Performance of high-temperature heat exchangers in biomass fuel powered externally fired gas turbine systems

Recently, there has been wide-ranging research on the idea of biomass fuel powered externally firing micro gas turbines; but only a small subset of these studies has used experimental work to evaluate the systems. These systems have not yet been employed in Malaysia for applications in thermal energy or power generation. The objective of this study is to determine the performance of a stainless steel high-temperature heat exchanger, which was built to transfer thermal power from a biomass gasifier-combustor to the pure air turbine working fluid. The study is based on experimental work using different air blower capacities as an air supply. The heat exchanger achieved 694 °C turbine inlet temperature with an average effectiveness of 62.5%.     

Evaluation of the ability of the hydrophobic nanoparticles of SiO2 in the EOR process through carbonate rock samples

More than 50% of oil remains in reservoirs after primary and secondary recovery processes. Consequently, methods of enhanced oil recovery (EOR) should be applied for more recovery from these reservoirs. In this study the ability of hydrophobic nanoparticles of sio₂ in EOR process through carbonate rock samples is studied. By employing hydrophobic nanosilica, we can lower interfacial tension between oil and nanofluid and then reduce the mobility ratio between oil and nanofluid in carbonate reservoirs; however, nanosilica can increase the viscosity of water exponentially. To evaluate this goal, core displacement experiment for carbonate core is conducted. These experiments are performed on the carbonate samples saturated with oil and brine that had got injected with nanosilica with six different concentrations. Investigating the outcomes shows that by rising nanoparticle concentration, the IFT between water and oil phases decreases and yields in decrease the mobility ratio between oil and nanofluid. For this, we measure the recovery level in different states of using 0.05, 0.1, 0.1, 0.15, 0.3, 0.6, 1.0, and 0 concentration of the nanoparticle. The outcomes achieved from our experiments reveals that employing hydrophobic nanosilica could increases the oil recovery factor.     

Drying Characteristics of Oil Palm Kernels

ABSTRACT

The drying characteristics of a single oil palm kernel suspended in a drying tunnel is studied. Luikov's unsteady state simultaneous heat and mass transpon equations are proposed as the governing equations. The model is simulated using the explicit and modified implicit Crank Nicholson finite difference algorithms. The desorption isotherms of the kernel warj determined using an environmental chamber and the data generated was found to fit the Hasley's and Henderson's equations well. The mass diffusion coefficient was determined by using a distributed system parameter identification technique where a weighted least square criterion between model and experimental average moisture content and temperature profiles is optimized using the Lagrangian algorithm within the constraints of the governing equations. The simulated parameter estimated drying characteristics were found to be in good agreement with experimental values.     

Mean drop size correlations and population balance models for liquid—liquid dispersion

Reliable models are required for accurate estimation of drop sizes which govern the interfacial area and rate of mass transfer in a system where various correlations and models have been improved for better accuracy and wider application breath. In this article, relevant semiempirical equations and population balance equation (PBE) models are reviewed. Semiempirical correlations are highly system dependent and limited to prediction of steady‐state drop size while PBE models could estimate transient drop size with considerations of inhomogeineity and flow spatial variation during drop size evolution. With appropriate model parameters determination, different PBE models can be used to reproduce experimental data for a similar system. © 2015 American Institute of Chemical Engineers AIChE J, 61: 1129–1145, 2015     

Fabrication and characterisation of triangle-faced single crystal diamond micro-cantilevers

Single crystal diamond offers superior properties for MEMS applications to polycrystalline forms of this material. Here, a process based solely on focussed ion beam milling (Ga), has been used to fabricate nanometre-width diamond cantilevers we lengths of several tens of microns. The procedure results in low damage structures with little Ga incorporation, following post-fabrication annealing. The triangular profile of a cantilever produced using this technique is shown, theoretically, to have a factor of three improved defection response to a load typically encountered during chemical sensing compared to a conventional rectangular lever of similar dimensions.     

Artificial Neural Network Modeling of the Deposition Rate of Lactose Powder in Spray Dryers

A spray dryer is the ideal equipment for the production of food powders because it can easily impart well-defined end product characteristics such as moisture content, particle size, porosity, and bulk density. Wall deposition of particles in spray dryers is a key processing problem and an understanding of wall deposition can guide the selection of operating conditions to minimize this problem. The stickiness of powders causes the deposition of particles on the wall. Operating parameters such as inlet air temperature and feed flow rate affect the air temperature and humidity inside the dryer, which together with the addition of drying aids can affect the stickiness and moisture content of the product and hence its deposition on the wall. In this article, an artificial neural network (ANN) method was used to model the effects of inlet air temperature, feed flow rate, and maltodextrin ratio on wall deposition flux and moisture content of lactose-rich products. An ANN trained by back-propagation algorithms was developed to predict two performance indices based on the three input variables. The results showed good agreement between predicted results using the ANN and the measured data taken under the same conditions. The optimum condition found by the ANN for minimum moisture content and minimum wall deposition rate for lactose-rich feed was inlet air temperature of 140°C, feed rate of 23 mL/min, and maltodextrin ratio of 45%. The ANN technology has been shown to be an excellent investigative and predictive tool for spray drying of lactose-rich products.     

Microwave-Assisted Aging of Organic–Inorganic Hybrid Nanocomposite of α-Naphthaleneacetate in the Lamella of Zn-Al-Layered Double Hydroxide

Microwave-assisted aging Zn-Al-layered double hydroxide with nitrate as the interlayer anion (ZANOL) and its nanohybrid with an organic moiety, -naphthaleneacetate (ZANAN), was done and the resulting properties of the materials compared. The results showed that intercalation of the -naphthaleneacetate (NAA) anion into the Zn-Al layered double hydroxide lamella is readily accomplished, resulting in the expansion of the interlayer spacing from 9.0 Å in the layered double hydroxide to 20.0 Å in the nanohybrid. This expansion accommodates the NAA anion of larger size than nitrate, as indicated by its molecular structure. For both methods, the resulting materials afforded a well-ordered organic–inorganic nanolayered structure. The Zn to Al ratio of the resulting nanocomposite is lower than the ratio present in the mother liquor at the beginning of the reaction, which implied less incorporation of aluminum ions from the mother liquor into the inorganic metal hydroxide layers. By using the microwave-assisted method, however, slightly more Al³⁺ ions were incorporated into the inorganic metal double hydroxide layers. In general, there is not much difference in the physicochemical properties of ZANANs aged by either the microwave or the conventional oil bath method. For both methods, longer aging time slightly enriched the organic content of the resulting nanohybrid and the inorganic Zn to Al ratio remained the same, independent of the aging time.     

Self-assembled nanocomposite of organic-inorganic hybrid: 2,4-dichlorophenoxyacetate in Zn-Al hydrotalcite-like layers

Hydrotalcite-like inorganic layers of Zn-Al, a host containing an organic moiety, 2,4-dichlorophenoxy-acetate, as a guest, was prepared by the spontaneous self-assembly method from an aqueous solution for the formation of a new layered organic-inorganic hybrid nanocomposite material. In this synthesis, the host- and guest-forming species were simultaneously included in the mother liquor, aged, and separated. Various Zn/Al ratios (R = 2, 3, and 4), concentrations of 2,4-dichlorophenoxyacetic acid (0.03-0.1 M), and pH (7 and 10) were studied to optimize the formation of the layered nancomposite. It was found that the optimum conditions for the formation of the nanocomposite were R = 4, pH 7, and concentration of 2,4-dichlorophenoxyacetic acid = 0.08 M. X-ray diffraction shows that this sample affords a nanolayered structure with a basal spacing of 24.6 A.