This study combines experimental and theoretical approaches to investigate steady-state, multi-dimensional heat conduction in polymeric fins. Surface temperature fields are measured using infrared thermography, while a normalized two-dimensional heat conduction model is developed and solved via integral transform techniques. Two base boundary conditions - prescribed temperature (Dirichlet) and prescribed heat flux (Neumann) - are analyzed to evaluate their impact on thermal behavior and parameter estimation. The Biot number is estimated using two approaches: (1) an inverse problem solved with the Levenberg-Marquardt (LM) algorithm and (2) a machine learning model based on Gradient Boosted Trees (GBT). Synthetic data generated from the forward model serve as the training set for the GBT approach, aligning with Problem-Informed Machine Learning (PIML) methodologies. Both approaches are then employed to estimate the convective heat transfer coefficient, while the material's thermal conductivity is experimentally measured using a Heat Flow Meter (FOX 50). Results indicate that the LM method provides interpretability and strong performance when sensitivity is adequate and regularization is applied, while the GBT demonstrates greater robustness in nonlinear regimes and with ample training data.

Hop essential oil (EO) play a key role in beer aroma and quality control. In this study, a simplified hydrodistillation method for hop EO extraction using a Box-Behnken design was optimized, varying hop mass, water volume and distillation time. Terpenes-myrcene, beta-caryophyllene and beta-farnesene-were quantified by GC-MS. Initial results demonstrated that EO yield increased with lower hop mass and longer distillation time, while myrcene extraction was favored by shorter times. Optimal conditions (0.9 g hops, 75 mL water, 60 min) were applied to extract and qualitatively analyze EOs from Polaris, Perle, Ariana, and Hallertauer Magnum hops. Perle and Magnum exhibited typical terpene profiles but elevated beta-farnesene levels and distinctive minor compounds. Ariana exhibited weak terpene signals but revealed uncommon esters. Overall, the method proved effective and resource-efficient, providing a practical tool for terpene profiling in underexplored hop varieties and supporting aroma characterization in the brewing industry.

This paper investigates the sensitivity of heat transfer and fluid flow to geometric uncertainties caused by roughness in microchannels. The study considers laminar, fully developed slip flow and temperature jump conditions in the momentum and energy equations, controlled by velocity slip (A) and temperature jump (AT) parameters, under traditional H1 and H2 heating conditions. Microchannels with nominally circular geometries are analyzed, incorporating random boundary variations defined by a roughness parameter, Sr & lowast; max. These variations generate unique geometries for each Sr & lowast;max, grouped into samples for numerical simulation and statistical analysis. The analysis shows that for every configuration, a normal distribution of Poiseuille and Nusselt numbers values is obtained for each Sr & lowast;max. An examination of the median and standard deviation of each sample reveals that increasing Sr & lowast; max leads to higher Poiseuille numbers and lower Nusselt numbers, indicating greater pressure drop and reduced heat transfer, respectively. The influence of slip length and temperature jump parameters was also assessed, revealing that while higher A values reduce the friction factor, these cases are more impacted by roughness. Conversely, although an increase in AT significantly reduces the Nusselt number due to added thermal resistance, cases with lower AT are more sensitive to roughness effects.

Radiation shields were specifically designed for tubes with polymeric patches in flare stacks and experimentally evaluated, as no studies have addressed the performance of radiation shields under low-to-moderate fluxes. The experimental apparatus consists of a lidless chamber wherein a tube with the patch is installed, while different configurations of shields are installed on its surface. Two heaters are positioned at the top of the chamber to simulate the heat flux from the flare. Thermocouples are placed on the internal surface of the tube, as well as on the shields and in the surrounding air to monitor the temperatures. Results indicate that a single shield encompassing the entire upper portion of the tube significantly reduces patch temperature, with marginal improvement when additional shields are used. Furthermore, perforated shields enhance convective heat transfer but fail to compensate for the increased exposure to radiation. Shields that allow more direct radiation to reach the tube resulted in overheating the patch due to heat conduction. An aged shield was tested, providing significantly less protection for the patch in comparison with clean shields. Finally, models are proposed and compared with experimental data, indicating that a 180 degrees shield is advantageous to maintain patch temperature within admissible limits.

