High Ambient Air Temperature Research Articles

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.

Relationships of Water Quality Parameters for Hydroponic Production of Kale (Brassica oleracea) with In-Ground Passive Cooling System

Greenhouses in Philippines are encountering high ambient air temperature problem. Along with this, the water quality directly affects the growth, development and yield of hydroponically grown plants. This study was conceptualized through the principle of cooling the nutrient solution that will effectively regulate plant’s growth and yield with relatively low investment and easier management. One of the essential elements of a functional hydroponics system is water quality monitoring, hence this study utilized a monitoring system for water quality parameters. Nutrient solution was closely monitored to maintain and ensure that nutrient levels are not too low to inhibit growth and not too high to be potentially toxic. The study was conducted to develop a monitoring system for environmental and water quality parameters of in-ground passive cooling system for hydroponic production of kale. Specifically, the study aimed to determine the relationships of water quality parameters such as pH, EC, TDS, and temperature for kale production, compare the performance of an in-ground passive cooling system (IGPCS) and without cooling system (Control) on hydroponically grown kale, and to evaluate the water productivity of the in-ground passive cooling system. This study utilized both in-ground passive cooling system (IGPCS) and control (without cooling system) to compare its performance based on the growth and yield of the kale, and to determine the water productivity of utilizing IGPCS. In addition, water quality parameter such as pH, EC, TDS, and temperature were closely monitored using the installed monitoring system, and relationships of these water quality parameters were established. The gathered data were analyzed using trend analysis in Microsoft Excel, Analysis of variance (ANOVA) was computed in Completely Randomized Design (CRD) and comparison among means were compared using Least Significant Difference (LSD) Test at 5% level. Results revealed that EC and TDS of nutrient solution are inversely proportional to pH and temperature of nutrient solution, moreover EC and TDS are directly proportional, also with pH and temperature of nutrient solution. The performance of the IGPCS and without cooling system is comparable with growth and yield of kale in terms of leaf length, leaf width, number of leaves, weight and yield at harvest, but are significantly affected by the location of growing pipes where crops received less and ample amount of sunlight. Since the temperature of IGPCS was reduced up to 3°C, kale plants with cooling system uptake less water compared to without cooling system and results to higher productivity. Therefore, regulating one of the water quality parameters directly affects other water quality parameters, so relationships of these water quality parameters were established through close monitoring of water quality parameters using the monitoring system. Utilization of IGPCS reduced the temperature of the nutrient solution up to 3°C which gave higher yield (44.01 g/plant) than without cooling system (41.18 g/plant). Kale production in tropical areas can have higher yield using the in-ground passive cooling system that reduced water consumption, resulting to higher productivity.

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 Methodology of Creating a Synthetic, Urban-Specific Weather Dataset Using a Microclimate Model for Building Energy Modelling

The relationship between outdoor microclimate and indoor building conditions requires the input of hourly weather data on the typical meteorological characteristics of the specific location. These data, known as typical meteorological year (TMY), are mainly deduced from the multi-year records of meteorological stations outside urban centres, preventing the actual complex interactions between solar radiation, wind speed, and high urban density. These factors create the urban heat island effect and higher ambient air temperatures, skewing the assumptions for energy demand in buildings. This paper presents a computational method for assessing the effect of the urban climate in the generation of typical weather data for dynamic energy calculations. As such, the paper discusses an evaluation method of pairing ENVI-met 4 microclimate and IES-VE building energy modelling software to produce a typical urban specific weather dataset (USWDs) that reflects the actual microclimatic conditions. The ENVI-met results for the outdoor microclimate conditions were employed to determine the thermal boundaries for the IES-VE, and then used to compute the building’s energy consumption. The energy modelling that employed the USWDs achieved better performance compared to the TMY, as the former had just a 6% variation from the actual electricity consumption of the building compared to 15% for the latter.

