Cooling Energy Demand Research Articles

Air quality and health co-benefits of climate change mitigation and adaptation actions by 2030: an interdisciplinary modeling study in Ahmedabad, India

Climate change-driven temperature increases worsen air quality in places where coal combustion powers electricity for air conditioning. Climate solutions that substitute clean and renewable energy in place of polluting coal and promote adaptation to warming through reflective cool roofs can reduce cooling energy demand in buildings, lower power sector carbon emissions, and improve air quality and health. We investigate the air quality and health co-benefits of climate solutions in Ahmedabad, India—a city where air pollution levels exceed national health-based standards—through an interdisciplinary modeling approach. Using a 2018 baseline, we quantify changes in fine particulate matter (PM2.5) air pollution and all-cause mortality in 2030 from increasing renewable energy use (mitigation) and expanding Ahmedabad’s cool roofs heat resilience program (adaptation). We apply local demographic and health data and compare a 2030 mitigation and adaptation (M&A) scenario to a 2030 business-as-usual (BAU) scenario (without climate change response actions), each relative to 2018 pollution levels. We estimate that the 2030 BAU scenario results in an increase of PM2.5 air pollution of 4.13 µg m−3 from 2018 compared to a 0.11 µg m−3 decline from 2018 under the 2030 M&A scenario. Reduced PM2.5 air pollution under 2030 M&A results in 1216–1414 fewer premature all-cause deaths annually compared to 2030 BAU. Achievement of National Clean Air Programme, National Ambient Air Quality Standards, or World Health Organization annual PM2.5 Air Quality Guideline targets in 2030 results in up to 6510, 9047, or 17 369 fewer annual deaths, respectively, relative to 2030 BAU. This comprehensive modeling method is adaptable to estimate local air quality and health co-benefits in other settings by integrating climate, energy, cooling, land cover, air pollution, and health data. Our findings demonstrate that city-level climate change response policies can achieve substantial air quality and health co-benefits. Such work can inform public discourse on the near-term health benefits of mitigation and adaptation.

Implementing natural ventilation and daylighting strategies for thermal comfort and energy efficiency in office buildings in Burkina Faso

In recent years, efforts to lessen the environmental impact of the building sector have focused more on passive strategies to develop eco-friendly buildings that reduce energy use and improve thermal comfort. To reduce the construction sector’s resource use, particularly in fast-urbanizing sub-Saharan countries, a paradigm shift is needed. Although integrated daylighting and natural ventilation solutions in building design and construction are still under development in sub-Saharan Africa, their scientific contributions to the construction industry are growing. Therefore, the purpose of this research is to investigate natural ventilation and daylighting improvements in Burkina Faso office buildings to maximize thermal comfort and energy efficiency. The country’s meteorological data from 2004 to 2018 was examined for climatic analysis and utilized in Integrated Environmental Solutions Virtual Environment (IESVE) for natural ventilation and daylight simulations and in Design-Builder (DB) for thermal comfort and energy consumption simulations. 4 simulation rounds were conducted in order to determine respectively from round 1 to 4 the effects of building shape, glazing type, window shading type, and window-to-wall ratio on the daylighting and natural ventilation office building model performances. The findings indicated that on a south–north axis orientation, a ”H”-shaped structure with blue-tinted glass, horizontal louvers for shading, and 30% window-to-wall ratio, is the best option. The best overall option reduced annual energy demand, cooling energy demand, and solar gains by 14.9%, 25.3%, and 68.3% respectively. Hourly average airflow increased by 64.8% and 2% in hot and cold seasons respectively. Indoor air temperature decreased by 3.4 °C in the hot season and increased by 0.4 °C in the cold season. The daylighting analysis results demonstrated benefits with measurements that did not reflect too much light, implying reduced glare and discomfort with Useful Daylight Illuminance (500-2500lux): 56%, Spatial Daylight autonomy (50%): 44.7%, Annual Sunlight Exposure: 12%. This research laid the groundwork for a sustainable, bioclimatic office building model in a landlocked developing nation like Burkina Faso by integrating Climate Based Design Modeling (CBDM) and natural ventilation parameters into the design process.