This paper is aimed at analysing the effects of roughness caused by random geometric uncertainties in microchannels and how these can influence heat transfer and pressure drop in fluid flow within such geometries. The shape of a microchannel is typically affected by significant uncertainty due to the small size of the cross-section, which is comparable to the typical wall-roughness length scale. While this uncertainty exists at any scale, it becomes amplified and critically important when the hydraulic diameter is smaller than a few tens of micrometer. The analysis is performed numerically, considering a nominally circular channel with random variations in its cross-section within a prefixed maximum extent, effectively representing roughness at the micro-scale. The adopted mathematical model considers fully developed heat and fluid flow by taking into account the effect of viscous dissipation and an irregular cross-section is generated by random geometric variations. The effects of an increasing wall roughness generally lead to an increase in the Fanning friction factor and a decrease in the wall heat transfer rate, as expressed by the Nusselt number.

The role of wall roughness in heat and mass transfer for fully developed viscous flows in square microchannels is investigated here. Since the roughness, which is the key geometrical feature to be investigated, introduces high velocity gradients at the wall, the effect of the viscous dissipation is considered. A fully developed flow in the forced convection regime is assumed. This assumption allows the two-dimensional treatment of the problem; thus, the velocity and temperature fields are simulated on the microchannel cross-section. The boundary roughness is modeled by randomly throwing points around the nominal square cross-section perimeter and by connecting those points to generate a simple polygon. This modification of the nominal square shape of the cross-section influences the velocity and temperature fields, which are computed by employing a finite element method solver. The heat and mass transfer is studied by calculating the Nusselt and the Poiseuille numbers as a function of roughness amplitude at the boundary. Each Nusselt and Poiseuille number is obtained by employing an averaging procedure over a sample of a thousand cases.

This work assesses the possible uses of a byproduct derived from oil sludge and palm kernel shell waste co-gasification. The thermochemical conversion process was performed in a reverse downdraft gasifier, varying the airflow from 30 to 60 L/min to produce four char samples (F30, F40, F50, and F60). The char chemical composition was determined by proximate and ultimate analyses, higher heating value, and x-ray fluorescence (XRF). Scanning electron microscopy (SEM) and Brunauer, Emmett, and Taller (BET) surface area techniques were utilized to evaluate the char’s physical structure. The results indicated that the char samples had a high carbon (40.37 to 53.33

The world’s energy demand increases daily, fostering the search for renewable fuels to reconcile production needs with environmental sustainability. To prevent the severe atmospheric impact of fossil fuels, reducing greenhouse gas emissions is both essential and urgent, reinforcing the necessity of developing and adopting renewable fuel alternatives. Therefore, this work aimed to produce bio-oil through sugarcane bagasse fast pyrolysis. The methodology is based on fast pyrolysis operation in a fluidized bed reactor (pilot plant) as a thermochemical method for bio-oil production. This research required the conditioning of the raw material for system feeding, along with optimizing key variables, operating temperature, airflow, and sugarcane bagasse feed rate, to achieve improved yields compared to previous studies conducted in this pilot plant. The sugarcane bagasse was conditioned through drying and milling, followed by characterization using various analytical methods, including calorific value, thermogravimetric analysis (TGA), particle size analysis by laser diffraction (Mastersizer—MS), and ultimate analysis (determining carbon, hydrogen, nitrogen, sulfur, and oxygen by difference). The bio-oil produced showed promising yield results, with a maximum estimated value of 61.64%. Fourier Transform Infrared Spectroscopy (FT-IR) analysis confirmed the presence of aromatic compounds, as well as ester, ether, carboxylic acid, ketone, and alcohol functional groups.

A capillary electrophoresis method was used to analyze the fermentable sugar distributions during barley mashing. Eight worts, prepared with pilsner malt, were mashed at controlled isothermal temperatures (61-75 degrees C) using an Arduino-monitored heating mantle. Samples were collected every 10 min over 90 min. Phthalic acid enabled indirect electrophoretic carbohydrate detection. Maltose production was favored at 61-67 degrees C, while 71-75 degrees C promoted maltotriose and glucose formation, aligning with alpha- and beta-amylase activity. Maltose concentration dropped by 18.2% above 75 degrees C compared to 61 degrees C. Principal component analysis grouped samples by mashing time, indicating enzyme activity patterns. Enzyme-specific activities were inferred: limit dextrinase (61 degrees C), beta-amylase (61-67 degrees C), and alpha-amylase (65-75 degrees C). The method outperformed a reference technique, offering greener, more efficient sample preparation while accurately quantifying five fermentable carbohydrates. Findings aid brewing optimization by enhancing recipe development, yeast selection, and temperature control for improved beer production.