Techniques for Extracting Pure Water from Atmospheric Air by a Solar Collector and Absorbent Materials: Recent Advances and Development

Because air is a clean, renewable source of water that is available everywhere, air extraction is regarded as one of the key means of supplying fresh water. Many researchers have looked into this issue. These investigations may be divided into two major categories. While the second group researches the direct absorption-regeneration of moisture from air, the first group works with the of air. This paper presents and explores previous theoretical and experimental works and study on the topic of extracting pure water from air and using different absorbent substances to absorb water vapor from the atmosphere. The fundamentals and improvements to the topic of pure water extraction and its great benefit were the use of different elements and materials when designing a prototype in the main components of the extraction systems. Drinking water is generated from the air by solar panels using solar energy and heat during the day. It has been discovered that some desiccant materials with good water absorbers, such as calcium chloride and silica gel, may be successfully utilized in the processes of extracting drinking water from ambient air by creating suitable designs. It has been demonstrated that using solar energy may change the high ambient air temperature, a primary cause of water scarcity, into a benefit.

High-temperature operatable triboelectric nanogenerator using microdome-patterned polyimide for self-powered sensors

Renewable energy has received attention all around the world to deal with environmental pollution and energy crisis. Triboelectric nanogenerators (TENGs) has emerged as a promising way to transition to green energy. However, typical TENGs exhibit inferior output, low heat-resistance, and low durability. Polyimide is one of the most mechanically strong and thermally stable thermoplastics, and it could be used to overcome the drawbacks of TENGs. Thus, polyimide has become a promising building material for robust TENGs. Herein, we have rationally designed and created an efficient polyimide tribo-surface with customizable non-close packed microdome arrays (md-PI) to assemble TENGs (md-TENG) for harvesting windmill energy and vibration from engine even with hot air and high humidity surrounding. The md-TENG fabricated with md-PI and flat aluminum can generate an exceptional output power of 1.42 W∙m−2. This is about 29 times higher than the output of a TENG using a normal flat PI. Additional FEM simulations are performed to analyze the relationship between the contact area and mechanical stresses on the md-PI. Moreover, the md-TENG possesses outstanding durability of over 16,000 cycles of contact-separation, and the device exhibits better outputs at elevated temperature. The newly developed md-TENG achieves excellent thermal stability and durability as well as superior electrical output, which are essential to expand the practical applications of TENG. To illustrate the strengths of md-TENG, we demonstrated a wireless communication self-powered IoT humidity sensor and a vibration TENG sensor at high ambient air temperature in the engine compartment of a car.

The combination of earth-to-air heat exchanger (EAHE) and phase change material (PCM) for indoor thermal environment regulation

The research and application of energy-saving technologies in buildings is receiving increasing attention. Phase change materials (PCM) is an effective passive cooling technology in the regulation of indoor thermal environment. However, in hot-summer and cold-winter regions, the high ambient air temperature makes it difficult to reduce PCM temperature to the phase change temperature in summer. Earth-to-air heat exchanger (EAHE), as an effective energy-saving ventilation technology, in combination with PCM can improve indoor thermal comfort. We performed full-scale experiments to investigate the combination of EAHE and PCM for indoor thermal environment regulation in a typical hot-summer and cold-winter region of China. After 24 hours of continuous operation in summer, variations in ambient and EAHE outlet air temperature range from 28.50 to 44.52 °C and from 22.78 to 24.78 °C respectively. EAHE can effectively precool fresh air, and its average cooling capacity and coefficient of performance (COP) are 1823.03 W and 16.6. The combination of EAHE and PCM has positive impacts on the regulation of indoor thermal environment. The indoor air temperature is in the 22-28 °C range for 69.0 % of the 24 h, and peak indoor air temperature is 31.14 °C. The hybrid system has a TDR of 0.84.

Postnatal exposure to ambient temperature and rapid weight gain among infants delivered at term gestations: a population-based cohort study.

