Question

Air at T1 = 32°C, p1 = 1 bar, 50% relative humidity enters an insulated chamber operating at steady state with a mass flow rate of 3 kg/min and mixes with a saturated moist air stream entering at T2 = 7°C, p2 = 1 bar. A single mixed stream exits at T3 = 17°C, p3 = 1 bar. Neglect kinetic and potential energy effects

Determine

(a) the relative humidity and temperature, in °C, of the exiting stream.

Answer 1

Answer:

4.5kg/min

Explanation:

Given parameters

$T_1 = 32^0 C, m_1 = 3 kg/min, T_2 = 7^0 C ,T_3 = 17^0$

if we take  

The mass flow rate of the second stream = $m_2(kg/min)$

The mass flow rate of mixed exit stream = $m_3 (kg/min)$

Now from mass conservation

$m_3 = m_2 + m_1$

$m_3 = m_2 + 3 (kg/min)$

The temperature of the mixed exit stream given as

$T_3m_3 = T_2m_2 +T_1m_1\\\\17 ( 3 + m_2) = 7 \times m_2 + 32 \times 3\\\\51 + 17 m_2 = 7 m_2 + 96\\\\10 m_2 = 96 - 51\\\\m_2 = 4.5 kg/min$

Therefore the mass flow rate of second stream will be 4.5 kg/min.