Earth Air Research Articles

Developing Vulnerability Index to Quantify Urban Heat Islands Effects Coupled with Air Pollution: A Case Study of Camden, NJ

Extreme heat events at urban centers in combination with air pollution pose a serious risk to human health. Among these are financially distressed cities and neighborhoods that are facing enormous challenges without the scientific and technical capacity for planning and mitigation. The city of Camden is one of those economically distressed areas with a predominantly minority population, a high unemployment rate, high poverty rates, and poor air quality (PM2.5 and ozone), and it remains vulnerable to heat events. This paper focuses on studying a coupled effect of Urban Heat Islands (UHIs) and Ozone-PM2.5 pollution at the neighborhood-scale in the city of Camden, using fine scale remotely sensed land-surface temperature and air quality data from the Community Multiscale Air Quality (CMAQ) Modelling System in the Geographic Information Systems (GIS) platform. To assess the impact of urban microclimate on the city of Camden, NJ, residents’ health, we identified several environmental and social parameters as the root causes of vulnerability imposed by extreme-heat and poor air quality. Vulnerability in terms of environment and social wellbeing was spatially quantified as two conceptual vulnerability-index models (i.e., environmental vulnerability index (EVI) and a social vulnerability index (SVI)) using multiple linear regression algorithm. Factors such as remotely sensed earth surface properties, built-environment components, air quality, and socio-economic data were incorporated in a holistic geographic approach to quantify the combined effect. Surface temperature gradient and Proportional Vegetation (Pv) generated from 30 m resolution Landsat 8 were sampled along with other variables in the city of Camden, NJ. Models incorporating Pv suggest better fit than models with normalized difference vegetation index (NDVI). Water fraction (33.5%, 32.4%), percentage imperviousness (32.5%, 32%), Pv (20.5%, 19.6%), and digital elevation model (DEM) (9%, 8%) have the highest contributions in both models. Two output maps identified the vulnerable neighborhoods in the city through comprehensive GIS analysis: Lanning Square, Bergen Square, Central Waterfront, Gateway, Liberty Park, and Parkside. This can provide useful information for planners and health officials in targeting areas for future interventions and mitigations.

The in-situ experiment of earth-air heat exchanger for a cafeteria building in subtropical monsoon climate

This in-situ experimental study reports the long-term monitoring results of an earth air heat exchanger (EAHE) used to provide ventilation in a cafeteria building, in Nantou, Taiwan. The EAHE consisted of 7 parallel buried pipes with a length of 50 m and a diameter of 0.25 m. The energy performance of the system was analyzed based on data of both sensible and latent heat exchange. The monitored results have been compared with other previous cases presented in the literature to clarify the effect of various climates and design conditions on the EAHE application. The results show that despite relatively high soil temperatures underground compared with the previous case study in temperate regions, the visible temperature difference between inlet air and outlet supply air was recorded in the summer. The annual COP can reach 27.2 while the specific surface area is 0.039 m2(m3hr−1)−1, which represents a relatively low heat transfer area compared with other cases. The conclusion is that considering uncontrollable soil temperatures, the use of a relatively low specific surface area is suitable for great cooling demand in a hot and humid climate, while the design target is on maximizing the heat transfer rate rather than a higher temperature difference.

Earth air heat exchanger, Trombe wall and green wall for passive heating and cooling in premium passive refugee house in Sweden

