Performance of heat pumps with direct expansion in vertical ground heat exchangers in heating mode

2015 ◽  
Vol 95 ◽  
pp. 120-130 ◽  
Author(s):  
Michele De Carli ◽  
Stefano Fiorenzato ◽  
Angelo Zarrella
Keyword(s):  
Heat Exchangers ◽  
Heat Pumps ◽  
Direct Expansion ◽  
Ground Heat Exchangers ◽  
Vertical Ground ◽  
Heating Mode

scholarly journals The energy source for heat pumps with vertical heat exchangers

2018 ◽  
Vol 44 ◽  
pp. 00157
Author(s):  
Piotr Rynkowski
Keyword(s):  
Heat Pump ◽  
Heat Exchangers ◽  
Electricity Consumption ◽  
Heat Pumps ◽  
Coefficient Of Performance ◽  
Temperature Analysis ◽  
Heat Flows ◽  
Ground Heat Exchangers ◽  
Vertical Heat ◽  
Vertical Ground

The paper presents the ground temperature analysis, heat flows and energy transferred from the soil massif by the vertical ground heat exchangers (VGHE). Three cases – with one, two and three vertical heat exchangers were compared. Their influences on the soil massif temperature in the heat exchangers area were shown. The mass flow and the temperature at the inlet and outlet side of the heat pump were measured in each circuit. Additional, the electricity consumption by the heat pump and energy supply to buffer vessel were measured. Finally, the Coefficient of Performance (COP) as a function of length of VGHE is shown for selected interval time.

Soil Profile and Ground Properties Influence on Vertical Ground Heat Exchanger Efficiency

2017 ◽  
Author(s):  
Michał Chwieduk ◽  
Artur Rusowicz ◽  
Hanna Jędzrzejuk
Keyword(s):  
Heat Exchanger ◽  
Soil Profile ◽  
Heat Exchangers ◽  
Heat Pumps ◽  
Symmetric Model ◽  
Ground Heat Exchanger ◽  
Ground Heat Exchangers ◽  
Calculation Results ◽  
Vertical Ground ◽  
The Impact

Soil properties have a significant impact on the performance of ground heat exchangers. Exchangers cooperating with heat pumps are a reliable and efficient source of renewable energy. In the article concentric vertical ground heat exchanger is analysed, which is a common application cooperating with heat pumps. Soil and ground properties have great im-portance during sizing the system, i.e.: determining the length, configuration and deployment of ground heat exchangers. With the depth the soil/ground type and its properties can change significantly. In addition, occurrence of a ground water can influence physical and thermal properties. Determination of soil type present at different depths in a specific location is possible by performing a soil profile. The article presents an analysis of the impact of two soil profiles on the efficien-cy of the vertical ground heat exchanger. The analysis was performed based on the model of a single heat exchanger made using CFD (Computational Fluid Dynamics) program. The model is divided into two parts: model of heat ex-changer together with grout filling the borehole, second: axis-symmetric model of the ground surrounding the exchanger. Both models are coupled by first-type boundary condition. Simulations of ground heat exchanger work are made for a part of heating season period. The calculation results were compared to reference one with uniform ground profiles. Dif-ference in heat rejected form ground in two analysed does not show high influence of ground layers on ground heat ex-changer performance. On the other hand, results strongly depends on analysed soil profile.

The Influence of Outer Weather Conditions on the Modelling of Vertical Ground Heat Exchangers

2013 ◽  
Vol 361-363 ◽  
pp. 276-280
Author(s):  
Pascual Álvarez Gómez ◽  
Ismael Rodríguez Maestre ◽  
F. Javier González Gallero ◽  
J. Daniel Mena Baladés
Keyword(s):  
Heat Exchangers ◽  
Carbon Dioxide Emission ◽  
Weather Conditions ◽  
Heat Pumps ◽  
Weather Data ◽  
Fluid Temperature ◽  
Ground Heat Exchangers ◽  
Ansys Cfx ◽  
Vertical Ground ◽  
Surface Borehole