Urban heat dome flow deflected by the Coriolis force

An urban heat dome forms over urban areas when synoptic winds are weak, which is widely seen during heatwaves and expected to become the ‘norm’ in the future due to climate change. The spatial and aerodynamic characteristics of the urban heat dome have a direct impact on city-scale heat distribution and associated building cooling energy demand and many human-environment interaction processes. As the hydraulic diameter of a city goes beyond 20 km, the Coriolis force that can deflect the flow of the heat dome comes into play. Our large-eddy simulations of a 400 km2 idealized square city show that the flow of the heat dome is markedly deflected by the Coriolis force. In the Northern hemisphere, the near ground convergence inflow is found to be drastically deflected counter-clockwise. At higher levels above ground, deflected airflow leaving the city center emerges gradually, and an anticyclone is eventually seen. The findings imply that, when urban characteristic diameter reaches beyond 10 km, the deflection of the urban heat dome in high-latitude regions has to be considered in order to understand city-scale heat transport at high-spatial resolution and to underpin the development of fine-tuned measures for local urban heat mitigation.

Development and validation of a transient simulation model of a full-scale PCM embedded radiant chilled ceiling

The recent significant rise in space cooling energy demand due to the massive use of air-conditioning systems has adversely changed buildings’ energy use patterns globally. The updated energy technology perspectives highlight the need for innovative cooling systems to address this growing cooling demand. Phase change material embedded radiant chilled ceiling (PCM-RCC) has lately acquired popularity as they offer more efficient space cooling together with further demand-side flexibility. Recent advancements in PCM-RCC applications have increased the necessity for reliable simulation models to assist professionals in identifying improved designs and operating settings. In this study, a transient simulation model of PCM-RCC has been developed and validated using measured data in a full-scale test cabin equipped with newly developed PCM ceiling panels. This model, developed in the TRNSYS simulation studio, includes Type 399 that uses the Crank-Nicolson algorithm coupled with the enthalpy function to solve transient heat transfer in PCM ceiling panels. The developed model is validated in both free-running and active operation modes, and its quality is then evaluated using several validation metrics. The results obtained in multiple operating scenarios confirm that the model simulates the transient behaviour of the PCM-RCC system with an accuracy within ±10%. Aided by this validated model, which offers the user detailed flexibilities in the system design and its associated operating schemas, PCM-RCC’s potentials regarding peak load shifting, energy savings, and enhanced thermal comfort can be investigated more reliably.

Evaluating the Influence of Passive Design Strategies on Cooling Energy Demand in Local Adobe, Stone and Concrete Dwellings in Wadi Hadramout, Yemen

Evaluating the Influence of Passive Design Strategies on Cooling Energy Demand in Local Adobe, Stone and Concrete Dwellings in Wadi Hadramout, Yemen

Thermal performance analysis and experimental verification of lithium-ion batteries for electric vehicle applications through optimized inclined mini-channels

Power units (i.e., batteries) of electric vehicles (EVs) generate heat while being charged or discharged, which deteriorates their performance and reliability over time. This paper investigates a comprehensive spectrum of geometric and thermo-fluidic parameters of a liquid coolant flowing through mini-channels. These are embedded in the surface of an EV battery to curtail overheating. Design parameters such as aspect ratio and angular orientation of the mini-channels were varied randomly to investigate several geometric configurations that are scarcely intuitive. The coolant mass flow rate and the fluid inlet temperature were also varied through a large dataset of randomly distributed values. A real-time EV driving cycle was implemented alongside an experimentally validated model to evaluate the battery operation, which evidenced the complex dependence of the battery’s thermal state with different levels of cooling retrofitting. The study also analyzed the parasitic power consumption arising from the pumping and cooling energy demands to drive the coolant system to achieve an optimally designed retrofit for a reliable battery performance. It was found that the mini-channel parameters considerably affect the thermal performance of the battery. However, the optimized case was found to have a minimum temperature difference in the battery and a minimum power requirement. The case with a fluid inlet velocity of 0.13 m/s, a fluid inlet temperature of 312.9 K, an aspect ratio of 1.7, and an inclination angle of 4.9° was found to be the most suitable, leading to a refrigeration power requirement of 0.85 W only. The battery temperature after the end of the driving cycle was maintained at 313 K.

