The ducts of an air heating system pass through an unheated area. As a result of heat losses, the temperature of the air in the duct drops by 4°C. If the mass flow rate of air is 125 kg/min, determine the rate of heat loss from the air to the cold environment. The constant pressure specific heat of air at room temperature is cp = 1.005 kJ/kg·K.

Question

Engineering

Ashlyn Fisher

3 February, 14:37

The ducts of an air heating system pass through an unheated area. As a result of heat losses, the temperature of the air in the duct drops by 4°C. If the mass flow rate of air is 125 kg/min, determine the rate of heat loss from the air to the cold environment. The constant pressure specific heat of air at room temperature is cp = 1.005 kJ/kg·K.

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Answers (1)

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Rhianna Craig · Answer 1

Q=8.375 KW

Explanation:

Given that

Change in temperature ΔT = 4°C

Mass flow rate m = 125 kg/min

We know that

1 min = 60 sec

m = 125/60 kg/s

m = 2.08 kg/s

The heat transfer Q given as

Q = m Cp ΔT

Given that Cp = 1.005 kJ/kg·K.

By putting the values

Q = m Cp ΔT

Q = 2.08 x 1.005 x 4 KW

Q=8.375 KW

Therefore heat loss from air is 8.375 KW.