High-power cables are equipped with circulating water; how is the amount of water required calculated?
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High-power cables are equipped with circulating water; how is the amount of water required calculated? Are there any relevant standards?
Thermal balance calculations are similar to those for the length of cooling water jacket tubes. The first step is to calculate the total heat amount Q at the hot end using power P, time t, and the formula Q = W = Pt. The second step involves calculating the heat exchange of the cooling water; for example, if the inlet water temperature is 32 degrees and the outlet water temperature is 37 degrees, Δt is obtained. Choose co-current or counter-current flow, and calculate the logarithmic mean temperature difference Δtm based on the temperature at the hot end and the temperature after cooling. In the third step, thermal equilibrium is achieved between the hot and cold sides, using the formula Q=CVΔt; with a specific heat capacity of water of 4.1868, the required flow rate of cooling water V can be calculated. At this point, based on the water volume V, the diameter of the upper and lower pipes can be estimated using a flow rate of 2 m/s. In the fourth step, use S=Q/KΔtm, look up the heat transfer coefficient K in a table, and thereby determine the heat exchange area S. Easy to obtain jacket length.
There is no fluid at the hot side here, so Δtm is not calculated; heat transfer through the wall is used instead.
In my opinion, the heating of a cable is caused by I^2*R, while the flow rate of water is determined based on heat balance