h. salarian

In contrast to commonly held beliefs in the province of Mazandaran, , alterations in climate have exposed this particular region to the issue of water scarcity. This predicament has rendered it crucial to direct attention to the various methods of managing water, such as the collection of rainwater, within this province. From this vantage point, the objective of this publication is to meticulously scrutinize and evaluate the feasibility of implementing a comprehensive plan for rainwater collection in the residential areas of Larijan, Amol, and Noor, which are situated within the Mazandaran province, based on both physical and social capabilities.

This is an applied study carried out from 2017 to 2021 in three cities of Mazandaran. The research process is segmented into three distinct stages in accordance with the nature of the data. The researcher employed indirect observation to extract physical (architectural) data, which were subsequently prioritized by experts utilizing the Delphi method. As for the technical data pertaining to the various components of the rainwater harvesting system, they were derived from the statistical analysis of rainfall and catchment levels observed during the study period, in addition to the optimal capacity of the tank. In terms of the social dimension, the requisite data were gathered through a questionnaire devised by the researcher, followed by an analysis conducted using a one-sample T test.

The primary physical factors that have a significant impact on water management in housing within the Mazandaran province encompass various variables such as "Roof area," "Roof slope," "Area and yard dimensions," "Area slope," "Gutter," "Dimensions and proportions," and "Insulation details." Regarding the quantity of water, the optimal volume stands at 5981 liters in Larijan city, 8632 liters in Amol city, and 7533 liters in Nur city. Furthermore, from a social perspective, the findings indicate an above-average level of citizen participation across all three cities, which is attributed to the implementation of rainwater extraction systems.

In conclusion, the cities within the Mazandaran province exhibit both physical and social capacities for the implementation of rainwater harvesting systems in residential settings. However, it is important to acknowledge that the main hindrance in this endeavor is the limited institutional (management) capacity.

The present study economically evaluates a combined hydrogen liquefaction configuration using combined heat and power system, photovoltaic cells unit and liquid air energy recovery for precooling under climatic states of Yazd, Iran. The LAC recovery is used to precool hydrogen. Moreover, the cascade refrigeration systems with helium and hydrogen refrigerants are employed to supply refrigeration and liquefaction. The rest of the power required for refrigeration cycles to liquefy hydrogen is supplied by PVC unit. This integrated structure generates liquid hydrogen by receiving 5559 kW of power from PVC unit, 60.79 kg/h of natural gas, 8000 kg/h of liquid air and 1028 kg/h of gaseous hydrogen as inputs. The annualized cost of the configuration is applied to economically evaluate the hydrogen liquefaction system using renewable energies. The developed integrated structure is economically evaluated by HYSYS V10 software and m-file code in the MATLAB package. The economic research results of the hybrid cycle indicate the period of return, prime price of liquid hydrogen production and additive value are 4.249 years, 5.432 USD/kg LH2 and 1.567 USD/kg LH2, respectively. The economic sensitivity examination of the combined system reveals POR increases from 2.295 to 13.97 years and net annual profit decreases from 32.66 to 5.366 MMUSD/year by increasing the gaseous hydrogen cost from 1.4 to 3.4 USD/kg LH2. Moreover, POR increases from 2.753 to 25.07 years and levelized cost of product increases from 5.02 to 7.488 US$/kg LH2 by increasing the capital cost from 52.5 to 217.5 MMUSD.

In the present study, an attempt has been made to use Computational Fluid Dynamics (CFD) in the assessment of hazardous gas dispersion over obstacles. For this aim, the accidental dispersion of hazardous gas from the hole and the effect of different parameters such as changes in inlet wind velocity, the direction of the pollutant cloud and its movement, mass fraction of gas dispersion, and the pressure distribution were numerically analyzed. The flow was assumed as three-dimensional, unsteady, turbulent, and compressible. Different turbulent models were used in modeling the gas release and the most accurate one was suggested. The numerical simulation demonstrated that the gas mass fraction increased significantly due to the sudden dispersion of the gas. The amount of gas concentration gradually decreased after the formation of pollutant clouds by moving in the horizontal direction. Moreover, gas mass fraction had decreased by increasing the height. Comparing the results revealed that the pollutant cloud did not cover the surrounding area in the wind velocity of 1 m/s. Therefore, the pollutant clouds generated in this case could not impose a threat. In higher wind velocities (3 m/s and 5 m/s), the pollutant cloud approximately covered the surrounding areas, which caused a severe threat. The maximum overpressure at the hole is 5.7 Pa for a wind velocity of 5 m/s, while the maximum negative pressure was about -7.1 Pa. The influencing radius was obtained about 9.3 m. The overpressure did not cause obvious damage to buildings but led to a slight hurt to humans.