enex_analysis.hx_fan

Heat exchanger and fan utility functions.

Functions for velocity-dependent UA calculation, HX performance solving, fan power curves, and HP schedule checking.

Functions

calc_UA_from_dV_fan(dV_fan, dV_fan_design, ...)

Calculate velocity-dependent UA via lumped scaling (Wang et al., 2000).

calc_fan_power_from_dV_fan(dV_fan, ...[, ...])

Calculate fan power using ASHRAE 90.1 VSD Curve.
enex_analysis.hx_fan.calc_UA_from_dV_fan(dV_fan, dV_fan_design, A_cross, UA, exponent=0.71)[source]

Calculate velocity-dependent UA via lumped scaling (Wang et al., 2000).

Parameters:

  • dV_fan (float) – Current fan flow rate [m³/s].

  • dV_fan_design (float) – Design fan flow rate [m³/s].

  • A_cross (float) – Heat exchanger cross-sectional area [m²].

  • UA (float) – Design UA value [W/K].

  • exponent (float) – Exponent for velocity scaling. Default is 0.71 for a 1-row configuration.

Returns:

Scaled UA value [W/K].

Return type:

float

Notes

Instead of the Dittus-Boelter tube-side exponent (0.8), this uses a simplified lumped exponent (default 0.71). This derivation assumes a 1-row plain fin-and-tube configuration (N=1) where the Colburn j-factor is proportional to Re^-0.29, leading to h ∝ V^0.71. Multi-row coils may use exponents between 0.5 and 0.8 depending on configuration. Reference: Wang et al. (2000), DOI: 10.1016/S0017-9310(99)00333-6

enex_analysis.hx_fan.calc_fan_power_from_dV_fan(dV_fan, fan_params, vsd_coeffs, is_active=True)[source]

Calculate fan power using ASHRAE 90.1 VSD Curve.

Parameters:

  • dV_fan (float) – Current flow rate [m³/s].

  • fan_params (dict) – Must contain fan_design_flow_rate and fan_design_power.

  • vsd_coeffs (dict) – VSD Curve coefficients (c1 through c5).

  • is_active (bool) – If False, returns np.nan.

Returns:

Fan power [W].

Return type:

float