I want to simulate the temperature change in gas cylinder due to sun light. The metallic cylinder filled with gas is kept in open atmosphere and the sun light is falling on it. Therefore, the radiation due to sun needs to be simulated along with the consideration of temperature change caused by convection. Any one please suggest that which simulation technique will be suitable for the said purpose.
i think the numerical simulation using literature and empirical equations would be suffice.
Rahul,
I'm with Amin. Assume a dumb flat plate, with an area of the tank's perpendicular cross-section. Give it a nominal albedo and emissivity.
Convective losses are harder to model, and will require an iterative code. I'd use something simple - a few lines of BASIC would suffice.
The hardest thing will be to come up with a realistic value for the emissivity of the tank - a polished tank material (stainless steel, for example) can have 0.1 of the emissivity of a plain cast iron surface.
The heat balance depends on the reflectivity *and* the emissivity - so if you can tell us what the cylinder is made of, and how it is finished, we can give you some pointers.
The limiting temperature will also be strongly affected by convective air flow - is the tank in an exposed site, or is it shielded from wind?
Rahul Kumar Soni, You wanted "the radiation due to sun needs to be simulated". First of all you should be clear on what solar radiations that Earth receives. Near infrared radiation and visible light are received by your gas Cylinder, Heat to the gas is caused by near infrared radiation.
Thanks @Amin and @James, I will surely look into the suggestions you have made. Actually, I have two cylinders kept at a distance. A splitter plate separates them and causes shadow to sunlight on one of the cylinder. Lets say sun is moving from east to west so during morning time the cylinder kept on the west side shall receive shadow. While the cylinder on east side shall be full brightened.
I want to try with different design of cylinders and separator that causes shadow. For this purpose, I believe that the simulation would be a good option for the same. In fact, I am planning to do the same in OpenFOAM. Please suggest if it is a good way to go.
@Padmanabha, yes sir, I indeed say that the infrared component of the sun light is responsible for the heating of cylinders, and I am focussing on that only.
Rahul,
A CFD code like OpenFOAM is certainly able to provide you with answers - eventually. Setting up a CFD scenario is not a simple task, but I commend your courage for trying it.
I would be inclined to first draw up an analytical model whereby you calculate the heat input from simple geometry, accounting for shadowing. And then, iterate the convective loss till you have stable temperatures.
So let's see:
radiative loss scales as: sigma x T^4 x emissivity x area x sky-factor
absorbed heating power varies as: (1-albedo) x cross-sectional_perpendicular_area (m^2) x insolation (W/m^2)
(calculating the cross-sectional perpendicular area is a non-trivial matter for a cylinder!)
convective loss goes as: Delta_T_above_ambient^some_power
plug in some numbers, and see whether you can simplify things... and it'll be a good check for the CFD results.
A WORD OF CAUTION IN YOUR RESEARCH. Please keep it in mind the following. You may be well aware of this. Anyhow, I mention here. The intensity of solar near infrared radiation that you measure vary from geographical location. In clear words, the intensity of near infrared radiation in Summer in hot places would be high. At the same time, intensity of near infrared radiation in Summer in places like Gulmarg, Srinagar cannot he high, because of presence of solar UV. This happens at high altitudes and when you approach continents towards North and South poles.
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