ABSTRACT
A mixed mode solar tunnel dryer was designed and fabricated for the purpose of drying fruit wastes from food processing industries. The dryer consists of a blower, a solar flat plate collector, a green house chamber with detachable trays for easy handling of biomass and a chimney. Tomato waste was taken as the raw material for the drying process. A 2 kg of tomato waste with initial moisture content of 71.1% (wb) was evenly spread on the surface to a thickness of 0.5 cm. Experimentation was carried out in the geographical location of Vellore, India having 12.91°N latitude, 79.13°E longitude. Equilibrium moisture content of the biomass using mixed mode solar dryer was attained in 7 h while it took 15 h in open solar drying. During the drying operation, the temperature of the dryer varied between 42 and 67°C. Exergy analysis and thin layer drying kinetic studies were conducted for better understanding of the various parameters that influence the drying of tomato waste. The study showed that mixed mode solar drying is an eco-friendly method for mitigation of fruit wastes and it is more effective than open solar drying.
Nomenclature
A | = | Area, m2 |
Cp | = | Specific heat, kJ/kg K |
DR | = | Drying rate, kg of water/kg of dry matter h |
Deff | = | Coefficient of effective moisture diffusion, m2/s |
Ea | = | Activation energy, kJ/mol |
Ex | = | Exergy, kW |
e | = | Thickness of drying bed layer, m |
g | = | Gravitational acceleration, m/s2 |
gc | = | Constant in Newton’s law |
J | = | Joule constant |
k | = | Drying constant |
M | = | Moisture constant, % |
Me | = | Equilibrium moisture content, % |
Mo | = | Initial moisture content, % |
Mt | = | Moisture content at time t, % |
M | = | Mass flow rate, kg/s |
MR | = | Moisture ratio |
N | = | Number of observations |
R | = | Gas constant, kJ/mol K |
T | = | Temperature, °C |
t | = | Time, h |
u | = | Specific internal energy, kJ/kg |
V | = | Velocity, m/s |
v | = | Specific volume, m3/kg |
W1 | = | Initial weight of sample, kg |
W2 | = | Dry weight of sample, kg |
ηEx | = | Exergetic efficiency, % |
µ | = | Chemical potential, kJ/kg |
Subscripts | = | |
a | = | Air |
da | = | Drying air |
db | = | Dry bulb temperature basis |
i | = | Inlet |
o | = | Outlet |
L | = | Losses |
amb | = | Ambient |
Additional information
Funding
Notes on contributors
S. Murugavelh
Dr. S. Murugavelh is an associate professor in CO2 Research and Green Technologies center at Vellore Institute of Technology, Vellore. He received his PhD in Chemical Engineering, Indian Institute of Technology Guwahati, Guwahati in 2013. He has published more than 20 peer reviewed articles. He has filed two patents. As a principal investigator currently he is working on a project “CoPyrolysis of agro-biomass with plastic waste for bio oil production in a tubular reactor: performance and emission characteristics of the bio oil blends in diesel engine” funded by Science and Engineering Research Board (SERB), India.
B. Anand
Mr. B. Anand is a PhD scholar and a Teaching cum Research Associate in CO2 Research and Green Technologies Centre at Vellore Institute of Technology, Vellore. His research areas are desalination, refrigeration & air conditioning, solar energy technologies, cogeneration and trigeneration. He is currently working on a project entitled “Mitigation of Urban Heat Island, combined production of desalination and cooling using modified vapor compression refrigeration system”. He is simultaneously working on a project entitled Experimental investigation on Trigeneration system for power, cooling and desalination.
K. Midhun Prasad
Mr. K. Midhun Prasad is a PhD scholar and working as a Junior Research Fellow in a project “CoPyrolysis of agro-biomass with plastic waste for bio oil production in a tubular reactor: performance and emission characteristics of the bio oil blends in diesel engine” funded by Science and Engineering Research Board (SERB), India. He has published and contributed for many research publications and international conferences.
R. Nagarajan
Mr. R. Nagarajan is a PhD scholar and a Teaching cum Research Associate in School of Mechanical engineering at Vellore Institute of Technology, Vellore. He holds a masters degree in automobile engineering. During his masters he worked in Automotive Research Association of India (ARAI) as for six months as a visiting student. He is currently working on “CO2 sequestration using algal biomass”.
S. Azariah Pravin Kumar
Mr. S. Azariah Pravin Kumar completed his bachelors in Mechanical Engineering and holds masters in Energy & Environment. He has also completed certification course on Industrial safety. His area of interests are solar drying and Biofuels.