Investigation of used PCM-integrated into building exterior walls for energy savings and optimization of PCM melting temperatures

In the study, the effects on the building's thermal energy performance of using two different phase change materials (PCMs) integrated into the exterior walls at various thicknesses and melting temperatures have been investigated. Four exterior wall types have been designed by changing the position of PCM integrated into the exterior wall for the purpose to decrease heating and cooling energy demand. For each wall type, three different thicknesses (layers) have been studied and energy savings that PCM provided by decreasing the heating and cooling energy demands have been calculated on a monthly and annual basis. According to the energy simulation analyses, the configuration provided the highest heating energy savings (21.32 %) on an annual basis is the three-layer BioPCM27 integrated exterior wall with a melting temperature of 21 °C. The monthly optimum melting temperatures of PCMs have been determined based on the charge and discharge processes of PCM integrated into the exterior walls by evaluating the results of hourly energy simulation analysis. The annual average optimum melting temperature varies between 18 and 19 °C, depending on the exterior wall and material types. The three-layer (3L) InfiniteRPCM21C configuration (Type 3) has the best thermal energy performance among all exterior wall types, with 24.45 % total energy savings in the cooling season and 14.76 % in the heating season.

The Vatic Weather File Generator (VWFG v1.0.0)

To combat climate change caused by cities, it is necessary to perform urban physics modeling to assess mitigation solutions suitable for future climates. A challenge is availability of reliable future weather files for investigation of future climate scenarios. This research aims to develop the Vatic Weather File Generator (VWFG) using the statistical downscaling approach to fill this gap. VWFG is novel by using a history of weather files over multiple years to downscale future climate model data utilizing (1) quantile–quantile bias corrections, (2) record matching by the Finkelstein–Schafer method, and (3) shifting–stretching corrections. This implementation of VWFG uses the CanRCM4 climate model (1980–2100) and the ERA5 reanalysis data product as weather files (1980–2020) for two Representative Concentration Pathway (RCP) scenarios. VWFG outputs are consistent with findings in other studies. Further, to investigate the performance of VWFG for a case in Toronto, Canada, the Vertical City Weather Generator (VCWG) is forced by VWFG to predict the building sensible heating and cooling energy demands for a two-story single-family residential house. It is found that the building sensible heating demand is reduced over time (∼ 15%–30% for RCP 4.5–8.5 W m−2) and the building sensible cooling demand is increased over time (∼ 20%–50% for RCP 4.5–8.5 W m−2). The amount of change is greater for RCP 8.5 than RCP 4.5 W m−2. VWFG is a simple, practical, and widely applicable tool for urban physics simulations of future climates, particularly in cases where reliable forcing data is lacking otherwise.

Green Walls as Retrofitting Measure: Influence on Energy Performance of Existing Industrial Buildings in Central Italy

Industrial buildings in Italy are currently highly energy intensive. Their old age prevents them from complying with current environmental and energy requirements; consequently, redevelopment initiatives should therefore be considered in order to improve the overall performances of these facilities. Within this framework, this research aims to evaluate the results achievable by introducing indirect green façades as retrofitting solutions. Starting from a real case study building located in central Italy, energy simulations were carried out using DesignBuilder, varying buildings’ geometry, dimensions and windows-to-wall ratios as well as greenery coverage percentage. The evidence shows an appreciable potential for green walls to improve the summer performance of industrial buildings, as they resulted in a reduction in cooling energy demand during the summer season of about 14%. Moreover, external surface temperature was reduced by 8 °C during the hottest days, ensuring higher durability in building components. Furthermore, indoor air temperature during the summer design week decreased by 0.6 °C. During the winter season, the green façades avoid exploiting free solar gains due to incident solar radiation, and a slight increase of about 4% occurred in heating energy needs. For this reason, the implementation of deciduous vegetation species should be evaluated for industrial buildings located in Mediterranean latitudes.

