Boonrit Prasartkaew

Off-grid agricultural cold chains suffer from high energy conversion losses due to intermediate electrical stages in traditional refrigeration. This study addresses the lack of empirical quantification by comparing Direct Mechanical Drive (DMD) and Electrical Power Generation (EPG) drive trains for an R-134a vapor compression refrigeration system. Under steady-state conditions (randomized block design), DMD achieved a statistically significant 13.89% reduction in biomass consumption over EPG (1840.0 vs. 2136.7 g/h; p < 0.001). The biomass consumption was evaluated based on the measured charcoal mass flow under the same lower heating value basis. Conversely, refrigeration COP was statistically equivalent (2.74 vs. 2.73; p = 0.815), confirming that drive-train architecture does not alter internal vapor compression thermodynamics. Only 19.6% of the compressor shaft power appeared as useful fluid-side compression work under this fractional-load operating condition, a volumetric rather than mechanical deficiency arising from operation at 7.7–15.5% of the compressor’s rated capacity. Referenced consistently to the primary biomass chemical energy input, the First-Law biomass-to-cooling system efficiency was 3.66% (equivalent to 5.34% when referenced to the syngas delivered to the engine), with a corresponding biomass-referenced exergy efficiency of 0.44%. Component exergy analysis revealed that the internal combustion engine (59.13% of total exergy destruction, ε = 13.1%) and the gasifier (32.4%, ε = 67.7%) dominated total system exergy destruction (15.49 kW). Furthermore, a 10-year life-cycle cost (LCC) analysis indicates DMD-Syngas yields net present value savings of 21,071.57 USD over gasoline-EPG, yielding a 0.14-year (~50-day) simple payback period on the 400.12 USD net incremental hardware capital cost (the gasification subsystem less the alternator–motor drive train that the direct-drive configuration does not require, and excluding one-time installation and training costs). When the fully installed cost is accounted for—including site preparation, process-water supply and effluent handling, low-voltage provision, installation labor, operator training and contingency—the incremental investment rises to 1298–2405 USD and the payback period extends to approximately 162–301 days. Under the least favorable combination examined, in which commercially purchased charcoal is imposed simultaneously with the upper installed-cost bound, capital recovery extends to approximately 1.4 years; the base case nevertheless recovers the incremental investment within the first operating year. An operational-phase (gate-to-gate) carbon assessment indicates near parity with the gasoline baseline on a strictly attributional basis (+120 to +1200 kg CO₂e yr⁻¹); a net saving of 8880–13,320 kg CO₂e yr⁻¹ arises only under the consequential scenario in which open-field burning of orchard residues is displaced and is further contingent on including black carbon in the accounting basket. This is not a full ISO 14040/44 life-cycle assessment, and the environmental outcome is therefore scenario-dependent rather than intrinsic to fuel substitution. These results demonstrate that mechanical drive-train optimization substantially enhances fuel economy without compromising refrigeration performance, providing a rigorous evidence base for scalable biomass-powered off-grid cold chains.

The energy efficiency of a floating photovoltaic (FPV) system with a single azimuth-axis sun tracking mechanism is examined in this work. Installing FPV systems over water surfaces has several advantages, including easier rotation along a vertical axis, land conservation, and increased energy efficiency because of the water's natural cooling effect. Floating PV with Single-Axis Tracking (FPVSAT) is a novel feature of simple tracking for FPV that was proposed in this study. Since most conventional horizontal-axis tracking systems revolve around the horizontal N-S axis, single-axis trackers that spin around the vertical axis are somewhat unusual. The PV panels can follow the sun's azimuthal direction all day long the vertical-axis tracking design, which maximizes solar energy capture while preserving mechanical simplicity appropriate for floating buildings. Using experimental data from a prototype installed in Lop Buri, Thailand, a mathematical model was created and verified. We compared fixed, linear tracking, and vertical-axis azimuth tracking setups using simulations with high-resolution meteorological data. The azimuth tracking arrangement produces the maximum energy production, according to the results, highlighting the promise of vertical-axis tracking FPV systems as an affordable and scalable substitute for optimizing solar energy generation, especially in tropical areas with fluctuating sun patterns.

This study evaluates the performance of floating photovoltaic (FPV) systems integrated with single-axis solar tracking (FPVSAT) as an innovative approach to enhancing solar energy capture. By utilizing water bodies for solar installations, FPV systems offer a dual benefit of land conservation and improved energy efficiency due to the cooling effect of the water surface. The incorporation of single-axis solar tracking further optimizes energy generation by dynamically adjusting the panels’ orientation to follow the sun's trajectory. To analyze the system, a mathematical model was developed and validated against experimental results obtained from an FPVSAT prototype tested in Mueang District, Lop Buri, Thailand. Simulations were performed using five-minute interval weather data, with comparisons made between fixed, linear tracking, and azimuth tracking configurations. The results demonstrate that single-axis tracking systems significantly enhance solar energy yield compared to fixed installations, with the azimuth tracking configuration providing the highest efficiency. The study highlights the importance of integrating solar tracking mechanisms into FPV systems, particularly in regions with variable solar conditions, to achieve sustainable energy generation. These findings underscore the potential of FPVSAT technology as a cost-effective and efficient alternative to traditional land-based PV systems.

Remote areas that are not within the maximum breakeven grid extension distance limit will not be economical or feasible for grid connections to provide electrical power to the community (remote area). An integrated autonomous sustainable energy system is a feasible option. We worked on a novel multi optimization electrical energy assessment/power management system of a microgrid network that adopted combined dispatch, load-following, and cycle-charging strategies (control system) that acted as a power interface module over the hybrid configuration of energy sources (grid network/downdraft biomass generator/solar photovoltaic), thermal load controller-boiler systems, and hybrid energy-storage technologies (lithium, iron flow, sodium sulfur, and flywheel) to enable the microgrid network to operate in the island (off grid), grid, and island-able (ability to isolate itself when it is connected to the grid network) modes efficiently and effectively. An optimal multitask control algorithm and the storage units of modeled power generation sources were executed with the HOMER software application to improve the energy system’s efficiency, promote effective storage management, minimize energy loss, and improve the lifespan of the microgrid network. The integrated energy system can work for both rural and urban areas.

The objective of this study is to evaluate the thermal efficiency of a concentrated solar collector for a high temperature air heating system. The proposed system consists of a 25-m² focused multi-flat-mirror solar heliostat equipped with a porous medium solar collector/receiver which was installed on the top of a 3-m tower, called 'tower receiver'. To know how the system efficiency cloud be improved by using porous medium, the proposed system with and without porous medium were tested and the comparative study was performed. The experimental results reveal that, for the proposed system, application of porous medium is promising, the efficiency can be increased about 2 times compared to the conventional one. In addition, due to the porous medium used in this study was the waste material with very low cost. It can be summarized that the substantial efficiency improvement with very low investment cost of the proposed system seem to be a vital measures for addressing the energy issues.

This experimental study aims at investigating on the performance of a high temperature solar water heating system. To approach the high temperature, a porous-medium concentrated solar collector equipped with a focused solar heliostat were proposed. The proposed system comprised of two parts: a 0.7x0.7-m² porous medium receiver, was installed on a 3-m tower, and a focused multi-flat-mirror solar heliostat with 25-m² aperture area. The porous medium used in this study was the metal swarf or metal waste from lathing process. To know how the system efficiency could be improved by using such porous medium, the proposed system with- and without-porous medium were tested and the comparative study was performed. The experimental results show that, using porous medium for enhancing the heat transfer mechanism, the system thermal efficiency was increased about 25%. It can be concluded that the efficiency of the proposed system can be substantially improved by using the porous medium.