scholarly journals Recoverable Resource Prediction of Shallow Geothermal Energy in Small Towns Using the Finite Volume Method: Taking the Central Urban Area of Danyang City, Jiangsu Province, as an Example

2019 ◽  
Vol 2019 ◽  
pp. 1-14
Author(s):  
Qing Zhang ◽  
Weiya Ge ◽  
Junyuan Jia ◽  
Fujin Tian ◽  
Xiaojun Chang ◽  
...  
Keyword(s):  
Heat Exchange ◽  
Heat Release ◽  
Finite Volume Method ◽  
Urban Area ◽  
Geothermal Energy ◽  
Heat Supply ◽  
Total Heat ◽  
Total Heat Release ◽  
Shallow Geothermal Energy ◽  
Volume Method

The ground-coupled ground-source heat pump (GSHP) system is a common method for shallow geothermal energy exploitation and utilization. GSHP has a great heat exchange rate and wide application range. In order to effectively exploit shallow geothermal energy in the central urban area of Danyang City, Jiangsu Province, based on finite volume method, it is adopted to simulate the amount of recoverable shallow geothermal energy in the study area through ground-coupled heat exchange. The simulation is conducted on the development trend of thermal transport and thermal balance in the study area from early June 2015 to the end of May 2025 to obtain the temperature distribution at different times. Under the presupposed working conditions, with the operation of a ground-coupled GSHP, thermal accumulation occurs in parts of the study area. To mitigate the problem of thermal accumulation, two schemes are proposed: (1) adding auxiliary cooling towers and (2) increasing the amount heated domestic water in spring and autumn. Both schemes mitigate thermal accumulation. For Scheme  1, the total heat supply for shallow geothermal energy in the central urban area of Danyang City in winter is 2.91 × 106 kW, and the total heat release in summer is 3.53 × 106 kW. For Scheme  2, the total heat release in summer is 3.52 × 106 kW and the total heat supply in winter is 2.90 × 106 kW. A ground-coupled GSHP system has significant applicability in the central urban area of Danyang City, where shallow geothermal energy has good exploitation prospects.

Zonation for Development of Shallow Geothermal Energy in Urban Area of Kaifeng City and some Relevant Suggestions

2014 ◽  
Vol 587-589 ◽  
pp. 355-360
Author(s):  
Chao Jun Yue ◽  
Zhan Shi Liu
Keyword(s):  
Heat Exchange ◽  
Urban Area ◽  
Geothermal Energy ◽  
Comprehensive Evaluation ◽  
Research Result ◽  
Exchange System ◽  
Heat Exchange System ◽  
Shallow Geothermal Energy ◽  
Development And Utilization ◽  
Kaifeng City

Through studying the current development condition of shallow geothermal energy in urban area of Kaifeng City and the corresponding data of geological exploration, by taking into account the various factors influencing the applicability of different heat exchange systems, and by means of GIS and AHP, a comprehensive evaluation and preliminary zonation for the development of shallow geothermal energy in urban Kaifeng are carried out . The research result indicates that the development of ground heat exchange system in the whole urban area of Kaifeng City is feasible and applicable. Furthermore, some suggestions about the development and utilization of shallow geothermal energy in the area are put forward.

Simulation of Electrical Heating with Multiple Transformers

2008 ◽  
Vol 39-40 ◽  
pp. 469-474
Author(s):  
Philip Simons ◽  
Andries Habraken
Keyword(s):  
Heat Release ◽  
Model Problem ◽  
Additional Constraint ◽  
Total Heat ◽  
Electrical Heating ◽  
Total Heat Release ◽  
Electrical Currents ◽  
Electric Potentials ◽  
Scalar Potentials ◽  
Simulation Package

In the simulation package GTM-X two methods are available that approximate the electric potentials in the glass melt in the presence of multiple transformers. Both methods control the grouped electrodes in such a way that power consistency is guaranteed, also for complicated electrode groupings and transformer systems. By power consistency we mean that the total heat release, as calculated from the potentials and currents at the electrodes, matches the power that is released in the volume cells. The first method approximates two scalar potentials; it may violate the constraint that electrical currents are conserved per electrode group. The second method solves for two scalar potentials per electrode group (or transformer); the result is that also this additional constraint can be satisfied. In this article, we discuss these two methods and show results for a model problem.

scholarly journals Comparative Study on Effects of Thermal Gradient Direction on Heat Exchange between a Pure Fluid and a Nanofluid: Employing Finite Volume Method

