Energy and Environmental Impact of Groundwater Heat Pumps in Urban Areas

2012 ◽  
Author(s):  
Vittorio Verda ◽  
Adriano Sciacovelli ◽  
Stefano Lo Russo ◽  
Glenda Taddia
Keyword(s):  
Heat Transfer ◽  
Environmental Impact ◽  
Heat Pump ◽  
Urban Areas ◽  
Fluid Dynamic ◽  
Heat Pumps ◽  
Thermal Plume ◽  
Groundwater Temperature ◽  
Groundwater Velocity ◽  
The Impact

Heat pumps are expected to play a major role in future energy scenarios. Proliferation of these systems in urban areas may cause issues related to environmental impact on water basins and interactions between installations. Both issues are associated with the thermal plume produced by the heat pump during operation and are particularly evident in the case of groundwater flow, because of the advective term of heat transfer. In this paper, the impact of heat pump installations is calculated through a thermo-fluid dynamic model of the subsurface which considers fluid flow in the saturated unit and heat transfer both in the saturated and unsaturated units. This model is coupled with the thermal request of the user and the heat pump performances through appropriate boundary conditions imposed at the wells. Various scenarios corresponding to different annual heating/cooling request, groundwater velocity, groundwater temperature variation are considered.

Technical Note. Influence of Material Used for the Regenerator on the Properties of a Thermoacoustic Heat Pump

2013 ◽  
Vol 38 (4) ◽  
pp. 565-570 ◽  
Author(s):  
Bartłomiej Kruk
Keyword(s):  
Heat Transfer ◽  
Temperature Gradient ◽  
Acoustic Wave ◽  
Heat Pump ◽  
Sound Wave ◽  
Heat Exchangers ◽  
Heat Pumps ◽  
Technical Note ◽  
New Materials ◽  
Modern Technologies

Abstract Research in termoacoustics began with the observation of the heat transfer between gas and solids. Using this interaction the intense sound wave could be applied to create engines and heat pumps. The most important part of thermoacoustic devices is a regenerator, where press of conversion of sound energy into thermal or vice versa takes place. In a heat pump the acoustic wave produces the temperature difference at the two ends of the regenerator. The aim of the paper is to find the influence of the material used for the construction of a regenerator on the properties of a thermoacoustic heat pump. Modern technologies allow us to create new materials with physical properties necessary to increase the temperature gradient on the heat exchangers. The aim of this paper is to create a regenerator which strongly improves the efficiency of the heat pump.

scholarly journals Local Heating Networks with Waste Heat Utilization: Low or Medium Temperature Supply?

Energies ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 954 ◽  
Author(s):  
Hanne Kauko ◽  
Daniel Rohde ◽  
Armin Hafner
Keyword(s):  
Low Temperature ◽  
Heat Pump ◽  
Urban Areas ◽  
Waste Heat ◽  
Local Heating ◽  
District Heating ◽  
Heat Pumps ◽  
Hot Water ◽  
Local Network ◽  
Medium Temperature

District heating enables an economical use of energy sources that would otherwise be wasted to cover the heating demands of buildings in urban areas. For efficient utilization of local waste heat and renewable heat sources, low distribution temperatures are of crucial importance. This study evaluates a local heating network being planned for a new building area in Trondheim, Norway, with waste heat available from a nearby ice skating rink. Two alternative supply temperature levels have been evaluated with dynamic simulations: low temperature (40 °C), with direct utilization of waste heat and decentralized domestic hot water (DHW) production using heat pumps; and medium temperature (70 °C), applying a centralized heat pump to lift the temperature of the waste heat. The local network will be connected to the primary district heating network to cover the remaining heat demand. The simulation results show that with a medium temperature supply, the peak power demand is up to three times higher than with a low temperature supply. This results from the fact that the centralized heat pump lifts the temperature for the entire network, including space and DHW heating demands. With a low temperature supply, heat pumps are applied only for DHW production, which enables a low and even electricity demand. On the other hand, with a low temperature supply, the district heating demand is high in the wintertime, in particular if the waste heat temperature is low. The choice of a suitable supply temperature level for a local heating network is hence strongly dependent on the temperature of the available waste heat, but also on the costs and emissions related to the production of district heating and electricity in the different seasons.

scholarly journals Characterization of the subsurface urban heat island and its sources in the Milan city area, Italy

2021 ◽  
Author(s):  
Alberto Previati ◽  
Giovanni B. Crosta
Keyword(s):  
Urban Heat Island ◽  
Urban Areas ◽  
Heat Fluxes ◽  
Shallow Aquifer ◽  
Heat Island ◽  
Groundwater Temperature ◽  
City Area ◽  
Groundwater Environment ◽  
Urban Heat ◽  
The Impact

