Effect Of Ambient Air Temperature Research Articles

The effect of ambient air temperature on meltwater production and flow dynamics in snow avalanches

The effect of ambient air temperature on meltwater production and flow dynamics in snow avalanches

Evaluating the effect of ambient air temperature on the sustainability aspect of naphtha‐based gas turbine power plant

AbstractThe exergy‐based sustainability indices have been a cause of concern for gas turbine power plant as its performance is very sensitive to air temperature. Hence, the present study evaluates the impact of atmospheric air temperature on exergy sustainability and ecological function of a naphtha‐based gas turbine power plant using EES. The outcome of the study shows that combustion chamber (CC_1) needs more attention compared with other components present, and it has least improvement potential as compared with other components. Further while carrying out parametric analysis with respect to ambient air, it was observed that for a 1.1°C increase in atmospheric air temperature a reduction in sustainability index about 0.66% was observed respectively, for GT_1. Thus, this study established that the power plant's exergy sustainability performance has a negative impact at high ambient air temperatures on exergy sustainability indices.

Evaluating the effect of ambient air temperature on the exergy sustainability of a 153MW gas turbine power plant

Evaluating the effect of ambient air temperature on the exergy sustainability of a 153MW gas turbine power plant

Human body heat-driven thermoelectric generators as a sustainable power supply for wearable electronic devices: Recent advances, challenges, and future perspectives

Thermoelectric generators are devices that directly convert heat flux or the temperature difference between two hot and cold surfaces into electricity. With the advancement of the Internet of Things (IoT) technology and the development of wearable and portable devices, the issue of providing a sustainable power source is one of the main challenges in the development path of these tools. Creating electric power by harvesting the waste heat from the human body is one of the effective solutions in this way. For this reason, the development and improvement of the technology of wearable thermoelectric generators have received much attention recently. Due to the low-temperature difference between the two sides of wearable thermoelectric generators and the high thermal resistance between the skin and the heated surface of these modules, the performance of these systems is highly dependent on their structural parameters and environmental factors. In this paper, it has tried to review all the previous studies regarding the impact of structural factors (such as the matching of internal and external thermal resistances, geometrical parameters of the module, design of heat source and sink, and flexibility of thermoelectric module) and environmental parameters (including the effect of ambient air temperature and humidity, skin temperature, and the interaction of power consumers with thermoelectric modules). Based on the studies, it seems that in optimizing the performance of wearable thermoelectric generators (WTEGs), it is necessary to consider the effect of the human body's thermoregulatory responses, such as skin temperature and sweating rate. The change in skin temperature directly affects the performance of WTEGs, and the change in sweating rate can also affect the thermal resistance between the skin and the hot plate and overshadow the matching of thermal resistances during operation.

Effect of Ambient Air Temperature on the Compression Wave Propagating along a Railway Tunnel

The parameters of the compression wave propagating in a railway tunnel are significantly influenced by the large ambient air temperature variation throughout the year. High-speed train entering a railway tunnel produces a wave of finite amplitude to propagate at sonic speed. The wave attenuates while propagation through viscous dissipation and inertial forces nonlinearly steepen the wave. As a result of the dependence of sound speed on air temperature, the wave characteristics are altered with changing temperature. Therefore, it is crucial to comprehend the impact of ambient air temperature on the properties of the compression wave in order to construct an aero-acoustically ideal railway tunnel system. The method of characteristics (MOC) has been used to solve Euler equations with steady and unsteady friction parameters in the current study. According to the findings, wave attenuation ratio is reducing along the tunnel length, and gradient is rising as train speed increases. The case study illustrates the key distance within a tunnel where the steepening ratio is at its highest point. This critical tunnel length is estimated to be 65 times the tunnel hydraulic diameter (300 km/h) for a particular air temperature (T = 323 K), and it decreases by 15% for a 70 K reduction (323K to 253K) in temperature. Similarly, the critical length falls by 40% for greater train speeds (500 km/h).