A consistent non-dimensional lumped-capacitance formulation for heat and mass transfer in alcoholic fermentation has been developed. The formulation stems from a generalization of previous dimensional models, written for an arbitrary number of fermentable species. A comprehensive dimensional analysis of the problem was performed, leading to a concise — and physically meaningful — set of dimensionless groups associated with the occurring physical and chemical phenomena, as well as a set of normalized governing equations. Numerical solutions for the normalized formulations were implemented for both isothermal and non-isothermal fermentation cases, and the results were verified by comparing with experimental data from previous studies. Finally, a parametric analysis was conducted for illustrating the effect of the proposed parameters on the solution of the problem. This analysis was presented for isothermal fermentation – demonstrating the effects of the dimensionless groups related to the Michaelis–Menten kinetics and the inoculation ratios – and for non-isothermal fermentation, demonstrating the effect of the heat transfer coefficient on the fermentation process.

Novel desiccant-assisted systems have been evaluated for reducing the work required in multistage air compression processes. While traditional inter-cooling is generally achieved by placing heat exchangers between compression stages, the systems herein proposed are based on harvesting heat rejection to drive a desiccant cooling system. This cooling effect is then used to cool the air between the compression stages below ambient temperature, and also to pre-cool the air prior admission to the first stage, allowing for a reduction of the compression work. In addition, desiccant dehumidification is also used to control the humidity of the air in the compression system. A model based on steady-state heat and mass transfer balances across all components is presented and computationally implemented for a two-stage compression system. Numerical results are analyzed in terms of a performance factor, showing that some configurations can achieve a reduction in compression work almost 60% greater than that achieved with conventional inter-cooling systems. A final test-case was also presented, based on inlet conditions extracted from weather data of Rio de Janeiro, Brazil, demonstrating that the proposed compression schemes could be used as a viable option for reducing compression work in multi-stage systems. The use of a waste-heat-driven desiccant-assisted system for reducing compression work and controlling humidity, is an important addition to applications of desiccant cooling.

This study examines the performance of a system that integrates solar collectors, a latent heat thermal energy storage system (LHTS) based on phase change material (PCM), and an organic Rankine cycle for power generation. Evacuated tube collectors with a total area of 212.4 m(2) were utilized to harvest solar energy, and packed beds of encapsulated PCM, each with a nominal volume of 3.4 m(3), were proposed as the LHTS. The integrated system maintains a nominal power generation target of 1.4 kW. Numerical models were verified and validated with data from similar systems found in the literature. Performance metrics, including net power generation, operating time, stored energy, and system efficiency, were evaluated under favorable conditions for a selected summer week, and under unfavorable conditions for a chosen winter week. The results indicate that the use of PCM can extend the system's operating time by 7-8 h during the summer week, and 5-6 h during the winter week, with a power output variation of up to 10 % throughout the central core of the operational period. Remarkably, the use of PCM allows this extension of operating hours with an efficiency reduction of up to 0.1 % irrespective of seasonal conditions.

This work evaluates the impact of air renewal on energy consumption for indoor environments. For this purpose, an analysis of the problem of air renewal at a Brazilian level was carried out, as well as research into the energy impact of air renewal without energy recovery and the different existing technologies for recovering energy from renewed air. On the other hand, the influence of heat-recovery systems was analyzed in three Brazilian cities (Manaus, São Paulo, and Brasília) for different environments, where a classroom in Manaus has an approximately 50% external air factor and a 42% sensible heat factor. However, classrooms in São Paulo and Brasília have a lower external air factor (27% and 8%, respectively) and a higher sensible heat factor (61% and 78%, respectively). Considering a system with heat recovery, the external air factor decreases to 23%, 10%, and 3% for Manaus, São Paulo, and Brasília, respectively. This allows us to understand the influence of heat-recovery systems, which reduce the external air factor and increase the sensible heat factor.