scholarly journals Finite Element Modeling of Geothermal Source of Heat Pump in Long-Term Operation

Energies ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1341 ◽  
Author(s):  
Elżbieta Hałaj ◽  
Leszek Pająk ◽  
Bartosz Papiernik
Keyword(s):  
Heat Pump ◽  
Thermal Energy ◽  
Heat Exchangers ◽  
Thermal Recovery ◽  
Small Scale ◽  
Term Operation ◽  
Ground Source ◽  
Space Cooling ◽  
Borehole Heat Exchangers

Model simulation allows to present the time-varying temperature distribution of the ground source for heat pumps. A system of 25 double U-shape borehole heat exchangers (BHEs) in long-term operation and three scenarios were created. In these scenarios, the difference between balanced and non-balanced energy load was considered as well as the influence of the hydrogeological factors on the temperature of the ground source. The aim of the study was to compare different thermal regimes of BHEs operation and examine the influence of small-scale and short-time thermal energy storage on ground source thermal balance. To present the performance of the system according to geological and hydrogeological factors, a Feflow® software (MIKE Powered by DHI Software) was used. The temperature for the scenarios was visualized after 10 and 30 years of the system’s operation. In this paper, a case is presented in which waste thermal energy from space cooling applications during summer months was used to upgrade thermal performance of the ground (geothermal) source of a heat pump. The study shows differences in the temperature in the ground around different Borehole Heat Exchangers. The cold plume from the not-balanced energy scenario is the most developed and might influence the future installations in the vicinity. Moreover, seasonal storage can partially overcome the negative influence of the travel of a cold plume. The most exposed to freezing were BHEs located in the core of the cold plumes. Moreover, the influence of the groundwater flow on the thermal recovery of the several BHEs is visible. The proper energy load of the geothermal source heat pump installation is crucial and it can benefit from small-scale storage. After 30 years of operation, the minimum average temperature at 50 m depth in the system with waste heat from space cooling was 2.1 °C higher than in the system without storage and 1.6 °C higher than in the layered model in which storage was not applied.

scholarly journals Finite element modeling of geothermal source of heat pump in long-term operation

2020 ◽  
Vol 154 ◽  
pp. 04003
Author(s):  
Elżbieta Hałaj
Keyword(s):  
Finite Element ◽  
Heat Source ◽  
Heat Pump ◽  
Heat Exchangers ◽  
Transport Model ◽  
Heat Pumps ◽  
Initial Temperature Distribution ◽  
Term Operation ◽  
Borehole Heat Exchangers

Heat pumps become more and more popular heat source. They can be an alternative choice for obsolete coal fired boilers which are emissive and not ecological. During heat pump installation designing process, especially for heat pumps with higher heating capacity (for example those suppling larger buildings), a simulation of heat balance of ground heat source must be provided. A 3D heat transport model and groundwater flow in the geothermal heat source for heat pump (GSHP) installation was developed in FEFLOW according to Finite Element Modelling Method. The model consists of 25 borehole heat exchangers, arranged with spacing recommended by heat pump branch guidelines. The model consists of both a homogeneous, non-layered domain and a layered domain, which reflected differences in thermal properties of the ground and hydrogeological factors. The initial temperature distribution in the ground was simulating according to conditions typical for Europe in steady state heat flow. Optimal mesh refinement for nodes around borehole heat exchangers were calculated according to Nillert method. The aim of this work is to present influence of geological, hydrogeological factors and borehole arrangement in the energy balance and long term sustainability of the ground source. The thermal changes in the subsurface have been determined for a long term operation (30 years of operation period). Some thermal energy storage applications have also been considered.

scholarly journals Ground-Source Heat Pumps with Horizontal Heat Exchangers for Space Cooling in the Hot Tropical Climate of Thailand

Energies ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1274 ◽  
Author(s):  
Arif Widiatmojo ◽  
Sasimook Chokchai ◽  
Isao Takashima ◽  
Yohei Uchida ◽  
Kasumi Yasukawa ◽  
...  
Keyword(s):  
Economic Growth ◽  
Heat Pump ◽  
Heat Exchangers ◽  
Life Cycle Cost ◽  
Heat Pumps ◽  
Ground Source Heat Pump ◽  
Ground Source Heat Pumps ◽  
Air Source Heat Pump ◽  
Ground Source ◽  
Space Cooling

