Papers by Keyword: Thermal Efficiency

Abstract: This study presents an in-depth analysis of heat loss mechanisms in a rotary kiln system used for biomass torrefaction, with briquetted biomass fuel serving as the primary thermal energy source. The study evaluates five principal heat loss pathways: wall heat loss, exhaust gas heat loss, hydrogen-related heat loss, moisture evaporation, and heat loss due to incomplete combustion. Experimental tests were conducted at three torrefaction temperatures (230°C, 250°C, and 270°C), and thermal energy losses were quantified through temperature measurements, energy balance equations, and gas composition analysis. Results indicate that while absolute heat loss values increased with higher torrefaction temperatures due to elevated energy input and system load, the percentage of heat loss relative to total input decreased, improving net thermal efficiency. Wall heat loss was the dominant component across all conditions but declined in percentage terms from 80.5% to 30.9% as temperature increased. The reuse of exhaust gas for drying briquetted biomass was also investigated, demonstrating that waste heat recovery significantly reduces drying time—from 19 hours at 230°C to 13 hours at 270°C—without compromising fuel integrity. These findings confirm that integrating exhaust gas utilization into the torrefaction process enhances energy efficiency, supports continuous operation, and reduces external energy demand, offering a viable strategy for sustainable biomass fuel processing at an industrial scale. The findings provide design guidance for integrating heat recovery into industrial-scale biomass torrefaction systems.

Abstract: This research investigates the effective moisture diffusivity (D_eff) and energy activation (E_a) as it affects thin layer drying of white yam (Dioscorea rotundata) slices using hybrid drying system under different parameters. These factors helps researchers and food producers to develop optimized drying processes for yam slices in order to minimize drying time, improve energy efficiency, and maintain high product quality. The experimental analysis highlight the interplay between pretreatments (Blanching, B; Sodium metabisulfite, SNa; Neem bark extract, SNBE and Control, C), drying systems (indirect solar drying: ISD and solar-powered hot-air supplemented drying: SPHSD under 0.8 m/s and 1.2 m/s air velocity, and air temperatures of 50 °C, 60 °C, and 70 °C) and slice thickness (5 and 3 mm) on white yam slices during drying. Important data were obtained using Arduino based data logging system for accuracy. Mass transfer during the entire drying of the yam slices took place entirely in the falling drying rate period and was described using Fourier approach based on Fick’s second equation of diffusion. The result demonstrated that D_eff and E_a is significantly affected by petreatment, slice thicknesses, air velocity and drying system. D_eff increased with rising drying temperature and air velocity. However, SPHSD, at 5 mm thickness exhibited a decrease in D_eff compared to 3 mm with values ranging from 1.647 × 10^-10 to 2.790 × 10^-10 m²/s within the investigated parameters. In contrast, ISD and sun-dried yam slices displayed relatively lower and fluctuating D_eff values (not higher than 1.4 × 10^-10), likely due to intermittency in solar radiation. Specific energy consumption varies from 6184.373 J/kg.K to 4620.571 J/kg.K for different thicknesses, temperature and air velocity. Thermal efficiency values which decreases with increased slice thickness ranges from 52.539 % to 39.347 %. Drying efficiency increases with increased temperature and air velocity for SPHSD (87.020 % to 93.169 %) while ISD has the least at 54.196 %.

