Mathematical Equations for Energy and Exergy Analysis of a Biomass Densification Operation System

Densification of biomass materials is a process of compressing or compacting biomass materials into a dense form like briquettes by application of pressure inside a container so as to be used as fuel for both domestic and industrial purposes. This operation requires energy to perform and it has been reported that high energy is being consumed during this operation. In order, to minimize the wastage of energy resource and still perform the function of compacting of loose biomass by a densification system, the energy and exergy analysis evaluation of the system which provides useful information required to choose appropriate variables and operating conditions for best performance of a system will have to be carried out. This led to the development of mathematical equations of energy and exergy analysis parameters for evaluating the performance of a biomass densification operation system via fuel and electricity as energy sources. The mathematical equations for energy and exergy analysis parameters developed are energy input, energy out, exergy input, exergy output and exergy destruction of the system. The numerical simulation of exergy analysis of densification operation system at applied force 150, 170, 190, 210, 230 and 250NK with operating speed of 10, 20, 30, 40 and 50mm/min using sawdust and huskdus at moisture content of 6, 10 and 14% was conducted in the laboratory using a prototype briquetting machine to verify the developed mathematical equations. The experimental exergy parameters data obtained from the laboratory investigation was compared with the predicted values of exergy parameters of the densification system obtained when the formulated mathematical equations were employed. Statistical package IBM SPSS 20.0 and graphical presentation of the results were used to conduct the comparison. The results obtained showed that that all the laboratory investigation values of piston displacement and exergy output compared favorably at (P>0.05) with the predicted values from the developed mathematical equations as little difference or no difference could be noticed in the trend of the pair of bar charts in all the figures for both sawdust and huskdust. This implies that the mathematical equations developed could be used to predict the piston displacement which can further be used to determine the exergy output (specific work done) and exergy destruction (work wasted) by the densification system and hence, better design for power required by a biomass densification operation system. Keywords - Exergy, Energy, Densification System, Biomass, Mathematical Equations