Research on stochastic characteristic of ground heat exchanger of ground source heat pumps with Monte-Carlo method

2011 ◽  
Author(s):  
Chen Zhihua ◽  
Chen Dechao
Keyword(s):  
Monte Carlo ◽  
Heat Exchanger ◽  
Monte Carlo Method ◽  
Heat Pumps ◽  
Ground Heat Exchanger ◽  
Ground Source Heat Pumps ◽  
Ground Source ◽  
Stochastic Characteristic

scholarly journals Field Test and Numerical Simulation on Heat Transfer Performance of Coaxial Borehole Heat Exchanger

Energies ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 5471
Author(s):  
Peng Li ◽  
Peng Guan ◽  
Jun Zheng ◽  
Bin Dou ◽  
Hong Tian ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thermal Properties ◽  
Heat Exchanger ◽  
Flow Rate ◽  
Thermal Response ◽  
Heat Pumps ◽  
Inlet Temperature ◽  
Borehole Heat Exchanger ◽  
Ground Source Heat Pumps ◽  
Ground Source

Ground thermal properties are the design basis of ground source heat pumps (GSHP). However, effective ground thermal properties cannot be obtained through the traditional thermal response test (TRT) method when it is used in the coaxial borehole heat exchanger (CBHE). In this paper, an improved TRT (ITRT) method for CBHE is proposed, and the field ITRT, based on the actual project, is carried out. The high accuracy of the new method is verified by laboratory experiments. Based on the results of the ITRT and laboratory experiment, the 3D numerical model for CBHE is established, in which the flow directions, sensitivity analysis of heat transfer characteristics, and optimization of circulation flow rate are studied, respectively. The results show that CBHE should adopt the anulus-in direction under the cooling condition, and the center-in direction under the heating condition. The influence of inlet temperature and flow rate on heat transfer rate is more significant than that of the backfill grout material, thermal conductivity of the inner pipe, and borehole depth. The circulating flow rate of CBHE between 0.3 m/s and 0.4 m/s can lead to better performance for the system.

Application of Artificial Neural Networks to Predict Heat Transfer From Buried Pipe for Ground Source Heat Pump Applications

2013 ◽  
Author(s):  
Hakan Demir ◽  
Ş. Özgür Atayılmaz ◽  
Özden Agra ◽  
Ahmet Selim Dalkılıç
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Numerical Study ◽  
Energy Resource ◽  
Heat Pumps ◽  
Burial Depth ◽  
Buried Pipe ◽  
Ground Source Heat Pumps ◽  
Ground Source ◽  
Artificial Neural

The earth is an energy resource which has more suitable and stable temperatures than air. Ground Source Heat Pumps (GSHPs) were developed to use ground energy for residential heating. The most important part of a GSHP is the Ground Heat Exchanger (GHE) that consists of pipes buried in the soil and is used for transferring heat between the soil and the heat exchanger of the GSHP. Soil composition, density, moisture and burial depth of pipes affect the size of a GHE. Design of GSHP systems in different regions of US and Europe is performed using data from an experimental model. However, there are many more techniques including some complex calculations for sizing GHEs. An experimental study was carried out to investigate heat transfer in soil. A three-layer network is used for predicting heat transfer from a buried pipe. Measured fluid inlet temperatures were used in the artificial neural network model and the fluid outlet temperatures were obtained. The number of the neurons in the hidden layer was determined by a trial and error process together with cross-validation of the experimental data taken from literature evaluating the performance of the network and standard sensitivity analysis. Also, the results of the trained network were compared with the numerical study.

Non stationary combination for the simulation of time-varying flow rates in closed-loop ground heat exchangers

2021 ◽  
Author(s):  
Gabrielle Beaudry ◽  
Philippe Pasquier ◽  
Denis Marcotte
Keyword(s):  
Heat Exchanger ◽  
Heat Pump ◽  
Closed Loop ◽  
Superposition Principle ◽  
Ground Heat Exchanger ◽  
Ground Source Heat Pump ◽  
Circulation Flow ◽  
Ground Source Heat Pumps ◽  
Flow Rates ◽  
Ground Source

<p>Ground source heat pump systems are among the most energy-efficient heating and cooling technologies. Their performance is strongly related to the accuracy of the ground heat exchanger sizing, hence requiring the forecast of the system’s temperature evolution in response to the anticipated thermal loads. Through this process, simulation techniques that make use of the superposition principle are commonly used to reduce the computational burden. In their current state, these techniques are however only suitable for addressing linear and stationary problems and do not apply to fundamental non stationary situations related to ground source heat pumps operation that involve time-variant parameters.</p><p>The present work addresses this issue by introducing a novel method based on the principle of superposition that tackles the fast evaluation of the temperature of a closed-loop ground heat exchanger operating with a dynamic heat load as well as time-variant circulation flow rates. The developed method relies on the non stationary combination, a technique borrowed from the field of seismic data processing. This technique achieves discontinuous transitions of convolution products that can be smoothened near transition times by realizing a linear interpolation over the duration of the fluid residence time.</p><p>The accuracy and efficiency of the proposed method are verified by comparing its results with those provided by reference 3D finite-elements models developed in the Comsol Multiphysics environment. For this purpose, comparative simulations<strong> </strong>representing the non stationary operation of a closed-loop system having time-variant circulation flow rates are conducted. The case of a single well is first investigated, followed by a borefield of eight wells to demonstrate the validity of the method in both scenarios.</p><p>Findings indicate that the proposed method can reproduce the reference results with a mean absolute error that is lower than 0.02 °C, and that it is faster than the numerical models by several orders of magnitude. These findings suggest that a broader range of operating scenarios can be handled by highly efficient simulation tools based on the superposition principle, which could foster the development of optimal operating strategies and lead to enhanced overall performances of ground source heat pump systems.</p>

Sign in / Sign up

Export Citation Format

Share Document