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Through this study, there are two variables of concern, namely the effect of the initial comparison of the combustion of raw materials of pine wood charcoal & coffee wood charcoal (70%: 30%, 30%: 70% and 50%: 50%) with mesh sizes of 100 and 250. The initial process of the study is the manufacture of charcoal in pine wood and coffee wood briquettes, pine wood and coffee wood are processed by carbonization at a temperature of 500°C, crushed, sieved using mesh 100 and 250, variations of 70%: 30%, 30%: 70% and 50%: 50% mixed with adhesive, given a pressure of 4 kg, and dried at a temperature of 80°C for 3 hours. The purpose of this study is to determine the comparative value of the combustion rate and calorific value of each briquette sample. The methodology used in this study is to conduct experiments on pine wood charcoal briquettes and coffee wood charcoal in testing the calorific value and combustion rate. From the research that has been done, it was found that the burning rate of briquette samples with variations of pine and coffee wood charcoal with variations of 70%: 30% mesh 100, the burning time is 189 minutes, while at mesh 250 the burning time is 215 minutes. The variation of briquette samples 30%: 70% at mesh 100 the burning time is 192 minutes and mesh 250 is 194 minutes. The variation of briquette samples 50%: 50% mesh 100 has a burning time value of 19 minutes and mesh 250 is 155 minutes. For coffee wood charcoal briquettes and pine wood charcoal at mesh 250 it can be said to meet the SNI 01-6235-2000 standard because the calorific value produced is ≥5000 cal / gram.

Coffee tree trunks are a low-demand biomass resource with potential to be converted into higher-value products, such as charcoal briquettes. This study investigates the effect of drying temperature and particle size (Mesh 30 and Mesh 250) on the performance of coffee wood charcoal briquettes using starch as a binder. Drying was conducted at temperatures of 60°C, 80°C, and 100°C. The briquettes were tested through combustion by heating 50 ml of water, while temperature changes were recorded every minute using a thermocouple until boiling point was reached. Additional analyses included moisture content, ash content, combustion rate, and calorific value.The results show that higher drying temperatures improve briquette performance. The highest combustion rate for Mesh 30 was 0.20 g/min at 100°C, while Mesh 250 reached 0.16 g/min at the same temperature. The calorific value increased with temperature, with Mesh 30 reaching 7178.02 cal/g and Mesh 250 achieving 7498.80 cal/g at 100°C. Although Mesh 30 briquettes exhibited competitive calorific values, their combustion stability was lower compared to Mesh 250.These findings indicate that drying temperature and particle size significantly influence the quality and performance of coffee wood charcoal briquettes

Diesel engines are widely used in the transportation and industrial sectors due to their high thermal efficiency and good operational durability. However, increased fuel consumption due to inefficiency of the injection system remains a common problem. Injector characteristics, particularly nozzle diameter and injection pressure, are important factors that affect the quality of fuel atomization, air-fuel mixing, and combustion efficiency. An inappropriate combination of parameters can cause suboptimal combustion and increase fuel consumption. This study aims to analyze the effect of variations in nozzle diameter and injection pressure on fuel consumption efficiency in diesel engines. The method used is an experiment with variations in nozzle diameter of 0.150 mm, 0.152 mm, and 0.154 mm and injection pressures of 400 bar, 420 bar, and 440 bar. Tests were conducted at engine speeds of 500 rpm, 1000 rpm, and 1500 rpm with a fuel consumption measurement time of one minute for each parameter combination. Fuel consumption was measured using the volumetric method and analyzed through the fuel volumetric flow rate, fuel mass flow rate, Brake Power (BP), and Brake Specific Fuel Consumption (BSFC). The results showed that the combination of a nozzle diameter of 0.150 mm and an injection pressure of 400 bar produced the lowest BSFC value, thus providing the best fuel consumption efficiency. Meanwhile, the combination of a nozzle diameter of 0.152 mm and an injection pressure of 420 bar showed the closest condition to optimal because it was able to provide a balance between atomization quality and the amount of fuel injected, resulting in efficient and stable combustion. Thus, the efficiency of a diesel engine is influenced by the balance of nozzle size and injection pressure, not solely by the lowest fuel consumption.

