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In this study, a new solar-based fuel cell-powered oxygenation and ventilation system is presented for COVID-19 patients. Solar energy is utilized to operate the developed system through photovoltaic panels. The method of water splitting is utilized to generate the required oxygen through the operation of a proton exchange membrane water electrolyser. Moreover, the hydrogen produced during water splitting is utilized as fuel to operate the fuel cell system during low solar availability or the absence of solar irradiation. Transient simulations and thermodynamic analyses of the developed system are performed by accounting for the changes in solar radiation intensities during the year. The daily oxygen generation is found to vary between 170.4 kg/day and 614.2 kg/day during the year. Furthermore, the amount of daily hydrogen production varies between 21.3 kg/day and 76.8 kg/day. The peak oxygen generation rate attains a value of 18.6 g/s. Moreover, the water electrolysis subsystem entails daily exergy destruction in the range of 139.9-529.7 kWh. The maximum efficiencies of the developed system are found to be 14.3% energetically and 13.4% exergetically.

Aim: To compare the incidence of in-hospital complications between diabetic normotensive and hypertensive diabetic patients presenting with acute myocardial infarction (MI) Methodology: This observational cohort study was conducted at National Institute of Cardiovascular Diseases Karachi from May 2019 to April 2020. We examined 220 diabetics with acute MI were included. 50% of the patients had high blood pressure and the rest had normal blood pressure. After enrollment in the study, selectees were observed for acute myocardial infarction complications in the hospital. Results: Most of the baseline characteristics were similar in both groups of patients. However, the hypertensive patients in the diabetes group had diabetes, high heart rate, and high blood pressure at reporting. The complication rates did not differ statistically between the two groups. The rates of complications occurred between diabetes and normotensive hypertension; Atrial fibrillation (AF) 15.5% vs 12.7% p = 0.194, respectively, ventricular tachycardia (LH) 14.5% vs 13.6%, AV block type-1 8.2% vs 7.3% p = 0.296, type2 AV block 2.7% vs 1.8% p = 0.352, complete heart block 11.8% vs 10% p = 0.313, acute congestive heart failure (CHF) 13.6% VS% 9.1 p = 0.137, left ventricular failure (LVF)19.1% vs 16.4% p = 0.259, cardiogenic shock (CS) 14.5% vs 10.9% p = 0.184, recurrent IM (Re-MI) 14.5% 10.9% p = 0.184 and mortality 14.5% vs 12.7 and% p = 0.326, respectively. Conclusion:It is concluded that diabetic patients with hypertensionhave not elevated risk of complications in the hospital after acute myocardial infarction. Key words: diabetes, hypertension, hospital complications, acute myocardial infarction

A new configuration of solar energy-driven integrated system for ammonia synthesis and power generation is proposed in this study. A detailed dynamic analysis is conducted on the designed system to investigate its performance under different radiation intensities. The solar heliostat field is integrated to generate steam that is provided to the steam Rankine cycle for power generation. The significant amount of power produced is fed to the PEM electrolyser for hydrogen production after covering the system requirements. A pressure swing adsorption system is integrated with the system that separates nitrogen from the air. The produced hydrogen and nitrogen are employed to the cascaded ammonia production system to establish increased fractional conversions. Numerous parametric studies are conducted to investigate the significant parameters namely; incoming beam irradiance, power production using steam Rankine cycle, hydrogen and ammonia production and power production using TEGs and ORC. The maximum hydrogen and ammonia production flowrates are revealed in June for 17th hour as 5.85 mol/s and 1.38 mol/s and the maximum energetic and exergetic efficiencies are depicted by the month of November as 25.4% and 28.6% respectively. Moreover, the key findings using the comprehensive dynamic analysis are presented and discussed.

A novel solar PV and wind energy based system is proposed in this study for capturing carbon dioxide as well as producing hydrogen, urea and power. Both Aspen Plus and EES software packages are employed for analyses and simulations. The present system is designed in a way that PEM electrolyzer is powered by the wind turbines for hydrogen production, which is further converted into ammonia and then synthesizes urea by capturing CO2 and additional power is supplied to the community. The solar PV is employed to power the cryogenic air separation unit and the additional power is used for the industrial purpose. In the proposed system, ammonia does not only capture CO2 but also synthesizes urea for fertilizer industry. The amount of electrical power produced by the system is 2.14 MW. The designed system produces 518.4 kmol/d of hydrogen and synthesizes 86.4 kmol/d of urea. Furthermore, several parametric studies are employed to investigate the system performance.

A novel configuration of hybrid wind-solar PV based cascaded ammonia synthesis is proposed in this article. A comprehensive dynamic analysis is conducted in this study which is substantial to explore the system functionality under different atmospheric conditions as the power achieved by the wind farm source is dependent on the wind speed and power extracted from the solar PV source depends upon solar radiation intensities. The system is designed to supply the electrical output extracted from the wind-solar PV sources to the proton exchange membrane electrolyser after meeting the system work requirements for hydrogen production. The produced hydrogen reacts with nitrogen separated from pressure swing adsorption to synthesize ammonia. A cascaded ammonia synthesis system is employed in this study to achieve high fractional conversion and simulated using Aspen Plus V11. Toronto is chosen as the geographical location for the dynamic simulation. The minimum exergetic efficiency is found to be 19.21% during the month of December and maximum exergetic efficiency is determined as 26.06% during the month of April. Similarly, the minimum energetic efficiency is found to be 18% during December and maximum energetic efficiency was determined as 24.42% during the month of April. In addition, the results obtained from comprehensive dynamic analyses are presented and discussed.

