Constant Temperature Conditions Research Articles

Heat Transfer Enhancement of Finned Copper Foam/Paraffin Composite Phase Change Material

Background: The employment of Phase Change Materials (PCMs) provides a potential selection for heat dissipation and energy storage. The main reason that hinders the wide application is the low thermal conductivity of PCMs. Combining the proper metal fin and copper foam, the fin/composite phase change material (Fin-CPCM) structure with good performance could be obtained. However, the flow resistance of liquid paraffin among the porous structure has seldom been reported, which will significantly affect the thermal performance inside the metal foam. Furthermore, the presence of porous metal foam is primarily helpful for enhancing the heat transfer process from the bottom heat source. The heat transfer rate is slow due to the one-dimensional heat transfer from the bottom. It should be beneficial for improving the heat transfer performance by adding external fins. Therefore, in the present study, a modified structure by combining the metal fin and copper foam is proposed to further accelerate the melting process and improve the temperature uniformity of the composite. Objective: The purpose of this study is to research the differences in the heat transfer performance among pure paraffin, Composite Phase Change Materials (CPCM) and fin/Composite Phase Change Material (Fin-CPCM) under different heating conditions, and the flow resistance of melting paraffin in copper foam. Methods: To experimentally research the differences in the heat transfer performance among pure paraffin, CPCM and Fin-CPCM under different heating conditions, a visual experimental platform was set up, and the flow resistance of melting paraffin in copper foam was also analyzed. In order to probe into the limits of the heat transfer capability of composite phase change materials, the temperature distribution of PCMs under constant heat fluxes and constant temperature conditions was studied. In addition, the evolution of the temperature distributions was visualized by using the infrared thermal imager at specific points during the melting process. Results: The experimental results showed that the maximum temperature of Fin-CPCM decreased by 21°C under the heat flux of 1500W/m2 compared with pure paraffin. At constant temperature heating conditions, the melting time of Fin-CPCM at a temperature of 75°C is about 2600s, which is 65% less than that of pure paraffin. Due to the presence of the external fins, which brings the advantage of improving the heat transfer rate, the experimental result exhibited the most uniform temperature distribution. Conclusion: The addition of copper foam can accelerate the melting process. The addition of external fins brings the advantage of improving the heat transfer rate, and can make the temperature distribution more uniform.

Effects of design parameters on flow fields and heat transfer characteristics in semicircle oblique-finned corrugated

In this study, a new technique for heat transfer enhancement through the introduction and analysis of a semicircle oblique-finned corrugated has been studied numerically. Different design parameters are employed, including the vertical gap ratio (H) of 0.03, 0.04, and 0.05, the horizontal gap ratio (V) of 0.15, 0.20, and 0.25, as well as oblique-angle (θ) of 10°, 20°, and 40° are examined. Finite volume method (FVM) and the κ-ε model are used to simulate turbulent air flows inside the targeted channels at constant temperature conditions (T = 300 K) over Reynolds number between 10,000–50,000. The findings indicate that the employment of the new technique resulted in increased heat transfer and, as a consequence, increased thermal-hydraulic performance (PEC) via improved fluid mixing. The results also indicate that the effect of frictional loss has been used to influence the target system's overall performance in the direction of minimising the effect of heat transfer. The results show that a small vertical gap ratio and a high horizontal gap ratio have a greater effect on both heat transfer rate and PEC than others. Generally, the best PEC of 2.469 has been observed when V = 0.15, H = 0.05, and = 40 are used as design parameters. In terms of Nusselt number and friction factor, new correlations for the new model of semicircle oblique-finned corrugated are also reported.

Analysis of heat transfer characteristics and entransy evaluation of high viscosity fluid in a novel twisted tube