The global prevalence of childhood obesity has risen dramatically recently. Previous studies found an association between rapid infant weight gain and childhood overweight. Evidence suggests that exposure to high ambient air temperatures during prenatal life and during adulthood is associated with birthweight and obesity respectively. The objective of this study was to examine whether exposure to high ambient temperatures during infancy is associated with rapid infant weight gain in Israel. This is a population-based historical cohort study using data from the Israeli national public network of maternal and child health clinics between 2008 and 2013. We assessed exposure to ambient temperature in the first year of life using a high-resolution hybrid spatio-temporal model and calculated annual mean and minimum temperatures for each infant based on daily mean and minimum temperatures at the community clinic location. We defined rapid infant weight gain as a World Health Organization weight z-score difference >0.67 between birthweight and weight at age one year. We estimated these associations using log-linear and general additive models and adjusted for population group, district, maternal age, parental education, parity, sex, gestational age, birthweight, calendar year and calendar month of birth. The study population included 217,310singleton-term infants. Adjusted models demonstrated a positive association between ambient temperature exposure and rapid infant weight gain. Compared to the third quintile of minimum temperature, infants exposed to the first and second quintile had an adjusted relative risk of 0.98 (95% CI 0.96, 1.00) and 0.97 (95% CI 0.95, 0.98), respectively, while those exposed to the fourth and fifth quintiles had an adjusted relative risk of 1.06 (95% CI 1.04, 1.07) and 1.02 (95% CI 1.00, 1.04) respectively. The associations with mean temperature were similar but slightly weaker. Exposure to higher ambient temperatures, of emerging importance in the climate change era, is associated with rapid infant weight gain in Israel. Future studies should use additional exposure, covariate, and outcome data to analyse the nature and the source of this association in more detail.

Modeling and optimization of water mist system for effective air-cooled heat exchangers

Air-cooled heat exchangers (ACHEs) are one of the most efficient and widely used equipment for heat exchange. However, the main disadvantages of ACHEs are their heat exchange performance is decreased by high ambient air temperature (Ta), especially on summer season. To solve this problem, a water mist system that sprays an amount of water is applied to ACHEs. However, the water mist system causes corrosion problems of the peripheral devices. Therefore, it is crucial to find a proper water mist system with optimized operating conditions that improve the cooling effect without corrosion. Herein, we developed the CFD model to find the optimal amount of water sprayed. Cooling effect and water evaporation ratio according to the amount of water sprayed and Ta were calculated using the CFD model. As a result of the calculation, the amount of water that gives the target cooling effect as all water evaporates is 3.364 kg/h and 7.928 kg/h at Ta of 303.15 K and 313.15 K, respectively. This study provides the optimal amount of water sprayed on the water mist system considering the cooling effect and corrosion according to Ta, and it can apply to the commercial processes.

Numerical investigation on combustion and emissions in a direct injection compression ignition engine fuelled with various hydrogen–methane–diesel blends at different intake air temperatures

Blending hydrogen and methane with diesel in compression ignition engines has been proven to improve both performance and emissions. This work further explores the combustion characteristics and emissions of a direct injection compression ignition (DICI) engine fuelled with various blend ratios of hydrogen, methane and diesel with respect to varying intake air temperatures, as the blend ratio can affect the mixture formation process in such high-speed in-cylinder phenomena. A numerical study using ANSYS Fluent was conducted based on a 0.406-litre Yanmar L100AE-D single-cylinder DICI engine running at 1500 rpm and was verified with a physical experiment using the same engine. The tri-fuel blend consisted of 60% diesel by mass with the remaining 40% made up with various ratios of hydrogen and methane (0%/40%, 12%/28%, 20%/20%, 28%/12%, and 40%/0%). The intake air temperatures were varied at 303 K, 318 K and 338 K, representing near-standard, high and extremely high ambient air temperatures, respectively. The results showed that the presence of methane and hydrogen in diesel fuel resulted in a higher in-cylinder pressure, temperature and heat release rate (HRR). Increasing the intake air temperature caused a proportional increase in the in-cylinder temperature, pressure and HRR. However, the presence of methane lengthened the ignition delay, while increasing hydrogen reversed the trend. While the presence of hydrogen–methane reduced the overall CO emissions, the effect of hydrogen on CO reduction was dominant. In addition, the presence of hydrogen–methane led to an increase in NOx emissions due to the high combustion temperature. The study suggested that an optimized intake temperature and the balanced use of tri-fuel in a direct injection compression ignition engine can significantly improve engine performance and emissions.

