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Multi-source information fusion based fault diagnosis of ground-source heat pump using Bayesian network

Review of analytical models for heat transfer by vertical ground heat exchangers (GHEs): A perspective of time and space scales

A numerical study on the sustainability and efficiency of borehole heat exchanger coupled ground source heat pump systems

The advancement of technology and renewable energy systems (RES) have evolved considerably through the years. Geothermal energy was first introduced in Italy in 1904 and has ever since dramatically increased in efficiency. One of the main types of RES, Ground Source Heat Pumps (GSHPs), are used for heating and cooling a space when coupled with Ground Heat Exchangers (GHEs). GSHPs extract or reject heat to the Earth via a network of tubes. The closed loop system, either vertical or horizontal, is the most common of the configurations. Alternatively, pipes can run all the way down to utilize natural underground water sources, when present, in an open loop configuration. GHEs have significantly higher performance over conventional air-to-air heat exchanger systems and the reduction of their cost and the improvement of their overall efficiency through their design are crucial in research. In this paper are presented and reviewed the design aspects of GHE systems. In particular are discussed the types of GHEs such as open or closed loop systems, vertical or horizontal, U-tube or spiral, energy piles and hybrid systems. A comparative analysis through the literature of the various geometrical aspects of GHEs and the geothermal investigation of the ground environment and the materials used in the construction of GHEs are also presented. Then is analyzed the modeling – experimental and mathematical – of GHEs, with terms that have been extensively studied, like borehole thermal resistance, thermal characteristics, thermal response test, line-source and cylindrical-source models, discussed in detail. Next a demonstration of designing a numerical model of a GHE system through a software, taking into consideration the thermal characteristics, is given. Finally, a comparative detailed list in the form of a table of more than 30 mathematical and/or experimental GHE studies is provided, focusing on the important factors analyzed and findings of each. The overall aim of the current review study is to help improve the efficiency and the total manufacturing cost of GHEs.

A review of the design aspects of ground heat exchangers

Optimization of operating parameters of ground source heat pump system for space heating and cooling by Taguchi method and utility concept

Experimental and modeling analysis of a ground source heat pump system

Experimental validation of a short-term Borehole-to-Ground (B2G) dynamic model

This work presents a validation of two common methods for designing vertical ground heat exchangers. Both a simulation-based design tool and the ASHRAE handbook design equation are used to find design lengths for four different real systems, using actual experimental data, including building loads as well as physical parameters as inputs. The measured minimum and maximum ground heat exchanger exiting fluid temperatures were used as the design constraint. The simulation-based design tool predicted the borehole length to within 6% in all cases, while the ASHRAE handbook design equation yielded systems with errors from –21% to 167%. Most of this error can be explained by the way loads are represented in the ASHRAE handbook equation, with differences in the borehole thermal resistance also playing a smaller part. The ASHRAE handbook equation relies on a very simple load representation; although this allows it to be used as a simple hand calculation, it also precludes it achieving acceptable accuracy. It does ...

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Félix Ruiz-Calvo

Papers

Experimental and modeling analysis of a ground source heat pump system

Experimental validation of a short-term Borehole-to-Ground (B2G) dynamic model

Validation of vertical ground heat exchanger design methodologies

A novel numerical approach for imposing a temperature boundary condition at the borehole wall in borehole fields

A novel TRNSYS type for short-term borehole heat exchanger simulation: B2G model