Considering the global scientific and industrial effort to utilize ammonia as an alternative to natural gas combustion to run power plants, it is crucial to objectively assess the literature before adjusting or proposing new and advancing techniques in ammonia plants while considering a variety of factors. As a result, this paper assesses the global effort to improve existing ammonia plants and identifies progress by evaluating the currently available dataset to identify knowledge gaps and highlight aspects that have yet to be addressed. Based on the literature reviewed in this study, it was found that the majority of the efforts to advance ammonia plants mainly focus on reducing energy consumption, implementing alternative methods to extract the necessary hydrogen and nitrogen in the process, and changing the cycle arrangement and operating conditions to make the industrial plants more compact. However, regarding carbon reduction in the ammonia production process, it is clear that the effort is less significant when compared to the global scientific and industrial progress in other areas.

We investigate and test the effectiveness of a novel window windcatcher device (WWC), as a means of improving natural ventilation in buildings. Using ANSYS CFX, the performance of the window-windcatcher is compared to a control case (no window-windcatcher), in three different geographic locations (Cardiff, Doha and Amman) which are representative of three different types of atmospheric conditions. The proposed window-windcatcher has been shown to improve both thermal comfort and indoor air quality by increasing the actual-to-required ventilation ratio by up to 9% compared to the control case as per the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) standards. In addition, the locations with minimum velocities have been identified. Those locations correspond to the regions with a lower infection risk of spreading airborne viruses such as SARS-CoV-2, which is responsible for the COVID-19 pandemic.

Hospital emergency departments (EDs) are hubs for highly transmissible infectious diseases, posing the highest risk of viral infection transmission. With the current COVID-19 outbreak, it has become clear that the ED design needs to be altered in order to be successful in containing the pandemic. The purpose of this study is to use a computational fluid dynamics (CFD) simulation to evaluate the ventilation system design for an emergency department at a university hospital. The kinetic energy and velocity patterns of turbulence were analyzed to determine which areas of the ED were most susceptible to viral transmission. Additionally, the impact of pressure suction on COVID-19 dispersion has been investigated. Three critical areas of the ED, overnight patient beds, surgical rooms, and resuscitation rooms, all had much higher air velocity, dispersion, and mixing levels than the rest of the department’s spaces, according to the simulation findings. Air transmission from these sites to adjacent regions is a possibility in the scenario studied, increasing the likelihood of the virus spreading from these locations and infecting people in the surrounding areas. The results of these simulations may be utilized to provide recommendations to the hospital administration about the placement of inlets and outlets, the separation of areas, and the interior design of the spaces and corridors.

Window-windcatchers, a passive ventilation method, have been shown to improve ventilation and enhance thermal comfort. Preliminary characterization of a novel window-windcatcher has been undertaken in a previous work, but no relationship had been identified between the actual ventilation rate ($Q_{act}$), the wind velocity ($V_{Tw}$) and crucial design parameters such as the fins angle ($ϴ$)). In this paper, the relationship that quantifies how the window-windcatcher’s performance depends on $V_{Tw}$ and $ϴ$ was determined. Additionally, for the first time, the ventilation performance of the window-windcatcher was optimized by studying the effects of $ϴ$ and the fins-wall distance ($D_{W-f}$) through a Computational Fluid Dynamics parametric study (ANSYS)|. In this optimization approach, the angle $ϴ$ and the distance $D_{W-f}$ corresponding to the maximum actual-to-required ventilation rate were found to be 80° and 45 cm, respectively. The actual ventilation rate increased by approximately 13.2% compared with the baseline design of the windcatcher ($ϴ$ and $D_{W-f}$ equal to 40° and 45 cm, respectively); this corresponds to an increase of approximately 8.6% in the actual-to-required ventilation rate, according to the ASHRAE standards.

Previous studies on window-windcatchers have shown their effectiveness in capturing the prevailing wind and redirecting it into a building, increasing the actual-to-required ventilation ratio by 9%, above what is required by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE). However, the effect of implementing the proposed system on energy performance, energy costs, and thermal comfort has not been studied. Therefore, here, we investigate and test the implementation of the window-windcatcher on a typical residential building, using a validated DesignBuilder model. Compared to the base case (no window-windcatcher), the total annual energy consumption of the entire building (${\mathrm{E}}_{\mathrm{tot},\mathrm{b}}$), and consequently the cost, is reduced by approximately 23.3% (i.e., from 18,143 kWh/year to 13,911 kWh/year) when using the window-windcatcher. The total annual reduction in thermal discomfort hours is estimated to be 290 h, which corresponds to an average monthly reduction of approximately 24 h.

Gas turbines must now comply with much stricter emission control regulations. In fact, to combat the greenhouse effect, regulatory authorities have drastically reduced allowable emission levels. For example, in less than 12 years, the United States’ Clean Air Act issued the New Source Performance Standards (NSPS), which tightened the NOx emission margin of natural gas combustion (from 75 ppm to 10 ppm). On the other hand, despite those efforts, the high demand for energy produced by fossil-fueled gas turbines in power plants has resulted in dramatic increases in anthropogenic CO₂ and NO_x emitted by gas combustors. Most systems responsible for these undesirable emissions are directly linked to power generation, with gas turbines playing a pivotal role. Yet, gas turbines are still widely used in power plants and will continue to meet the growing demand. Therefore, sequestration and separation techniques such as Carbon Capture and Storage (CCS) and Air Separation Units (ASU) are essential to reduce CO₂ and NO_x emissions while allowing large amounts of power to be generated from these systems. This paper provides an in-depth examination of the current state of the art in alternative working fluids utilized in the power generation industry (i.e., gas turbines, combustion). In addition, this paper highlights the recent contribution of integrating separation techniques, such as air separation, steam methane reforming, and water-gas shifting, to the power generation industry to facilitate a continuous and adequate supply of alternative working fluids.