Showing papers by "Mohammed Farid published in 2011"

A Review of Enzymatic Transesterification of Microalgal Oil-Based Biodiesel Using Supercritical Technology

Abstract: Biodiesel is considered a promising replacement to petroleum-derived diesel. Using oils extracted from agricultural crops competes with their use as food and cannot realistically satisfy the global demand of diesel-fuel requirements. On the other hand, microalgae, which have a much higher oil yield per hectare, compared to oil crops, appear to be a source that has the potential to completely replace fossil diesel. Microalgae oil extraction is a major step in the overall biodiesel production process. Recently, supercritical carbon dioxide (SC-CO2) has been proposed to replace conventional solvent extraction techniques because it is nontoxic, nonhazardous, chemically stable, and inexpensive. It uses environmentally acceptable solvent, which can easily be separated from the products. In addition, the use of SC-CO2 as a reaction media has also been proposed to eliminate the inhibition limitations that encounter biodiesel production reaction using immobilized enzyme as a catalyst. Furthermore, using SC-CO2 allows easy separation of the product. In this paper, conventional biodiesel production with first generation feedstock, using chemical catalysts and solvent-extraction, is compared to new technologies with an emphasis on using microalgae, immobilized lipase, and SC-CO2 as an extraction solvent and reaction media.

Recovery of lignin and water soluble sugars from plant materials

Abstract: In one aspect, a process for treating woody plant material is provided, the process involving contacting the plant material with a continuous flow of an aqueous ethanol solution at elevated temperature and pressure under conditions that promote extraction of ethanol-soluble lignin from the plant material and retention of hemicellulose sugars, xylose and cellulose in the treated plant material solids. In another aspect, a process for extracting hemicellulose sugars from lignin-depleted plant material solids is provided, the process involving contacting lignin-depleted plant material with water at elevated temperature and pressure under conditions that promote extraction of hemicellulose sugars from the plant material; and recovering hemicellulose sugars from the liquid mixture.

Experimental and numerical investigations on the effect of using phase change materials for energy conservation in residential buildings

Abstract: Phase change materials, which melt and solidify at a specified temperature range, can be employed effectively to store energy as latent heat of melting in a large number of applications. They can be used to increase the thermal mass of buildings by mixing them with building materials such as gypsum or concrete. The constructed research facilities of this study show that the application of phase change materials could significantly reduce variation in the indoor temperature of buildings by absorbing heat during the day and releasing it at nright. The objective of this article was to show experimentally and through computer simulation using SUNREL that phase change material impregnated in building materials can provide thermal energy storage benefits. For these simulations paraffin (RT21), which is a mixture of paraffin, has been used as the phase change material because of its desirable thermal and physical attributes, including its melting temperature of 21°C (69.8°F), which is close to human comfort temp...

Computer simulation and experimental measurments for an experimental pcm-impregnated office building

Abstract: In building construction, the use of phase change materials (PCMs) allows the storage/release of energy from solar radiation and/or internal loads. The application of such materials for lightweight construction such as wooden houses improves thermal comfort and reduces energy consumption. The objective of this paper was to show experimentally and through a computer simulation (EnergyPlus) that PCM impregnated in building walls can provide significant thermal energy storage benefits. For these simulations Paraffin (RT21) was used because of its desirable thermal and physical attributes. The results obtained clearly illustrate that the use of PCM can effectively reduce daily fluctuations of indoor air temperatures and thus reducing the need for cooling and heating devices.

Thermal Pyrolysis of Polyethylene: Kinetic Study

Abstract: Thermogravimetric analysis (TGA) was used to measure the kinetic parameters of high density polyethylene in different operating conditions i.e. heating rate and nitrogen flow rate in a non isothermal condition. The Coats-Redfern method was used to calculate the kinetic parameters. An effort was made to investigate the effect of metal particles on plastic during pyrolysis. The results suggested that aluminum powder accelerates the pyrolysis reaction by enhancing the heat transfer. In addition, the kinetic reaction of pyrolysis was studied using a semi-batch reactor in a nitrogen atmosphere under isothermal and non-isothermal conditions. A first-order decomposition reaction was assumed and the rate constant was determined using an integral method. The rate constant was measured at different temperatures and was used to calculate the apparent activation energy and the pre-exponential factor of the reaction in an isothermal condition. Kinetic parameters were measured for individual compounds with carbon numbers ranging from C 9 to C 50 using the semi batch reactor under isothermal condition. Key words : Kinetic; High density polyethylene; Isothermal; Non isothermal; TGA; Semi batch reactor

Modelling of Phase Change Material Implemented Into Cold Storage Application

Abstract: Loss of electrical power for cold storage facilities leads to an increase in temperature and can result in the loss in quality and value of stored products. This article proposes the use of a passive system integrated into the walls of the cold storage facility to limit the rise in temperature due to power loss. Experimental application of phase change material into a domestic freezer has shown that the temperature rise during loss of power is limited. With phase change material, the air temperature remained constant at –8°C (17.6°F) for 7 h, compared to without phase change material where the air temperature rises continuously to well above –8°C (17.6°F) in just 1 h. Computational fluid dynamics results show a reasonable match with experimental results. The computational fluid dynamics model is then extended to model a large cold storage facility to show that phase change material can have significant improvement to the thermal performance of an industrial-size cold store.

Microindentation of Microencapsulated Phase Change Materials

Abstract: Due to the small size of microcapsules (1-1000 µm) used in a large number of applications, the individual rupture force of an individual particle has been difficult to obtain. A new technique involving nanomechanical testing was used in this study. We propose a standard method of testing the individual rupture force of Micronal®DS5008 microcapsules with an average size of approximately 11.2µm. Microcapsules were subjected to compressive force testing to determine the amount of force required to rupture the microcapsules. In order to find the mechanical properties of these microcapsules a standard nanoindentation system was setup with a 10µm radius diamond head cone indentation tip and the individual microcapsules were compressed till rupture occurred.

Fire protection of steel structure through the application of phase endothermic reactions

Abstract: Fire protection is an essential and mandatory aspect of any steel structures design. This project aims to improve on existing fire protection systems, thereby reducing the risk of building collapse associated with fire. This was done by designing a novel fire protection system, which utilised the endothermic decomposition of magnesium hydroxide. The system consisted of an outer layer of gypsum board and an inner mass of magnesium hydroxide. The protection method was then compared against existing protection methods; namely solid concrete encasement protection and hollow gypsum board protection. Thermo gravimetric analysis was carried out on the decomposition reaction. The experimental work showed that the addition of the magnesium hydroxide has two positive impacts. Firstly it increases the thermal mass of the system and secondly it removes heat through its endothermic decomposition. The effect of thermal mass and insulation was evident when only magnesium oxide was used for protection, which increased the time for the steel to reach 550 degreesC from 50 to 88 minutes (76% increase). When magnesium oxide was replaced by magnesium hydroxide, the time needed for the steel to reach 550 degreesC was increased further to 112 minutes (giving a total increase of 124%).