The investigation of an SGT5-2000E gas turbine power plant performance in Benin City based on energy analysis

• The effect of change in ambient air temperature on the performance of the SGT5 -2000E Gas turbine Power Plant was analyzed for this location. • The average net power output was 97.33% of the guaranteed value. • For this location, a 1 0 C rise in ambient air temperature, there are drops of 1.16% in net power output and 1.58% net thermal efficiency, a 1.58% increase in SFC and HR, and a 0.64% decrease in WR. • This study has suggested efficient ways of overcome drawbacks observed. In order to address the growing global energy demand and save energy from operating gas turbine power plants, the performance and losses from existing gas turbine power plants need to be studied. In view of this, this research work aims at carrying out the energy analysis of the SGT5-2000E Gas Power Plant for off-design conditions. The energy analysis was conducted using operating data collected from the power plant to evaluate the thermal efficiencies, specific fuel consumption (SFC), heat rate (HR), work ratio (WR) and energy losses with the aid of MATLAB software. The effects of ambient air temperature and compressor pressure ratio on the thermodynamic performance were carried out. Energy analysis results obtained showed that the average net thermal efficiency of the SGT5-2000E Gas Power Plant was found to be 30.21% at the ambient air temperature range from 21 to 35 0 C, the compressor pressure ratio of 10.73 to 10.96, the net power output of 148.92MW to 160. 70MW, and 60.16% of the fuel energy input was lost to the power plant surroundings as waste heat. Also, the results obtained revealed that for a 1 0 C rise in ambient air temperature, there are drops of 1.16% in net power output and 1.58% net thermal efficiency, a 1.58% increase in SFC and HR, and a 0.64% decrease in WR. Furthermore, the results obtained showed that there was a lower performance of the plant at high ambient air temperature and a lower compressor pressure ratio and the exhaust gas waste heat can be utilized for a combined heat and power system. Accordingly, the study has provided an understanding of suitable information about the power plant that can be used for efficient operation and waste minimization as ways of performance enhancement of the SGT5-2000E Gas Turbine Power Plant in Benin City.

A numerical study on characteristics of heat transfer in hydrogen filling storage vessel by charging conditions

Recently, studies on alternative energy and new energy has been actively conducted due to environmental pollution issues. In particular, hydrogen, which is new energy, has no greenhouse gas emissions and can be produced from compounds such as water and organic matter and has no regional bias. Hydrogen electric vehicles have advantages such as high energy density and low charging time compared to electric vehicles based on battery. Many studies are being conducted on storage vessels because hydrogen is charged in storage vessel.Therefore, in this study, first, we compared experimental data with numerical analysis data to verify the numerical method and identify the relationship between Nu and Re numbers. As a result, the relationship of Nu=0.015Re0.9 was derived. Second, we applied the relationship of dimensionless number to the Fortran code to verify the results of the coded program by comparing them with those of the commercial program. Third, based on the developed Fortran code, the variables were set such as APRR(Average pressure ramp rate), inflow temperature, initial pressure and ambient air temperature.As a result of the analysis, the final charging temperature increases as the APRR rises and the final charging temperature decreases as the inflow temperature decreases. Furthermore, the increase in initial pressure has a small effect on the final temperature reduction and the effect of ambient air temperature on the final charge temperature was minimal. It is considered that the final charging temperature of the hydrogen charging storage vessel can be effectively adjusted according to the APRR and inflow temperature setting through the main effect analysis.

Characteristic analysis of compressed air energy storage system based on intermediate cooling

With the shortage of traditional fossil energy and the aggravation of global warming, the demand for transformation from traditional fossil energy to renewable energy becomes more and more urgent. Compressed air energy storage technology is a guaranteed technology to overcome the time limit of renewable energy and achieve sustainable, efficient and large-scale application of renewable resources. In order to solve the traditional compressed air energy storage technology energy output variety is single, there is low grade energy waste defects. This paper presents a compressed air energy storage system based on intermediate cooling. Through the intercooler, the system adjusts the inlet temperature of the expander, improves the output cooling quality, and realizes the coupling operation of refrigeration and energy storage. This paper establishes a thermodynamic model of the system, analyzes the effects of ambient air temperature and inlet temperature of expander on system performance, and compares the energy efficiency ratio of the system with that of compressed air refrigeration system. The simulation results show that the system can adjust the inlet temperature of expander to increase the net power consumption and achieve high quality cooling output.

