Low Enthalpy Geothermal Resources for Local Sustainable Development: A Case Study in Poland

Many regions in Poland face the problem of air pollution. These regions include, though are not exclusive, to health resorts, an important element of the healthcare industry. Poor air quality is mainly associated with the domestic sector, which is dominated by individual solid fuel and coal boilers. One option for reducing emissions is to use alternative energy sources for heating purposes. Therefore, the paper presents an analysis into the possibility of using low enthalpy (low temperature) geothermal energy in health resort areas. The main purpose of the article is to estimate the potential of soil and water as the lower source for a heat pump. The article presents analyses of geological and hydrogeological conditions based on which the thermal parameters of the rock mass were determined, which were thermal conductivity and unit heat output for 1800 operating hours per year. The calculated values were used to perform a spatial analysis of the data and create maps of the average thermal conductivity for horizontal ground heat exchangers (HGHE) to a depth of 2 and 10 m and vertical ground heat exchangers (VGHE) in depth ranges up to 30, 60, and 90 m. The heating power of the intakes, located in the research area, were estimated using empirical formulas. In addition, a detailed analysis of the physicochemical parameters of groundwater in terms of the requirements indicated by four heat pump manufacturers is presented. The results of the presented research makes it possible to assess the potential of low-temperature geothermal energy and to characterize the suitability of the selected location for the use of HGHE, VGHE, and wells. As a result, the discussed area was found to have a high potential for the use of ground source heat pumps and a moderate potential for the use of low-temperature systems based on groundwater.

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Analysis and Comparison of Some Low-Temperature Heat Sources for Heat Pumps

Energies ◽

10.3390/en12101853 ◽

2019 ◽

Vol 12 (10) ◽

pp. 1853 ◽

Cited By ~ 3

Author(s):

Pavel Neuberger ◽

Radomír Adamovský

Keyword(s):

Heat Transfer ◽

Low Temperature ◽

Heat Source ◽

Heat Pump ◽

Heat Exchangers ◽

Ambient Air ◽

Heat Transfer Fluid ◽

Heat Sources ◽

Ground Heat Exchangers ◽

Temperature Heat

The efficiency of a heat pump energy system is significantly influenced by its low-temperature heat source. This paper presents the results of operational monitoring, analysis and comparison of heat transfer fluid temperatures, outputs and extracted energies at the most widely used low temperature heat sources within 218 days of a heating period. The monitoring involved horizontal ground heat exchangers (HGHEs) of linear and Slinky type, vertical ground heat exchangers (VGHEs) with single and double U-tube exchanger as well as the ambient air. The results of the verification indicated that it was not possible to specify clearly the most advantageous low-temperature heat source that meets the requirements of the efficiency of the heat pump operation. The highest average heat transfer fluid temperatures were achieved at linear HGHE (8.13 ± 4.50 °C) and double U-tube VGHE (8.13 ± 3.12 °C). The highest average specific heat output 59.97 ± 41.80 W/m2 and specific energy extracted from the ground mass 2723.40 ± 1785.58 kJ/m2·day were recorded at single U-tube VGHE. The lowest thermal resistance value of 0.07 K·m2/W, specifying the efficiency of the heat transfer process between the ground mass and the heat transfer fluid, was monitored at linear HGHE. The use of ambient air as a low-temperature heat pump source was considered to be the least advantageous in terms of its temperature parameters.

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Ground-Source Heat Pump Systems: The Effects of Variable Trench Separations and Pipe Configurations in Horizontal Ground Heat Exchangers

Energies ◽

10.3390/en14133919 ◽

2021 ◽

Vol 14 (13) ◽

pp. 3919

Author(s):

Yu Zhou ◽

Asal Bidarmaghz ◽

Nikolas Makasis ◽

Guillermo Narsilio

Keyword(s):

Thermal Conductivity ◽

Effective Thermal Conductivity ◽

Heat Pump ◽

Heat Exchangers ◽

Element Model ◽

Fluid Temperature ◽

Ground Source Heat Pump ◽

Carrier Fluid ◽

Ground Heat Exchangers ◽

Ground Source

Ground-source heat pump systems are renewable and highly efficient HVAC systems that utilise the ground to exchange heat via ground heat exchangers (GHEs). This study developed a detailed 3D finite element model for horizontal GHEs by using COMSOL Multiphysics and validated it against a fully instrumented system under the loading conditions of rural industries in NSW, Australia. First, the yearly performance evaluation of the horizontal straight GHEs showed an adequate initial design under the unique loads. This study then evaluated the effects of variable trench separations, GHE configurations, and effective thermal conductivity. Different trench separations that varied between 1.2 and 3.5 m were selected and analysed while considering three different horizontal loop configurations, i.e., the horizontal straight, slinky, and dense slinky loop configurations. These configurations had the same length of pipe in one trench, and the first two had the same trench length as well. The results revealed that when the trench separation became smaller, there was a minor increasing trend (0.5 °C) in the carrier fluid temperature. As for the configuration, the dense slinky loop showed an average that was 1.5 °C lower than those of the horizontal straight and slinky loop (which were about the same). This indicates that, when land is limited, compromises on the trench separation should be made first in lieu of changes in the loop configuration. Lastly, the results showed that although the effective thermal conductivity had an impact on the carrier fluid temperature, this impact was much lower compared to that for the GHE configurations and trench separations.