Impact of the Climate Change and the Recent Development of an Artificial Tropical Estuary on the Mobility and Distribution of Phosphorus: Case of Vridi Channel (Côte d'Ivoire)

This study focused on the effects of the climate change and the recent modification of Vridi channel on the mobility and distribution of phosphorus (P) in its superficial sediments. To best estimate this fact, the annual mobility and distribution of P were followed and compared before and after this development during two different annual periods, marked differently by the climate change effects. The first annual period has covered the period from April 2014 to March 2015 and this channel presented its former hydromorphology, with hydroclimatic conditions very close to that normal of Abidjan district. The second period annual has covered the period from October 2018 to September 2019 and this channel presented its current hydromorphology and, characterized by a rainfall drop and high ambient air temperatures compared to that normal of Abidjan district.
 A monthly sampling has been done at 5 cm below the surface sediment in this channel during each annual period. The mobility and distribution of P was assessed in the superficial sediments of this channel according two sequential extraction protocols: the modified Van Eck method and the modified Olsen method. Total phosphorus was assessed according AFNOR NF X31-147.
 The total phosphorus contents and all P fractions contents of these superficial sediments assessed by these two sequential methods and obtained over the period from April 2014 to March 2015 are higher than those determined over the period from October 2018 to September 2019. Thus, the recent development of this estuary, with as a corollary the modification of the physical and chemical characteristics of its superficial sediments, would have had the effect of clearing P towards the Atlantic Ocean and/or accelerating its sedimentation; hence the reduction of eutrophication risk of this aquatic ecosystem.

Numerical study on the characteristics of temperature distribution in continuous welded rail by solar radiation and rail orientation

In summer, the high ambient air temperatures and increased solar radiation cause rises in rail temperatures, and rails can experience the buckling. In this study, a thermofluidic analysis was conducted to predict the temperature of a rail. Numerical simulations were performed by changing the orientation of the rails. The south-north rail and the east-west rail was named “0° rail” and “90° rail”, respectively. The numerical results from the 0° and 90° rails were validated by comparing them with measured values. Based on this validation, the temperature distribution of a 45° rail was analyzed. The total amount of energies received by the rail were in the order of 0° > 45° > 90°. The results of this study showed that the temperature of a rail can be sufficiently predicted through numerical simulation, and this approach can be used in a forecast to predict a time when buckling might occur.

Heat Extremes, Public Health Impacts, and Adaptation Policy in Germany

Global warming with increasing weather extremes, like heat events, is enhancing impacts to public health. This essay focuses on unusual extreme summer heat extremes occurring in Germany at higher frequency, longer duration, and with new temperature records. Large areas of the country are affected, particularly urban settlements, where about 77% of the population lives, which are exposed to multiple inner-city threats, such as urban heat islands. Because harm to public health is directly released by high ambient air temperatures, local and national studies on heat-related morbidity and mortality indicate that vulnerable groups such as the elderly population are predominantly threatened with heat-related health problems. After the severe mortality impacts of the extreme summer heat 2003 in Europe, in 2008, Germany took up the National Adaptation Strategy on Climate Change to tackle and manage the impacts of weather extremes, for example to protect people’s health against heat. Public health systems and services need to be better prepared to improve resilience to the effects of extreme heat events, e.g., by implementing heat health action plans. Both climate protection as well as adaptation are necessary in order to be able to respond as adequate as possible to the challenges posed by climate change.

ВИКОРИСТАННЯ НАДЛИШКУ ХОЛОДОПРОДУКТИВНОСТІ ХОЛОДИЛЬНИХ МАШИН ПРИ ОХОЛОДЖЕННІ ПОВІТРЯ НА ВХОДІ ГТУ

The processes of the gas turbine inlet air cooling by exhaust heat conversion chillers, which utilizing the gas turbine exhaust gas heat, converting it into cold were analyzed. The use of two-stage air cooling has been investigated: to a temperature of 15°C – in an absorption lithium-bromide chiller and below to a temperature of 10°C – in an ejector chiller as stages of a two-stage absorption-ejector chiller. To simulate air cooling processes, the program "Guentner Product Calculator", one of the leading manufacturers of heat exchangers "Guentner", was used. The possibility of using the accumulated excess refrigeration capacity of a combined absorption-ejector chiller, which is formed at reduced current heat loads on air coolers at the gas turbine inlet, to cover the refrigeration capacity deficit arising at increased heat loads due to high ambient air temperatures has been investigated. The refrigeration capacity required to the gas turbine inlet air cooling was compared to an excess refrigeration capacity which excess of the current heat load. The considered air cooling system provides pre-cooling of air at the gas turbine inlet by using the excess refrigeration capacity of the absorption-ejector chiller, accumulated in the cold accumulator, to provide the required refrigeration capacity of the air pre-cooling booster stage. The simulation results proved the expediency of the gas turbine inlet air cooling using the accumulated excess refrigeration capacity of the combined absorption-ejector chiller. The proposed solution reduces by about 50% the design refrigeration capacity and, accordingly, the cost of the installed absorption lithium-bromide chiller, which acts as a high-temperature stage for cooling the ambient air at the gas turbine inlet.

