T. G. Chuah

Fatty Acids as Phase Change Materials (PCMs) for Thermal Energy Storage: A Review

Abstract Thermal energy storage (TES) technologies in general and phase change materials (PCMs) in particular, have been topic in research for the last 20 years. Traditionally, available heat has been stored in the form of sensible heat (typically by raising temperature of water, rocks, etc). Latent heat storage on the other hand, is a novel and developing technology, which has found considerable interest due to its operational advantages of smaller temperature swing, smaller size, and lower weight per unit of storage capacity. The interest on thermal energy storage by using fatty acids as PCM has risen in recent times since they have desired thermodynamic and kinetic criteria for low temperature latent heat storage. An added advantage is that fatty acids are derived from the vegetable and animals oil that provides an assurance of continuous supply. This article will review the development of fatty acids as PCMs for solar thermal energy storage application.

A CFD Study on the Prediction of Cyclone Collection Efficiency

This work presents a Computational Fluid Dynamics calculation to predict and to evaluate the effects of temperature, operating pressure and inlet velocity on the collection efficiency of gas cyclones. The numerical solutions were carried out using spreadsheet and commercial CFD code FLUENT 6.0. This paper also reviews four empirical models for the prediction of cyclone collection efficiency, namely Lapple [1], Koch and Licht [2], Li and Wang [3], and Iozia and Leith [4]. All the predictions proved to be satisfactory when compared with the presented experimental data. The CFD simulations predict the cyclone cut-off size for all operating conditions with a deviation of 3.7% from the experimental data. Specifically, results obtained from the computer modelling exercise have demonstrated that CFD model is the best method of modelling the cyclones collection efficiency.

Biological treatment of produced water in a sequencing batch reactor by a consortium of isolated halophilic microorganisms

Produced water or oilfield wastewater is the largest volume of a waste stream associated with oil and gas production. The aim of this study was to investigate the biological pretreatment of synthetic and real produced water in a sequencing batch reactor (SBR) to remove hydrocarbon compounds. The SBR was inoculated with isolated tropical halophilic microorganisms capable of degrading crude oil. A total sequence of 24 h (60 min filling phase; 21 h aeration; 60 min settling and 60 min decant phase) was employed and studied. Synthetic produced water was treated with various organic loading rates (OLR) (0.9 kg COD m−3 d−1, 1.8 kg COD m−3 d−1 and 3.6 kg COD m−3 d−1) and different total dissolved solids (TDS) concentration (35,000 mg L−1, 100,000 mg L−1, 150,000 mg L−1, 200,000 mg L−1 and 250,000 mg L−1). It was found that with an OLR of 0.9 kg COD m−3 d−1 and 1.8 kg COD m−3 d−1, average oil and grease (O&G) concentrations in the effluent were 7 mg L−1 and 12 mg L−1, respectively. At TDS concentration of 35,000 mg L−1 and at an OLR of 1.8 kg COD m−3d−1, COD and O&G removal efficiencies were more than 90%. However, with increase in salt content to 250,000 mg L−1, COD and O&G removal efficiencies decreased to 74% and 63%, respectively. The results of biological treatment of real produced water showed that the removal rates of the main pollutants of wastewater, such as COD, TOC and O&G, were above 81%, 83 %, and 85%, respectively.

Removal of Heavy Metals from Steel Making Waste Water by Using Electric Arc Furnace Slag

This work investigated the reduction of chemical oxygen demand (COD), biological oxygen demand (BOD), total suspended solids (TSS) and the concentration of heavy metals of wastewater from a steel making plant. Adsorption experiments were carried out by electric arc furnace slag (EAFS) in a fixed-bed column mode. The raw wastewater did not meet the standard B limitations, having high values of BOD, COD, TSS, Iron, Zinc, Manganese and Copper. After passing through the fixed bed column, BOD, COD and TSS values decreased to 1.6, 6.3 and <2 mgL-1, respectively while the concentration of Iron, Zinc, Manganese and Copper were 0.08, 0.01, 0.03 and 0.07 mgL-1, respectively. The results confirmed that EAFS can be used as an efficient adsorbent for producing treated water that comply with the Standard B limitations for an industrial effluent.

Effect of MAPP and TMPTA as compatibilizer on the mechanical properties of cellulose and oil palm fiber empty fruit bunch–polypropylene biocomposites

The effect of compatibilizers, namely, maleic anhydride grafted polypropylene (MAPP GR-205) and trimethylolpropane triacrylate (TMPTA), on the mechanical and morphological properties of the PP-cellulose (derived from oil palm empty fruit bunch fiber) and PP-oil palm empty fruit bunch fiber (EFBF) biocomposites has been studied. The ratio of PP : cellulose and PP : EFBF is fixed to 70 : 30 (wt/wt%) while the concentration of the compatibilizer is varied from 2.0 to 7.0 wt%. Results reveal that at 2.0 wt% of MAPP concentration, tensile strength of PP-EFBF biocomposite is significantly improved. This is due to the enhanced EFBF matrix adhesion resulting in an improvement in EFBF biocomposite performance. There are no significant changes observed in the PP-cellulose biocomposite properties upon the addition of MAPP. In contrast to the tensile strength, flexural modulus and impact strength are significantly improved with the addition of 2.0 wt% TMPTA to PP-cellulose biocomposite. The enhancement of mechanical properties in the presence of TMPTA is believed to be attributed to crosslinking of multifunctional monomer with the hydroxyl groups of cellulose.

