Open Access Original Research Article

Thermodynamic Concepts on Efficiency of Aircraft Engines

Faradiba Faradiba, Endah Yuniarti

Physical Science International Journal, Page 1-7
DOI: 10.9734/psij/2021/v25i130231

Along with the development of engine technology to be able to produce maximum efficiency in aircraft jet engines, various modifications were made to the machine tools. Modifications are made by taking into account four main factors, namely: maximum power output, reduced engine weight, low fuel consumption and maximum aircraft payload. This research uses a meta-analysis method, namely the analysis of several research results in line with what has been done previously regarding the efficiency of aircraft jet engines. The thermodynamic concept related to the heat engine which implements the brayton cycle that maximum efficiency can be done by reducing wasted heat energy and maximizing the work produced. From this concept, several attempts to maximize aircraft efficiency, such as modification of design that have a significant impact on weight reduction, fuel barrier design with low fan pressure, high bypass design ratio are also carried out in an effort to reduce aircraft noise levels. Aircraft noise levels can also be minimized by modifying the nozzle and ejector on the engine.

Open Access Original Research Article

Experimental Study of a Stationary Hot Air Solar Collector Built with Hemispherical Concentrators and Enhanced with Fresnel Lenses

Thierry S. M. Ky, Salifou Ouedraogo, Moctar Ousmane, Boureima Dianda, Emmanuel Ouedraogo, Dieudonné J. Bathiebo

Physical Science International Journal, Page 8-22
DOI: 10.9734/psij/2021/v25i130233

Aims: This paper is about a solar collector made of hemispherical concentrators. This collector is sun tracking free, and used for natural convection. Lenses are used on top of each concentrator to improve its efficiency.

Study Design: The Solar collector is made of hemispherical concentrators with Fresnel lenses axially-centered to those concentrators and placed on top of each one of them. Those concentrators are covered with a 4 mm glass for a greenhouse effect. The concentrators generate hot spots that heat the inside air. There is no need for receivers at the hot spots.

Methodology: from Inlet to outlet, temperatures are measured as well as inlet air speed, which allow the efficiency evaluation.

Results: Although those measurements were conducted in a cloudy period, temperature difference from the inlet to the outlet was around 55°C to 65°C. This result is superior to previous studies of the same system without lenses which gave temperature difference around 35°C to 45°C. It is sharply superior to that of usual black-painted convective system with fined plates that gives a temperature difference of around 20°C to 25°C.

Conclusion and Perspectives: The global efficiency calculated using measurement values reaches 56%. This is far greater compared to previous black plate systems’ efficiency of 29%, giving an efficiency increase of 93%, but expected knowing that we are using a concentration system for convection.

Open Access Original Research Article

Strain Field Development of a Rectangular Dislocation Loop in a Semi-Infinite Medium with Verification

Luo Li, Tariq A. Khraishi

Physical Science International Journal, Page 23-38
DOI: 10.9734/psij/2021/v25i130234

This paper considers a rectangular Volterra dislocation loop lying beneath and parallel to a free surface in a semi-infinite material. The paper utilizes the displacement field of an  infinitesimal dislocation loop to obtain the strain field and then integrate over a finite rectangular area. For the loop, it can have three non-zero Burgers vector components. The stress field   is also obtained from Hooke’s law for isotropic materials. Analytical and numerical verifications of the strain and stress fields are performed. In addition, the effect of the free surface on  stresses is displayed versus depth from the surface. Verification includes satisfaction of the zero-traction boundary condition, the stress equilibrium equations and the strain compatibility  equations.

Open Access Original Research Article

Evaluating the Contamination Degree and Risk Assessment of Heavy Metals Around Active Dumpsite Environment: A Case Study of Ozoro Community, Delta State, Nigeria

A. N. Ogbaran, H. Uguru

Physical Science International Journal, Page 39-51
DOI: 10.9734/psij/2021/v25i130236

The use of lowlands for refuse collection point (dumpsite) is a very common practice in Nigeria. However, people cultivated the areas within the vicinity of the dumpsites, without knowledge of the risk of these heavy metals. Therefore, this study was done to evaluate the risk of heavy metals pollution of soils within the vicinity of an active dumpsite. Four (4) soil samples (from 4 locations) at a depth of 0–20 cm were collected from the vicinity of the dumpsite. The heavy metals (e.g. iron lead, nickel and cadmium) concentration of the collected soil samples were analyzed according to American Society for Testing and Materials (ASTM) International methods. Pollution indices (contamination factor, enrichment factor, pollution load index and geoaccumulation index) were used to ascertain the level of heavy metals contamination of the dumpsite area. Results obtained from the soil tests revealed that, the dumpsite area had high heavy metals concentrations. The heavy metals concentrations were of this ranged: iron 3420 mg kg-1 to 4323 mg kg-1, lead 28.92 mg kg-1 to 58.84 mg kg-1, nickel 2.89 mg kg-1 to 6.91 mg kg-1, and cadmium from 1.04 mg kg-1 to 2.05 mg kg-1. The heavy metals concentrations ranked as Fe > Pb > Ni > Cd. Pollution indices results showed that cadmium had the highest contamination factor, enrichment factor, pollution load index and geoaccumulation index values, which portrayed that the dumpsite soil was heavily contaminated with cadmium. Results of the correlation showed a strong correlation (r = 0.87) between iron and nickel, indicating that the two heavy metals got their pollution from the source(s). Results obtained from this study will further help the government and environmental regulators to plan and carried out suitable remediation strategies, to clean the environment.

Open Access Original Research Article