Journal of Thermal Analysis and Calorimetry

Flow and heat transfer characteristics in smooth, sinusoidal and zigzag-shaped microchannel with and without nanofluid have been investigated by finite volume method. Effects of amplitude and wave length of sinusoidal and zigzag-shaped microchannel, volume of fraction and Reynolds number on heat transfer, performance evaluation criterion were evaluated. The results show that by increasing volume fraction of Copper oxide nanoparticle, Nusselt numbers are increased. Obtained results show that if only the increase in heat transfer is considered, using sinusoidal microchannels without nanoparticles is more effective method than using of nanoparticles in smooth microchannels. By analyzing the effect of wavelength and amplitude on changes of Nusselt number, it can be found that by decreasing sinusoidal and zigzag-shaped microchannel wavelengths, Nusselt number will increase. Also, we concluded that for selection of the best microchannel, the zigzag shaped one is a more appropriate one as compared to the sinusoidal microchannel.

We report the effect of lignin-coated cellulose nanocrystals (L-CNCs) on the crystallization behavior of poly(lactic acid) (PLA). PLA/L-CNC nanocomposites were prepared by melt mixing, and the crystallization behavior of PLA was investigated using differential scanning calorimetry. Isothermal crystallization data were analyzed using Avrami and Lauritzen–Hoffman secondary nucleation theory, while the equilibrium melting temperature was determined using the nonlinear Hoffman–Weeks method. The lignin-coated cellulose nanocrystals acted as a nucleating agent and significantly increased the rate of crystallization and degree of crystallinity of PLA in PLA/L-CNC nanocomposites. The Avrami exponent, n, increased in the presence of L-CNCs, displaying a conversion from lamellar morphology to two-dimensional crystal growth. PLA/L-CNC nanocomposites also gave lower values of the nucleation parameters, $$K_{\text{g}}$$ and σ e, due to a reduction in the activation energy for nucleation.

In order to evaluate the pozzolanic activity of a natural pozzolan (NP) of rhyolitic composition, several pastes were prepared by mixing the pozzolan with hydrated lime, in different ratios. The pastes were stored in standard conditions (RH = 99 ± 1%, T = 25 ± 1 °C) and evaluated using thermal analysis (TG-DTA), X-ray diffraction, compressive strength tests and mercury intrusion porosimetry, up to 270 days of curing. The obtained results showed that the compounds formed are CSH and C4ACH11 (monocarboaluminate). The calcium hydroxide consumption increases as the initial amount of the natural pozzolan in the paste augments. As the NP/lime ratio increases, the open total porosity and total cumulative volume decrease, while the bulk density increases. The maximum strength development is obtained for NP/lime ratio of 2.

In this study, ten different blends were prepared with binary and ternary combinations of diesel, palm oil biodiesel (0 vol%, 15 vol%, 20 vol% and 30 vol%), and diethyl ether (0 vol%, 5 vol% and 10 vol%) and were tested in a diesel engine. The experiments were performed on various engine loads (500 W, 750 W, 1000 W and 1250 W) and various injection timings (25° CA bTDC, 30° CA bTDC and 35° CA bTDC) at a fixed crankshaft speed of 3000 rpm. The prepared blends were compared in terms of exergy and exergoeconomics. It may be said that exergy efficiency and specific exergy cost of work for blends improved with increasing injection timings at high engine loads. However, at low engine loads, these parameters worsened with increasing injection timings. As a result, at 500 W, relative exergy efficiency of D70PO20DE10 was 0.57 for 25° CA bTDC and 0.54 for 35° CA bTDC. However, at 1250 W, this value was 0.59 for 25° CA bTDC and 1.16 for 35° CA bTDC. Similarly, at 500 W, relative specific exergy cost of work for D70PO20DE10 was 5.29 for 25° CA bTDC and 5.94 for 35° CA bTDC. However, at 1250 W, this value was 5.31 for 25° CA bTDC and 2.66 for 35° CA bTDC. Finally, it can be concluded that neat diesel had the best results compared to all blends considered in this study in terms of exergy and exergoeconomics.

In the present research, mechanical and thermal properties of high-density polyethylene/wood flour were improved by incorporating nanoclay (Cloisite 30B) and antioxidant (Irganox B225) in the compound. Design of experiments was carried out to optimize composition among nine compounds and to investigate the effect of nanoclay and antioxidant (0–5 phr) and (0–0.4 phr), respectively. The results of mechanical tests showed approximately 24% increase in the tensile strength of compounds containing 2.5 and 5.0 part per hundred (phr) of the nanoclay in the composite compared with the same samples without nanoclay. The tensile modulus of composites increased 7.3% by increasing the level of nanoclay from 0 to 2.5 phr. However, a further increase in the nanoclay content led to a 4.3% decrease in tensile modulus. Evaluation of the thermal oxidation stability of samples confirmed that the thermal oxidation of composites decreased with increasing nanoclay from 0 to 5.0 phr and increased significantly with the addition of the antioxidant.

In present work, CuZr4(PO4)6, which is a complex phosphate of NASICON family, has been characterised as ceramic pigment. To this purpose, its thermal stability, colour properties and some other important pigment characteristics were studied. In order to obtain pure phase ceramic powder of CuZr4(PO4)6, several synthesis approaches were attempted. The thermal transformations in the reaction mixtures were investigated by DTA-TG and XRD analysis. Thermal stability of the obtained products was studied using heating microscopy, DTA-TG and XRD analysis. Colouring performance and lightfastness of CuZr4(PO4)6 were tested within commercial ceramic glazes, and its colour in powder and glaze is described by means of CIELAB and CIELCh systems. It is shown that CuZr4(PO4)6 ceramic powder has sufficient thermal stability and attractive colouring properties to be used as ceramic pigment.