The cooling of spaces in tropical regions, such as Southeast Asia, consumes a lot of energy. Additionally, rapid population and economic growth are resulting in an increasing demand for space cooling. The ground-source heat pump has been proven a reliable, cost-effective, safe, and environmentally-friendly alternative for cooling and heating spaces in various countries. In tropical countries, the presumption that the ground-source heat pump may not provide better thermal performance than the normal air-source heat pump arises because the difference between ground and atmospheric temperatures is essentially low. This paper reports the potential use of a ground-source heat pump with horizontal heat exchangers in a tropical country—Thailand. Daily operational data of two ground-source heat pumps and an air-source heat pump during a two-month operation are analyzed and compared. Life cycle cost analysis and CO2 emission estimation are adopted to evaluate the economic value of ground-source heat pump investment and potential CO2 reduction through the use of ground-source heat pumps, in comparison with the case for air-source heat pumps. It was found that the ground-source heat pumps consume 17.1% and 18.4% less electricity than the air-source heat pump during this period. Local production of heat pumps and heat exchangers, as well as rapid regional economic growth, can be positive factors for future ground-source heat pump application, not only in Thailand but also southeast Asian countries.

scholarly journals A Heat Pump-Based Multi-source Renewable Energy System for the Building Air Conditioning: The IDEAS Project Experience

2021 ◽  
Vol 65 (1) ◽  
pp. 12-22
Author(s):  
Silvia Cesari ◽  
Alessia Natali ◽  
Barbara Larwa ◽  
Eleonora Baccega ◽  
Elena Mainardi ◽  
...  
Keyword(s):  
Renewable Energy ◽  
Heat Pump ◽  
Thermal Energy ◽  
Heat Exchangers ◽  
Large Scale ◽  
Energy System ◽  
Building Envelope ◽  
Small Scale ◽  
Solar Panels ◽  
Renewable Energy System

The current paper presents the state-of-the-art of the ongoing IDEAS research project, funded under the Horizon 2020 EU framework programme. The project involves fourteen partners from six European countries and proposes a multi-source cost-effective renewable energy system for the decarbonisation of the building envelope. The system features a radiant floor fed by a heat pump for the building thermal management. The heat pump can exploit sun, air, and/or ground as thermal sources through the use of photovoltaic/thermal solar panels, air heat exchangers, and shallow ground flat-panel heat exchangers. Thermal energy storage is achieved by means of phase change materials spread along several system components, such as: radiant floor to increase its thermal inertia, solar panels for cooling purposes, ground to enhance soil thermal capacity. Within the project framework, a small-scale building, featuring a plethora of sensors for test purposes, and two large-scale buildings are meant to be equipped with the renewable energy system proposed. The small-scale building is currently in operation, and the first results are discussed in the present work. Preliminary data suggest that while multi-source systems coupled with heat pumps are particularly effective, it is complex to obtain suitable thermal energy storages on urban scale.

scholarly journals It Works—Long-Term Performance Measurement and Optimization of Six Ground Source Heat Pump Systems in Germany

Energies ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4691 ◽  
Author(s):  
Franziska Bockelmann ◽  
M. Norbert Fisch
Keyword(s):  
Heat Pump ◽  
Heat Exchangers ◽  
Control Strategies ◽  
Ground Source Heat Pump ◽  
Cooling Systems ◽  
Heating And Cooling ◽  
Ground Source ◽  
And Performance ◽  
Term Performance

Long-term studies of ground source heat pump (GSHP) heating and cooling systems for six different buildings (commercial, institutional and multi-family buildings) were conducted in Germany by Steinbeis-Innovationszentrum (SIZ) energy+. Three of them are equipped with borehole heat exchangers, and the others use energy piles as heat exchangers. This paper deals with a demonstration of the investigated buildings, the measured values and performance, and the obtained results include important findings and experiences, problems encountered and possible preventive measures to avoid mistakes. After ten years of operation, it can be stated that the systems work and achieve their planned efficiency but require constant control and regulation to avoid faulty operation. An analysis of the implemented control strategies shows that, for all these heating and cooling systems, holistically coordinated control strategies that are verified during commissioning are required.

Study on Operation Strategies of a Hybrid Ground-Source Heat Pump System with Surface Water Heat Exchangers for an Exhibition Building

2014 ◽  
Vol 672-674 ◽  
pp. 436-440
Author(s):  
Yu Dai Liu ◽  
Guo Xia Hu ◽  
Yan Qu
Keyword(s):  
Surface Water ◽  
Heat Pump ◽  
Heat Exchangers ◽  
High Efficiency ◽  
Heat Extraction ◽  
Ground Source Heat Pump ◽  
Pump System ◽  
Heat Pump System ◽  
Term Operation ◽  
Ground Source

In this study, a hybrid ground-source heat pump (GSHP) system with surface water heat exchangers is employed in an exhibition building in Shanghai to provide with high-efficiency energy for space cooling and heating and also solve the problem of thermal imbalance of the soil because of a significant imbalance between the annual heat rejection to the ground and the annual heat extraction from the ground. The operation strategies were put forward based on the annual building hourly load to make the hybrid GSHP system in a high-efficiency status during the long-term operation. The results show that the hybrid GSHP system can effectively solve the heat accumulation problem and decrease in system performance for the ten-year long run.

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