A novel idea of wind energy based methanol and hydrogen production is proposed in this study. The proposed system utilizes the industrial carbon emissions to produce a useful output of methanol. There are several pros of manufacturing the methanol as it has the capability to be employed as conventional automotive fuel as it carries the advantages of efficient performance, low emissions and low flammability risk. The designed system comprises of the major subsystems of wind turbines, proton exchange membrane fuel cell (PEMFC), methanol production system and distillation unit. The Engineering Equation Solver (EES) and Aspen Plus are utilized for system modeling and comprehensive analysis. The proposed system is also investigated to operate under different wind speeds and different wind turbine efficiencies. The proposed integration covers all the electric power required by the system. The industrial flue gas including CO2 reacts with hydrogen to produce methanol. The designed system produces both methanol and hydrogen simultaneously. For the performance indicator, efficiencies of the overall system are calculated. The exergetic efficiency is found to be 38.2% while energetic efficiency is determined to be 39.8%. Furthermore, some parametric studies are conducted to investigate the distillation column performance, methanol and hydrogen capacities and exergy destruction rates.

A new system developed here conducts the thermal management of the flue gas from the cement industry and employs this heat for the drying of raw materials before reaching to the preheating ...

A novel idea of solar driven steam-autothermal hybrid reforming system (SAHRS) is proposed with onboard carbon capturing system in the existence of carbon emissions taxes. The CO2 produced by the steam methane reforming is employed to the autothermal reforming as input and cryogenic air separation unit is integrated to provide autothermal reforming with oxygen and ammonia synthesis with nitrogen. The autothermal reforming is modified with further integration of water gas shift reactor (WGSR) which converts carbon mono-oxide into carbon dioxide by reacting with steam and this CO2 is captured in the carbon capturing system using aqueous ammonia. Some amount of hydrogen produced by the autothermal reforming is employed to the ammonia synthesis reactor to achieve onboard ammonia for CO2 capture. The system generates enough power to overcome the required power and supply power as a final commodity as well. The present system is essentially designed for cleaner production and industrial applications. The performance indicator for the designed system is defined in terms of energy and exergy efficiencies which are found to be 53.4% and 45.0% respectively. The carbon emissions produced by the system and tax saving by the aqueous ammonia based CO2 capturing are also calculated in the proposed study.

This paper presents an innovative use of waste heat recovered from a cement slag for multigeneration purposes, including power, ammonia, heat, hot water and oxygen production. A novel approach of ammonia production is employed in this study. The proposed system consists of four major subsystems; copper-chlorine (Cu-Cl) cycle, cryogenic Air Separation Unit (ASU), ammonia synthesis reactor and two steam Rankine cycles. The Aspen plus 9.0 version is employed for modeling and simulation of the proposed system. A comparative study is also conducted considering the different CuCl cycle based integrated systems for multigenerational purpose with numerous energy sources. The parametric studies are carried out by varying parameters, namely flow rate, compressor and turbine discharge pressures and ammonia reactor conversion rate. The exergy analysis is comprehensively conducted for each of the system components through exergy balance equations and exergy efficiencies. The overall exergy efficiency of the designed system is found to be 36.1%. Further results are also presented and discussed.

A new integrated energy system employing the cement slag waste heat is uniquely proposed in this study. The core focus of the proposed system is to generate clean hydrogen thermochemically and convert it into ammonia. The designed system consists of the copper–chlorine (Cu–Cl) cycle, a cryogenic air separation unit and a steam Rankine cycle while the useful commodities produced by the proposed system are hydrogen, ammonia, oxygen, hot water and electricity. A CO2 emission analysis is also conducted to calculate the emissions which can be avoided by recovering this waste heat. The Aspen Plus simulation software is utilized to model and simulate the proposed integrated system. A thermochemical water splitting process is incorporated into the system for hydrogen production. The cryogenic air separation unit is integrated in order to separate nitrogen from the air. This proposed system also reduces the environmental effects of the flue gas emitted by the cement industry. Multiple parametric studies are performed to investigate the system performance by varying operating conditions and state properties. The energy analysis is implemented on each component of the designed system. The overall energy efficiency of the system is concluded as 30.1%. The amount of CO2 emissions which can be avoided by utilizing this waste heat is 29.64 ktonne/5 years.

This paper examines the performance and viability of a cement slag waste heat recovery system combined with a thermochemical copper-chlorine cycle for hydrogen production combined with hydrogen compression and a reheat Rankine cycle. The waste heat from the cement slag is recovered as a heat source for high-temperature reactions in the copper-chlorine cycle. The clean hydrogen production from waste heat recovery is examined with respect to both energy and exergy efficiencies. The integrated system is simulated and modeled in Aspen Plus. The multigeneration system utilizes the industrial waste heat and significantly reduces operating costs from the waste heat recovery. The overall energy efficiency of the integrated system is obtained as 32.5% while the corresponding exergy efficiency becomes 31.8%.