With the increasing number of migrants and refugees, there is a need for energy-efficient and low impact temporary housing that can accommodate millions of displaced peoples worldwide. This study describes a design proposal for a premium passive refugee house that uses three main passive heating and cooling solutions (Earth Air Heat Exchanger, Trombe wall, and green wall) and is suited to the Swedish climate. The purpose of the combination of the three passive systems is to reduce cooling and heating loads to conserve a significant amount of primary energy and thus mitigate the impact of the house’s energy use on the environment through a reduction in emissions. The house is designed to fulfill its energy needs from renewable sources and produce an annual surplus of 180 kWh/m2/annum. The methodology applied is a dynamic system modeling and simulation approach using TRNSYS and ANSYS software. The simulation results showed a heating load of 7.9 kWh/m2/annum and a cooling load of 2.8 kWh/m2/annum, with total energy consumption reaching 18.4 kWh/m2/annum. Preliminary feasibility costing showed a payback time of 7.4 years out of the 25-years suggested lifetime of building using the three passive solutions. The amount of CO2 emissions is 231.1 kg CO2e/annum with a primary energy demand of 0.032 GJ/m2/annum. As a follow-up to the initial study, a proof of concept has been implemented in Lund, Sweden, in an urban living lab to verify the simulation results through a 12-month post-occupancy monitoring and evaluation study.

Time Series Data Prediction using IoT and Machine Learning Technique

Time series analysis and prediction have been widely accepted in various domains from last two decades. Business analytics, Medical drugs & pharmaceutical, Dynamic Marketing, Weather forecasting, Pollution measures, financial portfolio analysis and Stock market prediction are the favorite domains among research communities under time series analysis. Since air quality is one of the paramount factors which make life possible on earth and monitoring air quality data as time series analysis is a one of prime area. The most affected air quality parameters on health are carbon monoxide (CO),carbon dioxide (CO2), Ammonia(NH3) and Acetone ((CH3)2CO). In this paper we have taken the sensor’s data of three specific locations of Delhi and National Capital Region (NCR) and predict air quality of next day using linear regression as machine learning algorithm. Model is evaluated through four performance measures Mean Absolute Error (MAE), Mean Square Error (MSE), Root Mean Square Error (RMSE) and Mean Absolute Percentage Error (MAPE). The study further assesses with benchmark model and obtains significant results.

Evaluation of two earth–air heat exchangers efficiency of different pipe materials within a warm temperate climate

The Earth-Air Heat Exchanger (EAHE) system was used for many years for both primary heating and cooling applications, especially in the building sector. Its energy performance can be influenced by three principal factors: the EAHE pipe material, the airflow rate, the soil characteristics and the moisture content. The state of the art shows a divergence about the effect of the pipe material on the performance of the EAHE. The aim of this study is to provide an adequate response to this problematic based on experimental analysis. In this regard, we tested two EAHEX of different materials: PVC and Zinc. The comparative study was conducted under a warm temperate climate in the north of Algeria. The data analyses showed that the pipe material can significantly affect the EAHE performance during periods when the EAHE passes from heating to cooling mode. Furthermore, the air outlet temperature differences provided by EAHE Zinc and those of PVC up to about 7.5°C.

Comparative CFD analysis of helical shaped earth air pipe heat exchanger using water tube as a thermal reservoir using different pipe materials

Common configuration of EAPHE system usually consider single or U shaped configuration, which requires large installation area and are not suitable for installation under small home or office setup. This major drawback can be overcome by using helical shaped air pipe, which reduces installation area up to 60%. Performance of EAPHE deteriorates after long run due to thermal saturation in the soil near to pipe surface. In this paper problem of thermal saturation of soil is attempted by proposing water pipe of three different pipe materials. Water pipe act as thermal reservoir to absorb heat from surrounded soil and maintains constant heat transfer after 24 hours of long run. Thermal performance of Earth Air Pipe Heat Exchanger (EAPHE) has been investigated under four different type of model developed using helical air pipe and comparison were made in terms of temperature drop, soil temperature at 0.05m and 0.25 m from pipe, change in water temperature, COP and effectiveness of the system for the continuous 72hours of run.