An analytical model for predicting the flame length of fire lines and tree crown scorching

In forest fires, the fire plume can heat tree crowns and cause the mortality of live vegetation, even though the surface fire spread is of low burning intensity. A lot of empirical or semi-empirical correlations have been built to link the fire intensity and flame height to the crown scorch height. These correlations lack the basic physical processes of heat transfer and thermal response of needles and leaves. Besides the flame height, the fire plume temperature and velocity are also of great importance to quantify the heat transfer to the tree crown. Accordingly, an analytical model, derived from a system of differential equations, describing the conservation of mass, momentum, energy, and chemical composition, is proposed to predict the properties of a fire plume from a line fire. The flame height predicted by the analytical model matches experimental measurements of small, medium, and large line fires, showing a considerable robustness of the proposed model. With an assumption of the lethal temperature of live vegetation, the analytical model can also predict the crown scorch height against available empirical correlations and experimental data. In addition, an analysis of the effect on the flame length of the distance between the fire and the ground surface indicates that it would be better to simulate the wildland fire front by a gaseous line fire above the ground surface. The effect of ambient air temperature and fireline residence time (or heating time of foliage) on the crown scorch height is also quantified. It is found that the hot plume can heat the live foliage to reach a lethal temperature of 60°C under a heating time of 60 s.

Modification of the effect of ambient air temperature on cardiovascular and respiratory mortality by air pollution in Ahvaz, Iran.

OBJECTIVESThis study investigated the modification of temperature effects on cardiovascular and respiratory mortality by air pollutants (particulate matter less than 2.5 and 10 µm in diameter [respectively], ozone, nitrogen dioxide, carbon monoxide, and sulfur dioxide).METHODSPoisson additive models with a penalized distributed lag non-linear model were used to assess the association of air temperature with the daily number of deaths from cardiovascular and respiratory diseases in Ahvaz, Iran from March 21, 2014 to March 20, 2018, controlling for day of the week, holidays, relative humidity, wind speed, air pollutants, and seasonal and long-term trends. Subgroup analyses were conducted to evaluate the effect modification for sex and age group. To assess the modification of air pollutants on temperature effects, the level of each pollutant was categorized as either greater than the median value or less than/equal to the median value.RESULTSWe found no significant associations between temperature and cardiovascular and respiratory mortality. In the subgroup analyses, however, high temperatures were significantly associated with an increased risk of cardiovascular mortality among those 75 years old and older, with the strongest effect observed on day 0 relative to exposure. The results revealed a lack of interactive effects between temperature and air pollutants on cardiovascular and respiratory mortality.CONCLUSIONSA weak but significant association was found between high temperature and cardiovascular mortality, but only in elderly people. Air pollution did not significantly modify the effect of ambient temperature on cardiovascular and respiratory mortality.

An equivalent temperature drop method for evaluating the operating performances of ASHP units jointly affected by ambient air temperature and relative humidity

It has been known that the actual operating performances of a space heating ASHP unit are significantly impacted by the joint effect of ambient air temperature, Ta, and relative humidity, RH. To enable a convenient evaluation of the operating performances of a space heating ASHP unit with a reasonable accuracy, an equivalent temperature drop (ETD) method has been developed. The ETD method transferred the impacts of frosting-defrosting on the operating performances of ASHP units into that of an equivalent ambient air temperature drop, so that the joint effects of Ta and RH on the actual operating performances of the ASHP units may be assessed using a single parameter of equivalent ambient air temperature. In this paper, the models for predicting the output heating capacity of an ASHP unit operated at both frosting and non-frosting conditions were firstly established through either regression analysis or referring to previous related studies. Secondly, with the availability of the models, the ETD method was developed for evaluating the actual operating performances of ASHP units at different ambient conditions. Thirdly, the developed ETD method was verified by a field study on the operating performances from an ASHP unit installed in Beijing. The field study results demonstrated that for any frosting operating conditions, using the ETD method, a corresponding non-frosting condition at which the field ASHP would output the same heating capacity may be identified. Furthermore, the use of ETD method can also distinguish the individual impacts from either Ta or RH on the actual operating performances of an ASHP unit.