A multigeneration system for hydrogen production linked with a glassmaking process via thermal management is examined in this study. The exhaust gas is interconnected with a Rankine cycle and the copper-chlorine (Cu–Cl) cycle for hydrogen production. The present system consists of a steam Rankine cycle, Cu–Cl cycle with multistage compression, double-stage organic Rankine cycle, and multi-effect desalination system. A Cu–Cl cycle based on the four-step model is employed with the proposed system. The useful system outputs are electricity, hydrogen, and fresh water. The simulation software packages utilized in the analysis and modeling are Engineering Equation Solver and Aspen Plus. The energy efficiency of the overall system is 36.5% while 38.1% is the exergy efficiency. The parametric studies are conducted to investigate the system performance. In addition, the effects of exhaust gas variables, such as flow rate, temperature, and pressure are examined to investigate the system performance.

The thermochemical Cu Cl cycle has received greater attention by numerous researchers during the past decade as a promising hydrogen production method because of some operational advantages. The present paper analyzes three different configurations of the Cu Cl thermochemical cycle, namely three, four and five step ones thermodynamically. Some comparative parametric studies are conducted in order to investigate the overall energy and exergy efficiencies of the cycles considered. The Aspen plus is the software tool employed for the modeling and simulation of the cycles. The energy and exergy efficiencies of the five-step CuCl cycle are found to be 38.8% and 70.2% while the three-step CuCl cycle has an energy efficiency of 39.6% and an exergy efficiency of 68.1%, respectively. On the other hand, the four-step CuCl cycle provides the highest energy and exergy efficiencies of 41.9% and 75.7%. A parametric study is also conducted to investigate the effect of varying ambient temperature on the exergy efficiencies of all three cycles. The present study results further reveal that the cycle performance can be enhanced by improving the thermal management and reducing the exergy destructions.

The increasing environmental limits and carbon emissions taxes are substantial to develop the efficient systems for offering an effective energy utilization. This study proposed a new biomass-based gasification-assisted configuration for the renewable hydrogen production system offering efficient energy utilization. A multi-effect desalination system is employed for water desalination which is converted to steam and fed to the entrained flow gasifier. The integrated heat recovery steam generator gains the additional heat from the syngas to generate steam using fresh water from the desalination unit. The produced hydrogen is supplied to the multistage compression unit that stores hydrogen at high pressure. Industrial aspen plus software V9 version is employed for the simulation under the RK-SOAVE property method. The production of hydrogen before the water gas shift reactor is 129.5 mol/s and after the water gas shift reactor is found to be 171 mol/s. The thermodynamic performance of the biomass energy-assisted system is determined through overall energetic and exergetic efficiencies that are revealed to be 40.86% and 38.63%. Numerous sensitivity studies are performed to explore the performance of the designed system and presented and discussed.

Construction projects are prone to a number of risks due to their complexity, dynamic nature, capital intensive nature and involvement of many stakeholders. These risks if left unmanaged will negatively influence the completion cost and other primary objectives of construction projects. Numerous studies have been conducted globally to determine the potential risks that negatively impacts construction projects; however, the risks aren’t alike across all the regions and the potential degree of impact may changes with time. This study assessed the impact of risk factors on completion cost of construction projects in Nigeria. Data was collected using structured questionnaires administered to 192 construction practitioners using convenience sampling technique. Descriptive statistics (mean and standard deviation) were used to analyse the data. The study found ‘inadequate cost estimate’ (MS = 4.39), ‘risk incurred due to bribery and corruption’ (4.30), ‘increase in prices of materials’ (4.25), ‘increase in cost of labour’’ (4.11), ‘poor cash flow management’ (4.04) ‘mistakes/errors in design’ (4.04) and ‘mistakes during construction’ to be the topmost risk factors that impact on project completion cost. The study concludes that ‘economic’, ‘financial’ and ‘contract administration and project management’ related factors group are those with high impact on project completion cost.

A solar-wind hybrid trigeneration system is proposed and analyzed thermodynamically through energy and exergy approaches in this paper. Hydrogen, electricity and heat are the useful products generated by the hybrid system. The system consists of a solar heliostat field, a wind turbine and a thermochemical copper-chlorine (Cu-Cl) cycle for hydrogen production linked with a hydrogen compression system. A solar heliostat field is employed as a source of thermal energy while the wind turbine is used to generate electricity. Electric power harvested by the wind turbine is supplied to the electrolyzer and compressors and provides an additional excess of electricity. Hydrogen produced by the thermochemical copper-chlorine (Cu-Cl) cycle is compressed in a hydrogen compression system for storage purposes. Both Aspen Plus 9.0 and EES are employed as software tools for the system modeling and simulation. The system is designed to achieve high hydrogen production rate of 455.1 kg/h. The overall energy and exergy efficiencies of the hybrid system are 49% and 48.2%, respectively. Some additional results about the system performance are obtained, presented and discussed in the paper.