Abstract: In a hot and dry climate country, performance of a gas turbine power cycle is low. Incorporation of a regenerator in the cycle and a spray cooler before compression of inlet air enhances its performance. Accordingly, this study focuses on the effect of regeneration and cooling of the inlet air on performance of an open cycle gas turbine plant, which mainly includes improvement in its thermal efficiency and reduction in specific fuel consumption. In this context, a suitable mathematical model is developed on the basis of fundamental understanding of thermodynamics and gas turbine relations. This model is then used in simulations by developing a code on Java platform where ambient temperature, pressure ratio and regenerator effectiveness are considered as major system parameters. In the simulation, a comparison among a simple Brayton cycle, a regenerative cycle and a regenerative cycle with spray cooler is considered under different system parameters. It is predicted that there is a significant increase in thermal efficiency and a significant decrease in specific fuel consumption on incorporation of regenerator and spray cooler to the cycle. However, addition of a spray cooler is applicable above an optimal pressure ratio (≈6) and in the high temperature environmental condition. As an example, 12.89% increase in thermal efficiency is found at a regenerator effectiveness of 0.85 on addition of spray cooler before compression of inlet air at an ambient temperature of 328K, and subsequent reduction in specific fuel consumption is found as 2.85% at pressure ratio of 10.

Abstract: In this study, we perceived the thermo-physical boundary and the thermal efficiency of zinc oxide for volume fraction in polylactic acid based on a heat energy storage system was examined by using the T-history method. The use of the T-history method for the assessment of thermo-physical boundary describes the specific heat capacity and thermal conductivity enhanced in solid as well as liquid phases of the mixture until the addition of 0 to 0.025% of volume part of zinc oxide in the polylactic acid nanocomposite. After the addition of the zinc oxide, the heat of fusion falls and polylactic acid has a high rate of fusion related to 0.025% volume part of zinc oxide mixed with polylactic acid. Further zinc oxide-based polylactic acid nanocomposite has 31.30% and 13.5% higher solid as well as liquid thermal conductivity in comparison with polylactic acid. Moreover, raise the particle size and analysis as well as distributions found by dynamic light dispersing method for different volume parts of zinc oxide mixed on polylactic acid. In contrast to the thermal efficiency analysis of 0.025% of volume fraction zinc oxide in polylactic acid nanocomposite has a 30.6% high heat transfer rate related to pure polylactic acid along the stage of 4 minutes. Further, the addition of zinc oxide above 0.025% volume fraction in polylactic acid, rise the particle settlement rate freely. Whatever can become to end that 0.025% volume fraction of zinc oxide in polylactic acid mixed thermal energy storage arrangement outcome of maximum thermo physical property and thermal efficiency.

Abstract: Blanching is an important stage of post harvesting processing of turmeric, which destroys the viability of the fresh rhizomes and eliminates the raw odor. Large amount of crop residue and wood is consumed during conventional turmeric boiling process. Solar-based turmeric blanching system had been developed to show the viability of concentrated solar power for agricultural produce processing and contribute to CO₂ mitigation. Experiments were conducted for several days in the month of April 2019, to study the performance of 16-m² Scheffler concentrator for turmeric blanching. Turmeric was blanched in batches of 10 kg. Average 110 kg turmeric was successfully processed in a day. From the experimental data analysis, it is perceived that the thermal performance of the system directly depends on beam radiation. Average efficiency of 19.35 % was achieved with average beam radiation 721 W/m². Minimum blanching time was found as 27 minutes with an average steam flow rate 5.30 kg/hr. Power available at reflector, receiver, and blanching vessel is presented to identify energy losses at each component of blanching system.

Abstract: Worldwide, natural fiber insulation is in high demand, offering not only thermal comfort but also soundproofing. Another important aspect for which these biodegradable materials is popular is that it presents no health risk. Due the soft texture, natural fibers can be introduced very simply in any type of construction. Regardless of the vertical or inclined mounting, the stapling or gluing of the material gives stability. For example, the wool insulation is made from natural fibers, washed and treated. These wool fibers are held together either mechanically or using up to 12% polyester fibers to form semi-rigid tiles/mattresses or rollers. With a higher price than mineral wool, natural insulation is ideal for eco-friendly wooden houses. Depending on the type of construction, the wool can be mounted in a single layer or several layers, of different thicknesses [1]. For the evaluation of the thermal efficiency of the wool panel’s insulation four variants of insulating panels based on 100% wool were accomplished. Using a specialized simulation program, it is found that the heat losses through the walls themselves represent 86% of the total heat loss and the heat losses through the windows/doors to the outside represent 14% of the total heat losses.

