The relative humidity, RH, at sea level can be calculated from measured values o

Question

The relative humidity, RH, at sea level can be calculated from measured values of the dry-bulb temperature, T_db, and the wet-bulb temperature, T_wb, by: RH = VP/SP times 100 where VP is the vapor pressure given by: VP = e 16.78 T_wb - 116.9/T_wb + 237.3 - 0.066858 (1 + 0.00115T_wb) (T_db - T_wb) and SVP is the saturated vapor pressure given by: SVP = e^16.78 T_db - 116.9/T_db + 237.3 (temperatures in degrees Celsius). Write a user-defined function for calculating RH for given T_db and T_wb. For the function name and arguments, use RH = RelHum(Tdb, Twb). The input arguments Tdb and Twb are the dry-bulb and wet-bulb temperatures, respectively in degree F. The output argument RH is the relative humidity in percent (rounded to the nearest integer). Another function to convert the temperature entered from Fahrenheit to Celsius must be written and called by the main function RelHum. For the function name and arguments of the temperature unit conversion, use TC = TFtoC (TF). Use the function to determine the relative humidity for the following conditions: a. T_db = 75 degree F and T_wb = 69 degree F b. T_db =93 degree F and T_wb = 90 degree F

Explanation / Answer

MATLAB code: RelHum.m

function RH = RelHum(Tdb, Twb)
TdbC = TFtoC(Tdb);
TwbC = TFtoC(Twb);
syms Tdb Twb
VP(Tdb,Twb) = exp(((16.78*Twb)-116.9)/(Twb+237.3))-0.066858*(1+(Twb*0.00115))*(Tdb-Twb);
SVP(Tdb) = exp(((16.78*Tdb)-116.9)/(Tdb+237.3));

RH = round(vpa((VP(TdbC,TwbC)*100)/SVP(TdbC)));

end

function TC = TFtoC(TF)
TC = ((TF - 32)*5)/9;
end

a) RelHum(75,69) = 74

b) RelHum(93,90) = 89

DO THUMBS UP ^_^

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