• A novel twisted tube is to improve the secondary flow distribution inside the tube. • Heat transfer performance and entransy evaluation are investigated numerically. • The novel twisted tube reduces the entransy dissipation compared with the plain tube. • Effects of geometry parameters and Reynolds number are analyzed comprehensively. The non-uniformity of the secondary flow distribution in the twisted oval tube has impeded its further improvement of the heat transfer performance. A novel twisted tube (NTT) improves the distribution of the secondary flow and enlarges the effect of the secondary flow on the main flow, intensifying the radial mixing and equalizing the temperature distribution of the fluid, which strengthens the convective heat delivery in the near wall region and the core zone comprehensively. Heat transfer characteristics and entransy evaluation of water and engine oil in the NTT are investigated in the low Reynolds number ( Re ) region. The heat delivery performance of the NTT improves with the reduction of the distance ratio ( DR ) and the twist pitch ratio ( PR ), and also raises with the increase of Re . The friction factor of the NTT increases with the reduction of DR and PR , and decreases with the rise of Re . Compared with the twisted oval tube, the NTT could elevate the Nusselt number and enlarge the friction factor by 1.49–1.56 times and 1.32–1.41 times, respectively. Compared with the plain tube, the NTT could improve the Nusselt number and increase the friction factor by 2.42–2.76 times and 1.48–1.56 times, respectively. The equivalent thermal resistance of the NTT decreases with the reduction of DR and PR and reduces with the increase of Re . The Case 4 with the minimum DR and the smallest PR shows the supreme heat transfer performance and the lowest equivalent thermal resistance. The NTT could reduce the entransy dissipation remarkably, compared with the plain tube, the NTT could decrease the equivalent thermal resistance by up to 58% for water under the condition of constant wall temperature and could reduce the equivalent thermal resistance by as much as 53% for engine oil under the condition of given heat flux on the tube wall.

Fine aggregate sizes effects on the creep behavior of asphalt mortar

Asphalt mortar consists of fine aggregates dispersed in an asphalt mastic (a matrix of asphalt binder and filler) and can have a significant influence on the high-temperature performance of asphalt mixtures. However, the fine aggregate sizes (FAS) governing the creep performance of asphalt mortar is not well understood. The effect of different FAS on the creep properties of asphalt mortar was investigated through experimental and numerical methods. A static compressive yield test and a dynamic triaxial creep test were performed on various asphalt mortar samples to determine their creep response under different conditions of temperature and stress level. It was found that the maximum strain in the asphalt mortar gradually reduces with an increase in FAS under the conditions of constant temperature – constant stress level, different temperature – constant stress level, and constant temperature – different stress level. Further, the modified Burgers model was proposed as a viscoelastic prediction model of asphalt mortar. A viscoelastic fitting analysis was carried out to validate the proposed model and the results indicated its adequacy for predicting the asphalt mortar’s creep response. At the end of the study, a grey relation entropy (GRE) analysis was done to quantify the degree of influence of the various FAS on the viscoelastic behavior of asphalt mortar. From the GRE analysis, FAS between 0.15 mm and 0.3 mm was found to be the most crucial. Below 0.15 mm FAS, asphalt mortar is mostly viscous. It begins to show elastic properties when the maximum FAS is between 0.15 mm and 0.3 mm, while above 0.3 mm and towards 2.36 mm the asphalt mortar increasingly becomes more elastic. The findings from this study can be useful to pavement engineers and other pertinent stakeholders seeking to optimize the aggregate gradation design of asphalt mixtures through the fine aggregate portion in order to enhance rutting resistance performance.

Experimental evaluation on mechanical and thermal insulation properties of shotcrete under constant‐variable temperature

AbstractOne of the commonly used stabilization systems for rock tunnel is shotcrete. However, the hydration of shotcrete is usually accompanied by the development of internal defects and micro damage under high temperature. Additionally, in the actual high‐temperature engineering, the temperature of the rock tunnel exhibits irregular changes. Therefore, in this study, the curing conditions of constant temperature (23°C, 40°C, 60°C, 80°C) and variable temperature (23–40–60–80°C, 80–60–40–23°C) are set, respectively. The mechanical properties and structural properties of polyurethane shotcrete and ordinary Portland shotcrete are introduced. It is determined that the limit temperature for inhibiting the development of sprayed concrete's compressive and splitting strength is between 60°C and 80°C, and the limit temperature for inhibiting the development of bond strength is about 40°C. Meanwhile, the influence of high temperature on the thermal insulation performance of shotcrete is considered. The results that the self‐foaming performance of polymer(polyurethane) reduces the thermal conductivity of shotcrete. Based on this phenomenon, the heat transfer model of shotcrete at room and high temperature is established to clarify the heat transfer process of shotcrete. Results will provide theoretical basis for further research of durability and heat insulation performance of protective spraying material for tunnel under high temperature.

Field theory description of ion association in re-entrant phase separation of polyampholytes.

