Ali Rabah - Academia.edu (original) (raw)

Papers by Ali Rabah

Journal of Energy Conservation

Since the independence of South Sudan, Sudan lost 75% of its oil reserves, this led to major fuel... more Since the independence of South Sudan, Sudan lost 75% of its oil reserves, this led to major fuel shortages country wide, the fuel shortage raised the fuel prices and the overall transport prices. Scarcity led to black market trade of fuel specially in states away from the Capital City (Khartoum). Managing the available stock comes first before increasing the supply amount in order to solve the problem, one of the major fuel consumers to be managed is the transport sector specially the long haulage freight transport. Moving freight in Sudan is constrained by inadequate infrastructure and high costs. This paper covers specifically the long haulage freight transport between Khartoum State and Western side of the country (Darfur Region), Contributing to manage fuel consumption for trucks, taking into account trucks types used, roads, environmental impacts and mitigation measures applicable to save fuel . The results showed that the primary reason for the excessive fuel consumption is t...

Journal of Thermal Science and Engineering Applications

This work investigated the operation conditions of a rotary regenerator operating at low regenera... more This work investigated the operation conditions of a rotary regenerator operating at low regeneration temperatures, which is widely used in solar desiccant air conditioning systems. A rigorous experimental rig that facilitates the measurement of axial, radial, and angular airflow temperature distribution is used. The measurements covered balanced flow at a wide range of rotational speeds (0–24 rpm), regeneration temperatures (40–70°C), and airflow rates (160–530 kg/h). The influences of those parameters on the rotary regenerator effectiveness are presented. The results revealed that the critical effectiveness occurs at 5 rpm (equivalent to 4≤Cr∗≤13). This is lower than that for rotary regenerators operating at high regeneration temperatures and airflow rates. The results also concluded that the Kays and London correlation is sufficient for rotary regenerators operating at low regeneration temperatures. It predicted the experimental data with an average absolute percent deviation of ...

Proceeding of International Heat Transfer Conference 12

Forschung im Ingenieurwesen

ABSTRACT This work presents an analytical solution for the periodic heat transfer problem of rege... more ABSTRACT This work presents an analytical solution for the periodic heat transfer problem of regenerators used in air conditioning, which are operating at low regeneration temperatures and mass flow rates. These types of regenerators are characterized by NTU/Cr (au)< 1. The partial differential equations for hot and cold airflows as well as the regenerator matrix were solved using a successive transformation of variables. They were reduced to the ordinary Bessel differential equation of the type xfaEuro(3)+f'-xf=0. The conventional initial and reversal boundary conditions were used in this work. The solution gives a correlation for the prediction of the regenerator effectiveness. Besides the effectiveness, the solution facilitates the calculation of the matrix temperature distribution and exit airflow temperatures. The result is compared with the available numerical and analytical solutions from literature. The result of this analysis reveals that the consideration of a non-linear matrix temperature distribution as in some previous work for low temperature regenerators just complicates the solution procedure with no significant improvement in the accuracy within the parameter space typical for air conditioning applications.

Journal of Chemical Engineering and Materials Science

This work presents two developments in Antoine vapor pressure correlation: (1) Generalization of ... more This work presents two developments in Antoine vapor pressure correlation: (1) Generalization of the correlation using the principle of corresponding state; (2) Prediction of the Antoine coefficients form molecular weight. The coefficients of the generalized correlation are correlated to molecular weight (r 2 =0.99) for the group of normal alkanes (C 1 to C 20). The method is validated using experimental data obtained from reliable literature covering 169 vapor pressure data points covering 11 fluids. The method reproduced the experimental data with a grand absolute average percent deviation (AAPD) of 2.93 while the original Antoine correlation reproduced the same data with 1.90. The method provides a simple procedure for the prediction of Antoine coefficients. On the other hand, the developments, significantly reduces the number of coefficients of C 1 to C 20 from (3×20=) 60 to (3×3=) 9. This saves the labor work needed for storage and processing of the large number of coefficients values.

Journal of Energy, 2016

The study aimed to develop energy flow diagram (Sankey diagram) of Sudan for the base year 2014. ... more The study aimed to develop energy flow diagram (Sankey diagram) of Sudan for the base year 2014. The developed Sankey diagram is the first of its kind in Sudan. The available energy balance for the base year 2012 is a simple line draw and did not count the energy supply by private and mixed sectors such as sugar and oil industries and marine and civil aviation. The private and mixed sectors account for about 7% of the national grid electric power. Four energy modules are developed: resources, transformation, demand, and export and import modules. The data are obtained from relevant Sudanese ministries and directorates and Sudan Central Bank. “e!Sankey 4 pro” software is used to develop the Sankey diagram. The main primary types of energy in Sudan are oil, hydro, biomass, and renewable energy. Sudan has a surplus of gasoline, petroleum coke, and biomass and deficit in electric power, gasoil, jet oil, and LPG. The surplus of gasoline is exported; however, the petroleum coke is kept as...

Khartoum University Engineering Journal, Apr 8, 2013

Khartoum University Engineering Journal, Nov 18, 2012

Journal of Petroleum Technology and Alternative Fuels, Dec 31, 2014

Journal of Thermal Science, 2012

The objective of this work is to provide analytical solution of the conservation equations govern... more The objective of this work is to provide analytical solution of the conservation equations governing the desiccant wheel. The conservation equations describing the moisture exchange between wheel matrix and airflows are complicated partial differential equations (PDEs). This complication is brought about by space and time variations of moisture content. In this work conservation equations of moisture in the matrix and in airflow were solved using the method of successive transformation of variables. In this process the complicated PDEs were reduced to an ordinary Bessel differential Eq. of the type ; which has a general solution of . The analytical solution has facilitated exact determination of moisture distribution in the matrix and in supply and regeneration airflows. It can also be used to accurately predict the wheel performance parameters such as moisture removal and latent effectiveness. In addition provision of analytical solution to the problem has made significant contribu...