Resistive and capacitive technology recipes for peak cooling load reductions in the global south

Buildings in the Global South are expected to drive a tripling of global cooling energy demand by 2050. In countries such as India, growth in energy use far outstrips growth in population, often to the ratio 3:1. While several building-level technologies exist that could help reduce peak and total demand, the technologies, or combination of technologies, that would offer the greatest peak reduction in the range of climates in the Global South is unknown as previous work has focused on mid latitudes. Hence, we use computer simulations to study, for the first time, six different cooling-driven peak-shaving technologies covering 19 different climates in the Global South. Using Latin Hypercube Sampling to account for the uncertainties arising from building variants and technology performance, we conduct a total of 266,000 annual hourly simulations. While thermally activated building systems and phase change materials deliver the largest reductions in peak and total demand, water storage is the most consistent in reducing the peak, yet had a possible increase in annual demand. We also develop technology combinations, or “recipes”, which suggest that the range of attainable peak and total demand reduction is between 19% - 95% and 20%–99% respectively, depending on the climate. Given the scale of the potential reduction, our results justify the investment in such technologies by governments and others to deliver major reductions in energy demand and peak load in the Global South, but if incorrectly designed, it is clear they may result in reduced energy security and increased carbon emissions.

Comparative Study of the Impact of Bio-Sourced and Recycled Insulation Materials on Energy Efficiency in Office Buildings in Burkina Faso

This research presents a comparative study of different bio-sourced and recycled insulation materials and their impact on energy consumption of office buildings located in Ouagadougou, a city with a dry hot climate. A thorough assessment of the country’s meteorological and urban development data from 2004 to 2018 was conducted for climatic data. EnergyPlus was used for thermal comfort based on the American Society of Heating, Refrigerating, and Air-conditioning Engineers Standard (ASHRAE) 55 adaptive comfort model and energy analysis by calculating and comparing the yearly energy consumption, heat transfer through the building envelope, and discomfort degree hours. A four-story “H”-shaped office building made of cement blocks with a fixed north–south orientation and a 30% window-to-wall ratio served as the base case for this study to perform two rounds of multiple simulations and evaluate the most effective insulation material. First, exterior walls were insulated, and then the roof and inner floors were insulated using the best material from the first round. The findings confirmed hemp wool as the best performing bio-sourced insulation material, which reduces by 25.8% and 17.7% the annual cooling energy demand at 114,495 kWh and the annual energy consumption at 203,598 kWh, respectively, contributing to saving up to 43,852 kWh in annual energy consumption. Hemp wool impacted wall, roof, and internal floor heat transfer by reducing them by 90.86% at 12,583 kWh, 85.1% at 6666 kWh, and 88.1% at −2664 kWh, respectively, while the discomfort degree hours were reduced by 17.6% at 9720.12. The outcomes provide patterns, explanations, and inferences that may be generalized to other projects in Burkina Faso, especially, and sub-Saharan African countries, in general, where most buildings are not well insulated. The availability of these bio-based and recycled insulation materials may also serve as proof to foster a circular economy in the Burkina Faso construction industry.