Redefining physiological responses of moose (Alces alces) to warm environmental conditions.

We tested the concept that moose (Alces alces) begin to show signs of thermal stress at ambient air temperatures as low as 14°C. We determined the response of Alaskan female moose to environmental conditions from May through September by measuring core body temperature, heart rate, respiration rate, rate of heat loss from exhaled air, skin temperature, and fecal and salivary glucocorticoids. Seasonal and daily patterns in moose body temperature did not passively follow the same patterns as environmental variables. We used large changes in body temperature (≥1.25°C in 24hr) to indicate days of physiological tolerance to thermal stressors. Thermal tolerance correlated with high ambient air temperatures from the prior day and with seasonal peaks in solar radiation (June), ambient air temperature and vapor pressure (July). At midday (12:00hr), moose exhibited daily minima of body temperature, heart rate and skin temperature (difference between the ear artery and pinna) that coincided with daily maxima in respiration rate and the rate of heat lost through respiration. Salivary cortisol measured in moose during the morning was positively related to the change in air temperature during the hour prior to sample collection, while fecal glucocorticoid levels increased with increasing solar radiation during the prior day. Our results suggest that free-ranging moose do not have a static threshold of ambient air temperature at which they become heat stressed during the warm season. In early summer, body temperature of moose is influenced by the interaction of ambient temperature during the prior day with the seasonal peak of solar radiation. In late summer, moose body temperature is influenced by the interaction between ambient temperature and vapor pressure. Thermal tolerance of moose depends on the intensity and duration of daily weather parameters and the ability of the animal to use physiological and behavioral responses to dissipate heat loads.

Investigation into Operating Conditions of a Dry Mechanical Draft Cooling Tower at the TETs-12 Cogeneration Power Station of PAO Mosenergo

The results of the comprehensive investigation into operation of a dry mechanical draft cooling tower (DMDCT) of a PGU-220 power unit at the TETs-12 cogeneration power station of PAO Mosenergo are presented. Thermal performance of the main and auxiliary DMDCTs and their individual sections is examined. To determine the cooling-air flowrate, a rake consisting of 11 velocity transducers and thermocouples was installed at the fan outlet above the fan diffuser of the examined section. The DMDCT heat balances calculated on the basis of water- and cooling-air conditions agree with each other with a maximum error of 8%. The overall thermal performance indices of the main and auxiliary DMDCTs were lower than those specified by the supplier. Performance of DMDCT fans was investigated at different blade angles α. According to our calculations, the effect of better fan performance in terms of an increase in the power of a steam turbine in a combined-cycle unit at α > 15° does not compensate for an increase in the power consumption of fan motors and even reduces the amount of delivered power. Therefore, the range of α = 10°–15° for the fans of the main DMDCT may be considered optimal. As to the auxiliary cooling tower, an increase in the air flow at α = 17° can offer a wider operation range for the fans at high ambient air temperatures, which is important considering limitations on the supply temperature (below 35°С) of the auxiliary equipment cooling water. The investigation of DMDCT operation during the cold season yielded the dependence of the minimum heat load of DMDCT, required for its safe operation, on the ambient air temperature. The study into the performance of the humidification system revealed that its efficiency is inadequate. The best solution to this problem is to replace the normal humidification nozzles with nozzles with smaller diameter holes to improve water dispersion that will prevent the water drops from falling onto the ground and improve the efficiency of the humidification system while decreasing the water flow to the humidification nozzles.

Effects of local ambient air temperatures on wind park performance: case of the Kaberten wind park

ABSTRACT The aim of this work is to investigate the effect of extreme high ambient air temperature on the performance of a wind farm operating in Algeria Saharan area. The analysis is carried out using in-situ field-data and the Wind Atlas Analysis and Application Program (WAsP). The predicted annual energy production is compared to the actual performance of the wind farm. Then the influence of the air density variation on the AEP prediction is evaluated. It is shown that the error on predicted AEP is reduced when one take into account the monthly variation of the air density.