Coatings ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1481
Author(s):  
Aimad Koulali ◽  
Aissa Abderrahmane ◽  
Wasim Jamshed ◽  
Syed M. Hussain ◽  
Kottakkaran Sooppy Nisar ◽  
...  
Keyword(s):  
Heat Exchange ◽  
Temperature Gradient ◽  
Finite Volume Method ◽  
Finite Volume ◽  
Thermal Gradient ◽  
Heat Transmission ◽  
Gravity Forces ◽  
Fluid Layers ◽  
Gradient Orientation ◽  
Volume Method

This work aims to determine how the temperature gradient orientation affects the heat exchange between two superposed fluid layers separated by zero wall thickness. The finite volume method (FVM) has been developed to solve the governing equations of both fluid layers. To achieve the coupling between the two layers, the heat flow continuity with the no-slip condition at the interface was adopted. The lower part of the space is filled with a nanofluid while the upper part is filled with a pure fluid layer. We have explored two cases of temperature gradient orientation: parallel gradient to gravity forces of our system and perpendicular gradient to gravity forces. We took a set of parameters, Ri and ϕ, to see their influence on the thermal and hydrodynamic fields as well as the heat exchange rate between the two layers. The main applications of this study related to biological systems such as the cytoplasm and the nucleoplasm are phase-separated solutions, which can be useful as models for membranelles organelles and can serve as a cooling system application using heat exchange. The Richardson number and the volume of nanosolid particles have a big impact on the rate of change of heat transmission. When a thermal gradient is perpendicular to gravity forces, total heat transmission improves with increasing solid volume percentage, but when the thermal gradient is parallel to gravity forces, overall heat transfer decreases significantly.

Numerical and Experimental Study of Merging Fires in Square Arrays

2007 ◽  
Author(s):  
Kohyu Satoh ◽  
Liu Naian ◽  
Liu Qiong ◽  
K. T. Yang
Keyword(s):  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
Forest Fires ◽  
Large Scale ◽  
Gas Flow ◽  
Fire Spread ◽  
Total Heat ◽  
Total Heat Release ◽  
Convective Gas Flow

In large-scale forest fires and city fires, merging fires and fire whirls have often been observed, which cause substantial casualties and property damages. It is important to know particularly where and under what conditions of weather such merging fires and fire whirls appear in cities or forests. However, there have been no adequate answers, since the detailed physical characteristics about them are not fully clarified yet, although previous studies have examined the phenomena of merging flames. Therefore, we have carried out preliminary studies and found that the merged tall fires can enhance the fire spread, and developed a method to analyze burn-out data of fire arrays. If sufficient knowledge can be obtained by relevant experiments and numerical computations, it may be possible to mitigate the damages due to merged fires and fire whirls. The objective of this study is to investigate the merging conditions of fires in square arrays in laboratory experiments and also by CFD numerical simulations, varying the size of square array, inter-fire distance and heat release rate, to judge ‘unmerged’ or ‘merged’ conditions in the fire array. It has been found that the fire merging is dependent on the inter-fire distance in the array and also on the total heat release rate of all fires surrounding the center region of the array. Also found that the experimental and simulated results on the merged and unmerged cases in the fire array, as affected by the total heat release rate and the inter-fire distance, which control the convective gas flow into the array, behave very similarly. Therefore, it can be concluded that the fire merging in array fires are highly based on the convection in the flow field due to fires and can be predicted by simple CFD simulations.

Development and testing of an innovative energy wall system in Torino (Italy)

2020 ◽  
Author(s):  
Matteo Baralis ◽  
Marco Barla
Keyword(s):  
Heat Exchange ◽  
Exchange Rates ◽  
Urban Areas ◽  
Geothermal Energy ◽  
High Efficiency ◽  
Cost Benefit ◽  
Energy System ◽  
Test System ◽  
Existing Building ◽  
Shallow Geothermal Energy