AbstractUrban areas are major contributors to the alteration of the local atmospheric and groundwater environment. The impact of such changes on the groundwater thermal regime is documented worldwide by elevated groundwater temperature in city centers with respect to the surrounding rural areas. This study investigates the subsurface urban heat island (SUHI) in the aquifers beneath the Milan city area in northern Italy, and assesses the natural and anthropogenic controls on groundwater temperatures within the urban area by analyzing groundwater head and temperature records acquired in the 2016–2020 period. This analysis demonstrates the occurrence of a SUHI with up to 3 °C intensity and reveals a correlation between the density of building/subsurface infrastructures and the mean annual groundwater temperature. Vertical heat fluxes to the aquifer are strongly related to the depth of the groundwater and the density of surface structures and infrastructures. The heat accumulation in the subsurface is reflected by a constant groundwater warming trend between +0.1 and + 0.4 °C/year that leads to a gain of 25 MJ/m2 of thermal energy per year in the shallow aquifer inside the SUHI area. Future monitoring of groundwater temperatures, combined with numerical modeling of coupled groundwater flow and heat transport, will be essential to reveal what this trend is controlled by and to make predictions on the lateral and vertical extent of the groundwater SUHI in the study area.

scholarly journals Numerical simulation of urban thermal plume merging

2021 ◽  
Author(s):  
Shuojun Mei ◽  
Chao Yuan ◽  
Wenhui He ◽  
Tanya Talwar
Keyword(s):  
Air Quality ◽  
Thermal Comfort ◽  
Urban Areas ◽  
Turbulence Models ◽  
Wave Radiation ◽  
Thermal Plume ◽  
Water Tank ◽  
Surface Cooling ◽  
Thermal Plumes ◽  
The Impact

<p>Densely packed urban buildings trap outgoing long-wave radiation, leading to reduced surface cooling and increased building surface temperature. In calm conditions, poor natural ventilation causes both thermal comfort and air quality issue. The buoyancy flow generated by heated urban surfaces is the main driving of the urban flow and pollutant dispersion. A 3D numerical modelling is conducted to investigate the thermal plumes merging and buoyancy-driven airflow in urban areas. The performances of four different turbulence models, i.e., two URANS (Unsteady Reynolds-averaged Navier–Stokes equations) models and two LES (Large-Eddy Simulation) models are evaluated by comparing the velocity field with previous water tank measurements. Validation results show that all four turbulence models can capture the bending of thermal plumes toward the centre, and LES models provide a better prediction on the vertical velocity profiles, while both URANS models show underestimation. The plume merging mechanism is analysed with the high accuracy LES results. Both pressure difference and swaying motion caused by mean flow and turbulence are important for plume merging. The turbulence coherent structure of plume merging is analysed by a quadrant analysis, which shows ejection and sweep events could significantly change with the building density. A case study with complex urban geometry is conducted to show the impact of thermal plumes merging in the real high-density urban areas. The convergence airflow at the pedestrian level is estimated to 2 m/s under a surface-air temperature difference of 5 °C, which is comparable to wind-driven ventilation and beneficial to thermal comfort and air quality.</p>

scholarly journals Economic Analysis and Environmental Impact Assessment of Heat Pump-Assisted Distillation in a Gas Fractionation Unit

Energies ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 852 ◽  
Author(s):  
Jisook Lee ◽  
Yongho Son ◽  
Kwang Lee ◽  
Wangyun Won
Keyword(s):  
Environmental Impact ◽  
Economic Analysis ◽  
Impact Assessment ◽  
Heat Pump ◽  
Environmental Impact Assessment ◽  
Fossil Fuels ◽  
New Technologies ◽  
Heat Pumps ◽  
Environmental Drivers ◽  
Feed Composition

The depletion of fossil fuels and environmental pollution (e.g., greenhouse gas emissions) through the combustion of fossil fuels have stimulated studies on new technologies able to curtail the energy consumption of existing fractionation units. In this regard, heat pumps have garnered substantial attention due to their potential to improve the process energy efficiency. This study aims to provide extensive economic analysis and environmental impact assessment of the application of heat pumps under different conditions and scenarios. For this purpose, we first selected three important conditions: feed composition, plant capacity, and fuel price. Then, we performed a range of analyses to identify the major costs and environmental drivers. The economics and environmental impact of heat pump-assisted distillation was investigated and compared with those of conventional distillation.

scholarly journals Groundwater-Related Issues of Ground Source Heat Pump (GSHP) Systems: Assessment, Good Practices and Proposals from the European Experience

