A 4-m * 5-m * 6-m room is to be heated by a base-board resistance heater. It is desired that the resistance heater be able to raise the air temperature in the room from 5 to 25°C within 17 min. Assuming no heat losses from the room and an atmospheric pressure of 100 kPa, determine the required power of the resistance heater. Assume constant specific heats at room temperature.

Question

Physics

Ramon Santana

26 March, 11:17

A 4-m * 5-m * 6-m room is to be heated by a base-board resistance heater. It is desired that the resistance heater be able to raise the air temperature in the room from 5 to 25°C within 17 min. Assuming no heat losses from the room and an atmospheric pressure of 100 kPa, determine the required power of the resistance heater. Assume constant specific heats at room temperature.

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Gracelyn Mason · Answer 1

Answer:2.11kW

Explanation:

1. V = 4x5x6 = 120m3

2. M = p1V / RT1 = 100kpa x 120m3 / 0.287 kpa. m3/kg. k (273+5)

M = 150.40kg

3. Wein Delta t = MCvavg (T2-T1)

= 150.44 x 0.718 x (25-5) / 17 x 60

= 2159.44/1020 = 2.117kW