Journal of Engineering

This study presents an energy and exergy thermodynamic analysis using the EES program for a domestic refrigerator working with R-134a using a vapor compression refrigeration cycle. The analysis focuses on the system components, including the compressor, condenser, evaporator, and expansion device. The study aims to improve refrigerator performance by minimizing entropy generation and finding the optimum design points. The results show that the compressor has the lowest exergy efficiency of 25%, while the evaporator has the highest exergy efficiency of 98%. The study concludes that the design of the refrigerator mainly depends on thermal conductance calculations rather than surface inner area estimation.

This study investigates the electrokinetic (zeta) potential on the membrane surface charge density, effective membrane charge density, and Donnan potential at two different concentrations of sodium chloride (0.001 M and 0.01 M) at various pH values from 3 to 9. The effective pore radius for a nominal 0.9 nm ceramic TiO₂ NF membrane was evaluated. Experiments were conducted using Microelectrophoresis technique for measuring membrane zeta potential, effective pore radius, and Donnan steric pore model (DSPM). The TiO₂ membrane isoelectric point (net membrane charge equals zero) was found at pH of 3.7 and 3.5 for 0.001 M and 0.01 M NaCl, respectively. The results showed that the NF membrane zeta potential changes its sign from positive to negative after the isoelectric point. The evaluated effective pore radius was found to be 0.56 nm using DSPM, and the membrane equivalent effective thickness was 2×10⁻⁶ m.

Direct contact membrane distillation is an effective method for producing fresh water from saline water. In this study, two samples were used as feed solutions: RO waste from Al-Hilla Coca-Cola Factory (TDS= 2382 mg/l) and Haji Ali drainage water (TDS= 4127 mg/l). A polytetrafluoroethylene (PTFE) hydrophobic membrane supported with polypropylene (PP) was used in a flat sheet form with a plate and frame cell. Results proved that membrane distillation is an effective technique to produce fresh water with high quality from brine with low salinity content. The volume of treated water decreased due to fouling accumulated on the membrane surface. The temperature on both sides of the membrane surface and TDS of permeate were measured every 30 minutes of experiment time, with some tests made on feed and permeate ions. The experiment lasted 180 minutes under the same operating conditions.

The present study addresses the behavior of gases in cultivation media as an essential factor to develop the relationship between the microorganisms that are present in the same environment. This relationship was explained via mass transfer of those gases to be a reasonable driving force in changing biological trends. Stripping and dissolution of oxygen and carbon dioxide in water and dairy wastewater were investigated in this study. Bubble column bioreactor under thermal control system was constructed and used for these processes. The experimental results showed that the removal of gases from the culture media requires more time than the dissolution. For example, the volumetric mass transfer coefficient for the removal of oxygen is 1.67 min⁻¹ while the volumetric mass transfer coefficient for dissolution of the same gas is 3.18 min⁻¹. The same thing occurred with carbon dioxide, where the data showed that the volumetric mass transfer coefficient of the dissolution of CO₂ is 0.66 min⁻¹ while the volumetric mass transfer coefficient for the removal process is 0.374 min⁻¹. However, the two processes (dissolution and removal) with CO₂ take more time than that with O₂. Therefore, the production of gases due to metabolic processes in bacteria or microalgae remains in culture’s media for a certain period even if that media is sparged by air. Thus, this will give enough time for both microorganisms to consume those gases.

This study investigates the municipal solid waste generation in Babylon Governorate, which is influenced by changes in lifestyles, population growth, social and cultural habits, and improved economic conditions. The study divides municipal solid waste into residential and commercial solid wastes. Residential solid wastes are represented by household wastes, while commercial solid wastes include commercial, institutional, and municipal services wastes. The study uses relational stratified random sampling to divide the total population into clusters based on socio-income levels. The results show that Babylon Governorate has an average residential solid waste generation rate of 0.587 kg per capita per day. When commercial solid waste is included, the solid waste generation rate reaches 0.802 kg per capita per day, representing a 36.6% increase.

Due to the great evolution in digital commercial cameras, several studies have addressed the use of such cameras in different civil and close-range applications such as 3D models generation. However, previous studies have not discussed a precise relationship between a camera resolution and the accuracy of the models generated based on images of this camera. Therefore, the current study aims to evaluate the accuracy of the derived 3D buildings models captured by different resolution cameras. The digital photogrammetric methods were devoted to derive 3D models using the data of various resolution cameras and analyze their accuracies. This investigation involves selecting three different resolution cameras (low, medium, and high) and evaluating their calibration accuracies. Assessing the accuracy of the three selected cameras in capturing indoor and outdoor objects; and analyzing the accuracy and the quality of the produced models. The study revealed that: 1) It is recommended to use the photos of a high-resolution camera for producing precise 3D models of objects in the outdoor environment, especially when the camera/object distance is more than 40 m because the accuracy of the produced models can be precise (RMSE ±10.36mm) with excellent quality; 2) The low-resolution camera can be utilized to produce adequate 3D models of objects in the indoor environment (RMSE ±6.32mm), especially when the camera/object distance is less than 40 m

The study highlights the spatial and temporal changes in land cover for Al-Dalmaj marsh and its surrounding area using various analysis methods, including the supervised maximum likelihood classification method, the Normalized Difference Vegetation Index (NDVI), Geographic Information Systems (GIS), and Remote Sensing (RS). The research analyzed Landsat images from three different years (1990, 2003, 2016) to determine changes in wetlands, drylands, and other land classes. The results indicated an annual increase in vegetation from 980.68 km² in 1990 to 2072.98 km² in 2016. Water coverage fluctuated, decreasing from 185.95 km² in 1990 to 68.27 km² in 2003, then rising to 180.23 km² in 2016. These data can be used to inform plans for increasing tourism, protecting areas, and setting up renewable energy sources like solar power stations.

Both the double-differenced and zero-differenced GNSS positioning strategies have been widely used by geodesists for different geodetic applications that demand reliable and precise positions. This study focuses on producing uninterrupted series of satellite orbit and clock products using different criteria and assesses these products using Precise Point Positioning (PPP). The double-difference processing technique was used to achieve the goal of this study by Bernese GPS software version 5.0. Twenty-two globally distributed IGS stations were selected to run PPP based on the generated products and then compare the results with corresponding PPP results created based on the IGS rapid products. The comparison pointed to a significant improvement in the generated precise products, which have considerably increased the precision of positions.