scholarly journals Actualization of prospects of thermal usage of groundwater of mines during liquidation

2019 ◽  
Vol 123 ◽  
pp. 01046 ◽  
Author(s):  
Ivan Sadovenko ◽  
Oleksandr Inkin ◽  
Nataliia Dereviahina ◽  
Yuliia Khryplyvets
Keyword(s):  
Heat Transfer ◽  
Mine Water ◽  
Heat Removal ◽  
Heat Pumps ◽  
Heat Transfer Fluid ◽  
Circulation System ◽  
Heating And Cooling ◽  
Environmentally Safe ◽  
Mathcad Software ◽  
Almost All

The aim of the paper is justification of the economically efficient technological scheme for development of a thermal resource of “Stashkov” mine after its closure, ensuring the maintenance of a favorable energy and ecological-hydrogeological regime in the region. A geotechnological scheme of environmentally safe usage of mine water was justified, involving water pumping up to the surface, heat removal and water reverse pumping into the seams. The suggested circulation system is characterized by an increased energy balance, since it is used to extract almost all the groundwater heat, as well as part of the heat of host rocks. In order to estimate the effectiveness of usage of this technology, calculations of usage of mine water as a source of low-potential energy in heat pumps in comparison with other alternatives (groundwater and surface water streams) using Mathcad software were performed, and it was established that this gives great conversion coefficients of mine water. A geotechnological scheme of usage of mine water was developed, which considers heat transfer, filtration direction, velocity and temperature of groundwater during pumping and removal of heat-transfer fluid from an aquifer for heating and cooling of buildings. The mechanism of heat removal in a flooded rock massif of amine during liquidation was studied with justification of environmentally safe usage of mine water.

Mine water as a resource: space heating and cooling via use of heat pumps

2003 ◽  
Vol 11 (2) ◽  
pp. 191-198 ◽  
Author(s):  
David Banks ◽  
Helge Skarphagen ◽  
Robin Wiltshire ◽  
Chris Jessop
Keyword(s):  
Mine Water ◽  
Heat Pumps ◽  
Space Heating ◽  
Heating And Cooling ◽  
Resource Space

scholarly journals Numerical Evaluation of a HVAC System Based on a High-Performance Heat Transfer Fluid

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3298
Author(s):  
Gianpiero Colangelo ◽  
Brenda Raho ◽  
Marco Milanese ◽  
Arturo de Risi
Keyword(s):  
Heat Transfer ◽  
High Performance ◽  
Cooling System ◽  
Electrical Energy ◽  
Simulation Software ◽  
Heat Transfer Fluid ◽  
Hvac System ◽  
Dynamic Simulations ◽  
Heating And Cooling ◽  
The University

Nanofluids have great potential to improve the heat transfer properties of liquids, as demonstrated by recent studies. This paper presents a novel idea of utilizing nanofluid. It analyzes the performance of a HVAC (Heating Ventilation Air Conditioning) system using a high-performance heat transfer fluid (water-glycol nanofluid with nanoparticles of Al2O3), in the university campus of Lecce, Italy. The work describes the dynamic model of the building and its heating and cooling system, realized through the simulation software TRNSYS 17. The use of heat transfer fluid inseminated by nanoparticles in a real HVAC system is an innovative application that is difficult to find in the scientific literature so far. This work focuses on comparing the efficiency of the system working with a traditional water-glycol mixture with the same system that uses Al2O3-nanofluid. The results obtained by means of the dynamic simulations have confirmed what theoretically assumed, indicating the working conditions of the HVAC system that lead to lower operating costs and higher COP and EER, guaranteeing the optimal conditions of thermo-hygrometric comfort inside the building. Finally, the results showed that the use of a nanofluid based on water-glycol mixture and alumina increases the efficiency about 10% and at the same time reduces the electrical energy consumption of the HVAC system.

scholarly journals Using buildings' foundation as a GHE in moderate climates

2020 ◽  
Author(s):  
Lazaros Aresti ◽  
Paul Christodoulides ◽  
Georgios A. Florides
Keyword(s):  
Heat Transfer ◽  
Reinforced Concrete ◽  
Heat Pumps ◽  
Scale Model ◽  
Space Heating ◽  
Zero Energy ◽  
Ground Source Heat Pumps ◽  
Heating And Cooling ◽  
Zero Energy Building ◽  
Energy Piles