The effects of climate variability and seasonal influence on diarrhoeal disease in the tropical city-state of Singapore - A time-series analysis.

Diarrhoeal disease is common and imposes substantial health and economic burdens across the globe, especially in the African and Southeast Asian regions. Besides causing high mortality and morbidity, diarrhoeal disease has also been associated with growth and cognitive shortfalls in children in low-resource settings. Extreme weather events brought about by climate change may increase diarrhoeal disease and impact vulnerable populations in countries regardless of levels of development. We examined the seasonal and climatic influences of acute diarrhoeal disease reports in Singapore, a city-state located in Southeast Asia. We used a time-series analysis, adjusting for time-varying potential confounders in a negative binomial regression model and fitting fractional polynomials to investigate the relationship between climatic factors (temperature, relative humidity and rainfall) and reported diarrhoeal disease. We included 1,798,198 reports of diarrhoeal disease from 2005 to 2018. We observed annual trimodal peaks in the number of reports. Every 10% increase in relative humidity in the present week was positively associated with an increase in reports one week later [Incidence Rate Ratio (IRR): 1.030, 95% CI 1.004-1.057] and negatively associated with a decrease in reports six weeks later (IRR: 0.979, 95% CI 0.961-0.997). We observed effect modification of relative humidity on the risk of diarrhoeal disease in the first calendar quarter (January to March). There was weak evidence of a delayed effect of ambient air temperature on reports of diarrhoeal disease one week later (IRR: 1.013, 95% CI 0.998-1.027). No threshold effects of climatic factors were observed. Each week of school holidays was associated with a 14.4% reduction in diarrhoeal disease reports (IRR: 0.856, 95% CI: 0.840 to 0.871). Public holidays were associated with a reduction in reports in the same week and an increase a week later. Diarrhoeal disease is highly seasonal and is associated with climate variability. Food safety and primary healthcare resource mitigation could be timed in anticipation of seasonal and climate driven increases in disease reports.

Effect of angle of attack and wind direction on limiting input heat flux for solar assisted thermoelectric power generator with plate fin heat sink

This paper focuses on establishing the dependence of limiting value of input heat flux for solar assisted thermoelectric generators (TEG) on Angle of Attack (AOA) and wind direction of heat sink of TEG. Current study investigates the limiting input heat flux for TEGs with allowable hot side temperature of 150 °C. A fin block with eight fin configuration and fin length of 60 mm is chosen as heat sink configuration for TEG. Computational Fluid Dynamics (CFD) model is developed and analyzed in this work after validation with published experimental results. CFD model consists of four TEGs encapsulated within a target block and a finned block, placed within a domain which simulates low speed wind tunnel. Air flow in the wind tunnel simulates the outdoor wind conditions. Concentrated solar flux is applied on the face of target block. Effect of ambient air temperature on limiting input heat flux is also studied. Dependence of limiting input heat flux on Angle of Attack (AOA) and wind direction, which arises due to the two axis tracking of Sun by Fresnel lens concentrator has been quantified and it is observed that maximum limiting input heat flux occurs at 30° AOA. Maximum limiting heat flux reaches 24,000 W/m2 for 30° AOA under 5 m/s wind velocity. It is also observed that maximum input heat flux varies by 42.49% with change in wind velocity from 1 to 5 m/s. Maximum limiting input heat flux occurs at 45° for horizontal rotation. Area of square array Fresnel lens concentrator varies by 6.29% for 5 m/s wind velocity when AOA is considered to when AOA is not considered for calculation of Fresnel lens area.

