Iranica Journal of Energy and Environment (IJEE)

8-12

Authors: Fatemeh Ardestani and Shiva Shafiei

Saccharomyces cerevisiae is known as the most widely used eukaryotic microorganism for biological studies. In present study, cell growth profile of Saccharomyces cerevisiae in a batch submerged culture was evaluated with three different non-structured kinetic models. Fitness assessment of experimental data on cell growth by models was performed using the curve-fitting tool in Excel and Mat-lab software. Obtained results showed Verhulst kinetic model with R2 equal to 0.97 was the most appropriate to describe the biomass growth rate of Saccharomyces cerevisiae. Maximum specific cell growth rate by Verhulst model was 0.59 h 1. Other kinetic constants were also determined for all the studied models.

18-25

Authors: Banin Rupani, Ramchandra Gadre, Kisan Kodam and Ghasem D. Najafpour

Consumption of Polyunsaturated fatty acid omega-3 is the most recommended fatty acids which have a health benefits for brain, kidney and eye. The conversion of plant-derived omega-3 (n-3) -linolenic acid (ALA, 18:3n-3) to long-chain eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3) can enhance ALA sufficient diets in compare to ALA deficient diets. Alpha-linolenic acid (ALA) was extracted and enriched from flax seed oil. Commercial lipases Candida rugosa, Pseudomonas cepacea and P. fluorescens were used for transesterification of ALA enriched from flax seed oil into olive oil TAG back bone. Gas chromatography of olive oil showed it contained high amounts of oleic acid(C18:1, n-9), linoleic acid (C18:2, n-6) and palmitic acid (C18:0) with 0% of ALA. Among the commercial lipase C. rugosa has more preference to ALA and 27% of ALA was incorporated to TAG back bone of olive oil. In 24 hours reaction time, the ALA concentration in TAG of olive has increased to 26% while oleic acid decreased to 60% and palmitic acid decreased from 25 to 7%. The highest incorporation of ALA into olive oil (29%) occurred for ALA: olive oil mole ratio (1:2). There was a decline in incorporation of ALA in olive oil backbone with an increase in the amount of water. ALA incorporation of 25% occurred with 100 μl water while without water it was 27%; it decreased to 15% with 1 ml of water.

34-41

Authors: Amin Hajizadeh

This paper presents an intelligent state feedback controller of a non-inverting buck-boost converter for fuel cell power sources. The proposed control strategy uses fuzzy logic control and state feedback control in order to combine advantages of both controllers. Fuel cell DC/DC converters often have to be able to both step-up and step-down the input voltage and provide a high efficiency in the whole range of output power. Non-inverting buck-boost converters provide both step-up and step-down characteristics. In this paper a statespace average model of converter is obtained and the effect of using a state feedback controller in order to stabilize and regulate the output voltage has been proposed. The use of intelligent state feedback controller allows choosing the proper pole placement of system and using inductor current as a feedback provides a fast dynamic response. Simulation results showed the capability of proposed control strategy during different conditions in fuel cell electric vehicles.

51-58

Authors: A.A. Zinatizadeh, M. Pirsaheb, A.R. Kurdian, S. Zinadini, A. Dezfoulinejad, F. Yavari and Z. Atafar

An artificial neural network (ANN) was used to forecast natural airborne dust as well as five gaseous air pollutants concentration by using a combination of daily mean meteorological measurements and dust storm occurrence at a regulatory monitoring site in Kermanshah, Iran for the period of 2007-2011. We used local meteorological measurements and air quality data collected from three previous days as independent variables and the daily pollutants records as the dependent variables (response). Neural networks could be used to develop rapid air quality warning systems based on a network of automated monitoring stations. Robustness of constructed ANN acknowledged and the effects of variation of input parameters were investigated. As a result, dust had a decreasing impact on the gaseous pollutants level. The prediction tests showed that the ANN models used in this study have the high potential of forecasting dust storm occurrence in the region studied by using conventional meteorological variables.

67-72

Authors: Ali Tarjoman Nejad and Ali Farzi

The prospect of LNG could become a major global energy source is one of the most debated issues. The Liquefied Natural Gas (LNG) supply chain and the properties that make this fuel environmental friendly is in high demand for energy supply. In this paper, at first, the process of converting the natural gas to LNG was simulated; then, the process is optimized to archive minimum energy consumption per ton of LNG produced. Using a three stage exchanger is the best way for minimization of energy consumption in LNG production unit. Outlet pressure from the compressor and also type of refrigerant in cooling system is very effective on rate of energy conservations. The best mass fraction for refrigerants in liquefaction cycle are 0.88 for methane and 0.12 for ethane. For subcooling cycle that fraction is defined as 0.6 for methane and 0.4 for nitrogen. The optimized pressure in outlet of compressors in liquefaction cycle is 650 kPa; also, for the subcooling cycle is 1800 kPa. The amount of consumed energy was 14.91 kW per ton of produced LNG.

78-86

Authors: Ali M. AL-Salihi

Weather data can vary significantly from year to other, so there is a need to create a Typical Meteorological Year (TMY) data to represent the long-term typical weather data sets which are very important as inputs in modeling, designing and performance evaluation of energy balance calculations. In present study Finkelstein-Schafer statistical method was employed to analyze the long-term measured weather data of a 30-year period (1971-2000) for Baghdad province, which included six major meteorological parameter (Global solar Radiation, Sunshine Duration, Maximum, Minimum and Mean Temperature, Relative Humidity) Typical meteorological months from the period of considered years were selected by choosing the smallest (FS) deviation from the long-term of a TMY for Baghdad province.

94-100

Authors: K. Gopi, S. Balaji and B. Muthuvelan

Fifteen cyanobacteria species were isolated from fresh water and marine water resources from different parts of Tamil Nadu, India. Based on their morphological features they were identified through microscopic observations. The isolates were then screened for PHB production using nile red staining. It was found eleven of them were capable of producing PHB in their native forms. Further, PHB quantitative analysis by HPLC showed marine Phormidium sp with 7.60±0.005 mg/L (7.6%) of PHB, followed by Synechococcus sp with 4.59±0.012 mg/L (4.5%), Synechocystis sp with 3.74±0.007 mg/L (3.7%) and Anabaena sp with 2.31±0.012 mg/L (2.3%) of fresh water isolates. Among the isolates, Phormidium sp (VIT-BMN3) isolated from marine environments is reporting first time for its PHB production. In addition, biodegradable polymer extracted in hot chloroform is analysed by FTIR which showed strong bands near 1725 cm1, 2977 cm1 and 3437 cm 1 wave numbers and confirms the presence of ester carbonyl group (C=O), methylene C-H vibration and terminal OH group of PHB, respectively. Overall, nile red staining, HPLC analysis and FTIR spectrums obtained for all cultures conforms the PHB production by our isolates in their native conditions. Further studies of media optimization for increased PHB production are under the process.