The low thermal efficiency of Gas Power Plants (PLTG) due to exhaust gas heat loss drives the implementation of cogeneration at PLTGU Block II PT. PLN Indonesia Power UBP Semarang. This study analyzes the performance of the Gas Turbine Generator (GTG), combined cycle efficiency, and Exergy distribution using a 3-3-1 configuration. The research utilizes actual operational data from January 28, 2026, sampled at 10-minute intervals. Results indicate that cogeneration via a Heat Recovery Steam Generator (HRSG) significantly enhances plant efficiency. The GTG output ranged from 273–283 MW with an efficiency of 30.0–30.2%. Following combined cycle integration, system efficiency increased to 43.9–44.4%, a gain of approximately 14%, with a heat rate of 11,916–11,988 kJ/kWh. Exhaust heat of 665–713 MW was recovered to generate an additional 130 MW through the Steam Turbine Generator (STG). Exergy analysis reveals that the largest irreversibility occurs in the GTG combustion process (285 MW), followed by the HRSG (185 MW) and STG (49 MW).

Increasing in energy demand and limited fossil fuel reserves have driven the use of environmentally friendly alternative energy sources. This study aims to analyze the effect of pyrolysis temperature variations on the quality of biopellets made from bagasse and coffee husks. The materials were prepared in a 50:50 ratio with the addition of 15% tapioca flour as a binder. The pyrolysis process was carried out at temperatures of 450°C, 500°C, and 550°C for 120 minutes in oxygen-free conditions. The biochar resulting from pyrolysis was formed into biopellets, which were then tested for proximate composition, calorific value, and combustion rate. The results showed that an increase in pyrolysis temperature had a significant effect on the characteristics of the biopellets. A temperature of 550°C produced the lowest moisture content (8.436%), the highest fixed carbon content (62.191%), the highest calorific value (6293 cal/g), and the highest combustion rate (0.05789 g/sec). Conversely, ash content increased with rising temperature, while volatile matter content decreased. Thus, the best biopellets were obtained at a temperature of 550°C. This study confirms the potential of bagasse and coffee husks as raw materials for biopellets through pyrolysis temperature optimization to support the development of sustainable biomass energy.

This study aims to systematically evaluate the effect of Exhaust Gas Recirculation (EGR) variation on engine performance and exhaust emissions in dual-fuel diesel–CNG compression ignition engines, in response to increasing emission regulations and the need for cleaner yet practical combustion technologies. The research employs a comparative review approach, synthesizing experimental findings from selected peer-reviewed studies to analyze the influence of different EGR rates on key performance indicators, including Brake Thermal Efficiency (BTE) and Brake Specific Fuel Consumption (BSFC), as well as major emission components such as NOx, HC, CO, and smoke. The findings indicate that increasing EGR rates effectively reduce NOx and smoke emissions due to lower combustion temperatures and oxygen dilution; however, excessive EGR leads to deteriorated combustion efficiency, reflected in reduced BTE and increased HC and CO emissions. An intermediate EGR level, particularly around 10%, is consistently identified as providing the most favorable balance between emission reduction and performance retention in dual-fuel diesel–CNG operation. These results imply that optimized EGR control is a critical parameter for improving the environmental performance of dual-fuel engines without significant efficiency penalties, supporting its application as a transitional technology toward cleaner transportation systems. The originality of this study lies in its integrated comparative synthesis of performance–emission trade-offs across multiple EGR levels and fuel substitution ratios, offering a clearer operational insight that is not explicitly addressed in individual experimental studies.

Biomass is one of the materials that can be utilized as fuel. To ensure optimal quality, effective management of biomass is required to maximize its potential. One possible approach is the application of a biomass stove fueled by rubber wood pellets. By integrating a thermoelectric generator, data can be obtained to determine whether all aspects meet the established standards. This system is designed to generate electrical energy from combustion heat, supported by components such as a buck-boost converter and a 3V DC lamp. Testing was carried out using proximate and ultimate analyses on the fuel as well as the Water Boiling Test (WBT) on the stove, referring to SNI 8021:2020 and SNI 8021:2014 standards. The results showed that rubber wood pellets contained 7.64% moisture and had a calorific value of 4050 kcal/kg. The stove demonstrated an efficiency of 23.53%–37.28% and a fuel consumption rate of 0.61–0.77 kg/hour, both of which meet the requirements. In addition, the thermoelectric generator produced a voltage of 3.6 V and an electric current of 0.05 A, which are higher than those reported in previous studies (2.06 V and 0.01 A, respectively). Therefore, this thermoelectric biomass stove system is considered successful and feasible for further development as an alternative energy application.