A novel multi-generation integrated energy system is presented in this paper, consisting of a gas-steam combined cycle, four-step thermochemical copper-chlorine (Cu Cl) cycle, proton exchange membrane fuel cell (PEMFC) and a reverse osmosis (RO) desalination unit. Effective thermal management of waste heat is recognized as a key objective in the steel industry. Hydrogen, electricity, fresh water and heat are the useful outputs of the integrated system. The produced electricity supplies the electricity load required by the electrolyzer, compressor and pumps while the supplementary electricity is an additional system product. Aspen Plus and Engineering Equation Solver (EES) are used for modeling and simulation of the multi-generation system. The overall hydrogen production rate of the designed system is 51.8 kg/hr and the net power production is 1.7 MW. The overall energy efficiency of the multi-generation system is 63.3% and the exergy efficiency is 58.8%. Further sensitivity studies and outcomes are presented and discussed in this paper.

A novel integrated system for the production of hydrogen at a high pressure utilizing steel furnace waste heat is presented and analyzed in this paper. The system utilizes a hybrid thermochemical copper-chlorine (Cu-Cl) cycle. This study integrates the industrial waste heat source with the thermochemical Cu-Cl cycle combined with a hydrogen compression system. The electrical energy required by the system is provided by a supporting Rankine cycle. The hydrogen compression system compresses hydrogen to a pressure of 750 bars. The integrated system is simulated with Aspen Plus software. Energy and exergy analyses are performed for the integrated system. Results from the simulations are presented and discussed. The overall energy efficiency is 38.2% and overall exergy efficiency is found to be 39.8%.

An integrated trigeneration system for electricity, hydrogen and fresh water production using waste heat from a glass melting furnace is analyzed in this paper. The heat source for the integrated system is flue gas ejected from a glass melting furnace. This heat source is integrated with a thermochemical copper-chlorine (Cu-Cl) cycle for hydrogen production, reverse osmosis desalination for fresh water production, and Rankine cycle for electricity production. A four-step copper-chlorine cycle is used in this paper. The trigeneration system is modeled and analyzed in Aspen Plus simulation software and Engineering Equation Solver (EES). The reverse osmosis desalination unit provides the system with 17.4 kg/s of fresh water, while the hydrogen production rate is 12 g/s. Energy and exergy analyses are performed on the integrated trigeneration system. The overall energy and exergy efficiencies of the integrated system are 47.7% and 37.9%, respectively. Additional results and sensitivity studies are presented and discussed in this paper.

In this paper, a wind turbine energy system is integrated with a hydrogen fuel cell and proton exchange membrane electrolyzer to provide electricity and heat to a community of households. Different cases for varying wind speeds are taken into consideration. Wind turbines meet the electricity demand when there is sufficient wind speed available. During high wind speeds, the excess electricity generated is supplied to the electrolyzer to produce hydrogen which is stored in a storage tank. It is later utilized in the fuel cell to provide electricity during periods of low wind speeds to overcome the shortage of electricity supply. The fuel cell operates during high demand conditions and provides electricity and heat for the residential application. The overall efficiency of the system is calculated at different wind speeds. The overall energy and exergy efficiencies at a wind speed 5 m/s are then found to be 20.2% and 21.2% respectively.

A new energy system for power, hydrogen and fresh water production is proposed. The environmentally benign ocean thermal energy conversion (OTEC), wind and solar energy resources are utilized. The hybrid thermochemical CuCl cycle is used for hydrogen production, and the reverse osmosis (RO) desalination system is incorporated for producing fresh water. The presently developed system is analyzed through thermodynamic energy and exergy approaches. The energetic efficiency of the integrated trigeneration system is determined to be 45.3%, and the exergetic efficiency is found to be 44.9%. In addition to this, the energy efficiency of the OTEC power generation cycle is 4.5% while the exergy efficiency is found to be 12.9%. Furthermore, the CuCl hydrogen production cycle is examined to have exergetic and energetic efficiencies of 36% and 35.2%, respectively. Also, numerous parametric studies are performed to analyze the system performance at different operating parameters.

Although there has been the commercially employed and widely used Haber-Bosch ammonia synthesis process which requires the high operating pressure and temperature in addition to the relatively low conversion rates, there is a need for a more compact and modular, but more efficient and effective approach. In conjunction with this, the present study develops, tests and investigates a cascaded ammonia synthesis system to explore the room for improvement in the ammonia conversion efficiencies. A lab-scale prototype is developed to investigate the effect of cascading two ammonia synthesis reactors in series employing pre-reduced KMR catalyst and the experimental investigations revealed the improved ammonia synthesis rates using cascaded configuration. The scanning electron microscopy (SEM) results of the KMR catalyst are also presented at different magnifications of 2.00 kx and 50.0 kx. The Aspen Plus simulation results of the cascaded ammonia synthesis system have also been validated using the experimental results and validation shows the percentage difference ranging from 1.62–6.61%. The experimentally developed cascaded ammonia synthesis system is investigated under different operating temperatures and pressures. The experimental results revealed that the ammonia conversion efficiencies that range from 4.58–7.88% using the single reactor with pressure rise from 6 to 12 bar at the temperature of 370 °C, increase to the conversion efficiencies of 5.42–9.16% by employing cascaded ammonia synthesis design.