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Thermo-Economical Optimization of Ground Source Heat Pump With Horizontal Ground Heat Exchangers for a Heating Season in Istanbul: A Case Study

Volume 1C, Symposia: Fundamental Issues and Perspectives in Fluid Mechanics; Industrial and Environmental Applications of Fluid Mechanics; Issues and Perspectives in Automotive Flows; Gas-Solid Flows: Dedicated to the Memory of Professor Clayton T. Crowe; Numerical Methods for Multiphase Flow; Transport Phenomena in Energy Conversion From Clean and Sustainable Resources; Transport Phenomena in Materials Processing and Manufacturing Processes ◽

10.1115/fedsm2014-21483 ◽

2014 ◽

Author(s):

Hakan Demir ◽

Alişan Gönül ◽

Nurullah Kayaci ◽

Ş. Özgür Atayılmaz ◽

Özden Ağra

Keyword(s):

Soil Temperature ◽

Objective Function ◽

Heat Pump ◽

Heat Exchangers ◽

Burial Depth ◽

Ground Source Heat Pump ◽

Economic Optimization ◽

Ground Source Heat Pumps ◽

Ground Heat Exchangers ◽

Ground Source

A ground-source heat pump (GSHP) system has three major components: a heat pump, an earth connection and an interior heating or cooling distribution system. The most important part of a ground source heat pump (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 evaporator of the ground source heat pump. There are plenty of works on ground source heat pumps and ground heat exchangers in the literature. Most of the works on ground heat exchangers are based on the heat transfer in the soil and temperature distribution around the coil. Some of the works for thermo-economic optimization of thermal systems are based on thermodynamic cycles. In this paper, it was carried out that the thermo-economic optimization of a ground source heat pump system with horizontal ground heat exchangers operating in heating mode in Istanbul in Turkey. The monthly heat loads of a villa for every heating months were worked out by using TS825® program. Also, average soil temperature has been calculated according to soil surface temperatures taken from Turkish State Meteorological Service belonging to last ten years. An objective function was defined based on heating capacity, initial investment and operating costs of ground source heat pump (GSHP). Then, the effects of the soil thermal conductivity, burial depth and variation of soil temperature on the objective function were investigated. Also, variation of COP value was carried out for burial depth and different condensation temperatures monthly.

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The optimal parameters technique for the vertical ground heat exchangers of the geothermal heat pump systems

Journal of Physics Conference Series ◽

10.1088/1742-6596/1791/1/012023 ◽

2021 ◽

Vol 1791 (1) ◽

pp. 012023

Author(s):

B A Semenov ◽

D S Saponenko

Keyword(s):

Heat Pump ◽

Heat Exchangers ◽

Optimal Parameters ◽

Geothermal Heat ◽

Ground Heat Exchangers ◽

Geothermal Heat Pump ◽

Vertical Ground

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Application and Design Aspects of Ground Heat Exchangers

Energies ◽

10.3390/en14082134 ◽

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.

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Study on a design method for hybrid ground heat exchangers of ground-coupled heat pump system

International Journal of Refrigeration ◽

10.1016/j.ijrefrig.2016.12.020 ◽

2017 ◽

Vol 76 ◽

pp. 394-405 ◽

Cited By ~ 11

Author(s):

Kejuan Wei ◽

Wenxin Li ◽

Jiarong Li ◽

Yong Wang ◽

Lu Zhang

Keyword(s):

Heat Pump ◽

Heat Exchangers ◽

Design Method ◽

Pump System ◽

Heat Pump System ◽

Ground Heat Exchangers ◽

Ground Coupled Heat Pump

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Research on Fresh and Hardened Sealing Slurries with the Addition of Magnesium Regarding Thermal Conductivity for Energy Piles and Borehole Heat Exchangers

Energies ◽

10.3390/en14165119 ◽

2021 ◽

Vol 14 (16) ◽

pp. 5119

Author(s):

Tomasz Sliwa ◽

Tomasz Kowalski ◽

Dominik Cekus ◽

Aneta Sapińska-Śliwa

Keyword(s):

Thermal Conductivity ◽

Renewable Energy ◽

Heat Exchangers ◽

Geothermal Energy ◽

Cooling System ◽

Renewable Energy Sources ◽

Heat Pumps ◽

Cement Slurry ◽

Geological Conditions ◽

Borehole Heat Exchangers

Currently, renewable energy is increasingly important in the energy sector. One of the so-called renewable energy sources is geothermal energy. The most popular solution implemented by both small and large customers is the consumption of low-temperature geothermal energy using borehole heat exchanger (BHE) systems assisted by geothermal heat pumps. Such an installation can operate regardless of geological conditions, which makes it extremely universal. Borehole heat exchangers are the most important elements of this system, as their design determines the efficiency of the entire heating or heating-and-cooling system. Filling/sealing slurry is amongst the crucial structural elements. In borehole exchangers, reaching the highest possible thermal conductivity of the cement slurry endeavors to improve heat transfer between the rock mass and the heat carrier. The article presents a proposed design for such a sealing slurry. Powdered magnesium was used as an additive to the cement. The approximate cost of powdered magnesium is PLN 70–90 per kg (EUR 15–20/kg). Six different slurry formulations were tested. Magnesium flakes were used in designs A, B, C, and magnesium shavings in D, E and F. The samples differed in the powdered magnesium content BWOC (by weight of cement). The parameters of fresh and hardened sealing slurries were tested, focusing mainly on the thermal conductivity parameter. The highest thermal conductivity values were obtained in design C with the 45% addition of magnesium flakes BWOC.

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

Energies ◽

10.3390/en12071274 ◽

2019 ◽

Vol 12 (7) ◽

pp. 1274 ◽

Cited By ~ 5

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.

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