Abstract: The main purpose of this work is to evaluate the influence of the thickness and thermophysical properties of insulating materials on the maximum external surface temperature and energy gain provided for an intermittent ceramic kiln operating with natural gas as fuel. To evaluate the influence of independent variables on response variables, a factorial experimental design was developed. From the analysis of variance (ANOVA), it was possible to determine significant and well-adjusted mathematical models for both response variables. It was verified that the thickness and thermal conductivity of thermal insulation are the independent variables that have the greatest influence on the process efficiency.

Abstract: Several important key problems and issues remain to be addressed about the numerical analysis of friction stir welding. The main feature of the thermal numerical approach is to accurately compute the thermal distribution produced by the friction between the plate and the tool. It is well known that the downward force applied from the tool creates a distributed pressure between the shoulder and the workpiece. Based on this, a new expression to represent the heat generation in FSW is proposed. Results of thermal cycles, thermal histories, and shapes of the weld and HAZ obtained with the proposed expression in SAE-AISI 1524 carbon steel are presented. Results demonstrate that the energy input is strongly dependent on the tool advance speed, rotational speed, and the axial pressure necessary to produce yielding. For instance, at a constant increase in axial pressure, lower peak temperature increments are produced when higher tool advance speeds are chosen. The mathematical modeling has been investigated with a view to generate numerical data to provide values for further assessment and experimental comparison.

Abstract: The paper presents a developed method for assessment of gas distribution over the cross section of a shaft furnace working in the countercurrent conditions. This method is scientifically based on the fundamental principles of the countercurrent heat exchange theory in shaft furnaces, i.e. dependences of the temperature field throughout the burden bed height on the ratio between heat capacities of gas and burden flows. The ratio between the gas flow heat capacity and burden flow heat capacity at the stock line level is determined by the averaged gas temperature at the burden bed output. By comparing these data, we estimated directions for improving the gas distributing system. Efficiency of this method was assessed when analyzing the system of air supply to the shaft furnace at one of the Ural plants. The analysis showed the main drawbacks of the existing gas distributing system and enabled to determine the main directions for reconstruction of this system. On the basis of the analysis results related to operation of the tuyeres and distribution manifold, we proposed more efficient options of their parameters, i.e. manifold cross-section area, tuyere number and diameter, angle of tuyere inclination to the horizontal. These changes provided a uniform distribution of gases across the furnace and improved conditions for melt flow in the furnace. Thus, we established virtually equal conditions for development of heat and mass transfer processes in the work space of the shaft furnace. The modernized system of air supply to MMSK’s shaft furnace increased the furnace performance by 14.14% in terms of burden, by 23.27% in terms of matte, by 15.15% in terms of slag and by 6.65% in terms of thermal efficiency. At the same time, the following parameters were reduced: specific fuel consumption (anthracite) by 17.46% and dust discharge by 40.5%. When supplying air to the furnace through the inclined tuyeres, it became possible to reduce formation of accretions and provide new working conditions for operating personnel due to a more uniform gas distribution across the horizontal section of the furnace. Within six months of furnace operation the personnel had no problems related to its operation.

Abstract: The aim of this research was to find a way to reduce energy costs by using thermal image techniques for investigating the thermal efficiency of ceramic furnaces. The case study was “Ban Nam Jo Ceramic”. The researchers collected the information by performing an in-depth interview at the research area, collecting preliminary data and using the thermal camera in the technical analysis part. The researchers also measured the temperature and volume of gas in the furnace. After that, those data were used to calculate the energy balance and the thermal efficiency of ceramic kilns. The data showed that the first measured furnace had calculated thermal efficiency of 9.99%. After the maintenance, the thermal efficiency increased to 16.64%. Furthermore, the volume of liquid petroleum gas decreased by 40%, and the damage in products after firing decreased by 3 %.