A new configuration to convert the traditional ammonia synthesis plants into an environmentally benign process is proposed in this study. The proposed design is implemented by integrating three different types of natural gas reforming for clean hydrogen, methanol and ammonia synthesis. The solar heat source provides the absorption cooling unit with heat and natural gas reformers with steam. The CO2 emissions released by the natural gas reforming configuration reacts with hydrogen for methanol synthesis. A pressure swing adsorption unit separates oxygen for natural gas autothermal reforming and nitrogen for ammonia synthesis. A part of hydrogen produced by the natural gas reforming unit is designed to pass through a double-stage ammonia production reactor for ammonia synthesis. The proposed configuration yields 10 mol/s of H2 and 2.4 mol/s of NH3. The overall system energetic and exergetic efficiencies are found to be 66.83% and 68.55%. The present system yields 13.31 mol/s of CH3OH and 625.9 kW of cooling. Moreover, numerous sensitivity analyses are conducted on the proposed configuration and its performance assessment.

A new configuration of using hazardous industrial waste incineration system for energy generation and hydrogen production is proposed in this study. A heat recovery steam generator is used to generate steam for the double-stage Rankine cycle for electrical power generation. The additional heat from the incineration unit exhaust gas are employed to generate steam for the thermochemical Cu-Cl cycle. The CO2 emissions carried by the incineration reactor exhaust gases are captured using aqueous ammonia-based carbon capturing system. The Aspen Plus V9 software is employed for the designed system simulation. Numerous sensitivity studies are undertaken to investigate each subsystem of the proposed hazardous industrial waste incineration system. The proposed system generates 7.08 MW of electrical output and hydrogen production flowrate of 12.6 kmol/h. The exergetic and energetic efficiencies of the designed system are found to be 43.3% and 39.1%. Furthermore, the sensitivity analysis results are presented and discussed. The incineration plants treating the waste and converting waste into energy can be substituted for conventional energy production and this proposed environmentally benign integrated system will resolve environmental problems by employing the hazardous industrial waste to the new configuration of the incineration process for producing hydrogen and power with zero CO2 emissions.

This paper focuses on a new configuration of biomass gasification based cascaded ammonia synthesis and proposes two different configurations of ammonia synthesis system using the Stoichiometric and Gibbs reactors in the Aspen Plus V11. A new heat recovery technique from biomass gasification using syngas cooling is also proposed in this study. The proposed configuration comprises of a biomass gasifier, a heat recovery unit for syngas cooling, a combined cycle, water gas shift reactor system (WGSRS), pressure swing adsorption (PSA) and ammonia production unit. The ammonia based carbon-capturing system is incorporated to ultimately capture the CO2 emissions. The sensitivity analyses are conducted on each significant subsystem employed in the proposed configuration. The results obtained from the Gibbs reactors show that pressure has a positive effect while very high-temperature effects negative on the ammonia synthesis. The results also reveal that the cascaded ammonia synthesis offers high ammonia conversion rates. The designed system produces 21.9 kmol/h of ammonia and 3405 kW electrical power. The results obtained from the present sensitivity analysis are further presented and discussed.

The industrial flue gas emitted to the atmosphere is considered not only harmful to the environment but also a waste of plentiful resources of thermal energy. The thermal energy extracted from the industrial flue gas can be employed for multiple purposes. This study proposes a new configuration to integrate the thermal management of industrial flue gas for thermochemical copper-chlorine (Cu-Cl) cycle based ammonia synthesis. A reverse osmosis desalination unit is employed to supply the freshwater required by the thermochemical Cu-Cl cycle. To recover the heat from high-temperature oxygen stream, thermoelectric generators (TEGs) and organic Rankine cycle (ORC) are integrated with the proposed configuration to utilize the low-grade waste heat for power production. A portion of produced hydrogen through the thermochemical Cu-Cl cycle is supplied to the cascaded system for ammonia production. A double-stage cascaded ammonia synthesis system is integrated with the proposed configuration to achieve high fractional conversion. A multi-objective optimization using genetic algorithm is implemented to the proposed system using the MATLAB to investigate and determine the best-operating temperatures and pressures for the ammonia synthesis system. The proposed configuration produces 518.4 kmol/day of hydrogen and 226.8 kmol/day of ammonia. The overall exergetic and energetic efficiencies are found to be 28.7% and 40.8%. Moreover, the results obtained from the comprehensive sensitivity analyses are presented and discussed.

This study presents a novel configuration using the hydrogen-natural gas and ammonia-natural gas blends for practical applications and investigates the system performance comprehensively. Natural gas is blended with hydrogen and ammonia to investigate performance improvement. Wind energy source is employed to the proposed configuration for power generation using wind turbines. The power generated by the wind turbine is employed to the proton exchange membrane (PEM) electrolyser for hydrogen production. A part of hydrogen is employed to the PEM fuel cell for power production. The proposed system is used to investigate the effect of hydrogen and ammonia blends with natural gas to achieve better performance. In order to investigate the H2-CH4 blends, a part of the produced hydrogen is supplied to the mixing chamber from the hydrogen storage tank while ammonia input is supplied to the mixing chamber to improve the performance under NH3-CH4 blends. The results revealed that the combustion energy and exergy efficiencies increase from 84.8% to 94.8% and 62.5%–70.2% respectively and the overall energetic and exergetic efficiencies increase from 37.4% to 40.3% and 36.8%–39.8% respectively with hydrogen addition from 0 to 20%. In the case of ammonia-natural gas blends, the combustion energy and exergy efficiencies increase from 84.8% to 92.9% and 58.9%–64.4% respectively and overall energetic and exergetic efficiencies increase from 37.4% to 39.1% and 36.8%–38.5% respectively.

