Journal of Selected Topics in Energy

Investigation of performance and exhaust emissions in direct injection engine using coconut oil biodiesel

In this study, the performance and emission characteristics of a direct injection diesel engine using coconut oil biodiesel were investigated. For this aim, coconut oil was converted to its biodiesel via transesterification approach. Then, the effects of the biodiesel percentage in blend, engine load, and speed on brake power, brake specific fuel consumption (BSFC), nitrogen oxides (NOx), carbon dioxide (CO₂), carbon monoxide (CO), and particle matter (PM) have been considered. Fuel blends with various percentages of biodiesel (0%0 - %3%) at various engine speeds and loads were tested. The results indicated that blends of cocunut with diesel fuel provide admissible engine performance on the other side, emissions decreased so much.

Effect of Open Windows on Car Drag

Effect of open windows on car drag and consequently on the required power and fuel consumption has been investigated in this study. To do this, a simulated model as possible as similar to the actual model has been considered. For example round angles and side slopes have been considered. The drag caused by aerodynamic forces has been calculated, for different cases. Results show, as the percentage of windows opening increased, the car drag first decreased and then increased such that, the car drag with open windows for a certain percentage is equal to that of the closed windows car. This certain percentage depends on the car velocity.

Optimal cross section and elevation in wind catcher structures as a ventilation system in Traditional Iranian Architecture

The limited available energy resources and it basic role in industrial development, employing the renewable sources of energy including wind, sun, water and etcetera as appropriate choice described. Renewable energies are not only economically advisable, but even can contribute to provide a cleaner approach of energy production and healthier environment. Hence, assessment of some old structures such as Middle East wind catcher that are established on the ground of clean energies and adapting them to the modern age demands with optimizing models is noteworthy. This work, by keeping focus on calculus of variation and analysis of the wind load on the wind catcher structures and present an optimal more resistant model. Optimization of the design parameters of wind catcher structures led to a hyperbolic model with least wind catcher surface and a higher stability and strength compared with the older structures of this category.

Study the effect of volume fraction, size and shape of suspended nanoparticles in nanofluid on cylindrical heat pipe performance

Copper oxide nanofluid that is obtained by dispersion of copper oxide nanoparticles in water base fluid is used as heat pipe working fluid. Nanofluids because of having better thermophysical properties in comparison with conventional heat transfer fluids, cause heat pipe performance improvement as an effective heat transfer equipment. In this work, a computational fluid dynamic method (CFD) is used to study the effect of using nanofluid and varying volume fraction, size and shape of suspended nanoparticles in nanofluid on heat pipe thermal performance. The results show thermal resistance reduction and heat pipe performance improvement by using nanofluid in comparison with pure water. Also volume fraction enhancement, nanoparticle’s diameter reduction and using cylindrical nanoparticles cause the evaporator and condenser temperature gradient reduction that in low volume fractions the effect of using nanoparticles with small diameter on heat transfer is more than using non spherical nanoparticles