Policies for energy saving and carbon dioxide emission reduction have enouraged the use of efficient technologies in building thermal conditioning, like geothermal source heat pumps [. Most of the thermal models used to simulate the performance of vertical ground heat exchangers do not consider the effect of outer weather conditions, except for the setting of the initial ground temperature [. This paper shows a study to assess the effect of outer weather conditions on the outlet fluid temperature, especially during the upper part of the exchanger. Different depths for typical configurations of ground heat exchangers have been analysed. Detailed simulations have been developed for a full year of performance using a commercial finite volume computational fluid dynamics (CFD) code (©ANSYS-CFX). Outer weather conditions have been set by using synthetic hourly weather data and considering all of the heat transfer phenomena involved. Errors in outlet fluid temperature and surface borehole temperature have been estimated for the whole year of simulation.

scholarly journals Application and Design Aspects of Ground Heat Exchangers

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2134
Author(s):  
Luka Boban ◽  
Dino Miše ◽  
Stjepan Herceg ◽  
Vladimir Soldo
Keyword(s):  
Renewable Energy ◽  
Heat Exchangers ◽  
Geothermal Energy ◽  
Energy Demand ◽  
Design Parameters ◽  
Direct Expansion ◽  
Alternative Source ◽  
Ground Heat Exchangers ◽  
Point Of Interest ◽  
Constant Source

With the constant increase in energy demand, using renewable energy has become a priority. Geothermal energy is a widely available, constant source of renewable energy that has shown great potential as an alternative source of energy in achieving global energy sustainability and environment protection. When exploiting geothermal energy, whether is for heating or cooling buildings or generating electricity, a ground heat exchanger (GHE) is the most important component, whose performance can be easily improved by following the latest design aspects. This article focuses on the application of different types of GHEs with attention directed to deep vertical borehole heat exchangers and direct expansion systems, which were not dealt with in detail in recent reviews. The article gives a review of the most recent advances in design aspects of GHE, namely pipe arrangement, materials, and working fluids. The influence of the main design parameters on the performance of horizontal, vertical, and shallow GHEs is discussed together with commonly used performance indicators for the evaluation of GHE. A survey of the available literature shows that thermal performance is mostly a point of interest, while hydraulic and/or economic performance is often not addressed, potentially resulting in non-optimal GHE design.

Modeling and assessment of the efficiency of horizontal and vertical ground heat exchangers

Energy ◽  
2013 ◽  
Vol 58 ◽  
pp. 655-663 ◽  
Author(s):  
G. Florides ◽  
E. Theofanous ◽  
I. Iosif-Stylianou ◽  
S. Tassou ◽  
P. Christodoulides ◽  
...  
Keyword(s):  
Heat Exchangers ◽  
Ground Heat Exchangers ◽  
Vertical Ground

Modeling of vertical ground heat exchangers in the presence of groundwater flow and underground temperature gradient

2019 ◽  
Vol 192 ◽  
pp. 15-30 ◽  
Author(s):  
Iosifina Iosif Stylianou ◽  
Savvas Tassou ◽  
Paul Christodoulides ◽  
Lazaros Aresti ◽  
Georgios Florides
Keyword(s):  
Temperature Gradient ◽  
Groundwater Flow ◽  
Heat Exchangers ◽  
Ground Heat Exchangers ◽  
Vertical Ground

Comparison of effective thermal conductivity in closed-loop vertical ground heat exchangers

2011 ◽  
Vol 31 (17-18) ◽  
pp. 3669-3676 ◽  
Author(s):  
Chulho Lee ◽  
Moonseo Park ◽  
Sunhong Min ◽  
Shin-Hyung Kang ◽  
Byonghu Sohn ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Effective Thermal Conductivity ◽  
Heat Exchangers ◽  
Closed Loop ◽  
Ground Heat Exchangers ◽  
Vertical Ground
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