This study proposes a new configuration for synthesizing clean ammonia using clean hydrogen produced by the renewables. The proposed system mainly consists of proton exchange membrane electrolyser, pressure swing adsorption unit, compressor, ammonia synthesis reactors and condenser. The designed configuration uses a cascaded approach for ammonia synthesis by employing two reactors in series to achieve high conversion ratios and to reduce the recycle loops. The proposed system is simulated using industrial software Aspen Plus V11 and Aspen adsorption V11 and the obtained results are discussed in detail. The designed system is investigated under different operating conditions. In the Aspen Plus simulation, both stoichiometric and Gibbs reactors are installed alternatively to investigate the ammonia synthesis process in depths and to establish the effect of temperature and pressure on the ammonia production capacities. The maximum exergy destruction rate of 65.43 kW is offered by the primary ammonia synthesis reactor. The energetic efficiency of the clean ammonia synthesis system is found to be 61.14% and exergetic efficiency is 65.5%. Furthermore, the outcomes and generated results are presented and discussed.

In the present study, a solar-based clean ammonia synthesis system is newly developed and investigated experimentally. The required hydrogen for synthesizing ammonia is obtained through the proton exchange membrane based water splitting process powered by solar photovoltaic cells. The ammonia synthesis rate from the developed system is observed to be 0.016 mmol/s under the operating conditions considered. In addition, the developed system is investigated through thermodynamic energy and exergy approaches and the overall energy efficiency is found to entail a value of 1.9%. Also, the overall exergy efficiency is found to be 1.8%. Furthermore, the energy efficiency of the solar to hydrogen process is observed to be 2.4% and the corresponding exergy efficiency is evaluated as 2.1%. Moreover, the proton exchange membrane-based water electrolysis subsystem is found to have efficiencies of 19% and 15.3% both energetically and exergetically respectively. In addition, parametric studies are also performed to study the effects of changing operating conditions on the performance of the overall system as well as subsystems.

This paper presents a novel system of adding clean hydrogen to the natural gas for more effective and more efficient combustion. The proposed system includes a wind-photovoltaic hybrid system where both wind and solar energy sources are simultaneously utilized. A partial amount of electrical power produced by the wind turbines, PEM fuel cell and PV array is fed to the PEM electrolyser while the additional electricity is supplied to the community for use. In the hydrogen-natural gas blends, the fraction of hydrogen is taken from 0% to 20%, respectively, and the natural gas is reduced from 100% to 80% simultaneously to explore hydrogen addition effect in the combustion process. Although natural gas is cleaner than other fossil fuels, adding hydrogen to the natural gas makes it much cleaner and more environmental friendly. The blends of natural gas and hydrogen helps increase the combustion efficiency, decrease oxygen and reduce the emissions, in particular CO2. The results further reveal that the energetic efficiency of the combustion unit rises from 84.83% to 94.83% while the exergetic efficiency rises from 62.52% to 70.16% with the rise in hydrogen fraction from 0% to 20%. It is also found that the CO2 emissions decrease with the rise in hydrogen fraction in hydrogen-natural gas blends.

A biomass gasification based multi-generation system integrated with thermoelectric generators is developed and proposed for cleaner applications. The paper presents, analyzes and validates a novel integration of the thermoelectric generators in the proposed biomass gasification based system and discusses the possibility of better efficiency and energy use with reduced carbon emissions. The influences of varying biomass gasification parameters are also studied against the syngas composition. The major subsystems of the integrated system, such as gasification, cryogenic air separation unit, Brayton cycle, heat recovery and domestic hot water production is simulated using Aspen plus while the Engineering Equation Solver (EES) is employed to model thermoelectric generators, proton exchange membrane electrolyzer and organic Rankine cycle. The system operating conditions and their effects on system performance are investigated. The waste heat from the thermoelectric generators is employed to the organic Rankine cycle to produce power and work generated by thermoelectric generators is employed to the proton exchange membrane electrolyzer to produce hydrogen. The amount of hydrogen produced is about 0.13 kg/day, and the amount of heating achieved by the system is 1.4 MW. Likewise, the proposed system is capable of producing 22 kg/s of hot water for the domestic purposes. The overall energy and exergy efficiencies are found to be 58.03% and 32.78%. As compared to conventional systems with thermoelectric generation, the system proposed in this study carries unique and superior characteristics.

