Influence of Temperature in Radio Frequency Measurements of Moisture Content in Biofuel

Abstract

A method that permits the determination of moisture content in biofuel in a fast and representative way is under development. The method uses radio frequency waves within the range of 310 MHz to 800 MHz and measures the reflection coefficient in samples with volume of about 0.1 m 3 . The influence of sample temperature in the measurements is shown in this study. Two biofuel types were used, with moisture content varying between 31% and 63% and temperature varying between 1ºC and 63ºC. The data was evaluated with multivariate data analysis. Results show that it is not possible to identify the sample temperature as a principal component in a principal component analysis and partial least squares regression shows no correlation between temperature and the radio frequency data. For the frequency interval and the temperature range studied, it was not possible to detect any influence of sample temperature on moisture content prediction with the radio frequency method.

Determination of log moisture content using ground penetrating radar (GPR). Part 2. Propagation velocity (PV) method

“…However, in this study, only the latter case ( ε ⊥ ′ ) is considered. ε ′ and ε ″ depend also on the frequency, wood density, tree species, temperature, and wood tissue type ( Norimoto and Yamada 1972 ;Lin 1973 ;James 1975 ;Norimoto 1976 ;Norimoto et al 1978 ;Peyskens et al 1984 ;James et al 1985 ;Torgovnikov 1993 ;Salas et al 1994 ;Duchow and Gerhardt 1996 ;Kabir et al 1997Kabir et al , 1998Kabir et al , 2001Afzal et al 2003 ;Bucur 2003 ;Sahin and Ay 2004 ;Daian et al 2005Daian et al , 2006Paz et al 2006 ;Koubaa et al 2008 ;Holmes et al 2013 ).…”

Electrical Capacitance Characteristics of Wood Chips at Low Frequency Ranges: A Cheap Tool for Quality Assessment

“…The direct, traditional, and still widely recognized method of determining the MC of wood chips is oven drying [ 2 , 4 , 5 , 6 , 7 , 9 , 12 , 13 , 14 , 15 , 16 ]. Although oven drying is a standard and standardized [ 4 , 7 , 16 , 17 , 18 , 19 ] method, many authors [ 2 , 4 , 5 , 6 , 12 , 13 , 15 , 16 , 17 ] also point out its disadvantages: the method is destructive, slow, and labor consuming, with potential sources of errors including mainly sampling errors or sample size, and it cannot be used for real-time measurements.…”

“…Another previously relatively widely researched indirect method of determining MC is based on microwave measurements. Nyström and Franzon [ 12 ] and recently Paz et al [ 14 ] tested a radio frequency measurement system for biofuel MC determination. The tested radio frequency microwaves were within the range of 310 MHz to 1300 or 800 MHz, respectively.…”