Global wave number-4 pattern in the southern subtropics

<p>Presence of a stationary zonal wavenumber-4 (W4) pattern is revealed in the sea surface temperature (SST) anomaly over southern subtropics (20°S-55°S) using empirical orthogonal function analysis. This W4 pattern is found to be seasonally phase-locked to the austral summer (persists up to mid-autumn) and independent of other known tropical and extra-tropical climate phenomena. A thermodynamic coupling of atmosphere and the upper ocean helps in generating the W4 pattern, which later terminates due to the breaking of the ocean-atmosphere positive feedback. Due to anomalous convection over western subtropical pacific near the westerly jet, the signal appears first in the atmosphere during early November. Later, the disturbance gets trapped in the westerly waveguide which circumnavigates the globe and produces an atmospheric W4 pattern in early December (20-30 days later). Then, the signal transported to the ocean through the ocean-atmosphere feedback and sustained in the ocean (after it disappears from the atmosphere) as it has high specific heat capacity. During the positive phase of the W4 event, the cold SST anomaly develops over the southeastern and -western side (SE-NW) of Australia creating an anomalous divergence circulation. It favours the moisture transport towards the south-eastern region of the continent. Consequently, the specific humidity increases and causes an above-normal rainfall in a SE-NW axis over Australia. An opposite process is seen in case of a negative W4 event.</p>

New Technologies in the Production of Thermal Chemical Current Sources

It is proposed to use Li4Si alloys with Li content > 50 wt.% as anode materials. A technology for the synthesis of Li4Si in a pre-formed anode with thermal interaction Li with Si-containing composite material has been developed. It is proposed to use FeS2 as a cathode, which has a high theoretical capacity. A technology has been developed for using pyrite with an enrichment with FeS2 of at least 90 wt.%. As an electrolyte, eutectic mixtures “LiCl–KCl–LiF” were used. Gas-free pyrotechnic mixtures based on highly dispersed iron nanopowders with high specific heat release up to 1300 J/g and burning rates up to 100 mm/s have been developed. The pyrotechnic tape ignitors with a burning rate of 2.5 m/s are proposed, thus providing simultaneous ignition of the elements of the current sources and reducing the time of initiation and activation of the battery.

Thermal Analysis of Phase Change Material Based Heat Transfer Fluid in Solar Thermal Collector

Phase change materials (PCMs) are commonly used as energy storage mediums in solar thermal systems. This paper investigates the mixture of PCM doped with nanoparticles to be used as HTFs directly integrated in a U-pipe ETC to be applied in solar thermal collectors. The selected type of PCM-HTF in this study is erythritol (C4H10O4), with high specific heat capacity in liquid form, as well as its unique sub-cooling behavior. In order to overcome the low thermal conductivity of erythritol and further enhance specific heat capacity, a weight concentration of 1% multi-walled carbon nanotubes (MWCNT) is added. Additionally, to insure even distribution of MWCNT and consistent properties of the HTF, triethanolamine (TEA) is proposed to be incorporated as a dispersant. The samples were each tested in a Thermogravimetric Analyzer (TGA) and Differential Scanning Calorimeter (DSC) to analyze their thermal properties. The results from the DSC tests show 12.4% enhancement of specific heat capacity of the proposed HTF mixture as well as nearly 5° C depression of freezing onset temperature. This study allows for the optimization of the operating temperature range of the collector when integrated with these materials, where direct heat gain can be obtained in the collector.

AUTOCLAVING CELLULOSE NITRATES OBTAINED FROM FRUIT SHELLS OF OATS

Besides the targeted viscosity decrease, the high-temperature autoclaving of cellulose nitrates (CNs) can provide one of the key properties – chemical stability – which governs the operational process safety and guaranteed shelf life of CN-based products. Here we report the study results of the autoclaving of cellulose nitrates derived by esterification of pulp with mixed sulfuric-nitric acids. The pulp was obtained from an easily renewable domestic feedstock – oat hulls – agro-industrial residue. On the basis of experiments, regression relationships are suggested herein that enable the prediction of basic properties of CNs, depending on autoclaving time. The optimum high-temperature autoclaving time was identified that allows oat-hull CNs to be produced with the following characteristics: 12.14% nitrogen content, 12 mPa·s viscosity and 98% solubility in alcohol-ether mixture, which are similar to the characteristics of dinitrocellulose (Colloxyline-N). Ampule chromatography confirmed that the resultant CNs had a high chemical stability. The quantity of nitrogen oxide from thermal decomposition of CNs (90 °С, 192 h) was found to be 0.35 ml/g and was not above the permissible level for dinitrocellulose. Differential scanning calorimetry revealed that the oat-hull CNs are characterized by a high onset temperature of decomposition (200 °С) and a high specific heat of decomposition (7.36 kJ/kg), indicating a high chemical purity of the resultant product. The findings presented herein justify the use of oat-hull CNs in the manufacture of gun-propellant grains and composite explosives.

Thermal Analysis of Quaternary Molten Nitrate Salts Mixture for Energy Recovery System

Quaternary molten salt nitrate have been used very practically as medium for energy storage or heat transfer fluid in terms of energy recovery system. Quaternary molten salt nitrate is a mixture that can transfer heat to generate energy such as electricity. Mixed alkaline molten nitrate salt can act as a heat transfer fluid due to their advantageous in terms of heat recovery system due to high specific heat capacity, low vapour pressure, low cost and wide range of temperature in its application. This studies shows about determining the new composition of quaternary molten nitrate salts from different primary salts that can possibly give a high specific heat capacity with low melting point. The mixture of quaternary molten nitrate salts was then heated inside the box furnace at 150°C for four hours and rose up the temperature to 400°C for eight hours. Through heating process, the quaternary molten nitrate alkaline was completely homogenized. The temperature was then dropped to room temperature before removing the mixture from the furnace. The specific heat capacities of each sample were determined by using Differential Scanning Calorimeter, DSC. From the result of DSC testing, Sample 6 gives the highest point of specific heat capacity and low melting point which is 0.4648 J/g°C and 97.71°C respectively. In the nut shell, Sample 6 was chosen as a good mixture with good thermal properties that has a low melting point which is below 100°C but high specific heat capacity that may be a helpful in the application energy recovery system.

Thermal Simulation for Unconditioned Single Zoon with Modified Roof

Roof in the Iraqi houses normally flattening by a concrete panel. This concrete panel has poor thermal properties. The usage of materials with low thermal conductivity and high specific heat gives a good improvements to the thermal properties of the concrete panel, thus, the indoor room temperature improves. A Mathcad program based on a mathematical model employing complex Fourier series built for a single room building. The model input data are the ambient temperature, solar radiation, and sol-air temperature, which have been treated as a periodic function of time. While, the room construction is constant due to their materials made of it, except the roof properties are taken as a variable generated practically from the improved mixing ratios.The result showed that using concrete panel with components (cement, sand, coarse aggregate, wood ash and Alabaster aggregates) with a ratio (1:1:2:1:1) and 3-plastic layer denoted by roof No.4, gives the best improvement of the thermal performance for the building. Where, the thermal conductivity is reduced by 42% and the specific heat increased by 41.2% compared to the traditional concrete panel mixing ratio denoted by roof No.1. Also, the mechanical properties are agreed with the Iraqi standards No. 1107 on 2002.