Hi All
I have an insulated composite wall. I know all of the thicknesses, K values and the inner wall temperature T1. How do I determine the outer wall temperature, T2, if I don't know the heat transfer rate Q?
Thanks in advance for all of your help.
Hello, I am a high school student who produces theoretical projects and presents them to 3rd party organizations. Recently I have been thinking about the inefficiency of “Steam Turbines”. As a solution to this, I thought that I could suggest using a different liquid instead of water, which is used in the turbines because it is inexpensive but has a high specific heat, high boiling point and high boiling temperature.
After a short research, I thought that several different liquids might be suitable. I know I need further research :)
1. Alcohol
Upsides: Relatively low cost, very low boiling point, temperature and specific heat
Downsides: Safety issues, corrosive effect at high temperatures
Possible solution: Use a different alloy
Hello Alperen,
Interesting thoughts you have about changing the 'working fluid' in a steam turbine.
I am not an expert in this but when selecting a working fluid for big steam power plant (which is using Rankine cycle) a few things engineers must have thought about:
Availability of fluid- If it can be continuously provided in pure form from the nearest place/chemical plant to avoid additional costs of transportation
Reusability of the new working fluid
Comparison of heat transfer coefficient values at different stages in the power plant as there are numerous heat exchangers in the steam power plant apart from boiler and condenser
Scaling issues in pipe (buildup of minerals like calcium carbonate )
Viscosity value (should be low so it can be easily transported inside pipes without requiring very high pumping power)
Hello all, i hope you're having a nice day.
I have a question about analytical heat transfer coefficient (HTC) calculation/determination for a rectangular duct curved in a circle. I have found some literature on this topic and also found empirical equations for rectangular cross section straight water ducts/pipes heat transfer calculation based on dimensions of the duct and also some equations for circular cross section helical pipe coil HTC calculation [1]. But none for my specific problem. I know that with curvature of the pipe/duct, the HTC increases as a result of centrifugal forces inducing radial pressure gradient. Has any of you dealt with something similar in the past? If anyone has any experience or can recommend me some literature for my problem or help me in any other way I would be very grateful.
Best regards!
Gal Štempihar
[1] BERGMAN, Theodore L. Fundamentals of heat and mass transfer. John…
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Hello Mikhail Granovskiy,
Welcome to Thermodynamics Forum and thanks for sharing this!
Yes, you are right with given information in problem you might end up with 1 equation 2 unknowns. But if you are allowed to make engineering guess like ambient temp at right side as standard room temperature T1=25°C. Then you can solve the problem? In that case
Q = T5-T1/(Sum of all Rth)
Also, as you said convective heat transferred can be equated to this Q dot as there is no way of generating heat inside composite wall. But in that case if you want to use Newton's equation Q=hA(Ts-Tamb). You may not know 'h' value.
I could have commented better if you posted the entire problem :)