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RegeneratorHX

 

 

SUBPROGRAM RegeneratorHX implements a general numerical solution for a regenerator as described in section 8.10.5 of Nellis and Klein.

 

Inputs:

m_dot_HTCB      hot-to-cold blow mass flow rate (kg/s)

T_H_in                  hot fluid inlet temperature (K or C)

m_dot_CTHB   cold-to-hot blow mass flow rate (kg/s)

T_C_in          cold fluid inlet temperature (K or C)

c_f      specific heat capacity of the fluid (J/kg-K)

rho_r               density of regenerator material (kg/m^3)

c_r                  specific heat capacity of regenerator material (J/kg-K)

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)

h_CTHB       heat xfer coefficient, cold-to-hot blow (W/m^2-K)

V_r               volume of regenerator material (m^3)

A_s                 total surface area for heat transfer (m^2)

 

Outputs:

Q                     "heat transfer rate between hot and cold fluids (J/cycle)

T_H_out             "hot fluid outlet temperature (K or C)

T_C_out        "cold fluid outlet temperature (K or C)

 

Notes:

The numerical model uses 10 spatial nodes and 20 nodes in time for each blow process.  The number of nodes can be increased by changing N and M in the EES library program, if necessary.

 

The units of the inputs and outputs to this subprogram must be as indicate above, regardless of the settings in the EES unit system dialog.

 

Example:

$UnitSystem SI K Pa J

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/cycle]

T_C_out=407.4 [K]

T_H_out=365.1 [K]} 

 

 

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