Phase separation of several different overall neutral polyampholyte species (with zero net charge) is studied in solution with two oppositely charged ion species that can form ion pairs through an association reaction. Hereby, a field theory description of the system, which treats polyampholyte charge sequence dependent electrostatic interactions as well as excluded volume effects, is given. Interestingly, analysis of the model using random phase approximation and field theoretic simulation consistently shows evidence of a re-entrant polyampholyte phase separation at high ion concentrations when there is an overall decrease of volume upon ion association. As an illustration of the ramifications of our theoretical framework, several polyampholyte concentration vs ion concentration phase diagrams under constant temperature conditions are presented to elucidate the dependence of phase separation behavior on the polyampholyte sequence charge pattern as well as ion pair dissociation constant, volumetric effects on ion association, solvent quality, and temperature.

Optimization of variable-temperature drying ofCamellia oleiferaseeds

The processing method of Camellia oleifera fruit used in the industry was investigated, that is, fresh C. oleifera fruit was shelled in the drying equipment first and then the remaining C. oleifera seeds returned until the target moisture content (about 10% d.b.) was reached. The variable-temperature drying of C. oleifera seeds was investigated for the first time and the drying process was optimized and compared with constant-temperature drying. Two independent variables, including hot air drying temperature and air velocity, were studied by central composite design. The responses were drying time and quality of Camellia oil, including acid value and peroxide value. Results showed that the optimal constant-temperature drying conditions were drying at a temperature of 60.5°C and air velocity of 2.1 m/s. Under this condition, the total drying time was 607 min, and the acid and peroxide values were 1.72 mg/g and 0.12 g/100 g, respectively. The optimal variable-temperature drying conditions were drying at a constant air velocity of 2 m/s and a drying temperature of 55°C for 67 min, then 60°C for 213 min, and finally 65°C for 297 min. Under these conditions, the acid value was 1.75 mg/g and the peroxide value was 0.1 g/100 g. The optimal variable-temperature drying efficiency was 16.7% higher than that of constant-temperature drying when the optimization objective of drying time, acid value and peroxide value was 2:1:1.

Theoretical Analysis of MHD Mixed Convection From A Vertical Plate Embedded in a Porous Medium with a Convective Boundary Condition

An analytical approach has been used to study the heat and mass transfer from a vertical plate embedded in a porous medium experiencing a first-order chemical reaction and exposed to a transverse magnetic field. Instead of the commonly used conditions of constant surface temperature or constant heat flux, a convective boundary condition is employed which makes this study unique and the results more realistic and practically useful. The momentum, energy, and concentration equations derived as coupled second-order, ordinary differential equations are solved analytically a highly accurate and thoroughly tested using Homotopy Perturbation Method. The effects of Biot number, thermal Grashof number, permeability parameter, Hartmann number, Eckert number, Sherwood number and Schmidt number on the velocity, temperature, and concentration profiles are illustrated graphically. Proportional to the plate surface temperature, the local skin-friction coefficient, the local Nusselt number and the local Sherwood number were also presented analytically. The discussion focuses on the physical interpretation of the results as well their comparison with the results of previous studies.

Analytic Solution to Steady Heat Conduction with Transverse Radiation Heat Transfer

A unique analytic solution to the problem of steady heat conduction with radiative heat transfer normal to the conduction heat flow is presented. The solution is unique, as it does not assume zero temperature of the surroundings and addresses all possible tip boundary conditions for in-space applications. The temperature profiles in the direction of heat conduction are produced for a constant-temperature boundary condition at the base and three different boundary conditions at the tip: adiabatic, constant temperature, and radiative heat transfer. Approximate solutions to the implicit exact solution are also developed. An extended solution that includes convection for the adiabatic-tip boundary condition is also presented and compares very well to experimental data.

Lauric Acid as an Energy Storage Material to Increase Distillation Solar Productivity in Indonesia

The use of energy storage materials in a solar distillation system is intended to increase condensate production by making changes in the temperature of the system change slowly, not following fluctuations in the intensity of solar radiation that can change quickly and drastically. One of the effective energy storage systems is the use of Phase Change Materials (PCMs), materials that involve a phase change process in storing and releasing heat, because the latent heat involved in the phase change process has a large enough value under constant temperature conditions so that temperature stability in the system is achieved. The choice of PCM type used in solar distillation is determined by the average temperature that can be reached by the water in the basin, which is strongly influenced by local environmental conditions. This study compares the productivity of the distillate produced by the double slope solar distillation system that uses Lauric Acid as PCM and that does not use PCM. Both studies were conducted at the same time. The optimal amount of LA that must be added to the solar distillation system to get the highest increase in condensate production value is 7.54 kg of Lauric Acid for 64.8 kg of raw water..

