The number of coffee shops in Indonesia has grown from 1,083 stalls in 2016 to over 2,937 booths in 2019, representing a threefold growth. Coffee shop establishments must provide two essential kinds of equipment: espresso machines, which use pressure, and filter machines, which employ infusion. The issue lies in the exorbitant cost and immense power requirements of semi-automatic and automated espresso machines, which necessitate the use of a manual espresso machine for commercial operations. The equipment can generate satisfactory espresso but encounters several challenges; specifically, the espresso generated is characterized by inconsistency, constantly varying in quality. This might arise due to the erratic nature of the manufacturing process. The two objectives of this study are: (1) to design an economically efficient semi-automatic espresso machine capable of producing products that meet the international quality standards set by the Specialty Coffee Association (SCA standard) and (2) to investigate the impact of critical factors such as pressure, temperature, and grind size, on the consistent quality of the resulting coffee (measured by Total Dissolved Solids (TDS) and extraction yield (EXT)). The research employs the Research and Development (RD) methodology. The research findings indicate that the optimal levels of Total Dissolved Solids (TDS) and extraction yield (EXT) may be attained by using a pressure setting of 8 bars, a temperature of 90ºC, and a grind size of 3.2 on the scale. The technique for optimizing the response resulted in Total Dissolved Solids (TDS) levels of 10.03% and extraction yield (EXT) values of 19.56%. The results have been deemed acceptable based on the criteria set by the global standards of Specialty Coffee Association (SCA).

Offshore cranes are transport machines which are used to lift a heavy load to other places. The weight and strength of a crane are crucial parameters that must be considered during the design stage. There are many ways to optimize these aspects, such as suitable material selection and virtual simulation assistance using ANSYS software. The main goal of this study is to design and develop a structurally stable crane on the ship deck. This crane is modeled using CATIA software and analyzed using ANSYS software to obtain stress and displacement distribution on the crane structure. Maximum load is applied for four different elevation angles, namely (30°, 43°, 60°, and 80°). From the static structural simulation, the highest stress is obtained when the elevation angle of 30° is about 1030 MPa and deformation is 461.24 mm. The minimum fatigue life of the offshore crane at a luffing angle of 43° is 659.14 cycles.

This research focuses on improving hydropower production by designing a turbine for the MaliringanRiver in Kalimantan Selatan. The rotational speed and torque will be the focus of maximizing power generation. This research used Computational Fluid Dynamics (CFD) to understand how the fluid flows and how efficiently the turbine works. The simulations helped us see how the fluid flowed, the pressure differences, and the speed of the water inside the turbine. The software COMSOL Multiphysics imitates how the fluid behaves and interacts in real-life situations. The utilization of SOLIDWORKS played a crucial role in the turbine's design process, facilitating an accurate representation of the turbine's geometry and the subsequent fabrication of a prototype propeller turbine, featuring an outer diameter measuring 0.27 meters and an inner diameter measuring 0.113 meters. The methodology resulted in a power efficiency of 76.45%, showcasing the possibility of significant enhancements in the efficiency of hydropower generation. The broader ramifications of this study emphasize the feasibility of tailor-made turbines for local hydropower initiatives, thereby supporting Indonesia's renewable energy plan by providing sustainable and efficient energy alternatives. This study emphasizes the collaborative utilization of Computer-Aided Design (CAD) and CFD technologies in the progression of turbine technology, thereby establishing a basis for future investigations in hydropower optimization.

One of the main reasons for replacing R134a with R600a is the impact of global warming. In this study, a numerical approach was applied to investigate changes in automotive air conditioning (AAC) performance due to the replacement of R134a with R600a. A thermodynamic evaluation was carried out with evaporating and condensing temperatures of 5oC and 45oC, respectively. The study simulates AAC performance at five engine rotation speeds: 1000, 2000, 3000, 4000 and 5000 rpms. The results show that replacing R134a with R600a reduces the cooling capacity and input power by 45.42% and 47.02%, respectively. However, due to the dominant decrease in input power as compared to the decrease in cooling capacity, the COP of AAC increases by 2.93%. Although the increment in COP is relatively small, this replacement greatly contributes to the reduction of greenhouse gas emissions that causes the problem of global warming due to the lower GWP of R600a as compared to R134a.

