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.

The food security challenge continues to be one of the main issues that currently face the world despite improved economic development in many countries. The challenge is particularly unique in one of the world’s arid regions, the Gulf Cooperation Council (GCC). This paper analyses the food security strategies of Qatar (one of the six countries that make up the GCC), especially since 2017 when the blockade of the country by its neighbors began. Qatar’s current food sufficiency was made possible by the country’s swift and profound changes in its food production strategies to ensure food security for its population. In order to provide locally sourced foods to the population, private and public initiatives were activated to support small farmers to distribute and supply their farm produce to local markets. The results show that Qatar has shifted from importing some food commodities to locally producing a high proportion of its foods to the extent of becoming an exporter of some farm produce. However, this increase in the local food production was achieved at the cost of depleting the local groundwater at a rate higher than the natural recharge. This paper thus critically assesses the specific situation of food security in Qatar that could be used as an example for other countries aiming to strengthen their food security, especially during transnational crises when international food supply chains suffer from unavoidable disruption (e.g., COVID-19 crisis).

This study presents a thermal performance comparison of various working fluids operating in a parabolic trough collector. Fluids such as gases (helium, carbon dioxide, and air), liquid sodium, and liquids (pressurized water, Therminol VP1, and Syltherm 800) are evaluated. This study also examines the efficiency enhancement obtained from the dispersion of copper nanoparticles in water, Therminol VP1, and Syltherm 800 base fluids. The optimum parameters for nanoparticle concentration, volume flowrate, and inlet temperature to obtain the maximum efficiencies for each working fluid were evaluated in this study. The thermal model used in this study was modeled after the commercially available LS-2 collector, which is designed in the engineering equation solver (EES) and validated with results found in the literature. The results of the study show that the Cu/Syltherm 800 nanofluid showed the most enhancement in thermal efficiency with 0.141%, while Cu/water and Cu/Therminol VP1 had enhancements of 0.037% and 0.088% respectively.

Nanofluids consist of nanoparticles made of materials with high thermal conductivity suspended in a base fluid such as water. In theory, the presence of thermally conductive nanoparticles in a base fluid improves the heat transfer performance of the resulting nanofluid. This article numerically investigates the impact of nanoparticles on the energy performance of a district cooling system. The current work focuses on using Cu–water nanofluid as the working fluid for the secondary chilled water loop. It examines the effect of varying the nanoparticles concentration, nanofluid flowrate, and return temperature on the system energy performance. The numerical model is built using the engineering equation solver (EES) and validated using operational data obtained from the McQuay chilled water system operating in one of the university central facility plants. In the current numerical model, the Reynolds number in the shell side of the heat exchanger is varied between 2200 and 8800 at a volume fraction of 0.02. The result shows that for a fixed cooling capacity of 280 kW, the Cu–water nanofluid reduced the mass flowrate by 4.8% and the corresponding pump work input by 33.6%. This improved energy performance of the circulating water reduced the overall chiller system work input by 3.8% and increased the corresponding system coefficient of performance (COP) by 3.9%. The current findings reveal the potential impact and opportunity of nanofluids on the effectiveness of the district cooling system chiller water loop and the associated overall energy performance.