The Study of Thermal Properties of Blackberry, Chokeberry and Raspberry Seeds and Oils

The seeds of berry fruits are a component of fruit waste occurring in the production process. Circular economy rules focus on decreasing the amount of waste produced and reusing by-products when it is possible. To determine the possible applications of the studied fruit industry wastes, the thermal properties of berry seeds and of oil extracted from the tested material were examined. Differential scanning calorimetry (DSC), modulated differential scanning calorimetry (MDSC), and thermogravimetry (TG) of blackberry, chokeberry, and raspberry seeds were carried out. The properties of oil extracted in the Soxhlet apparatus were studied by pressure differential scanning calorimetry (PDSC), TG, and gas chromatography (GC) measurements. The results show that berry seeds lipids are from different melting fraction groups with a dominance of low-melting fraction, which consists of mono- and polyunsaturated fatty acids. There are also occurring residues of carbohydrates and inorganic, thermostable substances in the studied seeds. A GC analysis of oil confirms that the polyunsaturated fatty acids (PUFA) are most abundant and amount to 78.72 ± 0.06% in blackberry seed oil, 73.79 ± 0.14% in chokeberry seed oil, and 82.74 ± 0.03% in raspberry seed oil. The PDSC study showed that the most oxidative stable oil is blackberry seed oil, followed by raspberry and chokeberry seed oils. According to the obtained results, berry seeds can be used as a source of oil in food or other production chains. However, more detailed characteristics of berry seed oils are needed to determine their applicability.

A three-dimensional computational analysis of ellipsoidal radiator with phase change

Purpose The purpose of this paper is to solve the problem of a three-dimensional computational analysis for an elliptic-shaped cavity in a pipe under constant temperature. Design/methodology/approach The three-dimensional computational solution of governing equations was performed by using finite volume method with different temperature difference. Findings The parafin wax was chosen as a phase change material (PCM), and melting fraction, streamlines and isotherms are formed for different time step. It is found that position B give better results than that of position A, and temperature difference effects the duration of melting of PCM. Originality/value The three-dimensional analysis of melting in an ellipsoidal pipe with inner pipe with higher temperature is the main originality of this work.

A Comparative Study of Constrained and Unconstrained Melting Inside a Sphere

Present study is focused on the computational analysis of melting of PCM inside the spherical capsule. Both unconstrained and constrained melting is analyzed for the constant PCM volume and similar initial and boundary conditions. RT27 is chosen as the PCM for this study. Air is considered at the top of PCM inside the spherical capsule. Results are validated with the existing experimental and computational results and found to be in good agreement. Results obtained from present study are compared for the melting fraction, pattern and time. Composite diagrams are presented for the streamline and temperature contours.

Numerical Simulation of Packed Bed Cubical Storage Unit Filled with Spherical Capsules of PCM

Modern life and increasing demand on the energy make the saving of available energy in the packed bed of PCM capsules very important to use in the other time. A numerical investigation is proposed for storage of thermal energy using packed bed of spherical capsules filled with phase change material PCM. The spherical capsules are arranged as layers in the cubic vessel that exposed to heat transfer fluid. The fourth order Runge-Kutta method is applied to solve the energy balance equation of heat transfer fluid and the energy conservation equation of spherical capsules of PCM is solved using finite differences method with heat capacity method for phase change of PCM. The effect of Reynolds number and diameter of capsulated sphere are studied. The results illustrate that at constant porosity of packed bed the small diameter of capsulated spheres gives shorter time for melting, where at D=50mm & t=196.5sec the melting fraction of PCM is 0.09, while at D=10mm & t=196.5sec the melting fraction of PCM is 1.00. The results of present study have been compared with other previous results and give a good agreement.

Thermal Analysis of Phase Change Materials by Utilizing Nanoparticles

Latent TES systems utilize phase change materials (PCMs) which at a suitable temperature range can be melted and thus store thermal energy. The stored energy is removed during the reverse process which solidifies the PCM. Due to the superiority of high latent heat compared to sensible heat, PCMs can contribute to the reduction of the storage systems’ size offering a promising solution especially when coupled with solar collectors. Despite the aforementioned advantages, the relatively low thermal conductivity of PCM hinders their wide utilization. In the present study, a thermal analysis of phase change materials is carried out. Different types of phase change materials (PCMs) are analyzed at various temperature ranges. The energy equation for the PCM is solved by implementing a 1D explicit finite difference scheme in Matlab and the results are compared with corresponding results deriving from Comsol. The properties of the utilized PCMs are altered accordingly so as to take into account their variation during phase change. In this analysis, only the thermal behavior of a PCM is investigated while the gravitational effect is neglected. The results of the analysis regard the temperature variations within the phase change material, the stored energy in the PCM per volume unit, the process speed and the effect of thermal conductivity on phase change, especially on the melting front displacement. Primary results have shown that the stored energy depends on the heat source and on the utilized PCM. In order to tackle the problem of PCM low conductivity, nanoparticles are added so as to enhance the stored energy due to the higher thermal conductivity. Upon the addition of two types of nanoparticles, the enhancement of melting fraction and stored heat are determined.

An investigation of the melting process of RT-35 filled circular thermal energy storage system

One of the main solutions to the issue of global warming and greenhouse gas emission caused by burning fossil fuels is storing energy in an efficient way. In this work, the detailed melting process of RT-35 as a phase change material (PCM) inside a cylindrical latent heat thermal energy storage (TES) system is investigated both numerically and experimentally. To achieve this aim, an experimental setup comprising of a transparent vertical cylindrical enclosure as a latent heat TES system, a constant temperature bath, and a temperature regulator is built. Moreover, a numerical model using COMSOL multiphysics is developed to simulate the melting process and provide a more detailed information on the flow and thermal fields. The model is able to provide the temperature and velocity fields, heat transfer behaviour, melting fraction, and the trend of solid-liquid interface at different time intervals. To validate the numerical model, a comparison between melting fraction and solid-liquid interfaces of the numerical model and experimental work is conducted which shows a good agreement between experimental and numerical results.

Thermal processes in the formation of continental lithosphere

The thermal evolution of continental lithosphere in atectonic regions has been interpreted in terms of (1) conductive cooling, in the same way as oceanic lithosphere, but over much longer periods; (2) conductive cooling accelerated by erosion; (3) erosional removal of near-surface concentrations of heat-producing elements; and (4) various special temperature conditions assumed for its base. Although all of these factors influence lithospheric temperatures, particularly early in the development of continents, for times greater than 10 9 a, the thickness of the lithosphere and the processes by which it forms are of overriding importance. Continental lithosphere may develop by cooling and the thermal accretion of mantle material which has not been depleted of a basaltic first melting fraction, or it may develop by diapiric accretion of low-density, depleted mantle bodies rising from the upper parts of lithospheric slabs heated during their descent in subduction zones. The former process alone could not generate continental lithosphere with the observed characteristics. The latter process is likely to be important, possibly in combination with the former.