Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : efficiency


Numerical and Experimental Investigation of Solar Air Collectors Performance Connected in Series

J.M. Jalil; K.F. Sultan; L.A. Rasheed

Engineering and Technology Journal, 2017, Volume 35, Issue 3, Pages 190-196

In the present work, the investigation on the performance of series of solar air collectors to obtain high temperature air was performed. The first collector has been studied experimentally, while the rest of the series collectors have been investigated numerically with the same boundary conditions. The experimental and numerical results of the first collector show acceptable accruement, this lead to calculate the series of collectors numerically. The results indicated that collector’s series do not work with the same efficiency. The first collector will work at low inlet air temperatures, which lead to increase in the efficiency, on the contrary for the other collectors. The results showed that, it can be determined the required number of collectors in series that necessary to obtained the required outlet air temperature.

Laboratory Investigation on Efficiency of Model Stone Column Groups

Kais T. Shlash; Mohammed Y. Fattah; Maki J. Mohammed Al-Waily

Engineering and Technology Journal, 2009, Volume 27, Issue 9, Pages 1673-1690

As in piles, the efficiency of a group (Eg) of stone columns is defined as the ratio
between the capacity of the group to the capacity of each stone column in the group
multiplied by single stone column capacity. In this paper, the group efficiency of 24 model
stone columns installed in soft clay is considered. These groups consist of 2, 3 and 4
columns. The tests were conducted on stone columns with length to diameter ratio (L/D) of 6
and 8. A laboratory setup was manufactured in which two proving rings were used to
measure the total load applied to the soil-stone column system and the individual load carried
directly by the stone column. The foundation steel plates have 220 mm diameter and 5 mm
thickness. These plates contain 1, 2, 3 and 4 holes, respectively. The spacing between all
holes equals twice the stone column diameter (D), center to center.
The stone column capacity is taken as the load corresponding to a settlement equals
to 50% of the diameter of stone column. The results illustrated that the group efficiency
decreases with increasing the number of stone columns, also the stone columns with L/D of
(8) provided higher efficiency than those with L/D of (6).

Improvement of solar cell efficiency by using Two mirrors V-trough concentrator

Engineering and Technology Journal, 2009, Volume 27, Issue 3, Pages 126-130

V-trough concentrator with four mirrors has been designed and constructed. Its
effects on the silicon solar cell performance were studied with and with out cooling
system. It was shown that the cell efficiency was increased from 11.94 % to 15.46 %
with out cooling and from 13.3 % to 16.4 % with cooling system. The effect of a
combination between Fresnel lens and V-trough concentrator was studied also. The solar
cell efficiency was improved to 24 % with out cooling and the best efficiency
improvement was 26.6% with cooling system.