<p>Shallow Geothermal Energy, a Renewable Energy Source, finds application through Ground Source Heat Pumps (GSHPs) for space heating/cooling via tubes directed into the ground. There are two main categories of Ground Heat Exchanger (GHE) types: the horizontal and the vertical types. Ground Heat Exchangers (GHEs) of various configurations, extract or reject heat into the ground. Even though GSHP have higher performance in comparison to the Air Source Heat Pumps (ASHPs), the systems high initial costs and long payback period have made it unattractive as an investment. GSHP systems can also be utilized in the buildings foundation in the form of Thermo-Active Structure (TAS) systems or Energy Geo-Structures (EGS), with applications such as energy piles, barrette piles, diaphragm walls, shallow foundations, retaining walls, embankments, and tunnel linings. Energy piles are reinforced concrete foundations with geothermal pipes, whereby the buildings foundations are utilized to provide space heating and cooling. Apart from energy piles, another EGS system can be achieved by the incorporation of the building’s foundation bed as a GHE. Foundation piles are not required in all constructions, but a building’s foundation bed is mandatory. This configuration is still based on the principles of the energy pile.</p><p>Energy piles have yet to be applied in Cyprus and, thus, a preliminary assessment considered and investigated before application would be useful. The potential of the GSHP systems by utilizing the building’s foundation through energy piles is considered here, for a moderate climate such as Cyprus, towards a Zero Energy Building. Typical foundation piles geometry in Cyprus consists of a 10m depth, a 0.4m diameter and reinforced concrete as a grout material, which is used at the foundation bed of the building. A typical dwelling in Cyprus is selected to be numerically modelled in this study. It is a three-bedroom, two-storey house with a 190m<sup>2</sup> total floor area, matching the thermal characteristics of a Zero Energy Building (i.e., U-values of 0.4W/m<sup>2</sup>/K on all walls and ceiling and 2.25 W/m<sup>2</sup>/K on all doors and windows, respectively). A full-scale model is developed in COMSOL Multiphysics software, to examine the energy rejected or absorbed into the ground by taking the heating and cooling loads of the typical dwelling in Cyprus. The convection-diffusion equation for heat transfer is used with the three-dimensional conservation of heat transfer for an incompressible fluid on all domains except the pipes, where a simplified equation is used. Different months in winter and summer are accounted for the simulations and the fluid-in – fluid-out temperature difference is presented. Finally, an economic evaluation of the systems examined above is presented, in order to check its viability. It is concluded that utilizing the dwelling’s foundations can be a better investment than using GHEs in boreholes.</p>

scholarly journals Active magnetocaloric heat pipes provide enhanced specific power of caloric refrigeration

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Lena Maria Maier ◽  
Patrick Corhan ◽  
Alexander Barcza ◽  
Hugo A. Vieyra ◽  
Christian Vogel ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Pipes ◽  
Heat Transfer Fluid ◽  
Specific Power ◽  
Cooling Power ◽  
Cycle Frequency ◽  
Cooling Systems ◽  
Cooling Unit ◽  
Order Of Magnitude ◽  
Almost All

Abstract Today almost all refrigeration systems are based on compressors, which often require harmful refrigerants and typically reach 50% of the Carnot efficiency. Caloric cooling systems do not need any detrimental fluids and are expected to reach 60–70% of the Carnot limit. Current caloric systems utilise the active magnetocaloric regeneration principle and are quite cost-intensive, as it is challenging to achieve large cycle frequencies and thus high specific cooling powers with this principle. In this work, we present an alternative solution where the heat transfer from the heat exchangers to the caloric material is predicated on condensation and evaporation of a heat transfer fluid. Using thermal diodes, a directed heat flow is generated. Thereby we were able to build a cooling unit achieving a specific cooling power of 12.5 W g−1 at a cycle frequency of 20 Hz, which is one order of magnitude larger than the state-of-the-art.

scholarly journals Experimental Investigation on Thermal Performance of Double-U-tube Heat Exchanger Using CuO/water Nanofluid as Heat Transfer Fluid

2020 ◽  
Vol 165 ◽  
pp. 01022
Author(s):  
Ruiqing Du ◽  
Dandan Jiang ◽  
Yong Wang
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Thermal Performance ◽  
Transfer Process ◽  
Heat Transfer Process ◽  
Heat Transfer Fluid ◽  
Geothermal Heat ◽  
Tube Heat Exchanger ◽  
Heating And Cooling ◽  
Geothermal Heat Exchanger

By applying the shallow ground energy to supply building heating and cooling, the geothermal heat exchanger systems were considered as an energy-efficient building service system. In this study, the CuO/water nanofluid was employed as circuit fluids of the geothermal heat exchanger system, and the thermal performance of the heat exchanger was investigated. The results showed that the heat transfer process of CuO/water nanofluid became stable earlier than that water. Furthermore, the heat transfer rate of nanofluid was higher than that of water when the heat transfer process plateaued.

