Heat exchanger based on paraffin/expanded graphite composites for breathing air cooling in fire

The enormous amount of heat in fires can push inhalation temperature to ~500 K, which is fatal to the civilians. However, conventional rescue respirators are unable to control the breathing air temperature. In this work, we utilized paraffin/expanded graphite (EG) composites to construct a heat exchanger for breathing air cooling. The material itself can be used as the mechanical support, the heat spreader and the heat absorber at the same time. The composites of 0~35 wt% EG were prepared and characterized. The results showed the paraffin was uniformly absorbed in the porous structures of EG. And the paraffin/EG composite with 25 wt% EG has better performance both in simulation and experiment. The heat exchanger constructed by this composite shows good cooling efficiency by cooling the inlet air from 500 K to a breathable 313 K and sustaining for more than 20 minutes.

Evaluasi Termal Vertical Greenery System Tipe Green Facade pada Dinding Bangunan

Increasing of ambient temperature due to global warming has a direct impact on increasing the room temperature. Heat from surrounding is transferred to building wall and room. By installing the Vertical Greenery System (VGS) on the building wall, it can be an alternative for heat absorber and eco-friendly indicator. The aims of this study are to determine the temperature that can be reduced by VGS type Green Façade (GF) and achieve the energy consumption reduction because of GF installation. GF is installed on the building wall, property of Mining Engineering Department, Sriwijaya University, to measure its temperature, then compare it with the temperature on control wall. The results showed that the GF can reduce the room temperature up to 1,2oC, compared to the control wall and the average is 0,3oC. The decrease in average temperature causes a decrease in energy consumption due to the use of air conditioners by 1.56-1.92%. Keywords: global warming, green facade, thermal evaluation, vertical greenery system

Elimination of Congo Red Dye from Industrial Wastewater Using Teucrium polium L. as a Low-Cost Local Adsorbent

A novel adsorbent prepared from the leaf powder of Teucrium polium L. (TPLLP) was characterized and its ability for adsorption of Cong red (CR) was inspected. Influences of CR concentration, adsorbent dosage, time of agitation, pH of solution, and temperature on the performance of this adsorption were also examined. Three models of kinetic along with three different isotherm models were applied for analyzing the empirical data of this adsorption. Additionally, the thermodynamic constants of were decided. The surface area, pore volume, pore size, and pHZPC of Zn/Cu-TPLLP were found to be 2.6436 m2.g-1, 0.013317 cm3.g-1, 527.393 Å, and 8.8, respectively. The achieved outcomes indicate the positive influence of temperature, concentration of CR in the range of 20 to 900 mg/L, adsorbent mass in the range of 0.005 to 0.02 g, time of adsorption from 0 to 120 min, and pH from 5.5 to 8.5. Models of the 2nd order with R 2 ≥ 0.995 and Langmuir with R 2 ≥ 0.990 were the best among the other kinetic and isotherm models applied in this research. Moreover, superior capacities of 526.32, 666.67, and 909.09 (mg.g-1) were stemmed at 27, 42, and 57°C, respectively. The outcomes of the thermodynamic evidenced that this adsorption is spontaneous and a heat absorber.

The Investigation of Heat Absorber on the Efficiency of Slanted Double-Slope Solar Distillation Unit

A rise in utility consumption in rural areas have promoted the demand for the development of solar-based technologies for water purification system. This research aimed to develop a slanted double-slope solar distillation unit (SDSD) assisted by heat absorbers, which is employed as a distillation unit for generating clear distilled water from underground water. The prototype SDSD distillation unit developed in this research was evaluated based on production efficiency, productivity, distillation rate and temperature measured at different locations inside the device. Significant parameters that were varied included the types of heat absorber used (gasket, rubber, aluminum, high carbon steel and zinc) and the size of heat absorber (10 to 90% of surface area inside the SDSD). Results demonstrated an increase in the production of distilled water as the surface area of heat absorber decreases. This is because a reduction in surface area of the heat absorber allowed a more intense sunlight to enter the system. Maximum productivity peaked at 1.2 liter per day (24.9% efficiency). Monitored data in both the upper and bottom part of the distillation unit revealed the highest distillation rate at 15:00 each day. Distillation rate decreases with water height and insulator’s thermal conductivity, but increase with water speed. Additionally, a mathematical model was proposed which was capable of accurately predicting the production efficiency and productivity as a function of the heat absorber’s size and distillation time. Under the same operating conditions, aluminum was found to generate the best results relative to other types of heat absorber.