Activated carbon + HFC 134a based two stage thermal compression adsorption refrigeration using low grade thermal energy sources

A thermodynamic analysis is presented for the two stage thermal compression process for an adsorption refrigeration cycle with HFC-134a as the working fluid and activated carbon as the adsorbent. Three specimens of varying achievable packing densities were evaluated. The influence of evaporating, condensing/adsorption and desorption temperatures was assessed through three performance indicators, namely,the uptake efficiency, the coefficient of performance and the exergetic efficiency. Conditions under which a two stage thermal compression process performs better than the single stage unit are identified. It is concluded that two stage thermal compression will be a viable proposition when the heat source temperature is low or when adsorption characteristics are weak or when adequate packing densities are difficult to realize. (C) 2008 Elsevier Ltd. All rights reserved.

Thermal decomposition and combustion of ammine: AP pellets

Thermal decomposition and combustion of lithium perchlorate ammine:ammonium perchlorate (LPA:AP) and magnesium perchlorate ammine:ammonium perchlorate (MPA:AP) pellets have been studied using DTA, TG, and strand burner techniques. The DTA results of the ammine:AP pellets show that the addition of ammines lowers the ignition temperature of AP. However, isothermal TG of the ammine:AP pellets show that in the case of LPA:AP pellets the extent of decomposition increases with the increase in the concentration of LPA; whereas in the case of MPA:AP pellets the extent of decomposition decreases with the increase in the concentration of MPA. Similarly, LPA:AP pellets show higher burning rates compared to AP pellets. On the other hand, MPA:AP pellets show lower burning rates compared to AP pellets. Increasing the concentration of MPA in MPA:AP pellets completely suppresses the combustion. These results are explained on the basis of the thermal characteristics of the additives and their decomposition products.

Early recovery signs of an Australian grassland following the management of Parthenium hysterophorus L

Parthenium weed (Parthenium hysterophorus L.) is believed to reduce the above- and below-ground plant species diversity and the above-ground productivity in several ecosystems. We quantified the impact of this invasive weed upon species diversity in an Australian grassland and assessed the resulting shifts in plant community composition following management using two traditional approaches. A baseline plant community survey, prior to management, showed that the above-ground community was dominated by P. hysterophorus, stoloniferous grasses, with a further high frequency of species from Malvaceae, Chenopodiaceae and Amaranthaceae. In heavily invaded areas, P. hysterophorus abundance and biomass was found to negatively correlate with species diversity and native species abundance. Digitaria didactyla Willd. was present in high abundance when P. hysterophorus was not, with these two species, contributing most to the dissimilarity seen between areas. The application of selective broad leaf weed herbicides significantly reduced P. hysterophorus biomass under ungrazed conditions, but this management did not yet result in an increase in species diversity. In the above-ground community, P. hysterophorus was partly replaced by the introduced grass species Cynodon dactylon L. (Pers.) 1 year after management began, increasing the above-ground forage biomass production, while D. didactyla replaced P. hysterophorus in the below-ground community. This improvement in forage availability continued to strengthen over the time of the study resulting in a total increase of 80% after 2 years in the ungrazed treatment, demonstrating the stress that grazing was imposing upon this grassland-based agro-ecosystem and showing that it is necessary to remove grazing to obtain the best results from the chemical management approach.

Variation in rotary veneer recovery from australian plantation Eucalyptus globulus and Eucalyptus nitens

The processing of Australian plantation-grown Eucalyptus globulus and E. nitens into rotary veneer was shown to produce acceptable recoveries. Three plantation sites for each species were sampled. Silvicultural treatments (thinning and pruning) and growing environments varied between sites. Graded veneer recoveries were dominated by D-grade veneer across all six sites. Variation between the E. nitens sites was evident, with recoveries differing between sites reflecting silvicultural treatments. However, only minimal variation in recovery was shown between the E. globulus sites. The presence of similar levels of defects across all E. globulus sites indicates that the intensive silvicultural management at one site studied was not effective in the production of clear wood, and may possibly have adversely affected grade recovery. Veneer value analysis demonstrated only minimal differences between E. globulus sites. More variation was observed in the E. nitens value analysis; however, intensive silvicultural management implemented did not necessarily result in higher veneer value.

Thermal analysis of hydrazinium metal sulphates and their hydrazinates

Thermal analysis of hydrazinium metal sulphates, (N2H5)2 M(SO4)-I, and their hydrazinates, (N2H5)2−M(SO4)23N2H4−II, whereM=Fe, Co and Ni have been investigated using thermogravimetry and differential thermal analysis. Type II compounds on heating decompose through an intermediate I and metal suphlate to the respective metal oxides.

