Thermodynamic and Transport Properties of Biomass-Derived Furfural, Furfuryl Alcohol and Their Mixtures

The limited reserves and well-known disadvantages of using fossil energy sources have increased the need for appropriate renewable substitutes in the production of various chemicals and materials. Biomass has been shown to be worthy of attention since it can be converted to biofuels and value-added chemicals relatively easily. The design of biomass valorisation process requires knowledge on the thermodynamic behaviour of the biomass-derived compounds, such as furfural and furfuryl alcohol. The thermodynamic and transport properties of the binary system furfural + furfuryl alcohol were studied at various temperatures and pressures. Density, speed of sound and refractive index were measured in the temperature range T = (288.15–345.15) K and viscosity was measured at temperatures up to 373.15 K, all at atmospheric pressure. Further, the density of pure components was obtained in the temperature range (293.15–413.15) K for furfural and (293.15–373.15) K for furfuryl alcohol at pressures up to 60.0 MPa. The obtained density values were correlated using the modified Tammann–Tait equation with an average absolute deviation lower than 0.009% for furfural and furfuryl alcohol. The optimised parameters were used for the calculation of the isothermal compressibility, the isobaric thermal expansivity, the internal pressure and the isobaric and isochoric specific heat capacities. The reported data are a valuable source of information for the further application of the investigated compounds.

First-Principles Calculations of Stable Geometric Configuration and Thermodynamic Parameters of Cadmium Sulfide Thin-Film Condensates

Thin-film CdS layers obtained by the open evaporation method in vacuum are considered and cluster models for calculation of crystal, band structure and thermodynamic parameters are proposed. The thermodynamic parameters of the formation energy ΔE, enthalpy of formation ΔH, Gibbs energy ΔG, entropy ΔS and specific heat capacities at constant pressure and volume for cubic and hexagonal crystallographic modifications are determined. The stable crystal structure for cadmium sulfide was determined from the analysis of Gibbs energy temperature dependences for the sphalerite and wurtzine phases.

Calculating component temperatures in gearboxes for transient operation conditions

The knowledge of component temperatures during transient operation conditions is essential for an optimal design of a gearbox. This is because critical peak temperatures limit the transferable power as well as the load capacity. Moreover, understanding the thermal behavior of the gearbox is key to improving its efficiency. Therefore, the Thermal Network Method (TNM) of the calculation program WTplus was extended to calculate component temperatures in gearboxes for transient operation conditions. Specifically, the TNM considers the component masses and specific heat capacities of each node modelling the gearbox structure. This enables the algorithm to compute a corresponding system of differential equations and thus determine the temperature change over time. Therefore, WTplus can be used to identify critical gearbox component temperatures during load cycles. The applied method was validated with measurements collected at the FZG gear efficiency test rig.

Refraction of Oblique Shock Wave on a Tangential Discontinuity

The refraction of an oblique shock wave on a tangential discontinuity dividing two gas flows with different properties is considered. It is shown that its partial reflection occurs with the exception of the geometrical diffraction of an oblique shock. Another oblique shock, expansion wave or weak discontinuity that coincides with the Mach line can act as a reflected disturbance. This study focuses on the relationships that define the type of reflected discontinuity and its parameters. The domains of shock wave configurations with various types of reflected discontinuities, including characteristic refraction and refraction patterns with a reflected shock and a reflected rarefaction wave, are analyzed. The domains of existence of various shock wave structures with two types of reflected disturbance, and the boundaries between them, are defined. The domains of parameters with one or two solutions exist for the characteristic refraction. Each domain is mapped by the type of refraction with regard to the Mach number, the ratio of the specific heat capacities of the two flows and the intensity of a refracted oblique shock wave. The conditions of the regular refraction and the Mach refraction are formulated, and the boundaries between the two refraction types are defined for various types of gases. Refraction phenomena in various engineering problems (hydrocarbon gaseous fuel and its combustion products, diatomic gas, fuel mixture of oxygen and hydrogen, etc.) are discussed. The result can be applied to the modeling of the shock wave processes that occur in supersonic intakes and in rotating and stationary detonation engines. The solutions derived can be used by other researchers to check the quality of numerical methods and the correctness of experimental results.

Thermal Response at Room Temperature and Device Applications of Two Wood Species in Akure, South Western Nigeria

Thermal properties (Density, Thermal conductivity and Specific heat capacity) play important impact in the formation of devicesmade of wooden materials. This study examines the room temperature thermal response of ten bulk samples from the species of Pterygota macrocarpa and Antiaris africana wood species found in South Western Nigeria. The samples were processed into appropriate shapes to fit into the parallel plane arrangement to determine the thermal properties. Temperature dependent models were used to obtain the specific heat capacities of the samples within a temperature variation of 308.25𝐾 - 310.00𝐾. The results revealed that the thermal properties (thermal conductivities and specific heat capacities) increase as temperature increases for all the bulk samples considered. The results of the research showed that the selected wood samples could find useful applications in industrial insulating devices. Keywords: Wood material, Lee’s disc apparatus, Temperature and Thermal properties.