Equilibrium and Kinetic Study on Reactive Dyes Adsorption by Palm Kernel Shell-Based Activated Carbon: In Single and Binary Systems

The adsorption of two reactive dyes, Reactive Black 5 and Reactive Red E, onto palm kernel shell-activated carbon (PKSAC) was studied. The effect of the presence of more than one dye in solution on the equilibrium and kinetics of adsorption was investigated. Equilibrium isotherm models were applied to describe the adsorption capacities of single and binary systems. Adsorption of reactive dyes for single system can be represented by the Freundlich and the Redlich-Peterson models. For binary system, the equilibrium was described successfully by the modified extended Freundlich model. Experimental data showed that competitive adsorption for active sites on the carbon surface resulted in a reduction in the overall uptake capacity of the reactive dyes. The rates of adsorption in single system were found to agree well with the pseudosecond-order kinetic model. Finally, the chemical oxygen demand (COD) of the treated reactive dye solutions from single and binary systems showed that a minimum of 4 g/L dosage of PKSAC was needed to reduce the COD to an acceptable level according to the Water Quality Guidelines and the Pollutant Fact Sheets Guidelines.

Adsorption of Reactive Dyes by Palm Kernel Shell Activated Carbon: Application of Film Surface and Film Pore Diffusion Models

The rate of adsorption of two reactive dyes, Reactive Black 5 and Reactive Red E onto palm kernel shell-based activated carbon was studied. The experiment was carried out to investigate three models: film diffusion model, film-surface and film-pore diffusion models. The results showed that the external coefficients of mass transfer decreased with increasing of initial adsorbate concentration. In addition, it was found that the adsorption process was better described by using the two resistance models, i.e. film-surface diffusion.

Comment on: “Performance of Different Analytical Methods in Evaluating Grade Efficiency of Centrifugal Separators” by Ray M.B., Hoffmann A.C. and Postma R.S. (2000): J. Aerosol Sci., 31(5), pp. 563–581

Recently Ray, Hoffmann, and Postma (2000) have performed detailed experimental studies on a Stairmand high-efficiency cyclone, with a diameter of Full-size image (<1 K) and height of Full-size image (<1 K). The test dust was chalked (Snowcalk 40 from Blue Circle Industries) with a particle density of approximately Full-size image (<1 K) and a size range of 0.3–Full-size image (<1 K). The test dust was charged to the cyclone through a sandblasting nozzle with an air supply to the nozzle at an overpressure of Full-size image (<1 K). The inlet velocity was Full-size image (<1 K) and the dust load was Full-size image (<1 K) air, respectively. They evaluated a few analytical models, namely Barth (1956), Dietz (1981), Mothes and Loffler (1985), Leith and Licht corrected by Clift, Ghadiri, and Hoffman (1991) and Barth modified by Dirgo and Leith (1985). All these models were able to simulate correctly the trend of Rays experimental data. However, the quantitative agreement is not satisfactory.

Preparation of Conjugated p-Aminobenzamidine on Thermosensitive Poly(NIPAM) by Irradiation Grafted Process

A thermosensitive polymer that can either be soluble or insoluble in water was synthesized by electron beam irradiation N-isopropylacrylamide (NIPAM) and β-mercaptopropionic acid (MPA) without the presence of initiator. The polymer was then reacted with p-aminobenzamidine (PABA) using water-soluble carbodiimide (WSC) to introduce an affinity ligand. Radiation grafting of poly(NIPAM) and conjugation of ligand was successfully completed. It was found that the graft reaction could be done at higher dose and carboxyl group was introduced during irradiation of samples in air. Production and precipitate of the carboxylated poly(NIPAM) were investigated. Some results of direct radiation polymerization in this system are also given. The effect of radiation characteristics such as irradiation dose on the lower critical solution temperature (LCST) and conjugation of PABA on the prepared poly(NIPAM) has also been investigated. The precipitate of the grafted polymer has thermal sensitivity and their LCST is close to 35°C.

Physical Properties of Polyethylene Modified with Crude Palm Oil

The influence of small amount of crude palm oil (CPO) content on the physical properties of high density polyethylene (HDPE) and linear low-density polyethylene (LLDPE) was investigated. The HDPE and LLDPE containing 2%, 3%, and 5% CPO were prepared in a twin-screw extruder. Then films of 0.2 mm thickness were produced by using blown film technique. The improvement in tensile strength and elongation at break with a concurrent decline in density implied the enhancement in toughness of the polymers by the addition of CPO. A gradual increase in impact strength of HDPE with the CPO content further supported the previous notation. The enhancement in the physical properties in the presence of CPO is believed to be attributed to the increased chain mobility of the polymer along with improved orientation strengthening in HDPE and LLDPE. Evidence from scanning electron micrographs was also used to support this contention. The decline in impact strength of LLDPE with the addition of CPO is associated with the formation of defects in the amorphous phase of LLDPE.