Temperature Rise Effects on Dynamic Resistances for Laser Diodes With a Wavelength of 450 nm for Vehicle Headlight Applications

In this paper, a laser headlight power converter (LHPC) was developed to drive the InGaN-based blue beam laser diode (BBLD). The LHPC was composed of the four–switch step-up step-down converter (FSSUSDC), the FSSUSDC controller, and the current error compensator (CEC). When the BBLD dynamic resistance was increased under the high ambient air temperature, the FSSUSDC operated in the step-down mode, and the CEC employed the proportional-integral control, the BBLD driving current exhibited an ignition current spike, which could destroy the semiconductor material of the BBLD, resulting in optical output power decay. Therefore, a new four-gradation gain (FGG) control method was proposed to mitigate the ignition current spike of the BBLD. This paper presented the BBLD temperature characteristic, an analysis of the LHPC ignition current, a CEC compensation design, and an analysis and design of the FGG control.

Airborne Carcinogenic Trace Elements Distribution Associated with Long Term Exposure in Makkah Population

Background:More than 4 million international pilgrims visit Makkah each year during the Hajj and Umrah seasons. Since trace elements are natural ingredients that endure general biogeochemical cycling, conversion functions between environmental loadings, mass levels, and exposed receptors.Objective:This study aimed to evaluate the distribution of carcinogenic trace element levels related to long term exposure.Methods:Particulate Matter (PM10) sampling was conducted at six locations (Al-Haram, Arafat, Muzdalifah, Aziziyah, Al Nuzhah, and Al Awali). On-site measurement parameters included ambient temperature, wind speed, and direction over 37 weeks. Samples were investigated for Cd, Cr, As, Be, and Ni levels with inductive coupled plasma mass spectrometry. Quality assurance measures were achieved separately by analyzing a control sample to certify reliability, reproducibility, and linearity for each analysis.Results:Average particulate matter concentration for a one-year period presented significant variability, which exceeded the WHO guidelines for average exposure (25.0 µgm-3). PM10 average concentrations during round-1 (Spring), round-2 (Summer), round-3 (Autumn) and round-4 (Winter) were 120.1 ± 52.2 µgm-3, 223.4 ± 30.4 µgm-3, 77.6 ± 36.72, and 89 ± 62.7 µgm-3, respectively. The concentrations of Cd, Cr, As, Be, and Ni were found to be 0.098, 0.008, 0.26, 0.03, and 0.012 µgm-3, respectively.Conclusion:PM10 concentration was highly correlated (p-value <0.005) with Cd, Cr, As, Be, and Ni; thereby indicating the influence of manufacturing discharges and pollutants transported over long-distances. Higher ambient air temperatures may cause atmospheric instability in low air dispersion around Makkah. This highlights the importance of continuous air monitoring and calculation of dose exposure levels of both PM10 and trace elements.

Sustainability and thermoenvironmental indicators on the multiobjective optimization of the liquefied natural gas fired micro-cogeneration systems

Liquefied natural gas (LNG), a clean fuel type mainly containing methane, has been becoming more popular amongst the other fuels for the power generation systems. Although there are a lot of thermodynamic and thermoeconomic assessments about the LNG fired power generation systems, the environmental and sustainability aspects have still lack investigation, especially on the optimization step. To minimize this gap, a multiobjective optimization study is performed for the LNG fired micro-cogeneration system. The current study considers various objective functions from thermodynamic, environmental, thermoeconomic, and sustainability aspects. A newly developed sustainability index is used as one of the objective functions in the study. The approach is defined as the complex multiobjective optimization procedure that constitutes different multiobjective optimization groups to better understand and evaluate the different objective functions together. The controllable air temperature and relative humidity are selected as the external decision variables. The best trade-off regions are identified between 300.00 K and 313.15 K at the relative humidity of 90% while they are found between 310.15 K and 313.15 K at the relative humidity of 50%. The high relative humidity and ambient air temperature present the best climatic conditions for the optimal operation of the small-scale system during the indoor operations.