Gas turbines are one type of internal combustion drive, the initial mover utilizes gas combustion as a fluid to rotate the turbine with internal combustion. Gas turbines at private companies producing electricity use the initial movers, namely gas turbines and steam turbines. Therefore, it is also called the "Steam Gas Power Plant/PLTGU.”Private company especially in Block 2, uses two gas turbine units with Mitsubishi GT 2.1 specifications which are used as the initial drive of the generator. Types of overhauls in gas turbines are divided into three, including turbine inspection, combustor inspection, and major inspection. In maintaining the reliability of the GT 2.1 Gas Turbine, an overhaul combustion inspection was carried out in the combustion chamber because there was an increase in heat rate of 17,9% which caused a decrease in thermal efficiency and net turbine power of the GT 2.1 Gas Turbine by 17% and 2,1%. So that steps are taken to optimize the GT 2.1 Gas Turbine with the combustion inspection method by repairing and cleaning the combustion bucket nozzle. Increased thermal efficiency by 27,8% or 27,13% to 36,01% from data before overhaul. This was also followed by an increase in compressor power and turbine power so that the net turbine power increased by 38% or 141339,35 hp to 195246,54 hp.

The increase in the number of motorized vehicles has led to challenges in maintaining environmental air quality, combustion efficiency, and the sustainability of fossil fuels. An innovative solution to address these issues is the utilization of brown gas. This study aims to investigate the impact of introducing brown gas into the incoming air flow on the performance of an internal combustion engine. The brown gas flow rate varies based on the gas production rate resulting from variations in the addition of NaOH (10 g/l, 20 g/l, and 30 g/l) to every 1 liter of water in the generator. Gas production rates are measured using a flow meter. The influence of brown gas on gasoline engine performance is assessed through power testing with a chassis dyno test engine and exhaust emissions testing with a gas analyzer. The findings reveal that the highest flow rate of brown gas is achieved with the addition of 30 g/l NaOH during the electrolysis process. Introducing brown gas into the incoming air flow can increase maximum engine power by 15.5% and reduce CO exhaust emissions by 23.37%.

Coffee, one of Indonesia's largest commodities, is often processed using traditional methods and tools that rely heavily on manual labor and can be labor-intensive. To make the coffee roasting process more efficient and reduce the need for human effort, a coffee roasting machine can be used. This study aimed to analyze coffee roasting drums using computational fluid dynamics (CFD) to determine the optimal drum thickness and rotation speed in a coffee roasting machine. The study considered three different thicknesses (1mm, 2mm, and 3mm) and three different rotation speeds (60rpm, 65rpm, and 70rpm). The coffee roasting drum was modeled using CFD. The study's results showed that a drum thickness of 2mm and a rotation speed of 70rpm achieved the best heat distribution during roasting, reaching the desired temperature in 900 seconds. This information could be used to design a more efficient coffee roasting machine or improve the performance of existing machines.

The lightweight design of the rocket motor tube is a critical requirement for enhancing the rocket's flight performance. This study assesses the impact of wall thickness, cap thickness, and fillet radius on structural strength and the optimization of rocket motor tube weight using the finite element method with the assistance of Ansys software. A total of 12 finite element model variations, utilizing Aluminium 6061-T6, were developed and subjected to a uniform internal operating pressure load of 10 MPa. The design includes wall thickness variations of 8 and 10 mm, cap thickness options of 25 and 30 mm, and fillet radius dimensions of 20, 25, and 30 mm, allowing for a comprehensive comparison to achieve the required minimum safety factor while minimizing structural weight. The research concludes that increasing the fillet radius is a more recommended approach compared to increasing wall thickness and cap thickness. The results indicate that Model 9, with wall thickness, cap thickness, and fillet radius dimensions of 10 mm, 25 mm, and 30 mm, respectively, is the optimal choice due to its lightweight construction.