On Fluid Flow and Heat Transfer in a Pipe With a U-Bend

2013 ◽  
Author(s):  
Christopher G. Cvetkovski ◽  
Hoda S. Mozaffari ◽  
Stanley Reitsma ◽  
Tirupati Bolisetti ◽  
David S.-K. Ting
Keyword(s):  
Heat Transfer ◽  
Flow Characteristics ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Heat Pumps ◽  
Heat Transfer Fluid ◽  
Heated Wall ◽  
Dean Number ◽  
Ground Source Heat Pumps ◽  
Ground Source

Vertical ground source heat pumps operate by pumping a heat transfer fluid through a pipe buried in the ground. There is a U-Bend at its deepest point to return the fluid to the surface. Incidentally, the U-Bend does more than packing the extensive length of the heat transferring conduit within a single compact borehole. Large flow structures called Dean’s vortices are generated in the bend and these, along with the resulting turbulence produced, are known to significantly enhance the heat transfer processes, and hence, shorten the required length. This study examines the specific roles of Reynolds and Dean numbers on the flow structure and the resulting heat transfer in a pipe with a U-Bend. Water flowing in a pipe without and with heated wall was simulated using FLUENT. The model was verified based on available data in the literature. The efficacy of the local heat transfer rate along the pipe was cast with respect to the subtle changes in the flow characteristics under varying Reynolds number and Dean number.

scholarly journals A Fast-Reduced Model for an Innovative Latent Thermal Energy Storage for Direct Integration in Heat Pumps

2021 ◽  
Vol 11 (19) ◽  
pp. 8972
Author(s):  
Valeria Palomba ◽  
Andrea Frazzica
Keyword(s):  
Heat Transfer ◽  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Heat Pumps ◽  
Heat Transfer Fluid ◽  
Direct Integration ◽  
Storage Unit ◽  
Energy Storage Unit ◽  
Operating Modes

In the present paper, the numerical modeling of an innovative latent thermal energy storage unit, suitable for direct integration into the condenser or evaporator of a heat pump is presented. The Modelica language, in the Dymola environment, and TIL libraries were used for the development of a modular model, which is easily re-usable and adaptable to different configurations. Validation of the model was carried out using experimental data under different operating modes and it was subsequently used for the optimization of a design for charging and discharge. In particular, since the storage unit is made up of parallel channels for the heat transfer fluid, refrigerant, and phase change material, their number and distribution were changed to evaluate the effect on heat transfer performance.

Cooling and heating rate limits of a reversed reciprocating ericsson cycle at steady state

2000 ◽  
Vol 214 (1) ◽  
pp. 75-85 ◽  
Author(s):  
D A Blank ◽  
C Wu
Keyword(s):  
Heat Transfer ◽  
Steady State ◽  
Heat Pump ◽  
Heat Pumps ◽  
Coefficient Of Performance ◽  
Design Parameters ◽  
Optimized Design ◽  
Cooling Mode ◽  
Working Fluids ◽  
Heating And Cooling

The optimal cooling and heating rates for the reversed reciprocating Ericsson cycle with ideal regeneration are determined for heat pump operations. These limiting rates are based on the upper and lower thermal reservoir temperature bounds and are obtained using time and entropy minimization procedures from irreversible thermodynamics. Use is made of time symmetry (a second law constraint) to minimize cycle time. This optimally allocates the thermal capacitances of the cycle and minimizes internal cycle entropy generation. Although primarily a theoretical work, a very practical and extensive parametric study using several environmentally friendly working fluids (neon, nitrogen and helium) is included. This study evaluates the relative contributions of various system parameters to rate-optimized design. The coefficient of performance (COP), and thus the quantity of cooling or heating for a given energy input, is the traditional focus; instead this work aims at the rate of cooling or heating in heat pumps under steady state conditions and using ideal gases as their working substances. The results obtained provide additional criteria for use in the study, design and performance evaluation of employing Ericsson cycles in refrigeration, air conditioning and heat pump applications. They give direct insight into what is required in designing a reversed Ericsson heat pump to achieve maximum heating and cooling rates. The choices of working fluids and pressure ratios were found to be very significant design parameters, together with selection of regenerator and source—sink heat transfer parameters. The parameter most influencing both the heating and cooling mode COPs and the heat transfer rates was found to be the heat conductance of the thermal sink.

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