One way to overcome the scarcity of clean water through sustainable approach is by utilizing a solar distillation system. This easy-to-use technology is adopting tubular solar distillation. The three main components, which are the most essential for producing the amount of permeate, are the solar collector, tubular and heat exchanger (HE). This study aims to determine the performance of a tubular solar distillation device equipped with HE using a parabolic trough collector (PTC). The PTC has an area of 5.1 m² covered with a solar reflective chrome film. Aluminum tubular acts as the feedwater heater. The HE is placed inside the tubular, which acts as a coolant to convert the steam phase into freshwater/permeate and as a feedwater heater to flow into the tubular. In the present study, several parameters were tested: comprise temperature, solar radiation, pressure, humidity, mass flow rate, permeate productivity and efficiency. This study demonstrated the production of a sufficient amount of permeate, which was 5.32 L for 6 h. The efficiency of this device yielded a peak of 48.2% during solar radiation of 813 W/m² in an average ambient temperature of 32 °C, with an overall average of 44.59%.

This study investigates the effect of surface dimples on the unsteady aerodynamics of a National Advisory Committee for Aeronautics airfoil (NACA0012) at chord-based Reynolds numbers of Rec=5300 and 10 000 using direct numerical simulations. Dimples were placed on the suction side at non-dimensional chordwise locations of lD/c = 0.035 and 0.35, and the flow response was studied at a fixed angle of attack α=5°. At Rec=5300, dimples placed at lD/c = 0.35 reduced lift and drag fluctuations by 26.5% and 33.3%, respectively, with minimal change in mean forces. At Rec=10 000, the same configuration led to a sevenfold increase in force fluctuations, while the mean remained unchanged. The smooth airfoil exhibited irregular, aperiodic force signals at this Rec, whereas the dimpled case showed highly periodic behavior, indicating wake stabilization. Flow visualizations revealed that dimples generate streamwise vortices within the boundary layer. These vortices are found to have a stabilizing effect on wake dynamics at Rec=5300, reducing vortex breakdown and enhancing the coherence of wake structures. Spectral proper orthogonal decomposition (SPOD) showed that dimples redistribute modal energy depending on Reynolds numbers: at low Rec, they reduce broadband content and suppress unsteadiness, while at high Rec, they amplify dominant shedding modes and broaden the spectral energy distribution. Leveraging the SPOD energy modes, it is found that dimpled foil exhibits 26% lower spectral entropy compared to the smooth case at St≈2 and Rec=10 000, suggesting a more concentrated energy at one or few dominant modes. These results demonstrate that dimples can passively modulate unsteady forces and wake dynamics for a flow over a streamlined body, either suppressing or enhancing flow instabilities depending on the regime.

The development of proton exchange membrane fuel cells (PEMFC) has been focused on the membrane electrode assembly (MEA). In this research, MEA based on Pt/C mixed with activated carbon-chitosan-light metal, namely nickel, has been fabricated and tested on a PEMFC prototype. As a comparison, two commercial MEAs based on Nafion membrane were also tested, with a platinum-carbon electrocatalyst. It is found that the highest voltage achieved from the developed MEA without loading is 0.43 V, lower than the voltage achieved by the commercial MEA. When an electrical resistance load is given, a decrease in the electrical voltage was observed. However, the developed MEA is able to produce the largest power density value at an electric current density greater than 2 mA/cm². The developed MEA has shown good performance when compared to commercial MEA on the market. This preliminary research opens the potential for MEA development using more abundant and lower cost materials.

This paper investigates the implementation of heat pipe in the air conditioning system, specifically in an air circulating room. The use of air conditioning system in an air circulating room may increase the cooling load of the evaporator. In this experiment, the heat pipe is utilized for reducing the inlet air temperature in order to reduce the cooling load of the evaporator. Thermal analysis of the Heat Pipe Air Conditioning System (HPAC) is conducted with variation of vertically-installed adiabatic and initial air cabin temperature of 30°C with Air Conditioner (AC) setting temperature of 20°C; 18°C; 16°C. The thermal analysis is then compared with the HPAC without the adiabatic. The result shows that the utilization of vertically-installed adiabatic in the heat pipe of the HPAC decreases the inlet air temperature with cooling load of 5,981 kW; 6,978 kW; 7,477 kW, respectively to the AC setting temperature, compared to the HPAC without adiabatic with the result of 6,48 kW; 7,477 kW; 8,474 kW. The HPAC with vertically-installed adiabatic shows a lower energy use within the range of 29,1% – 37,7% for the AC compressor and 16,6% – 23% according to the cooling rate. The results indicate that the implementation of heat pipe with vertically adiabatic in the air conditioning system in a circulating room is more effective compared to without using the adiabatic.