Open Access Short communication

Exact Calculation of the Internal Energy of the Ideal Gas in Statistical Mechanics

Igor A. Stepanov

Physical Science International Journal, Page 1-5
DOI: 10.9734/PSIJ/2017/32822

Previously, in the calculation of the internal energy of the ideal gas in statistical mechanics, it has been supposed that the volume is a constant, which does not depend on any arguments. However, the volume depends on pressure and temperature and its partial derivative is not equal to zero. In this paper, the dependence of the volume on pressure and temperature is taken into account, and the internal energy is calculated exactly. It differs from the traditional internal energy by the product of the pressure and volume. This explains three paradoxes in thermodynamics. It follows that the isochoric heat capacity equals the isobaric one. It is shown that the derivation of the Mayer’s relation which connects the isochoric and isobaric heat capacities, is wrong.

 

Open Access Original Research Article

Simulation Study of Polymer Flooding Performance: Effect of Polymer Rheology

O. A. Falode, K. I. Idoko

Physical Science International Journal, Page 1-12
DOI: 10.9734/PSIJ/2017/30805

The use of enhanced oil recovery methods to improve oil productivity has grown and come to stay in the industry. This is as a result of its ability to improve productivity and sweep efficiency. Waterflooding, the most widely used method to recover oil becomes less effective when the mobility ratio is unfavorable and the displacement efficiency is low. This leads to viscous fingering or channeling that leads to significant bypassing of residual oil.

Augmenting injected water with polymer will increase the effectiveness of a conventional waterflood. However these Polymers used in the industry are pseudoplastic (shear thinning). This property is not a correct reflection of the sweep displacement. Polymer’s non-Newtonian behavior needs to be taken into account for the successful design and evaluation of polymer flooding projects. The objective of this work is to study the performance of polymer rheology on oil recovery under different fluid and rock properties.

This project uses ECLIPSE 100 to study the performance of polymer flooding on oil recovery. Sensitivity runs was made on polymer concentration, polymer injection rate, rock wettability, polymer rheology, heterogeneous reservoir, stratified reservoir with crossflow.

Based on the simulation studies and the hypothetical model built, Polymer flooding and waterflooding case was compared in which there is an increase of oil recovery by 20% over water flooding. Polymer flooding is effective in water-wet rock than oil-wet. This is because an oil-wet formation tends to hold back more oil in its minute pores and produce reservoir water. Increasing polymer concentration will lead to higher sweep but reservoir pressure and economics should be considered. Non-Newtonian polymer leads to lower oil recovery. This is due to the decrease in viscosity at high shear rate as a result of velocity contrast and instability.

 

Open Access Original Research Article

Open Access Original Research Article

Structural and Magnetic Properties of Nano Cu-Zn-Zr Ferrite for Magnetic Temperature Transducer (MTT)

O. M. Hemeda, M. M. El-Shahawy, H. E. Khedr

Physical Science International Journal, Page 1-15
DOI: 10.9734/PSIJ/2017/33042

Cu1-xZnx+yZryFe2-2yO4 (Cu-Zn-Zr ferrite) series of compositions with x= (zero, 0.4, 0.6, 0.8, 1) when y= (0.05, and 0.1) nanoparticles were synthesized using citrate sol-gel method. The prepared nanoparticles were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Lattice parameter, bulk density, theoretical density, and porosity were measured for (Cu-Zn-Zr ferrite) samples. The XRD pattern indicated that the average crystallite size found from 18-30 nm and from 17-24 nm, while the average particle size from TEM images are ranging from 21-39 nm and from 18-24 nm for y= (0.05 and 0.1) respectively. Magnetic hysteresis loop measurements illustrate that materials exhibit as soft ferrite properties at low Zn content, while at higher Zn content all materials behave as superparamagnetic materials without any saturation magnetization Ms. The initial magnetic permeability (µi ) at two frequencies 1 KHz and 10 KHz as a function of temperature was measured. A sudden change in µi appear around Curie temperature, making our samples good candidates for Magnetic Temperature Transducer (MTT) devices.

Open Access Original Research Article

A Comparison of Various Evapotranspiration Models for Estimating Reference Evapotranspiration in Sokoto, North Western, Nigeria

D. O. Akpootu, M. I. Iliyasu

Physical Science International Journal, Page 1-14
DOI: 10.9734/PSIJ/2017/32720

Evapotranspiration (ET) is an important component of the hydrological cycle and its accurate quantification is crucial for the design, operation and management of irrigation systems. Agricultural planning depending on evapotranspiration suffers due to inaccuracy in its estimation. The lack of meteorological data retrieved from ground stations required for accurate estimation of reference evapotranspiration (ET0) led in the development of various models for estimating ET0 . This present study compares various universally accepted ET models for estimating ET0 , the six models considered in this study for estimating ET0 for Sokoto, Nigeria (Latitude 13.02 ° N, Longitude 05.25°E and altitude 350.8 m above sea level) using measured meteorological parameters of monthly average daily global solar radiation, sunshine hour, wind speed, maximum and minimum temperatures and relative humidity covering a period of thirty one years (1980-2010) are Blaney- Morin-Nigeria, Priestly and Taylor, Makkink, Hargreaves and Samani, Abtew and the Jensen-Haise models using the FAO-56 Penman-Monteith model as a reference. Based on the FAO-56 Penman- Monteith model, the results showed that the lowest ET(4.6977 mmday-1) occurred during therainy season (August) while the highest ET(10.0600 mmday-1) occurred during the dry season (March). The statistical indicators of Root Mean Square Error (RMSE), Mean Bias Error (MBE), Mean Absolute Error (MAE) and coefficient of correlation (r) were used for the comparison of the six ET models. The results indicates that the Blaney-Morin-Nigeria is the most appropriate model for estimating  for ET0 this particular study area, with lowest RMSE (1.2147mmday-1) , MBE (-1.1581 mmday-1) , MAE (1.1581 mmday-1) and highest value of r (0.9822) . Based on the overall results, the Blaney-Morin-Nigeria model is recommended as an alternative to FAO-56 Penman-Monteith model for estimating ET0 in Sokoto, North – Western, Nigeria when temperature and relative humidity data are available.