Observations of ozone formation in southern African savanna and grassland fire plumes

Open biomass burning is one of the largest sources of aerosols and reactive trace gases into the atmosphere, having a significant effect on earth's radiative budget and air quality. Biomass burning degrades air quality by increasing both particulate matter and ozone levels. Unlike aerosols, ozone is not directly emitted in fires but it is frequently formed in ageing plumes. This is not surprising, as many of the reactive trace gases emitted in biomass burning including nitrogen oxides, carbon monoxide and volatile organic compounds, act as precursors for ozone formation. Geographically, Africa is the most significant source region of biomass burning emissions. Here, we report rapid ozone formation in daytime savanna and grassland fire plumes observed in South Africa. We observed higher ozone production in more flaming cases for plumes fresher than 1.5h. However, in plumes aged >1.5h combustion characteristics have no effect, but ozone production is positively correlated with nitrogen oxides. Furthermore, the plumes with highest ozone production also had the strongest secondary aerosol formation during plume ageing. Additionally, we report emission factors of nitric oxide and sulphur dioxide for southern African savanna and grassland fires. SO2 emission factor was on average 1.1 g kg−1, which is two to three times higher than previous observations for savanna and grassland. On the other hand, the average NO emission factor (2.6 g kg−1) agrees well with previous observations.

Analyis of periodical variability of insolation and soil temperature in the Crimea

According to the 22-year-old series of climatology NASA Surface meteorology and Solar Energy, the results of the analysis of the temporal series of local changes in insolation and the temperature of the earth and ground air in the Crimea are carried out. A statistical analysis was carried out and a continuous time-frequency wavelet analysis revealed increased (compared to other Crimean points) insolation and heating of the earth’s surface at Kara-Dag. Using the time-and-frequency continuous wavelet analysis, six regular astronomical fluctuations, the periods of which are comparable with the periods of seasonal fluctuations, lunar and lunar-solar tidal waves, were found in the spectral structure of data on the average daily insolation incident on the horizontal surface of the earth at Kara-Dag. Periodic oscillations comparable with fluctuations in solar activity and the dynamics of rotation of the Earth-Moon system are described by sinusoidal functions, the parameters of which are determined from observations. In the data on the average daily total insolation falling on the surface of the earth at the Kara-Dag point, regular periodic fluctuations were found over an interval of periods of ~(87―402) days. The most powerful harmonic oscillations are distinguished in the interval of periods ~(231―452) days; in the time interval ~(1995―2005) years, an increasing local increase in the vibrational energy is observed. An increase in the average annual average surface temperature in the Crimea in a southeastern direction has been recorded. In individual points, deviations from the general trend are observed, which may be associated with local geological processes. The greatest warming of the earth’s surface is observed at Kara-Dag, which corresponds to increased general insolation at this point. Using the method of calculating the functions of the mutual (two-channel) power spectral density, we established mutual correlations between the time sequences of observations of local changes in insolation and changes in the length of the day, the number of sunspots, and global temperature indices.

On Preheating of the Outdoor Ventilation Air

The growing popularity of buildings with integrated sub-systems requires a review of methods to optimize the preheating of ventilation air. An integrated system permits using geothermal heat storage parallel to the direct outdoor air intake with additional treatment in the mechanical room as a part of building an automatic control system. The earth–air heat exchanger (EAHX) has many advantages but also has many unanswered questions. Some of the drawbacks are: A possible entry of radon gas, high humidity in the shoulder seasons, and the need for two different air intake sources with a choice that depends on the actual weather conditions. In winter the EAHX may be used continuously to ensure thermal comfort, while in other seasons its operation must be automatically controlled. To generate missing information about EAHX technology we examined two nearly identical EAHX systems, one placed in the ground next to a building and the other under the basement slab. In another project, we reinforced the ground storage action by having a heat exchanger placed on the return pipes of the hydronic heating system. The information provided in this paper shows advantages of merging both these approaches, while the EAHX could be placed under the house or near the basement foundation that is using an exterior basement insulation.