Effects of Constant and Fluctuating Temperatures on Gene Expression During Gonadal Development

There is ample research demonstrating that temperature can have complex effects on biological processes, including the timing of when organisms respond to temperature; some responses occur rapidly while others require an extended exposure time. However, most of what we know about temperature effects comes from studies using constant temperature conditions, which are not reflective of natural, fluctuating temperatures. Species with temperature-dependent sex determination (TSD) present an ideal system to study the temporal aspects of the temperature response because prior research has established a number of temperature-responsive genes involved in TSD, albeit under constant temperatures. To investigate potential differences in timing of sexual development between constant and fluctuating incubation temperatures, we exposed Trachemys scripta embryos to two conditions that produce males (constant 26°C and 26 ± 3°C) and two that produce females (constant 31°C and 31 ± 3°C), and sampled embryonic gonads for gene expression analysisvia qPCR. We analyzed three genes involved in testis differentiation (Kdm6b,Dmrt1, andSox9) and two genes involved in ovary differentiation (Foxl2andCyp19A1). Results show that Kdm6b expression was significantly lower under fluctuating temperatures compared to constant temperatures. Foxl2 and Cyp19A1 expression were also lower under fluctuating temperatures, but not at all stages of development. These results suggest that constant temperatures caused increases in both Foxl2 and Cyp19A1 expression earlier (developmental stage 20) than fluctuating temperatures (stages 22 and 23). Dmrt1 and Sox9 expression did not differ between constant and fluctuating temperatures. These results highlight that not all genes in a temperature-dependent process respond to temperature in the same manner. Whether there are functional consequences of this variation remains to be determined.

Developing extreme heat acclimation in Bemisia tabaci Mediterranean (Hemiptera: Aleyrodidae).

Bemisia tabaci Mediterranean (MED) is a highly invasive cryptic species complex found in the world's tropical, subtropical, and temperate regions. It is a severe pest of various crops and a vector of plant pathogenic viruses, particularly geminiviruses. Thermal acclimation of insects is a critical for the survival in unfavorable temperature condition. We observed that great survival rate of B. tabaci MED at the uncontrolled greenhouse which had fluctuating temperature condition (FTC) from 10°C to 60°C in spring and summer season. Our study showed that while B. tabaci MED reared under FTC for 10 weeks from April to June, its survival rate was gradually increased when heat shock was treated50°C for 0.5 h. In contrast, the same heat shock treatment was lethal in the colony reared under constant temperature condition (CTC) at the controlled insectary. After being acclimated, the lethal temperatures LT50 , LT95 , and LT100 under CTC were 47.7°C, 50.1°C, and 50.3°C, whereas those under FTC were 59.8°C, 62.7°C, and 63.0°C, respectively. In addition, we observed that the transcript levels of three investigated heat shock protein (HSP) genes (hsp20, hsp70, and hsp90) were lower under FTC than under CTC. This study suggests that B. tabaci MED retains high heat acclimation ability, making it tolerant of extreme thermal conditions.

A Data Resource for Prediction of Gas-Phase Thermodynamic Properties of Small Molecules

The thermodynamic properties of a substance are key to predicting its behavior in physical and chemical systems. Specifically, the enthalpy of formation and entropy of a substance can be used to predict whether reactions involving that substance will proceed spontaneously under conditions of constant temperature and pressure, and if they do, what the heat and work yield of those reactions would be. Prediction of enthalpy and entropy of substances is therefore of value for substances for which those parameters have not been experimentally measured. We developed a database of 2869 experimental values of enthalpy of formation and 1403 values for entropy for substances composed of stable small molecules, derived from the literature. We developed a model for predicting enthalpy of formation and entropy from semiempirical quantum mechanical calculations of energy and atom counts, and applied the model to a comprehensive database of 16,417 small molecules. The database of small-molecule thermodynamic properties will be useful for predicting the outcome of any process that might involve the generation or destruction of volatile products, such as atmospheric chemistry, volcanism, or waste pyrolysis. Additionally, the collected experimental thermodynamic values will be of value to others developing models to predict enthalpy and entropy.

