J. Kunakemakorn, P. Wongsuchoto, P. Pavasant, N. Laosiripojana

J. Waewsak*, C. Chancham, M. Landry and Y. Gagnon

Abstract:The main objective of this paper was to analyze the statistical wind data obtained from measurements for the 12 months period of January to December 2008 at Thasala district in Nakhon Si Thammarat province, southern Thailand. The wind speed at heights of 20 m, 30 m, and 40 m above ground level were measured using 3-cup anemometers attached to booms on a 45 m lattice met tower. The recording interval was 10 min. The statistical wind data set was analyzed using Weibull distributions in order to investigate the Weibull shape and scale parameters. The Weibull parameters obtained from WAsP 9.0 analysis as well as from the probability density function and cumulative distribution function of graphical methods were compared and the mean bias error between the methods was determined. Results showed that the monthly Weibull shape parameter was in the range of 1.1-2.8, while the monthly Weibull scale parameter was in the range of 2.27-5.94 m/s corresponding to monthly mean wind speeds in the range of 2.2-9.4 m/s. The mean wind speeds at 20 m, 30 m, and 40 m determined by WAsP 9.0 from the observational data were in the range of 2.4-7.8 m/s, 2.7-8.3 m/s, and 3.1-8.8 m/s respectively. The monthly power density was in the range of 5.8-480.3 W/m² corresponding to the wind power class ranging from class 1- to class 4+. Results showed that strong and sufficient winds for power generation occurred during the months of January to July and in the month of October.

Keywords: Weibull Distribution, Power Density, Wind Energy, Probability Density Function, Power Class.

D.D. Anggoro* and N.A.S. Amin

B.O. Bolaji, M.A. Akintunde and T.O. Falade

Abstract: In this paper, the performances of three ozone-friendly Hydrofluorocarbon (HFC) refrigerants (R32, R134a and R152a) in a vapour compression refrigeration system were investigated experimentally and compared. The results obtained showed that R32 yielded undesirable characteristics, such as high pressure and low Coefficient of Performance (COP). Comparison among the investigated refrigerants confirmed that R152a and R134a have approximately the same performance, but the best performance was obtained from the used of R152a in the system. As a result, R152a could be used as a drop-in replacement for R134a in vapour compression refrigeration system. The COP of R152a obtained was higher than those of R134a and R32 by 2.5% and 14.7% respectively. Also, R152a offers the best desirable environmental requirements; zero Ozone Depleting Potential (ODP) and very low Global Warming Potential (GWP).

Keywords: Hydro-Fluoro-Carbon, refrigerants, ozone-friendly, performance characteristics, refrigeration system.

P. Krittayakasem*, S. Patumsawad and S. Garivait

Abstract: Using default emission factors might lead to both over and under estimates for evaluating the total emissions, because the emission factor is strongly affected by fuel properties, operation procedure, emission control etc. To decrease these errors, locally derived emission factors were developed by using site specific data, such as continuous emission monitoring system (CEMS), stack sampling and operation information data from the selected power plants. They were representative of each types of power plant in Thailand including thermal, gas turbine and combined cycle power plants. The locally derived emission factors, according to plant characteristics, were calculated from the annual gaseous emissions divided by either annual electricity generation or heat input in which unit were expressed in kg/MWh or kg/GJ. In order to compare, the locally derived emission factors might be different from the Intergovernmental Panel on Climate Change, IPCC emission factor from 1 to 4 times.
From the locally derived emission factors, the emissions inventory of the power generation sector and country-specific emission factors were evaluated. The average annual emissions inventory of electricity generation between 2001-2006 for CO₂, CO, NO_x, SO₂ and particulate matter were about 67, 0.03, 0.15, 0.04 and 0.005 million tons respectively. From the results of the nation grid emissions inventory between 2001-2006, the country-specific emission factors of the CO₂, NO_x, SO₂ and particulate matters were approximately 563.52, 1.26, 0.41 and 0.06 g/kWh respectively.