An experimental study to investigate typical temperature conditions in fuel tanks of European vehicles

Vehicular evaporative emissions have been recognized as an important source of volatile organic compounds to the environment and are of high environmental concern since these compounds have been associated to the formation of surface ozone and secondary organic aerosols. Evaporative emissions occur during any vehicle operation. In Europe, a revised legislative test procedure has been recently introduced to better control evaporative emissions during parking. However, emissions related to normal driving conditions—the so-called running losses—have received less attention compared with the other categories. The current study aims at giving some insights to the prevailing temperature conditions in fuel tanks of typical European vehicles during normal driving operation. The effects of ambient air temperature, trip duration, vehicle speed, and fuel tank level on the temperature reached by the fuel inside the tank under different real-world operating conditions were studied. Tank temperature can exceed 40 °C depending on ambient and driving conditions. Ambient temperature was found to be the most important parameter affecting the tank temperature. Trip duration and driving pattern may also have an influence on the tank temperature particularly when long trips combined with high vehicle speed are examined. Additionally, the difference between tank and ambient temperature was examined during the individual trips and was found to vary between 1 and 10 °C depending on the testing conditions. The most important parameters affecting the delta temperature were found to be the trip duration and the maximum vehicle speed. Finally, the purging strategy of two of the test vehicles was monitored, and the parameters affecting the purging flow rate were investigated. No strong correlation between the canister flow rate with ambient temperature, vehicle speed, or fuel level was observed in either of the tested vehicles. Substantially different canister flow rate levels between the two vehicles point to different purging strategies.

A computational approach thermoelectric power generators to estimate heat flux

This paper focuses on establishing the limiting value of input heat flux for thermoelectric generators (TEG) under different environmental and operating conditions. The current study investigates the limiting input heat flux for TEG’s with allowable hot side temperature of 150.A fin block with 8 fin configuration and fin length of 60 mm is chosen as heat sink configuration for TEG. Computational Fluid Dynamics (CFD) model is developed and analyzed in this work after validation with published experimental results. CFD model consists of 4 TEGs encapsulated within a target block and a finned block, placed within a low speed wind tunnel. Forced laminar air flow in the wind tunnel up to 14 m/s simulates the outdoor wind conditions. Concentrated solar flux is applied to the face of the target block. Effect of ambient air temperature, fin material is studied. Angle of Attack (AOA) and wind direction which arises due to the 2 axis tacking of sun by Fresnel lens concentrator has also been studied and it is observed that maximum heat flux reaches 24,850 W/m2 for the TEG at 14 m/s wind speed, 24,000 W/m2 for 30Angle of Attack (AOA) under 5 m/s wind velocity. It is also observed that maximum heat flux varies by 147.77% with a change in wind velocity from 0 to 5 m/s, while the change is 11.43% when the change from 5 to 14 m/s.

Study the Concentration of SO2 Emitted From Daura Refinery by Using Screen View Model

In this study, the concentrations of sulfur dioxide (SO2) were emitted from the Daura oil refinery units and their effect on the surrounding areas of the refinery were investigated, and also, study the atmospheric stability effective by using the Screen View model, and check the effect of the wind speed and direction on the spread of pollutants. 
 As indicated during this study, the physical factors of the sources of pollution, such as the height of the chimney, its diameter and the surrounding environmental conditions, contributed to the increase in the concentration of contaminants. It was generally observed that the concentration of SO2 increased by increasing the rates of airflow and ambient temperature. This work was prove the influences of weather conditions in the transmission and spread of pollutants such as wind speed, wind direction, atmospheric stability and ambient temperature, but the effect of ambient air temperature was lower than others variables.
 When the distance increases between the plume and the source of pollution, a heat exchange takes place with the surrounding atmosphere, the difference between the temperature of the emitted gas and the surrounding atmosphere decreases and the buoyant force increases. This leads to a lack of vertical movement that disperses the contaminants. In addition, the concentration of the pollutants decreases with the distance increases from the source of the pollution. In the present work, emission rate of SO2, and stack gas exit velocity calculated for all stacks (point sources) of the twelve production units during August 2013, and February 2014 by using the actual amounts of fuel consumed in Daura refinery in this period.

Effect of Ambient Air Temperature on the Performance of Petrol Engine

The purpose of the present study is to investigate the effect of ambient air temperature on the performance of spark ignition engine, and exhaust gas temperature. Various factors taken that affects the performance of four- stroke petrol engine. An experimental study is carried out to investigate engine performance parameters. The experimental results demonstrate that the method proposed to measure the intake ambient air temperature at different engine speeds. The different ambient air temperature was taken (10, 20, 30, 40 and 50°C) at different climate conditions and in the different engine speeds (1500, 2000 and2500 r.pm). The results of experimental shows that increasing ambient air temperature will improve the fuel consumption and thermal efficiency about (14%- 16%) consecutively. It is also shows decrease in the volumetric efficiency with increasing ambient air temperature. However, by increasing sucked air temperature, will lead to increase exhaust gas temperature.