An agile heating and cooling energy demand model for residential buildings. Case study in a mediterranean city residential sector

Climate change will affect people's health, especially in cities. Hence, energy planning will play a key role in the development of sustainable and resilient cities. Urban building energy models facilitate energy planning as heating and cooling demand becomes known, and the consequences of different planning actions can be modelled. This research presents an agile heating and cooling demand model. It combines a European standard's methodology, geometric information of buildings collected from cadastral and altimetric datasets using GIS-based technologies, solar irradiation analysis and the degree-days method. The model is validated with various case studies and then applied to several buildings in different environments.The model shows the strong influence of the building's age (design and materials), the building surface-to-volume ratio on the energy demand and the importance of the solar irradiation analysis. Furthermore, the model can predict the effects of the temperature rise on energy demand and prioritise the buildings to be retrofitted. Indeed, one of the conclusions obtained from the model is that advanced retrofitting of 17% of the most energy demanding buildings would obtain a 50% decrease in thermal demand; if the percentage was 50%, an 85% reduction could be reached. In conclusion, the energy planning tool hereby presented is a useful tool to viably foresee the energy demand of residential buildings and districts and the effects of climate change on their energy demand, as well as the consequences of countermeasures like retrofitting.

Performance of a Phase Change Material Battery in a Transparent Building

This research evaluates the performance of a Phase Change Material (PCM) battery integrated into the climate system of a new transparent meeting center. The main research questions are: a. “Can the performance of the battery be calculated?” and b. “Can the battery reduce the heating and cooling energy demand in a significant way?” The first question is answered in this document. In order to be able to answer the second question, especially the way the heat loading in winter should be improved, then more research is necessary. In addition to the thermal battery, which consists of Phase Change Material plates, the climate system has a cross-flow heat exchanger and a heat pump. The battery should play a central role in closing the thermal balance of the lightweight building, which can be loaded with hot return or cold outdoor air. The temperature of the battery plates is monitored by multi-sensors and simulated by the use of PHOENICS (Computational Fluid Dynamics) and MATLAB. This paper reports reasonable agreement between the numerical predictions and the measurements, with a maximum variance of 10%. The current coefficient of performance for heating and cooling is already high, more than 27. There is scope for increasing this much further by making use of the very low-pressure difference of the battery (below 25 Pascal), low pressure fans and the ventilation system as a whole.

A simulation-based study to evaluate the cooling potential of nocturnal radiative cooling systems for residential buildings in Egypt

During the first years of the last decade, Egypt used to face recurrent electricity cut-offs in summer. In the past few years, the electricity tariff dramatically increased. Radiative cooling to the clear night sky is a renewable energy source that represents a relative solution. The dry desert climate promotes nocturnal radiative cooling applications. This study investigates the potential of nocturnal radiative cooling systems (RCSs) to reduce the energy consumption of the residential building sector in Egypt. The system technology proposed in this work is based on uncovered solar thermal collectors integrated into the building hydronic system. By implementing different control strategies, the same system could be used for both cooling and heating applications. The goal of this paper is to analyze the performance of RCSs in residential buildings in Egypt. The dynamic simulation program TRNSYS was used to simulate the thermal behavior of the system. The relevant issues of Egypt as a case-study are firstly overviewed. Then the paper introduces the work done to develop a building model that represents a typical residential apartment in Egypt. Typical occupancy profiles were developed to define the internal thermal gains. The adopted control strategy to optimize the system operation is presented as well. To fully understand and hence evaluate the operation of the proposed RCS, four simulation cases were considered: 1. a reference case (fully passive), 2. the stand-alone operation of the RCS, 3. ideal heating & cooling operation (fully-active), and 4. the hybrid-operation (when the active cooling system is supported by the proposed RCS). The analysis considered the main three distinct climates in Egypt, represented by the cities of Alexandria, Cairo and Asyut. The hotter and drier weather conditions resulted in a higher cooling potential and larger temperature differences. The simulated cooling power in Asyut was 28.4 W/m² for a 70 m² absorber field. For a smaller field area of 10 m², the cooling power reached 109 W/m² but with humble temperature differences. To meet the rigorous thermal comfort conditions, the proposed sensible RCS cannot fully replace conventional air-conditioning units, especially in humid areas like Alexandria. When working in a hybrid system, a 10% reduction in the active cooling energy demand could be achieved in Asyut to keep the cooling set-point at 24 °C. This percentage reduction was nearly doubled when the thermal comfort set-point was increased by two degrees (26 °C). In a sensitivity analysis, external shading devices as a passive measure as well as the implementation of the Egyptian code for buildings (ECP306/1–2005) were also investigated. The analysis of this study raised other relevant aspects to discuss, e.g. system-sizing, environmental effects, limitations and recommendations.

