From b9f7f61801c58ec9d948a4ddf442b54d96790bf8 Mon Sep 17 00:00:00 2001 From: Steven Baltakatei Sandoval Date: Thu, 20 Apr 2023 07:20:12 +0000 Subject: [PATCH] feat(unitproc/python/):Add EVA-2020-02-2 humidity conversions - Note: See: - https://zdv2.bktei.com/gitweb/EVA-2020-02.git - https://zdv2.bktei.com/gitweb/EVA-2020-02-2.git - https://gitlab.com/baltakatei/ninfacyzga-01 --- unitproc/python/bkt-humidity | 185 +++++++++++++++++++++++++++++++++++ 1 file changed, 185 insertions(+) create mode 100644 unitproc/python/bkt-humidity diff --git a/unitproc/python/bkt-humidity b/unitproc/python/bkt-humidity new file mode 100644 index 0000000..437adc7 --- /dev/null +++ b/unitproc/python/bkt-humidity @@ -0,0 +1,185 @@ +#!/usr/bin/env python3 +# Desc: Humidity conversion functions from EVA-2020-02-2 +# Ref/Attrib: https://gitlab.com/baltakatei/ninfacyzga-01 + +def rel_to_abs(T,P,RH): + """Returns absolute humidity given relative humidity. + + Inputs: + -------- + T : float + Absolute temperature in units Kelvin (K). + P : float + Total pressure in units Pascals (Pa). + RH : float + Relative humidity in units percent (%). + + Output: + -------- + absolute_humidity : float + Absolute humidity in units [kg water vapor / kg dry air]. + + References: + -------- + 1. Sonntag, D. "Advancements in the field of hygrometry". 1994. https://doi.org/10.1127/metz/3/1994/51 + 2. Green, D. "Perry's Chemical Engineers' Handbook" (8th Edition). Page "12-4". McGraw-Hill Professional Publishing. 2007. + + Version: 0.0.1 + Author: Steven Baltakatei Sandoval + License: GPLv3+ + """ + + import math; + + # Check input types + T = float(T); + P = float(P); + RH = float(RH); + + #debug + # print('DEBUG:Input Temperature (K) :' + str(T)); + # print('DEBUG:Input Pressure (Pa) :' + str(P)); + # print('DEBUG:Input Rel. Humidity (%) :' + str(RH)); + + # Set constants and initial conversions + epsilon = 0.62198 # (molar mass of water vapor) / (molar mass of dry air) + t = T - 273.15; # Celsius from Kelvin + P_hpa = P / 100; # hectoPascals (hPa) from Pascals (Pa) + + # Calculate e_w(T), saturation vapor pressure of water in a pure phase, in Pascals + ln_e_w = -6096*T**-1 + 21.2409642 - 2.711193*10**-2*T + 1.673952*10**-5*T**2 + 2.433502*math.log(T); # Sonntag-1994 eq 7; e_w in Pascals + e_w = math.exp(ln_e_w); + e_w_hpa = e_w / 100; # also save e_w in hectoPascals (hPa) + # print('DEBUG:ln_e_w:' + str(ln_e_w)); # debug + # print('DEBUG:e_w:' + str(e_w)); # debug + + # Calculate f_w(P,T), enhancement factor for water + f_w = 1 + (10**-4*e_w_hpa)/(273 + t)*(((38 + 173*math.exp(-t/43))*(1 - (e_w_hpa / P_hpa))) + ((6.39 + 4.28*math.exp(-t / 107))*((P_hpa / e_w_hpa) - 1))); # Sonntag-1994 eq 22. + # print('DEBUG:f_w:' + str(f_w)); # debug + + # Calculate e_prime_w(P,T), saturation vapor pressure of water in air-water mixture, in Pascals + e_prime_w = f_w * e_w; # Sonntag-1994 eq 18 + # print('DEBUG:e_prime_w:' + str(e_prime_w)); # debug + + # Calculate e_prime, vapor pressure of water in air, in Pascals + e_prime = (RH / 100) * e_prime_w; + # print('DEBUG:e_prime:' + str(e_prime)); # debug + + # Calculate r, the absolute humidity, in [kg water vapor / kg dry air] + r = (epsilon * e_prime) / (P - e_prime); + # print('DEBUG:r:' + str(r)); # debug + + return float(r); + +def rel_to_dpt(T,P,RH): + """Returns dew point temperature given relative humidity. + + Inputs: + -------- + T : float + Absolute temperature in units Kelvin (K). + P : float + Total pressure in units Pascals (Pa). + RH : float + Relative humidity in units percent (%). + + Output: + -------- + T_d : float + Dew point temperature in units Kelvin (K). + + References: + -------- + 1. Sonntag, D. "Advancements in the field of hygrometry". 