Numerical parametric study of a new earth-air heat exchanger configuration designed for hot and arid climates

ABSTRACTThermal potential for cooling and heating can be achieved by new configuration of earth–air heat exchanger (EAHE). This paper presents a numerical investigation of thermal performance of a spiral-shaped configuration of EAHE intended for the summer cooling in hot and arid regions of Algeria. A commercial finite volume software (ANSYS FLUENT) has been used to carry out the transient three-dimensional simulations and the obtained results have been validated using the experimental and numerical data obtained from the literature. The agreement between our simulation results and those from literature is very satisfactory. A parametric analysis of the new geometry of (EAHE) has been performed to investigate the effect of pitch, depth, pipe length and of the flow velocity on the outlet air temperature and the EAHE’s mean efficiency as well as its coefficient of performance (COP). It has been shown that when the pitch space varies between 0.2 and 2 m the difference of outlet air temperature increases by 6 °C. When the air velocity increases from 2 to 5 m/s the mean efficiency decreases from 60 % to 33 % and the COP of the EAHE decreases from 2.84 to 0.46.

Laboratory characterization and modelling of the thermal-mechanical properties of binary soil mixtures

Binary soil mixtures are extensively used in the construction of geothermal-related earth structures such as geothermal energy piles (GEP), ground source heat pumps (GSHP) and earth air tunnel heat exchangers (EATHE). An evaluation of the binary soil’s thermal-mechanical properties is the key process in determining the final performance of geothermal-related projects. Therefore, the thermal-mechanical properties of binary soil mixtures were systematically investigated in this paper. A series of thermal and mechanical property tests was conducted on five sand-kaolin clay mixtures with sand contents ranging from 0% to 100% by dry weight. The experimental results indicated that the sand-clay mixtures achieved the theoretically densest state when the sand content reached the critical threshold. The further the binary mixture’s sand content was from the critical threshold, the lower the mixture’s density was. As the sand content increased, the shear stress-strain curves gradually shifted from strain-softening behavior to strain-hardening behavior due to the decrease in suction stress. The relationship between the sand content and the shear strength of the mixtures exhibited an “S” shape, which is attributed to the interaction between the sand and clay particles and varied with the sand contents. The shear wave velocity of the sand clay mixtures was found to decrease continuously with the increase in sand content until the sand skeleton had formed. In addition, the thermal conductivity of the binary mixed soil changed linearly with the sand content, and the upper bound of the critical threshold interval (77%) was found to separate the two different heat conduction modes. Finally, an elastic shear modulus (G0) model, which correlated to the tangent elastic modulus of the binary mixture (Em), and a more generalized thermal conductivity (K) model were formulated for the binary sand-clay mixtures, and the effectiveness and feasibility of the proposed models were validated by comparing the values predicted with the model and the experimental data.

Experimental Analysis of Effect of Soil Moisture on Thermal Performance of Earth Air Heat Exchanger

Earth Air Heat Exchanger (EAHX) systems are renewable energy systems based on the use of the high energy potential of the soil. Although it has a simple structure, there are multiple parameters that affect thermal performance. These parameters should be taken into consideration when installing the EAHX, which consists of a buried pipe system and a fan. In this study, the effect of humidification of the soil on which EAHX is placed by placing an irrigation line on thermal performance was investigated. In this study, two EAHX with the different material piping systems are discussed. In the study carried out at different airspeeds, inlet-outlet air temperatures, water temperature and air humidity were measured. It was determined that the decrease in the outlet temperatures of the systems using PVC and metal pipes was 10% compared to the dry condition. As a result of the study, it has been observed that moistening the soil increases EAHX efficiency. When the increase in cooling capacity and the additional cost caused by the irrigation system are compared, it is seen that the installation of soil humidification system is applicable in terms of energy efficiency.

Twenty‐Five Years of Lower Tropospheric Ozone Observations in Tropical East Asia: The Influence of Emissions and Weather Patterns

AbstractTropospheric ozone affects the Earth's radiative balance, oxidative capacity, and air quality, yet the long‐term ozone trend in East Asia and its driver(s) remain poorly understood. Here we present ozone measurements obtained during 1994–2018 on China's southern coast. The measurement location intercepts China's outflow most of the time and the inflow of tropical maritime air during summer. We found an overall increase in the ozone level (0.35 ppbv/year), and the increase occurred mainly during the first half of the 25‐year period but appeared to level off in recent years in Chinese outflow. Large ozone increase (~20% per decade) was found in the maritime air. Model simulations show that recent weather conditions have reduced maritime ozone, counteracting the impact of the growing Southeast Asia's emissions. Our results fill the gap in the long‐term ozone trend in Asia and highlight the complex interaction of weather and emissions in driving the ozone change.