Energy simulation and life cycle cost discussion for a novel fixed model in offices as a zero energy building in a country with hot and cold dry weather

This paper presents a new configuration of heating and cooling systems for a net zero energy building (NZEB).In this paper, one design for Net Zero Energy Building(NZEB) systems is simulated, which can provide cooling and heating needs in a wide variety of climates. This current model benefits from direct evaporating cooling (DEC) which is coupled with the ground instead of the chiller in order to reduce the consumption of energy, water usage, and humidity of indoor air. The PV cells and heat pump that are connected to the ground generate electricity and heating energy, respectively in the building besides domestic hot water is provided by solar collectors. This model is simulated in ten cities of Iran as a multi climate country with six various major climates. The Life Cycle Cost (LCC)is calculated for all of these cities and the value is compared with the usual systems. The results show the possibility of an NZEB in various dry weather in Iran, furthermore the thermal comfort situation is confirmed. The cooling energy demand proportion to other energy usage tends to be zero. The LCC value will be able to reduce to 50% of the usual systems.

Operational energy and embodied impacts of retrofitting the window frames of mixed-mode office buildings

Design decisions normally consider the building's operational phase as the main criterion to reduce energy expenses in a building. In less efficient buildings, reducing the operational energy becomes the most important aspect to address in the design, construction and operational phases, for it represents the highest life cycle energy flow. However, energy-efficient solutions often reduce operational energy demand by increasing the building's embodied energy and greenhouse gas emissions, which have been overlooked in energy performance analyses. This work aims at investigating the operational energy and the consequent embodied impacts resulting from the retrofit of the window frame of mixed-mode office buildings located in a hot climate, with a focus on reducing the cooling energy demand. The method consists of an experimental study based on a case study, in which the EnergyPlus and the SimaPro software tools are used to evaluate the operational energy and the environmental impacts. Results showed that reducing the WWR and increasing the window opening factor conveyed operational energy savings but in some retrofit scenarios tested, these retrofit measures were counterproductive from the CED and GWP perspective. The main scientific contribution of this work is understanding the importance of the building analysis from a life-cycle approach. The results obtained can assist companies and designers to make their decisions from a broader environmental perspective.

Shape Memory Polymer Foam for Autonomous Climate-Adaptive Building Envelopes

Reducing the continuously growing cooling energy demand of buildings is an important part of achieving global emission targets. Here, we present an innovative scenario of how the integration of a programmable material into a climate-adaptive building envelope (CABE) can create an energy-efficient thermal management system inherent to the material. This novel concept is based on a thermoresponsive shape memory polymer foam (SMP) and is designed to regulate the flow of ambient air through the building envelope in order to enable natural cooling of the structure. Hygrothermal simulation data obtained by the software WUFI® Plus indicate that significant cooling energy saving potential may be accessible with this type of concept. As a possible material basis for a corresponding adaptive element, a reactive foamed polyurethane-based SMP foam is proposed, which is capable of executing a thermoreversible shape change of more than 20% while having a suitable switching temperature range. Finally, the ecological impact of such a functional foam element is evaluated in detail as well as its influence on the overall balance of a façade construction by means of a life cycle assessment (LCA).

