Sun loading
Sun loading
(OP)
Hey ,
I have question I'm calculating the sun loading for Power generator installation in 20 ft hi cube container. The power generator itself after insulation the pipe produces 5kw of heat. Im thinking to do 2" thickness R7.5 insulation inside the container. S how do i calculate the sun loading and also to make sure is this required insulation. Because the insulation was recommended by a vendor who does insulation inside container. COuld anyone help me to solve this
I have question I'm calculating the sun loading for Power generator installation in 20 ft hi cube container. The power generator itself after insulation the pipe produces 5kw of heat. Im thinking to do 2" thickness R7.5 insulation inside the container. S how do i calculate the sun loading and also to make sure is this required insulation. Because the insulation was recommended by a vendor who does insulation inside container. COuld anyone help me to solve this
RE: Sun loading
You can start off with crude resistor network model to do initial feasibility analysis.
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RE: Sun loading
RE: Sun loading
You have a typical steel shipping container except it's double high? 20 feet? How long?
You have a internal combustion engine driven generator built with-in it?
You're considering insulation needs of this system?
Why are you concerned about solar heat gain in this container?
During operation?
During not operation?
Does the container have any ventilation?
If so, does it all close up when not operating?
Are there batteries in this container?
What geographic area is this system going to be applied in?
Will it have power supplied to it when not generating?
Keith Cress
kcress - http://www.flaminsystems.com
RE: Sun loading
yes it a waste heat recovery system. so there will input heat coming into system. So when its operating with insulation covering the heat exchanger's pipes the sytem itself emits 5 kw of heat
yes I'm planning to put ventilation
yes it does have batteries in electrical section
so i wanted to know i f have insulate or not.
if my stem itself creates more heat than outside temperature. I would think to go with low R-value for insulation
I'm concerned about heat load because it will be installed outside in Connecticut-United states.
Also i can size ventilation accordingly.
Also if i calculate the sun load i can figure if i need 2" thickness of insulation
Because during winter the temperature drops upto 14 F.
This is first time I'm calculating sunloading. That's why i wanted to what factors or data i should consider.
RE: Sun loading
Some rough numbers.
Heat Flux(Watts or BTU/hr) = U(insulation factor) x A(meters2 or ft2) X dt(delta temperature)
A horizontal metal surface has a U factor of 6.8W/m2
The sun hitting a flat metal surface can raise the temp 40C.
6.8W/m2 x 40C = 272W/m2 with a 40C temp difference.
For your 2.4m x 5.9m(20 foot) roof you have 14.2m2 x 272W/m2 = 3.8kW from just the roof.
However a flat metal roof with 2" of fiberglass insulation has a U valve of 0.91W/m2. This would reduce your heat flux to
0.91W/m2 x 40C = 36W/m2 with a 40C temp difference and hence a total load of 14.2m2 x 36W/2 = 516W of gain.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Sun loading
RE: Sun loading
RE: Sun loading
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm
RE: Sun loading
https://www.combustionresearch.com/U-Values_for_common_materials.html
3.8 without insulation.. Yes.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Sun loading
RE: Sun loading
RE: Sun loading
I seem to be getting a discrepancy. Your calculated solar constant seems a bit high; the value typically cited is around 1366 W/m^2, although NASA says 1361 W/m^2, your comes out to be more like 1516 W/m^2.
see also: https://arxiv.org/ftp/arxiv/papers/1606/1606.05258...
btw
That's at the mean value of Earth's orbit, so still need to factor in the atmosphere. The value used in MIL-HDBK-310 is 1120 W/m^2, but that's way more variable due to atmospheric transmission coupled with sun angle.
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm
RE: Sun loading
RE: Sun loading
No worries, I was just curious
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
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RE: Sun loading
RE: Sun loading
The "Fundamentals" volume TOC lists these tasty sounding topics -
LOAD AND ENERGY CALCULATIONS
Chapter 14. Climatic Design Information (TC 4.2, Climatic Information)
15. Fenestration (TC 4.5, Fenestration)
16. Ventilation and Infiltration (TC 4.3, Ventilation Requirements and Infiltration)
17. Residential Cooling and Heating Load Calculations (TC 4.1, Load Calculation Data and Procedures)
18. Nonresidential Cooling and Heating Load Calculations (TC 4.1)
19. Energy Estimating and Modeling Methods (TC 4.7, Energy Calculations)