Simulating the Performance of Solar Panels in Iraq

The solar energy is the most available, non-polluting and free source of energy. Solar photovoltaic energy is the fastest growing energy resource and it will someday become the dominant source of energy. Iraq is located 290N-370N latitude so, it has a good possibility of solar energy, which could be invested to generate the electrical power by the photovoltaic modules. The used databases in this study are hourly data of irradiance were obtained from Photovoltaic Geographical Information System (PVGIS) while air temperature and wind speed were obtained from the European Centre for Medium-Range Weather (ECMWF) for the period 1/1/2001-31/12/2012. Mathematical MATLAB program has been created to estimate the cell temperature and electrical power of a monocrystalline module for 200 sites in Iraqi areas. This study states the effects of environmental parameters on both the cell temperature and the electrical power of a monocrystalline PV module. Irradiance on tilt surface, ambient temperature, and wind speed are the key environmental factors in this study. By using Arc GIS, maps of electrical power and cell temperature distributions of a monocrystalline were drawn based on NOCT model.It has found that the effect of solar radiation on the output electrical power from the PV module is greater than the effect of ambient air temperature. Also, it has found that the monthly electrical power received from the module is varied throughout the months for the study area where the highest electrical power was recorded in June and the lowest electrical power recorded in December. Also, it varies in different sites, the southern part of Al- Qadisyah, western part of Dhi-Qar, northern part of Al-Muthannia and southwestern part of Al-Anbar provinces recorded the highest values of electrical power while the lowest value in the eastern part of Dihok.

Dual steady flow solutions of heat and pollutant removal from a slot ventilated welding enclosure containing a bottom heating source

Abstract Air conditioning and ventilation in buildings are major sources of energy consumption, particularly in large industrial buildings with significant pollutant and heat sources. Unfortunately, air flow motions in these slot-ventilated large building spaces are currently poorly understood, particularly concerning their special flow behaviours – multiple steady flows, i.e., identical boundary conditions but different initial conditions or load perturbations may lead to two or more flow solutions. Multiple steady enclosure flow behaviours essentially complicate the convective transport of air, heat and species, which has been vividly analyzed by streamlines, heatlines and masslines. In the present study, the flow mechanisms and transitions driven by combined natural and forced convections in an industrial building space for a welding process will be investigated through the numerical methodology of computational fluid dynamics. The research has taken into consideration the effects of ambient air temperature, indoor heating loads, and welding shifting position on multiple flow motions. The parameters governing the problem are the Reynolds number (103 ≤ Re ≤ 107) and the Grashof number (107 ≤ Gr ≤ 1013) and it is observed that the multiple-steady-regions can be maintained for a range of values of Gr/Re2, 150

Rayleigh wave technology for analysis dynamic modulus of asphalt mixtures: feasibility and application

ABSTRACT This study focused on the application of Rayleigh wave technology on a non-destructive determination of dynamic modulus of asphalt mixtures. A 3-D finite element numerical algorithm was developed to simulate Rayleigh wave propagation in a multi-layer half-space system. Numerical analysis verified the feasibility of Rayleigh wave technology to capture the mechanical property differences in shallow structures within asphalt pavements. Then, five asphalt mixtures were used in the experimental application of Rayleigh wave technology. A multichannel simulation with one receiver (MSOR) was adopted to generate Rayleigh waves in asphalt mixture samples. Changes in phase velocity-frequency energy spectra and wave velocity were used to evaluate effects of ambient air temperature and asphalt mixture type on wave propagation evolution in asphalt mixtures. Rayleigh wave technology was introduced to dynamic modulus analysis using various experimental temperatures and asphalt mixtures. Obtained modulus was compared with that using impact resonance method to evaluate the prediction precision for analysis dynamic modulus of asphalt mixtures.