I would like to choose DC Fan for forced heat convection in order to maintain the system within its operating temperature range.
The module will have the temperature difference up to 10-12 degree celsius on it surface during operation. Based on the Joule's heating(i2R), I calculated the heat emission as 27.9W heat. In the thermal images, I could also find hotspots on the wires and contacts.
How should I begin the selection as I have little knowledge on it?
You need to calculate the air flow rate produced from the fan. It is good to read about cross flow heat exchanger design.
Hallo Mr. Banihani,
Initially, I thought that using fins/fan for effective heat removal. I have to make the calculation how much of the heat can be removed by both methods and which is effective in terms of price and rate of heat removal.
Is there any good study material/review paper for cross flow heat exchanger design?.
Here's the fan flow equation: V = Q /(ρ.c.●t), m3/s V- fan flow rate, m3/s Q - the separated heat from the source, W, ρ- density of the medium / air - 1.15 / kg / m3, c- specific heat capacity of the medium / air - 1005 /, J /(kg. 0C) ●t- temperature difference of air / before and after the heat source for ventilation, for example 3 ° C/, °C
Dear Raam Kasinathan !
You should take care of flow velocity, direction and exposed surfaces to the air flow over battery.
Heat Transfer (Q) = hA(delT).
h-convective heat transfer coefficient will depend on flow velocity
A- is exposed area.
For air a rough estimate of convective heat transfer coefficient can be found in attached Fig.
In addition to the suggestion of Dr. Ehab Banihani, I would recommend to conduct some CFD related studies for flow analysis and optimization.
Analytical solution based on cross flow heat exchanger will give you a crude estimate. CFD studies may give you better estimate otherwise you can go for some experiments.
The problem is a bit more complex.
First you have as mentioned to determine a fin surface to be able to transfer the heat to the air. But you have to obtain on the fins lateral surfaces the air velocity you assumed and this implies not only a fan choice but also an air path. You will have to assure that all the air will go between the fins and along them. This will ask for a "duct". If you have difficulties to see how it should be done do not hesitate to ask I shall give you the basic indications and the reason they are optimal.
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