Modeling and Simulation of Solid Oxide Fuel Cell Integrated with Anaerobic Digester, Thermal Storage Unit and Solar Collector: A Net Zero Emission System

Table 2

List of symbols.

Symbol	Parameter	Unit
Anaerobic digester
	Concentration of organic matter	Kg m^-3
	Concentration of volatile fatty acids	Kg m^-3
	Methanogen concentration	Kg m^-3
	Acidogen concentration	Kg m^-3
	Flow rate of feed	m^3 day^-1
	Reactor volume	m^3
	Methanogen growth rate	Day^-1
	Acidogen growth rate	Day^-1
	Yield factor for hydrolysis	Constant
	Yield factor for acidogenesis	Constant
	Yield factor for methane gas production	Constant
	Acidogenic Monod half velocity constant	Kg m^-3
	Methanogenic Monod half velocity constant	Kg m^-3
	Retention time factor	Constant
Solid oxide fuel cell
	Open circuit voltage	V
	Number of fuel cell
	Standard reversible voltage	V
	Universal gas constant	J Mol^-1 K
	Operating temperature	K
	Faraday constant	C Mol^-1
	Partial pressure of hydrogen	Pa
	Partial pressure of oxygen	Pa
	Partial pressure of water	Pa
	Valve molar constant for hydrogen	Mol s^-1 atm^-1
	Flow rate of hydrogen	m^3 s^-1
	Constant	Mol s^-1 A
	Fuel cell current	A
	Optimum fuel utilization	Constant
	Ratio to H2 to O2	Constant
	Response time	S
Solar collector
	Collector outlet temperature	°C
	Ambient temperature	°C
	Heat transfer coefficient absorber and atmosphere	W m^-2 k^-1
	Heat transfer coefficient working fluid and atmosphere	W m^-2 k^-1
	Area of solar panel	m^2
	Specific heat of working fluid	J kg^-1 K^-1
	Mass flow rate of working fluid	Kg s^-1
	Solar irradiance	W m^-2
	Solar collector efficiency
	Heat transfer coefficient of solar collector	W m^-2 k^-1
	Density of working fluid	Kg m^-3
	Volume of working fluid	m^3
Thermal storage
	Heat stored	J
	Final temperature range of medium	K
	Initial temperature range of medium	K
	Mass of storage medium	Kg
	Specific heat of storage medium	J kg^-1 K ^-1