Articles

The processes of technical and technological development are unequivocally linked to increasing energy consumption, with a significant portion of energy being produced from fossil fuels worldwide. The reserves of natural energy sources such as petroleum, gas, coal, and turf are finite. The transition to renewable energy sources has been ongoing for a long time, but share in global energy consumption remains lower than desired. The main limitations include limited availability, inability to operate continuously throughout the year, high costs, and a lack of materials and devices capable of withstanding high temperatures and pressures. The goal of our research is to create a device that generates electricity using a new type of renewable energy source based on the thermal expansion and contraction of materials. This paper presents the construction, details, and working principles of the new device. The primary focus is on utilizing materials and components that are readily available. The proposed method has own advantages, addresses some of the aforementioned limitations, and can be particularly beneficial for providing electrical energy in remote areas. Calculations indicate that the device built using this new method will be competitive with appliances that utilize other renewable energy sources in terms of features and efficiency.

In this article, our investigation to study squeezing and statistical properties of the light by a two mode sub harmonic generator coupled to thermal reservoir via a single port-mirror. The equation of motion answers are then used to calculate the mean photon number, photon number variance, and quadrature variance for two mode cavity light. However, we have found that the degree of squeezing is indeed affected by the present of thermal light. The mean photon number of the system under consideration increases with increasing <math><semantics><mrow><mover accent="true"><mrow><mi mathvariant="normal">n</mi></mrow><mo>-</mo></mover></mrow></semantics></math>.

In this article the investigation of squeezing and statistical properties of light resulting by a non-degenerate three-level laser with the parametric amplifier and coupled to a thermal reservoir have been occurred. With the aid of master equation, stochastic differential equations were obtained. Applying solutions of resulting differential equations, quadrature variance, the mean and variance of photon number, the photon number correlation are calculated. However, the two-mode driving light has no effect on the squeezing properties of the cavity modes. On the other hand, parametric amplifier and thermal reservoir increase the mean and variance of photon number. Furthermore, employing the same solutions, we also obtain anti normally ordered characteristic function defined in the Heisenberg picture. For a linear gain coefficient of (A = 100), for a cavity damping constant of K= 0:8, µ = 0 and for thermal reservoir th = 0, the maximum intra cavity photon entanglement is found at steady state and at threshold to be 60%.

The main energy conservation opportunities in a dairy plant are in refrigeration, and steam generation. This paper aims to identify potential energy and water savings and opportunities to improve the thermal efficiency of a fluid milk processing plant, using energy analysis and Heat Integration methods. Methodologies for energy analysis and Pinch Analysis with the use of HENSAD and Aspen Energy Analyzer are applied. The main specific energy consumptions are defined as indicators of the progress of improved energy efficiency. The determination of energy performance indicators and energy targets of the heat exchanger network, as well as its design, allowed identifying opportunities for improvement to reduce fuel and water consumption through heat recovery in the milk pasteurization process. Current hot and cold utilities duties are satisfied, for a minimum allowable temperature difference of 20 °C. Total annual savings of 60 t of fuel oil and 15,800 m³ of water allow assessing the feasibility of an investment project for improved heat recovery.

The increasing popularity of carbon nanotubes has created a demand for greater scientific understanding of the characteristics of thermal transport in nanostructured materials. However, the effects of impurities, misalignments, and structure factors on the thermal conductivity of carbon nanotube films and fibers are still poorly understood. Carbon nanotube films and fibers were produced, and the parallel thermal conductance technique was employed to determine the thermal conductivity. The effects of carbon nanotube structure, purity, and alignment on the thermal conductivity of carbon films and fibers were investigated to understand the characteristics of thermal transport in the nanostructured material. The importance of bulk density and cross-sectional area was determined experimentally. The results indicated that the prepared carbon nanotube films and fibers are very efficient at conducting heat. The structure, purity, and alignment of carbon nanotubes play a fundamentally important role in determining the heat conduction properties of carbon films and fibers. Single-walled carbon nanotube films and fibers generally have high thermal conductivity. The presence of non-carbonaceous impurities degrades the thermal performance due to the low degree of bundle contact. The thermal conductivity may present power law dependence with temperature. The specific thermal conductivity decreases with increasing bulk density. At room temperature, a maximum specific thermal conductivity is obtained but Umklapp scattering occurs. The specific thermal conductivity of carbon nanotube fibers is significantly higher than that of carbon nanotube films due to the increased degree of bundle alignment.

Many attempts have been made to improve heat transfer for thermally integrated microchannel reforming reactors. However, the mechanisms for the effects of design factors on heat transfer characteristics are still not fully understood. This study relates to a thermochemical process for producing hydrogen by the catalytic endothermic reaction of methanol with steam in a thermally integrated microchannel reforming reactor. Computational fluid dynamics simulations are conducted to better understand the consumption, generation, and exchange of thermal energy between endothermic and exothermic processes in the reactor. The effects of wall heat conduction properties and channel dimensions on heat transfer characteristics and reactor performance are investigated. Thermodynamic analysis is performed based on specific enthalpy to better understand the evolution of thermal energy in the reactor. The results indicate that the thermal conductivity of the channel walls is fundamentally important. Materials with high thermal conductivity are preferred for the channel walls. Thermally conductive ceramics and metals are well-suited. Wall materials with poor heat conduction properties degrade the reactor performance. Reaction heat flux profiles are considerably affected by channel dimensions. The peak reaction heat flux increases with the channel dimensions while maintaining the flow rates. The change in specific enthalpy is positive for the exothermic reaction and negative for the endothermic reaction. The change in specific sensible enthalpy is always positive. Design recommendations are made to improve thermal performance for the reactor.