Nomenclature¶

Geometry¶

Parameters in the table below are related to the definition of borehole and pipe geometries.

Parameter	Units	Description
H	m	Borehole length
D	m	Borehole burial depth
r_b	m	Borehole radius
x	m	Position of borehole in x-axis
y	m	Position of borehole in y-axis
r_in	m	Inner radius of pipe
r_out	m	Outer radius of pipe

Parameters in the table below are related to the evaluation of fluid thermal properties in the media module.

Parameter	Units	Description
T	degC	Temperature of the fluid
P	Pa	Pressure of the fluid
rho	kg/m3	Density of the fluid
mu	Pa.s or N.s/m2	Dynamic viscosity
nu	m2/s	Kinematic viscosity
cp	J/kg.K	Specific isobaric heat capacity
k	W/m.K	Thermal conductivity
rhoCp	J/m3.K	Volumetric heat capacity

Parameters in the table below are used throughout pygfunction for the calculation of heat transfer in geothermal bore fields.

Parameter	Units	Description
time	s	The time in seconds
alpha	m2/s	Soil thermal diffusivity
h		Value of the dimensionless FLS solution
k_s	W/m.K	Soil thermal conductivity
k_g	W/m.K	Grout thermal conductivity
k_p	W/m.K	Pipe thermal conductivity
m_flow_borehole	kg/s	Mass flow rate(s) into a borehole
m_flow_network	kg/s	Mass flow rate(s) into a network (i.e.a borefield)
m_flow_pipe	kg/s	Mass flow rate through a pipe
Q_b	Watts	Total net heat extraction rate along borehole segment(s)
Q_f	Watts	Total net heat extraction rate of a fluid circuit (i.e. from inlet to outlet of a borehole pipe or network)
Q_t	Watts	Total net heat extraction rate of a borehole or network
R_b	m.K/W	Effective borehole thermal resistance
R_fp	m.K/W	Fluid to outer pipe wall thermal resistance
R_p	m.K/W	Conduction thermal resistance of a pipe wall
T_b	degC	Effective borehole wall temperature
T_f	degC	Fluid temperature