Candlenut shell is an organic waste that has a hard texture and has a high carbon element. The amount of candlenut shell produced from each processing of candlenut seeds is very large but has not been optimally utilized. For this reason, an effort is needed to utilize candlenut shells so that they do not become waste. In the manufacture of hazelnut shell briquettes, hazelnut shells are carbonized at 500 °, sifted with mesh 30 and 100 sieves, given a compressive load of 3 kg, 4 kg, 5 kg and 5.5 kg, the adhesive on hazelnut shell briquettes is starch and drying is carried out with a drying oven for 3 hours at a temperature of 80 °. The purpose of this study was to determine the effect of variations in pressure and particle size on the quality of hazelnut shell briquettes when viewed from the combustion rate and calorific value. The methodology used in this research is experimentation on hazelnut shell briquettes, testing hazelnut shell briquettes including testing water content, testing ash content, burning rate and calorific value of briquettes. From the results of the research on hazelnut shell briquettes with variations in pressure and mesh, the highest calorific value in hazelnut shell raw material briquettes is in the 5.5 Kg pressure specimen on mesh 30, namely 9855.18 Cal/gram and the bomb calorimeter test results are 7008.03 Cal/gram with an error rate of 24.40%, the higher the pressure will produce a higher calorific value as well. The highest combustion rate value is in hazelnut shell briquettes at a pressure specimen of 3 Kg mesh 100 with a value of 1.2 grams/minute the smaller the particle size, the higher or faster the combustion rate.

Through this research there are two variables observed, namely the effect of variations in briquette charcoal pressure and specific heat value on the composition of carbonisation of hazelnut shell charcoal with tapioca adhesive on specific heat value. The initial process of research in the form of making charcoal on hazelnut shell briquettes, hazelnut shells are carbonised at 500 °, sieved with mesh 30 and 100 sieves, given a compressive load of 3 kg, 4 kg, 5 kg and 5.5 kg, the adhesive on hazelnut shell briquettes is starch and drying is carried out with a drying oven for 3 hours at a temperature of 80 °. The purpose of this study was to determine the effect of variations in pressure and particle size on the quality of hazelnut shell briquettes when viewed from the combustion rate and calorific value. The methodology used in the research is by using hazelnut shell briquette experiments, hazelnut shell briquette testing includes testing through hardness and briquette calorimeter bomb value. Through the research, it was found that the highest calorific value was in the 4 kg pressure specimen on mesh 30, namely 9221.09 cal/gram while the lowest combustion rate was produced by the hazelnut shell briquette specimen with a pressure of 5 kg and 5.5 kg, which was 4076.17 g/min. Giving different compressive loads and mesh sieves can provide advantages to briquettes including increasing specific calorific value, reducing water content and slowing the combustion rate

Background: The global energy transition requires low-carbon solutions that can be integrated into existing thermal systems without drastic infrastructure changes. Hydrogen blending in conventional combustion systems has emerged as a promising pathway to reduce carbon emissions while maintaining operational flexibility. Objective: This study aims to experimentally evaluate the effect of hydrogen blending ratios (0–100% by volume) on thermal efficiency, CO₂ emissions, and NOx emissions, and to determine the optimal blending range based on technical and economic feasibility. Methods: An experimental thermal system prototype was developed and tested under controlled conditions with three repetitions per operating point. Performance parameters included combustion temperature, fuel consumption rate, and thermal efficiency, while emissions of CO₂ and NOx were measured using a calibrated gas analyzer. Data were analyzed using descriptive statistics, one-way ANOVA at a 0.05 significance level, confidence interval estimation, and linear regression to examine the relationship between hydrogen fraction and emission reduction. Results: The findings indicate that increasing hydrogen fraction significantly improves thermal efficiency, reaching 87.5% at 100% hydrogen, while CO₂ emissions decrease linearly to zero. However, NOx emissions increase with higher hydrogen content due to elevated combustion temperatures. Statistical analysis confirms that hydrogen ratio has a significant effect on efficiency and emissions, with a strong linear correlation between hydrogen fraction and CO₂ reduction. A blending range of 40–60% hydrogen provides the most balanced performance in terms of efficiency improvement, emission reduction, and cost feasibility.

In motor vehicles, there is heat energy wasted from combustion in the combustion chamber. The temperature in a motorcycle engine has work, if it exceeds the ideal working temperature and is forced, it will be fatal. Because it will damage the cylinder wall components, pistons, and piston handlebars. The purpose of this study is to determine the effect of adding variations in exhaust wrap thickness on heat from exhaust headers and heat transfer rates. The research approach used is Quantitative, Experimental. The data collection method uses thermocouple test equipment and datalogger. The data obtained was processed into graph data and analyzed using the anova one-way method. The results showed that by adding a variety of coating cloth (exhaust wrap) to the exhaust header can reduce the temperature that comes out of the exhaust header where by coating 3 layers of exhaust wrap can reduce the most optimal heat and also reduce the heat transfer rate from testing for 1 minute, 2 minutes and 3 minutes with exhaust wrap of 17.99 J/s without exhaust wrap,  6.47 J/s 1 layer exhaust wrap and -28.10 J/s 3 layers exhuast wrap.