Answer:
not sure if this helps but
Answer:
14.52 minutes
<u>OR</u>
14 minutes and 31 seconds
Explanation:
Let's first start by mentioning the specific heat of air at constant volume. We consider constant volume and NOT constant pressure because the volume of the room remains constant while pressure may vary.
Specific heat at constant volume at 27°C = 0.718 kJ/kg*K
Initial temperature of room (in kelvin) = 283.15 K
Final temperature (required) of room = 293.15 K
Mass of air in room= volume * density= (4 * 5 * 7) * (1.204 kg/m3) = 168.56kg
Heat required at constant volume: 0.718 * (change in temp) * (mass of air)
Heat required = 0.718 * (293.15 - 283.15) * (168.56) = 1,210.26 kJ
Time taken for temperature rise: heat required / (rate of heat change)
Where rate of heat change = 10000 - 5000 = 5000 kJ/hr
Time taken = 1210.26 / 5000 = 0.24205 hours
Converted to minutes = 0.24205 * 60 = 14.52 minutes
Answer:
Answer D
Explanation:
They need to be checked monthly
Answer:
Explanation:
a) the steady-state, 1-D incompressible and no energy generation equation can be expressed as follows:
b) For a transient, 1-D, constant with energy generation
suppose T = f(x)
Then; the equation can be expressed as:
where;
= heat generated per unit volume
= Thermal diffusivity
c) The heat equation for a cylinder steady-state with 2-D constant and no compressible energy generation is:
where;
The radial directional term = 
and the axial directional term is 
d) The heat equation for a wire going through a furnace is:
![\dfrac{\partial ^2 T}{\partial z^2} = \dfrac{1}{\alpha}\Big [\dfrac{\partial ^2 T}{\partial ^2 t}+ V_z \dfrac{\partial ^2T}{\partial ^2z} \Big ]](https://tex.z-dn.net/?f=%5Cdfrac%7B%5Cpartial%20%5E2%20T%7D%7B%5Cpartial%20z%5E2%7D%20%3D%20%5Cdfrac%7B1%7D%7B%5Calpha%7D%5CBig%20%5B%5Cdfrac%7B%5Cpartial%20%5E2%20T%7D%7B%5Cpartial%20%5E2%20t%7D%2B%20V_z%20%5Cdfrac%7B%5Cpartial%20%5E2T%7D%7B%5Cpartial%20%5E2z%7D%20%5CBig%20%5D)
since;
the steady-state is zero, Then:
![\dfrac{\partial ^2 T}{\partial z^2} = \dfrac{1}{\alpha}\Big [ V_z \dfrac{\partial ^2T}{\partial ^2z} \Big ]](https://tex.z-dn.net/?f=%5Cdfrac%7B%5Cpartial%20%5E2%20T%7D%7B%5Cpartial%20z%5E2%7D%20%3D%20%5Cdfrac%7B1%7D%7B%5Calpha%7D%5CBig%20%5B%20V_z%20%5Cdfrac%7B%5Cpartial%20%5E2T%7D%7B%5Cpartial%20%5E2z%7D%20%5CBig%20%5D)
'
e) The heat equation for a sphere that is transient, 1-D, and incompressible with energy generation is:
