The main objective is to assess effectiveness of continuous solar dryer integrated with desiccant thermal storage for drying cocoa beans. Two type of desiccants were tested, molecular sieve 13× (Na86 [(AlO2)86·(SiO2)106]·264H2O) as an adsorbent type and CaCl2 as an absorbent type. The results revealed that during sunshine hours, the maximum temperature within the drying chamber varied from 40 °C to 54 °C. In average, it was 9–12 °C higher than ambient temperature. These temperatures are very suitable for drying cocoa beans. During off-sunshine hours, humidity of air inside the drying chamber was lower than ambient because of the desiccant thermal storage. Drying times for intermittent directs sun drying, solar dryer integrated with adsorbent, and solar dryer integrated with absorbent were 55 h, 41 h, and 30 h, respectively. Specific energy consumptions for direct sun drying, solar dryer integrated with adsorbent, and solar dryer integrated with absorber were 60.4 MJ/kg moist, 18.94 MJ/kg moist, and 13.29 MJ/kg moist, respectively. The main conclusion can be drawn here is that a solar dryer integrated with desiccant thermal storage makes drying using solar energy more effective in term of drying time and specific energy consumption

A small compression ignition (CI) engine with a rated power of 4.41 kW has been tested in dual-fuel (diesel-biogas) mode without any significant modification. The objectives are to explore the effects of biogas flow rate and methane concentration on the performance and emissions of the CI engine run in dual-fuel mode. The experiments have been carried out at engine load and speed vary from 1000 rpm to 1500 rpm and 600 W to 1500 W, respectively. The results show that the output power and specific fuel consumption of the CI engine run in dual-fuel mode are higher than the CI engine run in pure diesel mode. Brake thermal efficiency of the CI engine run in dual-fuel mode strongly affected by biogas flow rate and methane concentration. There exists an optimum biogas flow rate for a maximum brake thermal efficiency. The biogas can reduce the diesel fuel consumption significantly. In the present CI engine, diesel replacement ratio varies from 15.3% to 87.5%. At engine load and speed of 1500 W and 1500 rpm, to get maximum efficiency, the present CI engine should be operated at biogas energy ratios of 15% and 18% using biogas with 60% and 70% methane concentrations, respectively

In the present work characteristics and performance of a natural vacuum desalination system using low grade heat source is studied numerically and experimentally. In the numerical work, a program to solve the governing equations in forward time step marching technique is developed. In the experimental work a lab scale natural vacuum system using electric heater as a heat source is designed and tested. The surface area of seawater in the evaporator is 0.5m. The numerical and experimental results show a good agreement. By using numerical simulations effect operating conditions such as heat source temperature, condenser temperature, heating coil surface area, and the present of heat recovery unit are explored. The simulation showed that, the present system with evaporator surface area of 0.2m2, operation time of 9h and source temperature of 80°C will produce 6.63L of fresh water ant thermal efficiency is 70.4%. The main conclusion can be drawn here is that the performance of the natural vacuum desalination system is mainly affected by maximum temperature in evaporator and minimum temperature in condenser. On the other hand, the surface area of heating coil and the heat recovery unit showed only a small effect

Typical adsorbent applied in solar-powered adsorption refrigeration cycle is activated carbon. It is known that activated alumina shows a higher adsorption capacity when it is tested in the laboratory using a constant radiation heat flux. In this study, solar-powered adsorption refrigeration cycle with generator filled by different adsorbents has been tested by exposing to solar radiation in Medan city of Indonesia. The generator is heated using a flat-plate type solar collector with a dimension of 0.5m×0.5m. Four cases experiments of solar-powered adsorption cycle were carried out, they are with generator filled by 100% activated alumina (named as 100AA), by a mixed of 75% activated alumina and 25% activated carbon (75AA), by a mixed of 25% activated alumina and 75% activated carbon (25AA), and filled by 100% activated carbon. Each case was tested for three days. The temperature and pressure history and the performance have been presented and analyzed. The results show that the average COP of 100AA, 75AA, 25AA, and 100AC is 0.054, 0.056, 0.06, and 0.074, respectively. The main conclusion can be drawn is that for Indonesian condition and flat-plate type solar collector the pair of activated carbon and methanol is the better than activated alumina

The oil palm (Elaeis guineensis Jacq.) represents Indonesian major agriculture crop, nevertheless, its cultivation and processing results in an excessive amount of waste biomass, namely, empty fruit bunches (EFB), which is not always properly processed or reused. Therefore, the present investigation was performed to attract wide public interest in proper waste management and reuse of waste biomass. The suitability of such waste biomass for bio-pellet fuel production within its ecological EFB reuse was the subject of investigation. Its fuel parameters, mechanical quality and microscopic analysis represented the set of experimental testing performed within the target purpose. Satisfactory result values were stated within oil palm EFB fuel parameters, namely, moisture content M_c—7.07%, ash content A_c—9.41% and energy potential NCV—15.06 MJ∙kg⁻¹. Mechanical analysis of the produced bio-pellet fuel proved outstanding results: Volume density ρ—1440.01 kg∙m⁻³ and mechanical durability DU—97.4% and 99.4% (according to ÖNORM M 7135 (2003) and ISO 17831-1 (2015)). Furthermore, results of compressive strength σ proved the requested high level; in simple pressure σ_p—10.83 MPa and in cleft σ_c—60.46 N·mm⁻¹. Stereoscopic microscope measurements proved a prevalent proportion of fiber >97% within the feedstock content, and scanning electron microscopy (SEM) of bio-pellet samples diagnosed cracks purely on the outer surface, not within their internal structures, which indicated high quality compacted products. In conclusion, the overall evaluation indicates the production of environmental-friendly high quality bio-pellet fuel, thus, proving the suitability of oil palm EFB for the production of bio-pellet fuel.