Energy and exergy analysis for torrefaction of
pigeon pea stalk (cajanus cajan) and eucalyptus
(eucalyptus tereticornis)
Rishikesh Kumar Singh
a
, Koushik Jena
b
, Jyoti Prasad Chakraborty
b
,
Arnab Sarkar
a,*
a
Department of Mechanical Engineering, Indian Institute of Technology (BHU), Varanasi, India
b
Department of Chemical Engineering & Technology, Indian Institute of Technology (BHU), Varanasi, India
highlights graphical abstract
Physical energy of NCG were 20
e122 kJ compared to 60e1004 kJ for
chemical part.
Energy of torrefied biomass
decreased to 9583e10802 kJ at
300
C.
Energy and exergy of both NCG
and liquid increased with increase
in temperature.
Recuperation of energy from liquid
had more potential as compared to
NCG.
article info
Article history:
Received 4 March 2020
Received in revised form
3 May 2020
Accepted 5 May 2020
Available online xxx
Keywords:
Pigeon pea stalk
Eucalyptus
Energy
Exergy
Irreversibility
abstract
Torrefaction of pigeon pea stalk and eucalyptus have been carried out in a tubular quartz
reactor at a temperature range of 200e300
C with constant residence time and heating rate
under nitrogen atmosphere. Under moderate torrefaction (250
C) solid yield for both types
of biomass have been in the range of 63e64% with byproducts in the range of 19e29%
(liquid) and 8e18% non-condensable gases (NCG). Maximum increase in HHV for pigeon
pea stalk and eucalyptus have been 45.4 and 39.8%, respectively. HHV and water content of
liquid product have been in the range of 7620e11200 kJ/kg and 52.8e83.5 wt%, respectively.
NCG mainly consisted of CO
2
and CO with former decreasing with increase in temperature.
Energy and exergy value of solid product decreased while for NCG and liquid increased
with increase in temperature. Energy and exergy value of solid have been highest followed
by liquid and then NCG. CO has been the main contributor in the total energy and exergy of
NCG. Exergy efficiency of solid product has been in the range of 52e54% under moderate
torrefaction. Irreversibility increased with increase in temperature. Recuperation of energy
from byproducts (liquid and NCG) could increase the energy recovery in solid by 8e9%.
© 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
* Corresponding author.,
E-mail address: arnab.mec@iitbhu.ac.in (A. Sarkar).
Available online at www.sciencedirect.com
ScienceDirect
journal homepage: www.elsevier.com/locate/he
international journal of hydrogen energy xxx (xxxx) xxx
https://doi.org/10.1016/j.ijhydene.2020.05.045
0360-3199/© 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
Please cite this article as: Singh RK et al., Energy and exergy analysis for torrefaction of pigeon pea stalk (cajanus cajan) and eucalyptus
(eucalyptus tereticornis), International Journal of Hydrogen Energy, https://doi.org/10.1016/j.ijhydene.2020.05.045