<p>Shallow geothermal energy (SGE) is increasingly being regarded as a valuable solution for space heating and conditioning because of high efficiency, diffuse availability and low environmental impact. Significant growth in the number of installations is envisaged as a result of energy policies and European Directives. Indeed, the obligations in the construction sector about the share of energy supply from renewable sources is increasingly pushing the design of new and renovated buildings. On the one hand shallow geothermal energy is suitable as a sustainable and distributed energy source. On the other hand, significant installation costs related to drilling of traditional installations represent an hampering factor. Thermally activating geostructures such as piles, diaphragm wall, tunnels and anchors can allow to include these costs in the construction of the structural elements. Moreover, a large availability of operational surface is represented by new and/or existing building heritage in urban areas as most of them  have underground levels that can be equipped with heat exchangers.</p><p>This contribution introduces a novel modular very shallow geothermal exchanger as part of a Heating, Ventilation and Air Conditioning (HVAC) system. The system concept allows its application not only to new structures and buildings but also to existing ones. While the low depths interested may penalize the heat exchange rates, on the contrary, extremely low installation costs make the cost-benefit ratio of this new technology extremely interesting and promising.</p><p>A first prototype consisting of three modules was designed by the authors and installed in an office building in Torino (Italy). External deployment of pipes to the basement wall in two different arrangements was realized in order to test system efficiency. Due to the experimental nature of the tests, a large number of sensors were placed to monitor the additional stresses and strains on the wall and the thermal regime of the partially saturated ground volume involved in heat exchange.</p><p>Preliminary thermal performance tests were performed together with numerical modelling re-interpretation. On the basis of the first tests and interpretation carried out, it was demonstrated that remarkable heat exchange rates of up to 20 and 27 W/m<sup>2</sup> could be injected/extracted from the ground in summer and winter respectively. Furthermore, the monitoring records suggest that extremely low affection of ground thermal status is operated by the system with respect to analogous non thermo-active walls. This evidence is extremely promising in the perspective of wide and dense diffusion of this new shallow geothermal energy system in urban areas where thermal interferences should be limited or avoided.</p>

scholarly journals Analysis of Combustion and Smoke Characteristics According to the Aging of Class 1E Cables in Nuclear Power Plants

2021 ◽  
Vol 35 (1) ◽  
pp. 20-27
Author(s):  
Seok-Hui Lee ◽  
Min-Ho Kim ◽  
Sangkyu Lee ◽  
Ju-Eun Lee ◽  
Min-Chul Lee
Keyword(s):  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Total Heat ◽  
Total Heat Release ◽  
Char Layer ◽  
Cone Calorimeter Test

In this study, combustion and smoke characteristics according to the aging of class 1E cables in nuclear power plants were analyzed through a cone calorimeter test. In the case of combustion characteristics, during the early period, which was the first peak of the heat release rate, the peak value of the non-aged cable was higher by approximately 20-50 kW/m<sup>2</sup> than that of aged cables. However, in the mid-late periods, which was the second peak, the value of the aged cables were higher than the non-aged cable due to the decrease in flame retardant performance with aging deterioration. In addition, the duration of the char layer of the aged cables was shortened by 200 s than that of the non-aged cables due to the unstable formation of char layer. The total heat release measured was approximately 1.4 times higher in the aged cables than in the non-aged cables. In the case of smoke characteristics, the smoke production rate and total smoke release show a similar trend with the heat release rate and total heat release. The total smoke release of the aged cables was measured to be higher than that of the non-aged cables. The tendency of the smoke factor increased with aging deterioration, and the values of the smoke factor in the aged cables beyond 4 years were approximately 1.76-2.0 times different from those in the non-aged cables. Consequently, the smoke risk increased with aging deterioration. Therefore, the risk of heat and smoke release increased as aging progressed.

Effect of Ignition Timing and Excess Air Ratio on Combustion Characteristic of Linear Engine

2013 ◽  
Vol 724-725 ◽  
pp. 1340-1343
Author(s):  
Zhao Lei Yin ◽  
Zhe Wang ◽  
Chen Le Sun ◽  
Tong Zhang
Keyword(s):  
Heat Release ◽  
Total Heat ◽  
Control Technique ◽  
Combustion Characteristic ◽  
Cylinder Pressure ◽  
Total Heat Release ◽  
Ignition Timing ◽  
Excess Air ◽  
Peak Cylinder Pressure ◽  
Linear Engine

Based on the linear engine prototype designed by the studying team, the combustion characteristic of the linear engine in certain revolution is investigated experimentally. The effect of ignition timing and excess air ratio on combustion characteristic of the linear engine is studied based on cycle-by-cycle control technique. The result shows that the ignition timing has effect on the combustion characteristic of linear engines in certain revolution. Advancing the ignition timing from 1.0mm BTDC (before the top dead center) to 3.0mm BTDC, the peak cylinder pressure increases, the interval between peak cylinder pressure timing and the top dead center reduces, the IMEP (indicated mean effective pressure) is down, the instantaneous heat release rises and the total heat release decreases. The excess air ratio has apparently effect on combustion characteristic of linear engines in certain revolution. Reducing the excess air ratio from 1.45 to 1.35, the peak cylinder pressure increases, the peak cylinder pressure timing is closer to the top dead center, the instantaneous heat release and the total heat release are larger.

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