In this study, we propose a new method to dissociate water vapor into hydrogen gas by microwave generated plasma. In one stage, steam flows by direct discharge into a custom developed reactor inside the 900 W microwave. The high energetic electrons produced by electric field acceleration of 2.45 GHz microwave collide with water vapor molecules, these molecules are ionized and dissociated into hydrogen and oxygen radicals. The concentration of hydrogen gas is found between 2500 and 8000 PPM. Also, the energy and exergy efficiencies fall below 10% to one another, where the energy efficiency ranges between 11.6% and 53.7% throughout the experiments. From these results, this study demonstrates a unique method of hydrogen production via water plasmolysis and investigates the energy and exergy efficiencies for applications involving the collection of hydrogen gas as an alternative fuel source.

In this study, hydrogen is investigated as a source of performance improvement for alkaline electrolyte entailing direct ammonia fuel cells via dual fuel utilization. Membrane electrolytes are utilized with anion exchange characteristics and the fuel cell performance is investigated with pure ammonia, ammonia-hydrogen blends and pure hydrogen. The power density is observed to be 1990.8 mW/m2 for pure ammonia fuel at peak point. However, this is found to increase to 2853 mW/m2 and 4471 mW/m2 when fuel blends of 80%NH3-20%H2 and 60%NH3-40%H2 are utilized respectively. The exergy efficiency at the maximum point power density increases from 14.2% to 22.1% and the energy efficiency rises from 15.2% to 22.8% as the fuel input is changed from pure ammonia to 60%NH3-40%H2 by mass. Also, the highest exergy efficiency of 29.1% and energy efficiency of 28.7% is obtained for the pure hydrogen fueled cell. In addition, the exergy destruction rate is determined to be 16.8 mW for the pure ammonia fuel cell at the maximum point power density, which decreases to 15.1 mW and 13.6 mW for 60%NH3-40%H2 and 80%NH3-20%H2 fuels respectively.

In this article, three different renewable energy methods are considered with wind, ocean thermal energy conversion (OTEC) and solar energy for clean hydrogen production, and Cu-Cl based thermochemical cycle is incorporated into systems to develop potential applications. In the proposed CuCl cycle configuration, the additional heat offered after the thermolysis reactor is recovered to heat the water before reaching the hydrolysis reactor. In the wind energy based hydrogen production system, the maximum exergy destruction rate is found to be 48.3 kW in the wind turbine. The turbine employed to the ocean thermal energy conversion system is found to be undergoing the highest exergy destruction rate of 143.3 kW. The energy and exergy efficiencies of the solar energy based thermochemical CuCl cycle are found to be 32.7% and 33.2% and the maximum exergy destruction rate of 350.69 kW is offered by the thermolysis reactor. The energetically improved configuration of the thermochemical CuCl cycle displays promising results compared to the earlier studies, such as lower heat requirements and higher efficiencies. The study indicates that there is a value to develop a clean OTEC based hydrogen production system and implement for practical applications. Furthermore, some sensitivity analyses are performed to investigate the performance of each system under different operating parameters and discussed.

In this study, a novel renewable energy based trigeneration system is developed based on the utilization of solar and geothermal resources in a combined manner. The present system includes the following useful outputs, namely electricity, hydrogen and cooling. A flash-steam geothermal power plant is used for producing electricity. The CuCl cycle is used for hydrogen production and an additional heat from the CuCl cycle is used in the absorption chiller for cooling. The energy efficiency of the trigeneration system is evaluated to be 19.6% while the exergy efficiency is found to be 19.1%. Furthermore, the CuCl hydrogen production cycle is determined to have an energy efficiency of 35.3% and an exergy efficiency of 35.9%. In addition, the energetic coefficient of performance of the absorption cooling system is evaluated as 0.54 and the exergetic coefficient of performance is 0.32. Moreover, several parametric studies are conducted to study the effects of varying operating conditions and system parameters on system performance.

An Energetically Improved Steam-Autothermal Reforming (EISAR) novel concept is proposed in this study, and a novel idea to combine steam methane reforming with CO2 and steam based autothermal reforming is introduced for practical applications. A urea synthesis unit is also integrated with the proposed system to justify the idea of clean hydrogen production. The CO2 produced by the steam methane reforming is captured in CO2 based autothermal reforming and CO2 produced by the autothermal reforming is captured by urea synthesis system which converts CO2 into urea by reacting is with ammonia. According to the designed heat management of molten salt, electric power of 4 MW is produced by the steam Rankine cycle which is supplied to a community of 400 households. During the night time, the community of 400 households is fed to be provided with electricity through PEM fuel cell which utilities a part of hydrogen from the storage tank. Both Engineering Equation Solver (EES) and Aspen Plus software packages are employed for system simulation. Several sensitivity studies, cost and carbon emission analyses and multi-objective optimization studies are undertaken for the designed system. The energy and exergy efficiencies for the present are found to be 59.1% and 31.1%, respectively. Furthermore, the results of current analyses and optimization studies are presented and discussed accordingly.