Aligned Magnetohydrodynamics (MHD) Flow of Hybrid Nanofluid Over a Vertical Plate Through Porous Medium

The future research on hybrid nanofluids need to be done as there are many applications of hybrid nanofluids. Some of them are electro-mechanical, renewable energy and manufacturing process application and also the application in automotive cooling. Therefore, this numerical study is conducted to investigate the aligned magnetohydrodynamics (MHD) flow of hybrid nanofluid over a vertical plate through a porous medium. The base fluid (water), silver and copper oxide flowed over a vertical plate in the presence of MHD and porous medium with boundary conditions of constant wall temperature by taking a few types of parameters into consideration. By using similarity transformation, the governing nonlinear partial differential equations are transformed into nonlinear ordinary differential equations. Keller Box method is applied to solve numerically the nonlinear ordinary differential equations and the system is solved by using Fortran programming. The results of the study are illustrated graphically to show the behavior of velocity and temperature also skin friction and Nusselt number of hybrids nanofluid affected by the parameters. It is found that the velocity profiles increase, and temperature profiles decrease when the angle of aligned magnetic field, the interaction of magnetic parameter and local Grashof number increase while the velocity profiles decrease, and temperature profiles increase when the porous parameter and volume fraction of nanoparticles parameter increase. Besides, the skin friction of Ag-CuO-water is less than CuO-water and Nusselt number of Ag-CuO-water is higher than CuO-water.

Benefits of Fuzzy Logic on MPPT and PI Controllers in the Chain of Photovoltaic Control Systems

This paper presents a comparative study between two maximum power point tracking (MPPT) algorithms, the incremental conductance algorithm (InC) and the fuzzy logic controller (FLC). The two algorithms were applied to a low photovoltaic power conversion system, and they both use different PI controllers and grid synchronization techniques. Moreover, both InC and FLC methods have Clarke and Park Transformation. To some extent, the incremental conductance and fuzzy logic controller approaches are similar, but their control loops are different. Therefore, the InC has classic Proportional Integrative (PI) controllers with simple phase-locked loops (PLL). At the same time, the FLC works with fuzzy logic PI controllers linked with the Second Order Generalized Integrator (SOGI). The proposed techniques examine the solar energy conversion performance of the photovoltaic (PV) system under possible irradiance changes and constant temperature conditions. Finally, a performance comparison has been made between InC and FLC, which demonstrates the effectiveness of the fuzzy controller over the incremental conductance algorithm. FLC turns to convert photovoltaic power easily, decreasing fluctuations, and it offers a quick response to the variation of solar irradiance (shading effect). The simulation results show a superior performance of the controller with fuzzy logic, which helps the inverter convert over 99% of the power generated by the photovoltaic panels. In comparison, the incremental conductance algorithm converts around 80%.

Carbon dioxide reduction using passive technique of incorporating phase change materials into envelopes: A case study of climate data from Saudi Arabia

Buildings have been studied by researchers from the perspectives of energy consumption and Carbon dioxide (CO2) production. From the former perspective, they have a share of 40% and from the latter one, their share reaches over 35%. Focusing on reducing the building share of 35%, three phase change materials were injected into the envelopes. The phase change range of the first material was between 17-19∘C, the second material was 22-24 °C and the third one was 24-26 °C. The phase change material performance under constant indoor temperature conditions (24-26 °C), was discussed. It can change the positive effect of phase change material (CO2 saving) to a negative effect (CO2 emission intensification). The first PCM (phase transition of 17-19∘C) in all conditions reduced the emission of CO2. But the annual reduction was limited to 4 to 6.8%. For the second substance, different behavior was observed on hot and cool days. On cool days, the positive effects were small but the negative effects were greater. However, the positive effect of this substance on hot days caused this substance (except 26 °C) up to 35.7%, condensed CO2 emission. At setpoint 26 °C, the second substance increases CO2 production by 2.22 kg.m−2 if it is installed inside envelopes. The third phase change material showed the best performance in all conditions and is introduced as an obstacle to the release of CO2.