Parametric Study of an Earth-Air Heat Exchanger Assisted by a Green Wall for Passive Cooling in Hot Climates

Cooling of buildings during summers in hot climates is an important issue for architects and builders and in terms of energy consumption, residential and tertiary buildings are among the highest consumers. This paper presents a numerical study, focused on a new design for a passive cooling system that uses an earth-air heat exchanger (EAHE), which was assisted by a green wall/air heat exchanger (GAHE) in hot climatic conditions. The tubes buried in the ground and the shadow of a vertical green wall offer considerable advantages for saving energy. The depth of the pipes in the ground was calculated by taking into account the physical properties of the soil. A parametric study was carried out by taking into account the pipe diameter, pipe length, pipe depth in the ground, and the velocity of air in the pipes. The vertical pipe in the green wall allowed a significant additional drop in the air temperature at low air velocities or small pipe depths in the ground. This means that shorter pipe lengths can be used in the earth-air heat exchanger to keep the air outlet temperature of the same order. For an earth air heat exchanger assisted by a green wall operating in hot climates, the design and operation parameters recommended are; pipe diameter 120 mm, length of the buried pipe 4 m, depth in the ground 30 m and air velocity 1 m/s.

A REVIEW ON PERFOMANCE ENHANCEMENT OF EARTH AIR HEAT EXCHANGER

Earth Air Heat Exchanger (EAHE) exploits the earth’s ground temperature to its maximum potential so as to carry out the heat transfer. This paper mainly focuses on the methods that are being used to improve the thermal efficiency of the EAHE, during its course of operation. Studies conducted by various researchers in the field of EAHE, regarding the method and modification done on the EAHE so as to improve its performance of heat exchange has been discussed in this paper. The paper also deals with the design aspects and parameters affecting the performance of the EAHE, which help in dealing with its installation and implementation.

Improving the performances of earth air heat exchangers through Constructal design

Improving the performances of earth air heat exchangers through Constructal design

Performance analysis of an earth–air heat exchanger integrated into an agricultural irrigation system for a greenhouse environmental temperature-control system

In this article, an earth–air heat exchanger (EAHE) system is applied in an agricultural greenhouse temperature-control system and integrated into the existing irrigation facilities to reduce the installation cost. In addition, an annual performance study and analysis are conducted for this system, and the mathematical model is verified with the experimental results; then, the energy-saving efficiency and economic benefits of the system are evaluated from the mathematical models and experimental data. The average difference between the experimental data and mathematical models is about 2.6%. This EAHE is buried under an existing irrigation channel; the channel is supplemented by an irrigation well, and the water temperature of the channel is stabilized by the well water. Compared with the traditional EAHE system, this system can achieve sufficient performance without a deep soil layer (above 5 m) and use the system's integrated existing facilities, significantly reducing the installation cost. According to the experimental results, a cooling capacity of 1.5–4.5 kW can be provided in summer under different weather conditions, a heating capacity of 0.7–2.8 kW can be provided in winter, and the greenhouse temperature can be maintained in the required range. Compared with the traditional heat-pump system, 561.6 kWh can be saved through this EAHE system in summer (operating for 90 days), with an energy-saving benefit of 74.3%, and 177.6 kWh can be saved in winter (operating for 30 days), with an energy-saving benefit of 67.3%. Moreover, the initial equipment costs can be reduced by 35.3%.