Space-time estimation of the urban heat island in Rome (Italy): Overall assessment and effects on the energy performance of buildings

The work investigates the Urban Heat Island (UHI) phenomenon and its effects on building energy performance using data from 23 weather stations in Rome (Italy). The processes are facilitated by an analysis of the urban fabric using a Geographic Information System (GIS) to provide correlations between urban features and UHI. The different weather-data were also used as input to perform dynamic simulations for estimating the heating and cooling energy needs of two typical residential buildings, characterized by different construction. The results reveal considerable differences regarding temperature, wind velocity and relative humidity, as a result of a prevailing UHI phenomenon during the whole year. The temperature differences as a result of the UHI reach about 5.4 °C during the day and exceed 4.5 °C at night. The impacts on the buildings’ energy demand for heating and cooling are significant. For an old building, the heating energy demands showed percentage differences ranging from −33.28% to −4.51%, and the cooling energy needs showed variations from −5.33% to 93.25%. On the other hand, considering a more recent structure, variations from −37.73% to 0.22% were obtained for the heating energy needs, and differences from −2.72% to 63.31% were identified for the cooling energy demands.

Impact of different roofing mitigation strategies on near-surface temperature and energy consumption over the Chicago metropolitan area during a heatwave event

This study examined the impact of cool roofs, green roofs, and solar panel roofs on near-surface temperature and cooling energy demand through regional modeling in the Chicago metropolitan area (CMA). The new parameterization of green roofs and solar panel roofs based on model physics has recently been developed, updated, and coupled to a multilayer building energy model that is fully integrated with the Weather Research and Forecasting model. We evaluate the model performance against with observation measurements to show that our model is capable of being a suited tool to simulate the heatwave event. Next, we examine the impact by characterizing the near-surface air temperature and its diurnal cycle from experiments with and without the different rooftops. We also estimate the impact of the rooftop on the urban island intensity (UHII), surface heat flux, and the boundary layer. Finally, we measure the impact of the different rooftops on citywide air-conditioning consumption. Results show that the deployment of the cool roof can reduce the near-surface temperature most over urban areas, followed by green roof and solar panel roof. The cool roof experiment was the only one where the near-surface temperature trended down as the urban fraction increased, indicating the cool roof is the most effective mitigation strategy among these three rooftop options. For cooling energy consumption, it can be reduced by 16.6 %, 14.0 %, and 7.6 %, when cool roofs, green roofs, and solar panel roofs are deployed, respectively. Although solar panel roofs show the smallest reduction in energy consumption, if we assume that all electricity production can be applied to cooling demand, we can expect almost a savings of almost half (46.7 %) on cooling energy demand.

An investigation into the effect of water injection parameters on synergetic mining of geothermal energy in mines

Cooling energy demands are high and increase with the mining depths in conventional mine cooling systems, which account for the most of the total energy consumption. The synergetic mining of mine geothermal energy (SMGE) is a subversive and promising approach for heat hazard control of deep mines with the advantage of low energy consumption and low cost. In this study, the similarity criteria for the similar simulation of SMGE are deduced by the equation analysis method, and the similarity criteria number between the full-scale model and the reduced-scale model is determined. Based on the geometric scale ratio of 1:100, a simulation experiment system including ventilation system and geothermal exploitation system is established. In addition, the influence of water injection parameters on cooling effect of roadway and heat recovery performance of the SMGE system is investigated. The results indicate that the temperature of surrounding rock is cooled gradually during the water injection and heat recovery in rock formation, which reduces the temperature increase rate of airflow in the roadway. When the injection water temperature is reduced from 28 °C to 11.5 °C, the cooling rate of roadway can be observable increased, but it results in a faster temperature decrease in production water with time. Increasing the water injection time from 35 min to 65 min will give rise to the temperature reduction degree of surrounding rock and decrease to the temperature increase rate of airflow in roadway. And the time of water injection is directly proportional to the water production flow rate in production well, but inversely proportional to the temperature in production water. A high injection rate facilitates the cooling rate of the roadway and increases the range of heat recovery in formation, but a small flow rate can achieve a better ultimately cooling effect under the same total water injection volume. Decreasing the water injection rate from 1.6 L/min to 0.6 L/min will increase the time of stable production flow and the rate of reduce in water temperature in the production well. Furthermore, changes in the level of the injection well position will result in different injected water seepage characteristics, which affects the cooling effect of roadway and heat recovery performance of the SMGE system simultaneously.