Journal of Energy, Mechanical, Material, and Manufacturing Engineering

Sound absorption coefficient from composites made from coconut fiber, paper, and styrofoam

Amalia Ma'rifatul Maghfiroh — Wed, 24 Jul 2024 00:00:00 +0700

Noise is an unpleasant/undesirable sound. Apart from noise, environmental problems are often faced by the community in the form of organic and inorganic waste resulting from several small/large industrial activities. Organic waste often encountered is young coconut fiber from activities in traditional markets. Paper waste comes from teaching and learning activities/offices. Styrofoam waste is included in the category of inorganic waste, which is very difficult to decompose, so it has a bad impact on the environment. Based on this, a composite was made from coconut fiber, paper and styrofoam so that it could be used as a sound absorber. Cylindrical composite specimens were made with different variations in composition and analyzed the differences in sound dampening ability in various compositions. The sound absorption capacity of the composite was measured at frequencies of 125 Hz, 250 Hz, 500 Hz, 750 Hz, 1,000 Hz, 2,000 Hz and 4,000 Hz. The composite acoustic test results obtained for samples A, B and C showed that the highest absorption energy was 49.57 dB at a frequency of 750 Hz for sample C. Meanwhile, the lowest absorption energy was 1.15 dB at a frequency of 500 Hz for sample A. The sound absorption coefficient values were obtained for all variations. The frequencies of samples A, B and C have good absorption coefficient values, namely ≥ 0.2. The lowest absorption coefficient value was 2.01 at a frequency of 750 Hz for sample C and the highest was 46.67 at a frequency of 500 Hz for sample A.

Future prospective of bioethanol production from sugar palm sap

Mustofa, Hariadi — Thu, 30 May 2024 00:00:00 +0700

The availability of fossil fuels is decreasing along with increasing environmental temperatures due to their use. Therefore, there is a need for other alternatives to overcome this problem, such as the use of bioethanol as an environmentally friendly renewable energy. This research was aimed to identify the potency of sugar palm (Arenga pinnata Merr) sap as a feedstock for bioethanol production. Two major aspects of the identification focus were the feedstock availability and the bioethanol production process. The feedstock identification was conducted by surveying the industry of sugar palm and collecting data of the volume of sugar palm sap. Then, the production process of bioethanol as final product was conducted in four stages. They are characterization of samples, pasteurization, fermentation, and distillation. The results show that sap samples collected from the farmers have pH = 3.1-3.2, density 0.96 gr/mL, and carbohydrate content 1.51%, respectively. Sugar palm sap was fermented with 0.03 m/v fermentation agent of yeast within 72 hours. After the fermentation process, the sugar palm sap contains 1.51% carbohydrates, 74% alcohol, and 63.96% ethanol. Furthermore, the distillation temperature of 78-80^oC resulted in a 7.44% v/v ratio of extract amount from the total volume of the distillation results. The bioethanol quantity can be increased by considering the process, especially during the fermentation.

The effect of tapioca starch concentration on mechanical properties of Sansevieria Trifasciata fiber-reinforced composites

Misbakh, Edi Widodo, Iis Siti Aisyah, Syahruddin, Nur Haizal Ariffin — Tue, 03 Sep 2024 00:00:00 +0700

This research investigates the impact of varying concentrations of tapioca starch (Manihot esculenta) on the mechanical properties of composites reinforced with Sansevieria trifasciata (Lidah mertua) fibers. The composites were fabricated using the hand lay-up method with SHCP 2668 polyester resin, mekpo catalyst, and alkali-treated fibers (5% NaOH). The fiber weight fraction was 30%, and the catalyst weight was 10% of the total specimen mass. The tapioca starch concentrations were 0%, 10%, 20%, 30%, 40%, and 50%, with a total matrix mass of 50 grams. Mechanical properties were evaluated through tensile tests (ASTM-D3039) and bending tests (ASTM-D790). The results indicated that composites with added tapioca starch exhibited improved tensile strength and a higher modulus of elasticity. However, for bending tests, the composites without added tapioca starch demonstrated better performance, showing a higher elastic modulus and better flexibility. In conclusion, adding tapioca starch enhances the tensile strength of the composites, making them stronger. Conversely, for bending applications, composites without tapioca starch are preferable due to their superior elasticity and bending strength.

Effect of airflow rate and honeycomb channels addition on the efficiency of bagasse-fuelled top-lit updraft (TLUD) gasification stove

Wed, 24 Jul 2024 00:00:00 +0700

The use of Liquefied Petroleum Gas (LPG) fuels has increased over time and has triggered the innovation of renewable fuels that do not affect the environment. This renewable fuel is biomass. Biomass is derived from organic materials of plants or animals that can be used as fuel. The conversion of biomass into thermal energy using gasification stoves can increase thermal efficiency up to twice that of conventional biomass combustion. Common stoves that use nowadays is Top-Lit Updraft (TLUD) gasifier that easy to optimize. This type of gasifier has a simple design and can be fuelled with any type of biomass with a water composition of less than 20%. Gasification stoves have so far been developed using various biomass fuels, one of which is bagasse waste. Bagasse is also easy to obtain in Indonesia because it has an abundant number of quantities. In addition to the fuel aspect, the ability of the gasification stove to produce good thermal efficiency depends on the stove design, such as stove type, stove dimensions, and combustion airflow rate. It is tested with the water boiling test method using variations of airflow rate of 2 m/s, 3.5 m/s, 5 m/s, and 6.5 m/s and honeycomb channels addition. As a result, it reached 30% thermal efficiency.

Optimization of staggered array configurations to enhance the aerodynamic performance of Darrieus wind turbines

Yosua Heru Irawan, Aditya Sukma Nugraha, Po Ting Lin — Thu, 01 Aug 2024 00:00:00 +0700

This research focuses on optimizing the arrangement of Darrieus wind turbines through an adjustable R array, which represents the spacing between the turbine rotors. The ANSYS Fluent solver, employing the k-epsilon turbulent model and sliding mesh technique, is utilized to predict turbine performance. Additionally, a grid independence test is conducted to validate the solver's effectiveness. The optimization of the R array is achieved using the conjugate gradient method. Simulation results indicate that a blade grid size of 1 mm results in an error under 1%. A smaller R array yields a lower average coefficient of power (Cp_average) due to the wake interactions between the rotors. The optimal spacing for each turbine to achieve a Cp_average value of 0.4088 is determined to be 1.772 meters.