The Impact of Assembly Configuration on Diaphragm-Embedded Fiber Bragg Gratings Pressure Sensors

In this paper, the experimental analysis of different assembly configurations for diaphragm-embedded optical fiber sensors is proposed. A fiber Bragg grating (FBG) is embedded in a nitrile rubber diaphragm, which is positioned in different front and back supports. The difference between such supports is their contact angles with the diaphragm, which leads to differences in the strain applied in the FBG prior to the sensor application. This prestrain condition in the diaphragm influences the sensor’s performance in terms of sensitivity, linearity and hysteresis. To that extent, there are 8 different configuration angles, namely 0°, 1.5°, 3.8°, 6.8°, 9.0°, 11.3°, 13.5° and 15°. The diaphragm-embedded FBG is positioned at each configuration and pressure is transversely applied on the diaphragm region (which transmits strain to the optical fiber) at constant temperature conditions. Results show a relation between the configuration angle and the sensor performance, where sensitivity and linearity presented opposite behaviors, i.e., lower angles (especially the 0° angle) lead to high linearity with a coefficient of determination (R <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ) of 0.992, whereas higher angles resulted in higher sensitivity with the highest sensitivity value of 13.26 pm/kPa. In contrast, the sensor hysteresis showed a peak value of 6.7% at 9.0° angle with hysteresis decrease in angles higher and lower than 9.0°. The smallest hysteresis of 0.2% is obtained at 1.5°. The obtained results can be used as a guideline on the development of diaphragm-embedded sensors with the additional degree of freedom from the possibility of customizing the diaphragm assembly configuration to achieve predefined performance parameters.

High Stability Carbon Dots Phosphor and Ultra-High Color Rendering Index White Light-Emitting Diodes

A new kind of carbon dots based phosphor is developed for light emitting diodes (LED) by adsorbing carbon dots to starch particles. The bonding mechanism is based on hydrogen bonding of surface functional groups of carbon dots and starch particles. Aggregation-induced quenching is avoided and the thermal stability of the carbon dots phosphor is enhanced. The carbon dots phosphor is used as color convert material for white LED devices. The white LED device fabricated has an ultra-high color rendering index of 93.9, almost pure white CIE coordinate at (0.332, 0.336) and moderate CCT at 5498 K. The photoluminescence intensity (PL) under constant temperature and alternative condition is both tested to study the thermal stability of the phosphor. The PL intensity shows no obvious change after 3 days of aging; only 4% of PL loss after 10 cycles of 25 °C /85 °C alternation. Based on its good PL properties and thermal stability, this carbon dots phosphor has great potential for white LED lighting.

Conditions Influencing Mould Growth for Effective Prevention of Wood Deterioration Indoors

Effective prevention of mould growth indoors is still an important topic considering that mould growth is frequently observed in buildings, it causes serious health hazards and can irreversibly damage infected objects. Several studies have been conducted and mould growth models developed. Despite that, some potentially important aspects such as water damage and spore contamination have received only little attention. The objective of the present study was to investigate the effect of the initial moisture content of wood and spore contamination on mould development indoors. The mould tests were performed in constant temperature (10, 20 and 30 °C) and relative humidity (91% and 97%) conditions. The results show that wetting of wood specimens prior to the test significantly accelerates mould growth at a temperature of 10 °C. For the other temperatures, the effect was insignificant. Similar results were obtained for the test involving dry (conditioned at RH 50%) and conditioned specimens (RH 91% or RH 97%). The results regarding initial spore contamination show that significantly longer periods are required for mould to develop without spore contamination at 10 °C and 20 °C, while at 30 °C the effect is relatively small.

Self-ignition temperature of the dust accumulations for sunflower and wood powders

Spontaneous combustion is a phenomenon that results from the heating of combustible organic powders by slow oxidation and which occurs through the air passage (created by an air depression) through the mass of dust. The oxidation phenomenon of combustible powders represents their reaction with atmospheric oxygen resulting in products of carbon dioxide, carbon oxide, water and other gases whose content depends on the temperature at which the oxidation takes place. The self-ignition of combustible dusts depends on their chemical composition, the properties of component substances, on the particle size and geometry of the material mass and, last but not least, on the temperature of the environment. Due to global worries of sustainability in construction engineering the trend is to use ecofriendly organic waste to various purposes as in construction materials. The challenge is that by using this kind of materials one should ensure the safety related to the process of such organic materials which are known to have combustible properties. The purpose of this work is to present the self-ignition behavior of combustible dusts such as sunflower and wood by means of drying tests under constant temperature conditions.