Factors affecting log traits and green rotary-peeled veneer recovery from temperate eucalypt plantations

High levels of percentage green veneer recovery can be obtained from temperate eucalypt plantations. Recovery traits are affected by site and log position in the stem. Of the post-felling log traits studied, out-of-roundness was the best predictor of green recovery.

Preparation and thermal stability of trioxalatocobaltates of bivalent metals KM2+ [Co(C2O4)3]·xH2O

Trioxalatocobaltates of bivalent metals KM2+[Co(C2O4)3]·x H2O, with M2+ = Ba, Sr, Ca and Pb, have been prepared, characterized and their thermal behaviour studied. The compounds decompose to yield potassium carbonate, bivalent metal carbonate or oxide and cobalt oxide as final products. The formation of the final products of decomposition is influenced by the surrounding atmosphere. Bivalent metal cobaltites of the types KM2+CoO3 and M2+CoO3—x are not identified among the final products of decomposition. The study brings out the importance of the decomposition mode of the precursor in producing the desired end products.

Thermal activation parameters for low temperature deformation of alpha-hafnium

Abstract is not available.

Cotton root systems and recovery of applied P and K fertilisers

With potential to accumulate substantial amounts of above-ground biomass, at maturity an irrigated cotton crop can have taken up more than 20 kg/ha phosphorus and often more than 200 kg/ha of potassium. Despite the size of plant accumulation of P and K, recovery of applied P and K fertilisers by the crop in our field experiment program has poor. Processing large amounts of mature cotton plant material to provide a representative sample for chemical analysis has not been without its challenges, but the questions regarding mechanism of where, how and when the plant is acquiring immobile nutrients remain. Dry matter measured early in the growing season (squaring, first white flower) have demonstrated a 50% increase in crop biomass to applied P (in particular), but it represents only 20% of the total P accumulation by the plant. By first open boll (and onwards), no response in dry matter or P concentration could be detected to P application. A glasshouse study indicated P recovery was greater (to FOB) where it was completely mixed through a profile as opposed to a banded application method suggesting cotton prefers a more diffuse distribution. The relative effects of root morphology, mycorrhizal fungi infection, seasonal growth patterns and how irrigation is applied are areas for future investigation on how, when and where cotton acquires immobile nutrients.

Combustion and Thermal Decomposition of Ammonium Perchlorate-Aluminium Composite Pellets: Mechanism for Aluminium Participation

Thermal behaviour of ammonium perchlorate-aluminium composites is studied using differential thermal analysis, thermogravimetry and differential scanning calorimetry. Electrical resistivity studies throw light on the mechanism of ammonium perchlorate decomposition at different aluminium contents. The differences observed in burning behaviour by earlier authors is explained in terms of porosity and thermal conductivity of the composite.

Ultrasonic velocities and thermal expansion coefficients of amorphous Se80Te20 and Se90Te10 alloys near glass transitions

Precise measurements of the ultrasonic velocities and thermal expansivities of amorphous Se80Te20 and Se90Te10 alloys are reported near the glass transition. The samples are produced by liquid quenching. The longitudinal and transverse velocities are measured at 10 MHz frequency using the McSkimin pulse superposition technique. The thermal expansivities,agr, are measured using a three-terminal capacitance bridge. Theagr-values show a sharp maximum near the glass transition temperature,T g. The ultrasonic velocities also show a large temperature derivative, dV/dT nearT g. The data are discussed in terms of existing theories of the glass transition. The continuous change inagr shows that the glass transition is not a first-order transition, as suggested by some theories. The samples are found to be deformed by small loads nearT g. The ultrasonic velocities and dV/dT have contributions arising from this deformation.

Thermal reactivity of metal oxalate hydrazinates

Metal oxalate hydrazinates MC2O4·2 N2H4 where M=Mg, Mn, Fe, Co, Ni, Cu, Zn and Cd have been prepared and characterised by chemical analysis and infrared spectra. Thermal reactivity and decomposition of these oxalato complexes have been studied using thermogravimetry and differential thermal analysis. Hydrazinates of Mn, Fe, Co, Ni and Cu oxalates exhibit autocatalytic decomposition behaviour whereas the others do not. This phenomenon can be attributed to the presence of a bridged hydrazine as well as the thermal stability of the anhydrous metal oxalates.

Study of switching characteristics and thermal noise in ferroelectric crystals both in the pure and radiation damaged state

The phase transition in gamma-irradiated triglycine sulphate (TGS) has been investigated by using a method based on the measurement of thermal noise. The results of a study of the polarization switching characteristics of gamma irradiated TGS and sodium nitrite (NaNO2) have also been presented. The effect of irradiation on the phase transition and the switching processes has been discussed.