enex_analysis.gas_boiler_tank

Gas boiler with hot-water storage tank — dynamic model.

System chain:

Combustion Chamber → Hot Water Tank → 3-Way Mixing Valve → Service Water

The combustion model uses a constant thermal efficiency eta_comb to relate fuel input to useful heat. Exhaust gas losses are (1 − eta_comb) × E_NG.

Exergy topology (4 components):

1. Combustion — NG chemical exergy, exhaust exergy

2. Tank — stored, loss, destruction

3. Mixing — destruction

4. System total — NG exergy input

Classes

GasBoilerTank([eta_comb, T_exh, ...])

Gas-fired boiler with storage tank.

class enex_analysis.gas_boiler_tank.GasBoilerTank(eta_comb=0.9, T_exh=70.0, burner_capacity=15000.0, r0=0.2, H=0.8, x_shell=0.01, x_ins=0.1, k_shell=25, k_ins=0.03, h_o=15, T_tank_w_upper_bound=65.0, T_tank_w_lower_bound=60.0, T_mix_w_out=45.0, T_sup_w=10.0, dV_mix_w_out_max=0.001, tank_always_full=True, tank_level_lower_bound=0.5, tank_level_upper_bound=1.0, dV_tank_w_in_refill=0.001, prevent_simultaneous_flow=False, on_schedule=None, stc=None, uv=None)

Gas-fired boiler with storage tank.

Combustion chamber heats water which is stored in an insulated tank. Service water is delivered via a 3-way mixing valve.

Parameters:

• eta_comb (float)

• T_exh (float)

• burner_capacity (float)

• r0 (float)

• H (float)

• x_shell (float)

• x_ins (float)

• k_shell (float)

• k_ins (float)

• h_o (float)

• T_tank_w_upper_bound (float)

• T_tank_w_lower_bound (float)

• T_mix_w_out (float)

• T_sup_w (float)

• dV_mix_w_out_max (float)

• tank_always_full (bool)

• tank_level_lower_bound (float)

• tank_level_upper_bound (float)

• dV_tank_w_in_refill (float)

• prevent_simultaneous_flow (bool)

• on_schedule (list[tuple[float, float]] | None)

__init__(eta_comb=0.9, T_exh=70.0, burner_capacity=15000.0, r0=0.2, H=0.8, x_shell=0.01, x_ins=0.1, k_shell=25, k_ins=0.03, h_o=15, T_tank_w_upper_bound=65.0, T_tank_w_lower_bound=60.0, T_mix_w_out=45.0, T_sup_w=10.0, dV_mix_w_out_max=0.001, tank_always_full=True, tank_level_lower_bound=0.5, tank_level_upper_bound=1.0, dV_tank_w_in_refill=0.001, prevent_simultaneous_flow=False, on_schedule=None, stc=None, uv=None)

Parameters:

• eta_comb (float)

• T_exh (float)

• burner_capacity (float)

• r0 (float)

• H (float)

• x_shell (float)

• x_ins (float)

• k_shell (float)

• k_ins (float)

• h_o (float)

• T_tank_w_upper_bound (float)

• T_tank_w_lower_bound (float)

• T_mix_w_out (float)

• T_sup_w (float)

• dV_mix_w_out_max (float)

• tank_always_full (bool)

• tank_level_lower_bound (float)

• tank_level_upper_bound (float)

• dV_tank_w_in_refill (float)

• prevent_simultaneous_flow (bool)

• on_schedule (list[tuple[float, float]] | None)

analyze_steady(T_tank_w, T0, Q_heat_target, *, return_dict=True)

Run a steady-state performance snapshot.

Parameters:

• T_tank_w (float)

• T0 (float)

• Q_heat_target (float)

• return_dict (bool)

Return type:

dict | DataFrame

analyze_dynamic(simulation_period_sec, dt_s, T_tank_w_init_C, dhw_usage_schedule, T0_schedule, tank_level_init=1.0, result_save_csv_path=None)

Run a time-stepping dynamic simulation.

Parameters:

• simulation_period_sec (int) – Total simulation duration [s].

• dt_s (int) – Time step size [s].

• T_tank_w_init_C (float) – Initial tank temperature [°C].

• dhw_usage_schedule (array-like) – DHW usage schedule.

• T0_schedule (array-like) – Outdoor temperature per step [°C].

• tank_level_init (float) – Initial fractional tank level (0–1).

• result_save_csv_path (str | None) – Optional CSV output path.

Returns:

Per-timestep result DataFrame.

Return type:

pd.DataFrame

postprocess_exergy(df)

Compute gas-boiler exergy variables.

Exergy topology (4 components):

1. NG chemical exergy, exhaust exergy

2. Water exergy (tank inlet/outlet, mixing valve)

3. Heat loss exergy, tank stored exergy

4. Component-level exergy destruction

5. Exergetic efficiency metrics

Parameters:

df (pd.DataFrame) – Result DataFrame from analyze_dynamic().

Returns:

DataFrame with exergy columns appended.

Return type:

pd.DataFrame