# Questions tagged [convection]

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### Calculating the convection coefficient of a green roof

as part of a course I have to calculate heat transfer through a green roof. I'm using Python to carry out an assessment over twenty years. The data I have are irradiance, wind speed, air temperature, ...
46 views

### How do I calculate the amount of watts that a heating element needs inside a box?

I have an aluminium box (6 mm thick) of about 13.6 m³. Inside the box is a ventilator that can move 140 m³/h and I want to keep the temperature inside this box at about 30 °C. The box is to be placed ...
31 views

### How to calculate internal convection loss in a sealed container?

Say I have a box with a 1m x 1m x 1m interior wall dimension. The side walls and the floor are 10cm of styrofoam, with a thermal conductivity of 0.03 W/m K. The top is 1cm thick opaque plastic with ...
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### Heat convenction through double pipe

I have a realistic scenario which involves a double contained PP plastic pipe which a section of the pipeline is placed outdoor. What I want to determine if insulation is required at all. The media is ...
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50 views

### What effect does airflow rate have on heat dissipation if the initial heat varies proportionally to the airflow rate?

If I have a server rack consuming 10 kW of power in an empty room with A/C, what effect does the rate of airflow from the rack's exhaust have on the temperature in the room and the load on the HVAC? I ...
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91 views

### Nusselt number equations for external flow over a single finned tube heat exchanger

I am designing a heat exchanger that will utilize a singular finned tube of around 2" diameter with 4 fins per inch that are 3/4" tall and .03" thick. I am looking at finding the ...
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### Can I neglect kinetic energy when modeling convective heat transfer for viscous, low mach airflow? Why or why not?

I'm looking at convective heat transfer for air flow over a solid at Ma=0.2. At this speed, it is plausible to model the flow as incompressible because of small density variations in the air. ...
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791 views

### Convective heat transfer coefficient in finite difference method boundary conditions

Suppose there is a cubic material with an internal heat source ($\Delta q / \Delta t =$ Constant), and is immersed in a sufficiently large amount of water. Now I would like to use finite difference ...
806 views

### How to determine if mass transfer convection is natural or forced?

I know that forced convection requires some external bulk flow, but is there an equation to determine which form of Convection is dominant? I looked around and found the Richardson number \$\mathrm{Ri}=...
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