A numerical simulation has been carried out to study the interaction of a cavitation bubble and an elastic membrane. Boundary element method is used to simulate the physics of the membrane between two fluids which are assumed to be same (water) for simplicity. The intent of this paper is to clearly investigate the bubble–membrane interaction. Elasticity of the membrane plays an important role on the behavior of the bubble. For example, a bubble near a ‘stiff’ membrane (high elasticity), jets toward it (the same as the rigid boundary). The influence of two main parameters, namely, dimensionless distance of the bubble center to the membrane initial position (H′) and the dimensionless elasticity of the membrane (E′) are discussed. We have considered the dimensionless distance of the bubble center to the membrane initial position in the range of 0.5 ⩽ H′ ⩽ 1 and a membrane of dimensionless elasticity in the range of 0.01 ⩽ E′ ⩽ 10. An increase in H′ leads to a decrease in the membrane displacement from its initial position. Also, increasing of E′ leads to a change in the behavior of the bubble from spherical collapse to jetting toward the membrane (in a same H′) and decreasing in membrane displacement.

Artificially roughened surface is a comon method to enhance the heat transfer in a flow passage. Energy, exergy and economic analysis of solar air heaters with different roughness geometries have been done. To improve the performance of the solar collector, 4 different types of roughness on the absorber plate have been used. It was found that the most efficient roughness is Discrete V Rib and the least expensive roughness is U-Shape turbulator. NSGA II and TOPSIS algorithms used to select the best roughness geometry.

In this paper, a system of simultaneous production of power and heat and cooling in a Kalina cycle has been analyzed by energy, exergy and economic aspects. To provide heat in the cycle heating unit, four types of solar thermal linear (PTC) and linear share (LFR) heat collectors, plate (dish) and vacuum tube, have been used. The results of the analysis of this cycle for the PTC collector compared to other collectors showed that this collector was superior in increasing the energy and exergy efficiencies of the system and also lowering the total cost rate and exergy destruction of the CCHP cycle. By using parametric studies tried to obtain the effect of increasing and decreasing some of the cycle component parameters to get the most cooling, heating and power output.

A popular and common method to enhance the heat transfer in a flow passage is to artificially roughen the surfaces with ribs, grooves or combination of ribs and grooves (rib-grooved surface). The artificial roughness is often used in heat exchanger systems, such as solar air heaters, nuclear reactors, electronic cooling devices and gas turbine blades .Among the artificially roughen the surfaces, rib-grooved surfaces are one of the popular techniques that are extensively used in plate heat exchanger manufacturing. In fact, the ribs, grooves and their combination increase the fluid flow turbulence near the wall by breaking the laminar sub layer and create local wall turbulence due to flow separation and reattachment, which disrupt the thermal boundary layer and reduce the thermal resistance and greatly enhance the heat transfer. In this paper, heat transfer enhancement of optimized rib-grooved surfaces in channels is multi objectively optimized applying the NSGA II algorithm. The distance between rib and groove was set from 0 to 3w. The optimized distance between rib and groove was d=2.2w which computed by considering maximum heat transfer and minimum friction factor, simultaneously. The effects of Reynolds number of 5000 to 30000 are so investigated. when the velocity of flow increases the nusselt number and pressure drop increase .When the distance between rib and groove increases the nusselt number increased while the friction factor decreases in optimization with NSGAІІ algorithm point=2.2w is the most optimized than other points for Reynolds from 5000 to 30000.