Keywords: Emission inventory, power plant, emission factor.

S. Jaichandar* and K. Annamalai

Abstract: Growing concern regarding energy resources and the environment has increased interest in the study of alternative sources of energy. To meet increasing energy requirements, there has been growing interest in alternative fuels like biodiesel to provide a suitable diesel oil substitute for internal combustion engines. Biodiesels offer a very promising alternative to diesel oil since they are renewable and have similar properties. Biodiesel is defined as a transesterified renewable fuel derived from vegetable oils or animal fats with properties similar or better than diesel fuel. Extensive research and demonstration projects have shown it can be used pure or in blends with conventional diesel fuel in unmodified diesel engines. This paper reviews the history of biodiesel development and production practices. Fuel-related properties are reviewed and compared with those of conventional diesel fuel. The effect of use of biodiesel fuel on engine power, fuel consumption and thermal efficiency are collected and analyzed with that of conventional diesel fuel. In the subsequent section, the engine emissions from biodiesel and diesel fuels are compared, paying special attention to the most significant emissions such as nitric oxides and particulate matter.

Keywords: Biodiesel, vegetable oil, methyl ester, diesel engine, performance, emissions.

A. Boonpoke, S. Chiarakorn, N. Laosiripojana, S. Towprayoon and A. Chidthaisong*

Abstract: The aims of this work were to synthesize the porous solid adsorbents and to study their carbon dioxide (CO2) adsorption capacities. Three adsorbents; activated carbon synthesized from bagasse (BAC) and from rice husk (RAC), and Mobil Composition of Matter number 41 (MCM-41) from rice husk silica (R-MCM-41) were investigated. The synthesized BAC, RAC and R-MCM-41 showed high thermal stability with the weight loss less than 0.1% for the temperatures below 150°C. N2 adsorption isotherm analysis indicates that BAC and RAC are microporous while R-MCM-41 is mesoporous materials. The BET surface areas were 923, 927 and 602 m2 g-1 for BAC, RAC and R-MCM-41, respectively. The total pore volumes were 0.53, 0.56 and 0.49 cm3 g-1, and pore sizes were 0.8, 0.8, and 2.43 nm for BAC, RAC and R-MCM-41, respectively. At 30°C these materials were able to adsorb 76.89, 57.13 and 23.32 mg-CO2 g-1-adsorbent, respectively. When the adsorption temperature increased, adsorption capacity of BAC, RAC and R-MCM-41 was decreased. This implied that physical process was the main mechanism of CO2 adsorption.

Keywords: Activated carbon, MCM-41, Carbon dioxide, Adsorption, Rice husk and Bagasse.

S. Chooklin, L. Kaewsichan* and J. Kaewsrichan

Abstract: Production of lactic acid from palmyra sap by fermentation has been studied using Lactobacillus casei TISTR 1500 as the producer organism. The effects of the physical and chemical properties of palmyra sap were determined. The pH, water content, total soluble solids, total sugars, and total nitrogen were 4.3, 86.2%, 14.8°Brix, 134.0 g L^-1, and 0.03 g L^-1, respectively. The fermentation took place in a flask under static conditions. The variation of 10.0-134.0 g L^-1 total sugars in the palmyra sap was carried out at 37°C for 24 h in a basal medium. The final lactic acid concentration, dry cell weight and productivity increased with the increment of total sugars of palmyra sap concentrations up to 134.0 g L^-1. The kinetic parameters of the palmyra sap of 134.0 g L^-1 total sugars revealed that the specific growth rate (m) was 0.05 h^-1, the maximum productivity (R_M)  was 2.02 g lactic acid L^-1 h^-1, the cellular yield coefficient (Y_X/S) was 0.20 g cell g^-1 sugar and the lactic acid yield (Y_P/S) was 0.78 g g^-1.

Keyword: Palmyrasap; Lactic acid; Lactobacillus casei TISTR 1500; Fermentation.