Performansi Alat Penukar Kalor Udara-Tanah (Earth-Air Heat Exchanger) dengan Siklus Terbuka di Kota Medan

The purpose of this study was to obtain the performance of an EAHE (earth air heat exchanger) with weather conditions in the Medan city. The research method carried out was experimental in the field for several days with varying weather conditions. The air conditioning system using an Air-Earth Heat exchanger has tested its performance by comparing the experimental results with the model of equations that have been developed by the previous researchers. The incoming air velocity 2 m/s is obtained by the output temperature on average for the results experiment with 27.1 o C and for theoretical results of 26.5 o C with an average air temperature of 32.1 o C. As for the incoming air velocity 3 m/s, the resulting output temperature averages for the experimental results of 27.3 o C and for theoretical results of 26.9 o C with an average air temperature that is 33.8 o C. The higher the air intake velocity, the higher the output temperature in the Air-Earth heat exchanger. At 2 m/s air velocity, the output temperature is 27.1 o C and then rises to 27.3 o C at air velocity enter 3 m/s. The effectiveness of the earth heat exchanger at the incoming air velocity 2 m/s for the experimental results was 0.84 while the theoretical calculation was 0.97. From the results of multiple regression analysis, it is found that the NTU and inlet air temperature values have a very strong relationship to the COP value. The correlation coefficient is 0.916 at a speed of 2 m/s and 0.959 at a speed of 3 m/s. The results show great potential for the development of ground-air heat exchangers as a passive cooling system building solution.

Exposure to Light Elicits a Spectrum of Chemical Changes in Soil

AbstractThe significance of photochemically active solar radiation is well substantiated in Earth's air and water environments, but no broad connection has yet been ascertained between sunlight and the chemical properties of land surfaces. Since it is obvious that sunlight strikes Earth every day, an inquiry into this connection was made in a simple experiment with a diverse group of 20 soils. Light‐induced alteration of most of the major elements in soil was evident, including significant changes in dissolved organic carbon, inorganic nitrogen, pH, phosphorus availability and sorption capacity, and soluble and mineral forms of iron, manganese, aluminum, silicon, and calcium. In many instances the extent of these changes could be predicted from initial values. This broad response to light attests to the vivid photochemistry of soils and has both pedological and edaphological implications that reach beyond the surface. The phenomena reported here affirm the opportunity for novel inquiries into the chemistry of soils and land surfaces in general.

Energy and exergy analysis of two novel hybrid solar photovoltaic geothermal energy systems incorporating a building integrated photovoltaic thermal system and an earth air heat exchanger system

In this paper, two novel configurations of the building integrated photovoltaic thermal (BIPVT)-compound earth-air heat exchanger (EAHE) system are proposed. Both the configurations operate in two modes, namely heating and cooling modes. In the heating mode of the configuration A, the cold outdoor air is twice preheated by passing through the EAHE and BIPVT systems. In the cooling mode of the configuration A, the hot outdoor air is precooled by flowing inside the EAHE system and the PV modules are cooled using the building exhaust air. The cooling mode of the configuration B is similar to the configuration A, while in the heating mode of the configuration B, the outdoor air first enters the BIPVT collector and then passes through the EAHE system. The energetic and exergetic performances of the configurations are investigated for climatic conditions of Kermanshah, Iran. In addition, the impacts of length, width, and depth of air duct located underneath the PV panels, air mass flow rate, length and inner diameter of the pipe of EAHE system on the annual average energetic and exergetic aspects of the best configuration of the BIPVT-EAHE system are evaluated. The outcomes revealed that the annual rate of thermal energy, electrical energy, and thermal exergy captured from the configuration A are respectively 3499.59, 5908.19, and 55.59 kWh, while these values for the configuration B are respectively 3468.16, 5969.87, and 51.76 kWh. In addition, it was found that the configuration A has superior energetic performance than the configuration B, while the overall exergetic performance of the configuration B is higher than the configuration A. Furthermore, it was depicted that both the energetic and exergetic performances of the suggested configurations intensify by augmenting the duct length, duct width, and tube diameter whereas they decline with an increase in the air mass flow rate and duct depth.