Question
An air-conditioning system provides a continuous flow of air to a room using an intake duct and an exit duct, as shown in the figure. To maintain the quality of the indoor air, the intake duct supplies a mixture of fresh air with a cold air stream. The two streams are mixed in an insulated mixing chamber located upstream of the intake duct. Cold air enters the mixing chamber at 5 °C, 105 kPa with a volume flow rate of 1.25 m3 /s during steady state operation. Fresh air enters the mixing chamber at 34 °C and 105 kPa. The mass flow rate of the fresh air is 1.6 times of the cold air stream. Air leaves the room through the exit duct at 24 °C.
Assuming the air behaves as an ideal gas with 𝒄𝒑 = 1.005 kJ/kg.K and 𝑹 = 0.287 kJ/kg.K, the rate of heat gain by the air from the room is ____________ kW(round off to two decimal places).
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