RegeneratorHX
Procedure RegeneratorHX implements a general numerical solution for a regenerator as described in section 8.10.5 of Nellis and Klein.
Starting with version 12.268, inputs can be provided in either SI or English units, as set with the Unit System command (or $UnitSystem directive) in the calling EES program.
Inputs:
m_dot_HTCB hot-to-cold blow mass flow rate (kg/s) or (lbm/hr}
T_H_in hot fluid inlet temperature (K or C) or (R or F)
m_dot_CTHB cold-to-hot blow mass flow rate (kg/s) or (lbm/hr}
T_C_in cold fluid inlet temperature (K or C) or (R or F)
c_f specific heat capacity of the fluid (J/kg-K or kJ/kg-K) or (Btu/lbm-R)
rho_r density of regenerator material (kg/m^3) or (lbm/ft^3)
c_r specific heat capacity of regenerator material (J/kg-K or kJ/kg-K) or (Btu/lbm-R)
t_HTCB time for hot-to-cold blow process (s)
t_CTHB time for cold-to-hot blow process (s)
h_HTCB heat xfer coefficient, hot-to-cold blow (W/m^2-K) or (Btu/hr-ft^2-R)
h_CTHB heat xfer coefficient, cold-to-hot blow (W/m^2-K) or (Btu/hr-ft^2-R)
V_r volume of regenerator material (m^3) or (ft^3)
A_s total surface area for heat transfer (m^2) or (m^2)
Outputs:
Q "heat transfer rate between hot and cold fluids (J/cycle kJ/cycle) or (Btu/cycle)
T_H_out "hot fluid outlet temperature (K or C) or (R or F)
T_C_out "cold fluid outlet temperature (K or C) or (R or F)
Notes:
The numerical model uses10 spatial nodes and 20 nodes in time for each blow process.
The RegeneratorHX library file calls RegeneratorHX2 in a .DLL file to do the calculations. RegeneratorHX2 has the same calling parameters as the RegeneratorHX subprogram but it provides the option to include M (the number of spatial nodes) and N (the number of nodes in time) as the last two inputs. RegeneratorHX2 can be directly called from an EES program, but in this case, the units of all inputs must be in standard SI (i.e., J, K, kg, m) as used in the following example.
Example:
$UnitSystem SI K Pa J
$VarInfo Q units=J
$VarInfo T_C_out units=K
$VarInfo T_H_out units=K
m_dot_HTCB=0.221[kg/s] "hot-to-cold blow mass flow rate"
T_H_in=450 [K] "hot fluid inlet temperature"
m_dot_CTHB=0.121 [kg/s] "cold-to-hot blow mass flow rate"
T_C_in=310 [K] "cold fluid inlet temperature"
c_f=4230 [J/kg-K] "specific heat capacity of the fluid"
rho_r=7000 [kg/m^3] "density of regenerator material"
c_r=450 [J/kg-K] "specific heat capacity of regenerator material"
t_HTCB=22 [s] "time for hot-to-cold blow process"
t_CTHB=35 [s] "time for cold-to-hot blow process"
h_HTCB=400 [W/m^2-K] "heat xfer coefficient, hot-to-cold blow"
h_CTHB=252 [W/m^2-K] "heat xfer coefficient, cold-to-hot blow"
V_r=0.045 [m^3] "volume of regenerator material"
A_s=8.2 [m^2] "total surface area for heat transfer"
CALL RegeneratorHX(m_dot_HTCB, T_H_in, m_dot_CTHB, T_C_in, c_f, rho_r, c_r, t_HTCB, t_CTHB, h_HTCB, h_CTHB, V_r, A_s : Q, T_H_out, T_C_out)
{Solution:
Q=1.745E6 [J]
T_C_out=407.4 [K]
T_H_out=365.1 [K]}