This work shows the power of the variational approach for studying the efficiency of thermal engines in the context of the Finite Time Thermodynamics (FTT). Using an endoreversible Curzon–Ahlborn (CA) heat engine as a model for actual thermal engines, three different criteria for thermal efficiency were analyzed: maximum power output, ecological function, and maximum power density. By means of ...

In high power solid-state-laser systems, one of the major problems is the thermal effect, which occurs in optically pumped laser materials. Heating of the laser medium causes thermal distortions, leading to degradation of beam quality. The main thermal effects in laser rods are thermally induced birefringence and thermal lensing effects. High efficiency, high power and good output beam quality ...

A phillipsite-faujasite tuff (faujasite) from Jordan has been activated and characterized to evaluate its efficiency in removing paraquat from synthetic wastewater and to specify optimum conditions with maximum efficiency of the faujasite tuff. Noticed variation in CEC is indicated and explained by selectivity of the faujasite to K(+) and Na(+). Removal of paraquat by using faujasite directly g...

Conversion of sunlight by photon-enhanced thermionic emission (PETE) combines a photonic process similar to photovoltaic cells, and a thermal process similar to conventional thermionic converters. As a result, the upper limit on the conversion efficiency of PETE devices is not the same as the Shockley– Queisser (SQ) limit that corresponds to the bandgap of the absorbing material, nor to the Car...

This paper presents the technical performance measurements of biogas premixed charge diesel dual fuelled engine. A 4-stroke research diesel engine was used for the performance analysis. The performance parameters like engine brake power, brake specific fuel consumption, volumetric efficiency and brake thermal efficiency were measured and compared with conventional diesel with different proporti...

This paper deals with the hydrodynamic and thermal analysis of a new type of porous heat exchanger (PHE). This system operates based on energy conversion between gas enthalpy and thermal radiation. The proposed PHE has one high temperature (HT) and two heat recovery (HR1 and HR2) sections. In HT section, the enthalpy of flowing high temperature gas flow that is converted to thermal radiation em...

An experimental and theoretical energy and exergy analysis was conducted for a cylindrical cavity receiver employed in a parabolic dish collector. Based on simultaneous energy and exergy analysis, the receiver average wall temperature and overall heat transfer coefficient were determined. A simplified Nusselt number for Heat Transfer Fluid (HTF) through the receiver as a function of Reynolds an...