Question

THERMODYNAMICS PROBLEM

1. Explanation and concept question Under what conditions, if any, the mass fractions and mole fractions of a mixture would be the same? а. (1 Mark) b A moist air sample undergoes a purely humidification process (increase in specific humidity only). Which one of the following properties will increase, decrease, or not change; relative humidity, wet bulb temperature, dry bulb temperature, and enthalpy of the moist air sample. The dry bulb temperature, the relative humidity, total pressure, and the air specific heat (cp) of a flow of moist air are given. Can you calculate the adiabatic saturation temperature without using the psychrometric chart? If your answer is yes, describe the calculation steps in a bullet format. (2 Marks) с. (4 Marks)

Answer 1

AcLiabati Satuaton temperatne dafud as that wto aur cam temp at whch waten the air to Satnahon at the same demp adaban ca briny An adiabahe Saturahor o a dente uhng mth onecan meatune theorehcally the adiabahc Saturahbr kmp alr As the air comes in Contect uth waken in the duct Heat & mars transfer blw waten &alr takes place infin'tely larg Stad'y then at the ext ar If the duct is State Awaten ane at Aften the cdiahahe Satunahr has achievedl a The wet-bulb temperatune stat Cemalhon Strady entuirg Dry Buls ter au'r wile be ders than the aleus Paht demp but gnertn than that mai= ma2=ma mwtmt mur d ma wtmf =mawr hus (wr-ur) m4 ma

Enengg balance yiela An mahr mahit msher (wrw)h= mahz mahi t ma -ur may flour rate hit (w-w) h= h CP Since d loo7 whene T2 the wet-buab temp Saturakal aur ungaturateel Cai'r o0l10'1m' Tiwid liquel waten at Ti whne drelahine humal conling & humidh'ftaton proces, the dry bulb of the the air decneases, ts uet bulb &the deur pornt tempr increases humicl'y The moistune Content d the relatine also increasesThe Senable heat o the aur meduces atent heat of the aur increases chencr ovenall inirease Entralpy of me eur. n the

Beth ane eaprems ratlo. Both mole frachon &mras frach'on ane undt leoterm cr les than1. Both gire values eiten ezual Y 7 Both ane independent of temp changes