1994. https://doi.org/10.1127/metz/3/1994/51 + 2. Green, D. "Perry's Chemical Engineers' Handbook" (8th Edition). Page "12-4". McGraw-Hill Professional Publishing. 2007. + + Version: 0.0.1 + Author: Steven Baltakatei Sandoval + License: GPLv3+ + """ + + import math; + + # Check input types + T = float(T); + P = float(P); + RH = float(RH); + + #debug + # print('DEBUG:Input Temperature (K) :' + str(T)); + # print('DEBUG:Input Pressure (Pa) :' + str(P)); + # print('DEBUG:Input Rel. Humidity (%) :' + str(RH)); + + # Set constants and initial conversions + epsilon = 0.62198 # (molar mass of water vapor) / (molar mass of dry air) + t = T - 273.15; # Celsius from Kelvin + P_hpa = P / 100; # hectoPascals (hPa) from Pascals (Pa) + + # Calculate e_w(T), saturation vapor pressure of water in a pure phase, in Pascals + ln_e_w = -6096*T**-1 + 21.2409642 - 2.711193*10**-2*T + 1.673952*10**-5*T**2 + 2.433502*math.log(T); # Sonntag-1994 eq 7; e_w in Pascals + e_w = math.exp(ln_e_w); + e_w_hpa = e_w / 100; # also save e_w in hectoPascals (hPa) + # print('DEBUG:ln_e_w:' + str(ln_e_w)); # debug + # print('DEBUG:e_w:' + str(e_w)); # debug + + # Calculate f_w(P,T), enhancement factor for water + f_w = 1 + (10**-4*e_w_hpa)/(273 + t)*(((38 + 173*math.exp(-t/43))*(1 - (e_w_hpa / P_hpa))) + ((6.39 + 4.28*math.exp(-t / 107))*((P_hpa / e_w_hpa) - 1))); # Sonntag-1994 eq 22. + # print('DEBUG:f_w:' + str(f_w)); # debug + + # Calculate e_prime_w(P,T), saturation vapor pressure of water in air-water mixture, in Pascals + e_prime_w = f_w * e_w; # Sonntag-1994 eq 18 + # print('DEBUG:e_prime_w:' + str(e_prime_w)); # debug + + # Calculate e_prime, vapor pressure of water in air, in Pascals + e_prime = (RH / 100) * e_prime_w; + # print('DEBUG:e_prime:' + str(e_prime)); # debug + + n = 0; repeat_flag = True; + while repeat_flag == True: + # print('DEBUG:n:' + str(n)); # debug + + # Calculate f_w_td, the enhancement factor for water at dew point temperature. + if n == 0: + f = 1.0016 + 3.15*10**-6*P_hpa - (0.074 / P_hpa); # Sonntag-1994 eq 24 + f_w_td = f; # initial approximation + elif n > 0: + t_d_prev = float(t_d); # save previous t_d value for later comparison + f_w_td = 1 + (10**-4*e_w_hpa)/(273 + t_d)*(((38 + 173*math.exp(-t_d/43))*(1 - (e_w_hpa / P_hpa))) + ((6.39 + 4.28*math.exp(-t_d / 107))*((P_hpa / e_w_hpa) - 1))); # Sonntag-1994 eq 22. + # print('DEBUG:f_w_td:' + str(f_w_td)); # debug + + # Calculate e, the vapor pressure of water in the pure phase, in Pascals + e = (e_prime / f_w_td); # Sonntag-1994 eq 9 and 20 + # print('DEBUG:e:' + str(e)); # debug + + # Calculate y, an intermediate dew point calculation variable + y = math.log(e / 611.213); + # print('DEBUG:y:' + str(y)); # debug + + # Calculate t_d, the dew point temperature in degrees Celsius + t_d = 13.715*y + 8.4262*10**-1*y**2 + 1.9048*10**-2*y**3 + 7.8158*10**-3*y**4;# Sonntag-1994 eq 10 + # print('DEBUG:t_d:' + str(t_d)); # debug + + if n == 0: + # First run + repeat_flag = True; + else: + # Test t_d accuracy + t_d_diff = math.fabs(t_d - t_d_prev); + # print('DEBUG:t_d :' + str(t_d)); # debug + # print('DEBUG:t_d_prev:' + str(t_d_prev)); # debug + # print('DEBUG:t_d_diff:' + str(t_d_diff)); # debug + if t_d_diff < 0.01: + repeat_flag = False; + else: + repeat_flag = True; + + # Calculate T_d, the dew point temperature in Kelvin + T_d = 273.15 + t_d; + # print('DEBUG:T_d:' + str(T_d)); # debug + + if n > 100: + return T_d; # good enough + + # update loop counter + n += 1; + return T_d; -- 2.30.2