Possible applications of ground coupled heat pumps in high geothermal gradient zones

2014 ◽  
Vol 79 ◽  
pp. 12-22 ◽  
Author(s):  
Antonio Galgaro ◽  
Giuseppe Emmi ◽  
Angelo Zarrella ◽  
Michele De Carli
2018 ◽  
Vol 4 (7) ◽  
Author(s):  
Andrijana Stevanović ◽  
Boban Jolović

One of the most used renewable energy sources worldwide is geothermal energy. Itrepresents the heat, originated by natural processes happen in the Earth interior. The hot springsphenomena are the most frequent natural manifestation of geothermal activity.Geothermal potentiality of some area can be estimated based on geothermal gradient. Geothermalgradient is a conductive terrestrial parameter that represents the degree of increasing of the Earthtemperature vs. depth. It is usually expressed in ⁰C/m or ⁰C/km. Different areas have differentthermal gradients and thus different geothermal potential. Generally, higher geothermal gradientscorrespond to areas containing more geothermal energy.Geothermal characteristics of the territory of the Republic of Srpska are closely related to itscomplex geological setting. It is the reason why geothermal characteristics are different from areato area. Higher geothermal potentiality is recognised in the northern parts of the entity, in the firstorder in Semberija, Posavina and Banja Luka regions.The use of geothermal energy with different fluid temperatures can be considered throughthe Lindaldiagram, who firstly proposed acomprehensive scale with appropriate temperatures for differentuses. High temperature fluids are mostly used for electricity production and moderate and lowtemperature fluids for the direct use.Despite the fact that the territory of the Republic of Srpska hasfavourable geothermal properties, utilization of this kind of renewable energy resource isinadequate. Especially indicative are data about the use of geothermal energy by heat pumps (inbad sense) in comparison with praxis of developed countries.Chemical composition of thermal waters plays very important role and can be used in itsexploration stage, for analyses of possibility of its use and for prediction of exploitation effects, aswell. This kind of renewable energyresource, highly ecologically recommended, must be consideredmore seriously in the future in the Republic of Srpska. Furthermore, it must be put into the energystrategic documentsin appropriate manner.


Clay Minerals ◽  
1994 ◽  
Vol 29 (4) ◽  
pp. 681-692 ◽  
Author(s):  
B. Humphreys ◽  
S. J. Kemp ◽  
G. K. Lott ◽  
Bermanto ◽  
D.A. Dharmayanti ◽  
...  

AbstractGrain-coating chlorite cements commonly occur within sandstones of late Middle and Upper Miocene age deposited in the North Sumatra back-arc basin. Chlorites from the Lower Keutapang Member contain Ca (maximum 0.75 wt% oxide) and show textural evidence for direct precipitation on grains. However, crystals are subhedral, showing curved faces and often ragged edges, and show a tendency to merge together. In overlying beds of the Upper Keutapang Member, grain-coating chlorite-smectite (20% smectite) cements display an identical morphology but are more siliceous, have a lower octahedral occupancy and contain higher total (Na + Ca + K). It is proposed that chlorite cements in the Keutapang Formation originated as smectite-rich cement rims whose initial precipitation was related to the breakdown of volcanic detritus in the sediments. Transformation to chlorite occurred subsequently during burial, facilitated by a high geothermal gradient in the back-arc basin.


Author(s):  
Yuefen Gao ◽  
Songling Wang ◽  
Guoqiang Zhang

Ground-coupled heat pump systems use the ground as a heat source and sink either with vertical or horizontal ground heat exchangers (GHXs) to supply heating in winter and cooling in summer. The ground heat source and sink has a near constant temperature, which is well suited to ground-coupled heat pumps, giving them consistent performance, regardless of the outdoor temperature. However, when the heat extracted from and rejected to the ground has great imbalance, the ground temperature will deviate from the original temperature with a long term operation. The deviation can reduce GHX performance greatly. As China has vast territory with variety climate, the annual cooling loads and heating loads are different at different places. And the imbalance between the extracted heat and the rejected heat also varies at different places. Therefore, it is necessary to analysis the regional suitability of the ground-coupled heat pump systems. The imbalance between the extracted heat and the rejected heat is analyzed by taking several typical cities in different climates. The new concepts of the Imbalance Ratio and the Extracted Heat to Rejected Heat Ratio are introduced as the weight factors to measure the imbalance in the ground. The values of the Imbalance Ratio and those of the Extracted Heat to the Rejected Heat Ratio are calculated. The optimum range of the Imbalance Ratio is recommended based on the vast investigation of the ground-coupled heat pumps. Some supplemental systems are put forward to supply heat in winter or to reject heat in summer at the places existing serious heat imbalance. The study is very meaningful to the scientific application of the ground-coupled heat pump systems in China.


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