spiral coils under groundwater flow. © 2015 Elsevier Ltd.


Yang D.,Jinan Key Laboratory of Renewable Energy Utilization Technologies In Buildings | Lu X.,Shandong Jianzhu University
Advanced Materials Research | Year: 2014

As Zibo power plant original steam pipes for a long time to run, the strength decreased and resistance was large, transformation was proposed to optimize. A mathematical model of the main steam pipe network was established to analysis changes of temperature, pressure and velocity vector before and after transformation. After transformation, the loss was significantly reduced,so transformation successfully achieve the optimization, adjustment and analysis functions of the main steam pipe network. © (2014) Trans Tech Publications, Switzerland.


Wang D.,Hong Kong Polytechnic University | Lu L.,Hong Kong Polytechnic University | Cui P.,Jinan Key Laboratory of Renewable Energy Utilization Technologies In Buildings | Cui P.,Shandong Jianzhu University
International Journal of Heat and Mass Transfer | Year: 2016

This paper presents a new transient analytical model for describing the heat transfer process of pile geothermal heat exchangers with spiral coils (PGHE-SC). A numerical model has been established based on the finite element method to validate this new analytical model, which shows a good agreement between the two models. The temperature responses for different heat transfer conditions were calculated and are discussed. When the thermal conductivities of pile is twice as the one of soil, the dimensionless temperature at middle of the pile is 0.3832 which almost twice as the temperature response of homogeneous case. The results indicate that the thermal difference between pile and soil is an important factor influencing PGHE-SC simulation/design. As this new model not only successfully takes the limited length of an energy pile into consideration but also distinguishes thermal properties in its modeling process, it may provide a desirable and better design tool for the PGHE-CS. © 2015 Elsevier Ltd.


Yu T.,Jinan Key Laboratory of Renewable Energy Utilization Technologies In Buildings | Liu P.,Hong Kong Polytechnic University | Chu G.,Shandong University of Technology | Li Y.,Northeast Forestry University
Advanced Materials Research | Year: 2012

Constant geothermal temperature is necessary to the long-term efficient operation of the ground source heat pump. SGSHP (Solar-Ground Source Heat Pump) system adopts solar energy as assistant heat source to maintain the geothermal temperature in cold regions. A design method based on equilibrium geothermal temperature was illustrated with an example of a villa in Beijing, China. Flowchart and control strategy of the combined system were introduced. Average heat collection efficiency and necessary area of the solar collector were derived on the basis of energy balance equation. Geothermal temperature variation was also researched to test if the solar energy and geothermal energy were reasonably matched. Results show that the combined system can maintain a constant geothermal temperature if it is well designed. The solar-ground source heat pump system is efficient, reliable and energy-saving. © (2012) Trans Tech Publications, Switzerland.

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