We assessed hospital infection control knowledge, attitude, and practice (KAP) of healthcare workers (HCWs) during the Hajj season of the Islamic y 1423 (2003). A self-administered structured questionnaire was used to collect the data. A total of 392 HCWs was studied, of whom 215 (54.8%) were nurses and 177 (45.2%) were doctors. 315 (80.4%) HCWs worked in hospitals, whereas 77 (19.6%) worked in primary healthcare centres. Of the 392 HCWs, 164 (41.8%) were from Makkah, and the remaining 228 (58.2%) were recruited from other regions in Saudi Arabia. A good proportion (81.8%) of HCWs correctly answered at least 5 of the 11 knowledge statements. However, obvious deficiency of knowledge appeared concerning other important hospital infection control measures. A smaller proportion (61.9%) of HCWs achieved a score of at least 4 out of 7 for attitude statements with unacceptable attitude for the remaining 3 areas. Response to questions concerning practice showed that nurses tended to be better than doctors (p-value=0.204), but both groups reported variable compliance to hospital infection control practices in terms of strict or near-strict adherence. In conclusion, training of HCWs is needed to improve KAP in infection control.

Approximately 2 to 3 million pilgrims perform Hajj every year. Planning for health care requires knowledge of the pattern of diseases, complications, and outcome of pilgrims who require hospitalization during the Hajj period.In a cross-sectional study we compiled data on all patients admitted to 1487 beds in four hospitals in Mena (793 beds) and three hospitals in Arafat (694 beds) from the seventh to the thirteenth day of the Hajj season of the Islamic year 1423, corresponding to 8 to 14 February 2003.Of 808 patients hospitalized, most (79%) were older than 40 years. There was no sex preponderance. A total of 575 (71.2%) patients were admitted to medical wards, 105 (13.0%) to surgical wards, and 76 (9.4%) to intensive care units. Most patients (84.8%) had one acute medical problem. Pneumonia (19.7%), ischemic heart disease (12.3%), and trauma (9.4%) were the most common admitting diagnoses. More than one third (39%) had co-morbid conditions. A total of 644 (79.7%) patients were discharged from the hospital in stable condition to continue therapy in their residential camps, 140 (17.3%) were transferred to other hospitals in Makkah for specialized services or further care, 19 (2.3%) were discharged against medical advice, and 5 (0.7%) patients died.This study provided information on the most common causes of hospitalization, pattern of diseases, and required medical services for pilgrims in Hajj. It is hoped that this data will be of help to health sector planners and officials to provide optimal and cost-effective health care services to pilgrims in Hajj.

BACKGROUND: Approximately 2 to 3 million pilgrims perform Hajj every year. We describe the pattern of diseases, complications, and outcome of pilgrims who required admission to intensive care units (ICUs) during the Hajj period of the Islamic year 1424 (2004). METHODS: This was a cross-sectional study of all patients admitted to 104 ICU beds in four hospitals in Mena and three hospitals in Arafat during the Hajj. RESULTS: Of 140 patients admitted to ICUs, 75 (54%) patients were older than 60 years. The risk of complications and death increased with age, with the highest risk noticed among pilgrims older than 80 years. Ninety-four (67.6%) patients were men. Eighty-nine (63.6%) patients were admitted with cardiovascular diseases and 37 (26.4%) patients with infections. Myocardial infarction (25%) and pneumonia (22%) were the most common admitting diagnoses. Trauma accounted for only 6.4% (9 patients) of admissions. Sixty-three (45.0%) patients recovered and were discharged or transferred to hospital wards in stable condition, 40 (28.6%) were transferred to tertiary care centers for specialized services, 21 (15.0%) were transferred to tertiary care centers after closure of the temporary hospitals in Mena and Arafat, 15 (10.7%) patients died, and one (0.7%) patient was ddischarged against medical advice. CONCLUSION: This study revealed information oo the pattern of diseases and the most common causes of admission of pilgrims to ICUs and the required medical services during Hajj. It is hoped that this information will be of help to health care planners and officials to provide optimal and cost effective health care services to pilgrims in Hajj.

Background the objective of this study was to evaluate the impact of annual review of the infection control practice in all Ministry of Health hospitals in the holy city of Makkah, Saudi Arabia, during the Hajj period of four lunar Islamic years, 1423 to 1426 corresponding to 2003 to 2006. Methods audit of infection control service was conducted annually over a 10-day period in six community hospitals with bed capacities ranging from 140 to 557 beds. Data were collected on standardized checklists on various infection control service items during surprise visits to the medical, pediatric, surgical, and critical care units, and the kitchens. Percentage scores were calculated for audited items. The results of the audit for hospitals were confidentially sent to them within four weeks after the end of Hajj. Results deficiencies observed in the first audit included lack of infection control committees, infection control units, infection control educational activities, and surveillance system and shortage of staff. These deficiencies were resolved in the subsequent audits. The average (range) scores of hospitals in 11 infection control items increased from 43% (20–67%) in the first audit to 78% (61–93%) in the fourth audit. Conclusion regular hospital infection control audits lead to significant improvement of infection control practice. There is a need to build a rigorous infection control audit into hospitals' ongoing monitoring and reporting to the Ministry of Health and to provide these hospitals with feed back on such audits to continuously strengthen the safety standards for patients, visitors, and employees.

This paper is a condensed description of a study of wind tunnel model simulations of dense gas clouds released instantaneously in the atmosphere, undertaken to assess the validity of the wind tunnel modelling technique as a dispersion prediction method [1]. The comparative data used was that obtained from the field trials carried out at Porton Down in 1976/7. In addition a number of scaling experiments were carried out in order to further investigate the modelling technique.