To solve this problem it is necessary to apply the concepts related to the Stefan-Boltzmann law which establishes that a black body emits thermal radiation with a total hemispheric emissive power (W / m²) proportional to the fourth power of its temperature.
Heat flow is obtained as follows:

Where,
F =View Factor
A = Cross sectional Area
Stefan-Boltzmann constant
T= Temperature
Our values are given as
D = 0.6m

The view factor between two coaxial parallel disks would be


Then the view factor between base to top surface of the cylinder becomes
. From the summation rule


Then the net rate of radiation heat transfer from the disks to the environment is calculated as





Therefore the rate heat radiation is 780.76W
Answer:
Explanation:
Dear Student, this question is incomplete, and to attempt this question, we have attached the complete copy of the question in the image below. Please, Kindly refer to it when going through the solution to the question.
To objective is to find the:
(i) required heat exchanger area.
(ii) flow rate to be maintained in the evaporator.
Given that:
water temperature = 300 K
At a reasonable depth, the water is cold and its temperature = 280 K
The power output W = 2 MW
Efficiency
= 3%
where;



However, from the evaporator, the heat transfer Q can be determined by using the formula:
Q = UA(L MTD)
where;

Also;




LMTD = 4.97
Thus, the required heat exchanger area A is calculated by using the formula:

where;
U = overall heat coefficient given as 1200 W/m².K

The mass flow rate:

The things that a scientist should consider while observing
the force is the environmental conditions,the force that is expected to act on
the dam, the means to contain that force,
and compare different types of designs in accordance with the location
of the dam
Answer:

Explanation:
First of all let's define the specific molar heat capacity.
(1)
Where:
Q is the released heat by the system
n is the number of moles
ΔT is the difference of temperature of the system
Now, we can find n with the molar mass (M) the mass of the compound (m).
Using (1) we have:


I hope it helps!