Water ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1573 ◽  
Author(s):  
Casasso ◽  
Sethi
Keyword(s):  
Groundwater Quality ◽  
Urban Areas ◽  
Plant Density ◽  
Heat Pumps ◽  
Pollutant Emissions ◽  
Groundwater Temperature ◽  
Ground Source Heat Pumps ◽  
Best Available Techniques ◽  
Ground Source ◽  
High Plant Density

Ground source heat pumps (GSHPs) gained increasing interest owing to benefits such as low heating and cooling costs, reduction of greenhouse gas emissions, and no pollutant emissions on site. However, GSHPs may have various possible interactions with underground and groundwater, which, despite the extremely rare occurrence of relevant damages, has raised concerns on their sustainability. Possible criticalities for their installation are (hydro)geological features (artesian aquifers, swelling or soluble layers, landslide-prone areas), human activities (mines, quarries, landfills, contaminated sites), and groundwater quality. Thermal alterations due to the operation of GSHPs may have an impact on groundwater chemistry and on the efficiency of neighboring installations. So far, scientific studies excluded appraisable geochemical alterations within typical ranges of GSHPs (±6 K on the initial groundwater temperature); such alterations, however, may occur for aquifer thermal energy storage over 40 °C. Thermal interferences among neighboring installations may be severe in urban areas with a high plant density, thus highlighting the need for their proper management. These issues are presented here and framed from a groundwater quality protection perspective, providing the basis for a discussion on critical aspects to be tackled in the planning, authorization, installation, and operation phase. GSHPs turn out to be safe and sustainable if care is taken in such phases, and the best available techniques are adopted.

The Impact of Fin Deformation on Condensation Heat Transfer Coefficients in Internally Grooved Tubes

2013 ◽  
Author(s):  
Sunil Mehendale
Keyword(s):  
Heat Transfer ◽  
Heat Exchangers ◽  
Thermal Contact ◽  
Heat Pumps ◽  
Condensation Heat Transfer ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Condensing Heat Transfer ◽  
The Impact ◽  
Tube Expansion

In HVACR equipment, internally enhanced round tube (microfin) designs such as axial, cross-grooved, helical, and herringbone are commonly used to enhance the boiling and condensing performance of evaporators, condensers, and heat pumps. Typically, such tubes are mechanically expanded by a mandrel into a fin pack to create an interference fit between the tube outside surface and the fin collar to minimize the thermal contact resistance between tube and fin. However, during this expansion process, the internal enhancements undergo varying amounts of deformation, which degrades the in-tube thermal performance. Extensive data on condensing heat transfer coefficients in microfin tubes have been reported in the open literature. However, researchers have seldom used expanded tubes to acquire and report such data. Hence, it is always questionable to use such pristine tube data for designing heat exchangers and HVACR systems. Furthermore, the HVACR industry has been experiencing steeply rising copper costs, and this trend is expected to continue in coming years. So, many equipment manufacturers and suppliers are actively converting tubes from copper to aluminum. However, because of appreciable differences between the material properties of aluminum and copper, as well as other manufacturing variables, such as mandrel dimensions, lubricant used, etc., tube expansion typically deforms aluminum fins more than copper fins. Based on an analysis of the surface area changes arising from tube expansion, and an assessment of the best extant in-tube condensation heat transfer correlations, this work proposes a method of estimating the impact of tube expansion on in-tube condensation heat transfer. The analysis leads to certain interesting and useful findings correlating fin geometry and in-tube condensation thermal resistance. This method can then be applied to more realistically design HVACR heat exchangers and systems.

Energy Saving and Emission Reduction in Power Generation Sector for China’s Heat Pump Heating

2012 ◽  
Vol 608-609 ◽  
pp. 961-964
Author(s):  
Xia Chen ◽  
Li Wang ◽  
Li Ge Tong ◽  
Shu Feng Sun ◽  
Xian Fang Yue ◽  
...  
Keyword(s):  
Power Generation ◽  
Energy Saving ◽  
Heat Pump ◽  
Emission Reduction ◽  
Co2 Emission ◽  
Positive Impact ◽  
Current Trend ◽  
Northern China ◽  
Heat Pumps ◽  
The Impact

China is ranked as the world’s largest emitter of carbon dioxide (CO2). The CO2 emission from urban central heating (UCH) is responsible for 4.4% of China’s total CO2 emission. It is proposed that heat pump heating (HPH) could serve as a replacement for UCH to help realize energy-saving and emission-reduction goals to a greater extent. In northern China, 30% of urban building area is covered by urban decentralized heating (UDH). Replacing UDH with HPH is the current trend in China. In this paper we analyze the impact of replacing coal with heat pumps on the power generation sector in China. The results show that HPH has a positive impact on the power generation sector. By considering simultaneous replacement of UCH and UDH with HPH, the efficiency of power generation at the valley electricity time is increased by 0.512%; the ratio of peak–valley difference is decreased by 25.3%; the obtained reduction of CO2 emission cumulatively contributes to approximately 10.96% of this target.

scholarly journals The importance of site on house heating energy modelling in Wellington - Integrating EnergyPlus with ENVI-met for site modelling

2021 ◽  
Author(s):  
◽  
Wendy Sunarya
Keyword(s):  
Design Process ◽  
Urban Areas ◽  
Fluid Dynamic ◽  
Ground Surface ◽  
Building Design ◽  
Building Energy ◽  
Design Strategies ◽  
Site Location ◽  
Energy Modelling ◽  
The Impact

<p>Site is an important factor in the building design process, where it is analysed to determine design strategies for responding the microclimate. It is also considered important in Building Energy Simulations (BES) where a weather file is used to represent the site location and its microclimate. However, many cases of BES in the design process use weather file from a nearby weather station rather than site specific microclimate. In fact, site microclimate can be affected by nearby parameters such as ground surface and vegetation, with unknown effects. In the Wellington, New Zealand context, micro-climates vary widely due to the local topography while suburban houses can be located on the side or bottom of a hill. These houses are likely to have different exposure to the sun and wind which can influence energy consumption for space heating.  Many studies about site-parameters impacts mainly focus on the vegetation and nearby buildings effect on microclimate. Only a few estimated the impact of site-parameters on building energy use and mostly their cases are in urban areas (flat terrain). Unfortunately, site parameters, such as altitude and slope, associated with the Wellington topography (hilly terrain) have never been examined. This thesis investigates the importance of site parameters on house heating energy modelling for the Wellington context. BES software, EnergyPlus, was used and explored to identify limitations in modelling site parameters. An attempt was made to solve these limitations through the integration with microclimate software. Three microclimate software programmes were reviewed: ENVI-met, UWG (Urban Weather Generator) and CFD (Computational Fluid Dynamic) software.  ENVI-met was selected to generate the local air temperature and relative humidity affected by site parameters, which was used for EnergyPlus weather-file modification. A parametric study of ENVI-met basic input with model evaluation was also conducted. The results of parametric test integrating ENVI-met with EnergyPlus showed that ENVI-met mostly produce insignificant impacts of site parameters on house heating energy, unlike the results found in the literature review. This is likely due to the cool weather conditions (winter in Wellington) used in simulation, which suggests that the idea of microclimate modelling using ENVI-met is not applicable for house heating energy modelling in the temperate, Wellington context.</p>

scholarly journals CHALLENGES OF SNOW DISPOSAL AND INNOVATIVE SOLUTIONS IN THE CONDITIONS OF NUR-SULTAN

2021 ◽  
Vol 26 (1) ◽  
pp. 20-29
Author(s):  
M. T. Yermekov ◽  
◽  
O. V. Rozhkova ◽  
S. G. Sandibekova ◽  
Ye. T. Tolysbayev ◽  
...  
Keyword(s):  
Urban Areas ◽  
Sewage Treatment ◽  
Heat Pumps ◽  
Successful Implementation ◽  
Snow Melting ◽  
Sewer System ◽  
Snow Removal ◽  
Advantages And Disadvantages ◽  
The Impact ◽  
The City

Introduction. In this paper, we analyze various methods of snow removal in urban areas and consider the most cost-effective and efficient solutions for snow removal and disposal using heat from sewage drains by means of stationary snow-melting points (SMP) in Nur-Sultan. In cooperation with Astana su Arnasy specialists, responsible for the operation of the city sewer system, as well as cleaning and disinfection of urban sewage drains, we reviewed the main advantages and disadvantages. Methods. The paper looks into the possibility of utilizing heat from sewage drains with the help of heat pumps. This method has been successfully tested at a sewage treatment plant and is currently used to heat auxiliary premises. The same principle can be applied in SMPs with a separate discharge of meltwater to the storm sewer. Results. Having studied the experience of using various methods for snow removal in urban areas, we find that snow removal with the use of sewage drains through the creation of special snow-melting complexes integrated with the city sewer system is the most promising method for Nur-Sultan since it allows for reducing costs, intensifying the process of snow melting, and eliminating the hazardous impact of meltwater on the environment. Conclusion. To ensure successful implementation and use of this snow removal method in Nur-Sultan, it is required to conduct a number of additional studies on the impact of sewage treatment plants on the technological processes, as well as to test options for separating sewage drains with the help of heat pumps, and, based on the studies conducted, to determine the final configuration of snow-melting complexes.

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