Free and forced convection of heat in gases and liquids

Heat Transfer by Natural Convection from a Horizontal Isothermal Circular Cylinder in Air

“…Also presented in that table are interpolated values of Nu taken from the experimental data of Clemes et al [3] and values of Nu taken from the correlation of Morgan [1]. It is seen that mean values from the experiments, correlations, and analyses agree within 6% in the range 10 [54], Farouk and Guceri [55], and Sako and Chiba [59] over the Ra range 10-10 7 . Clemes et a1.…”

“…The percent coefficient of variation is defined by V = 100a Nu/Nu m , where a Nu is the standard deviation and NU m is the mean value. V varies from 4.57% to 15.5%, with an average value V.V of 10.6% but with no dependency on Ra. Morgan [1] has suggested that the large dispersions in Nu measured at constant Ra could be attributed to one or more of the following causes: heat conduction to supports and temperature sensors, an undersized containment volume, temperature loading, and distortion of the velocity and temperature fields by movement of the bulk fluid.…”

Investigating and calculating the temperature of hot-spot factor for transformers

“…In the (4), h represents the heat transfer coefficient, A is the area, ∆𝜃 𝑜𝑖𝑙 corresponds to the oil temperature gradient, and q indicates the amount of heat generated by the relevant losses. The natural flow of convection oil across longitudinal, leaned and vertical sheets and tubes can be determined by the following integral approach on the basis of heat transfer theory [14]- [16].…”

“…As a thermal chain, Figure 4 offers the top-oil temp model. Centered on the principle of heat flow and thermal-electrical analogy [1]- [3], [14]. Where, the total heat generated by losses in a transformer is…”

“…The change in the warmth temperature is greater than the change in the concentration of the coil at the tip of the wind, which can see in Figure 1 whenever the changes due to stray losses are factor into the equation. Even so, this conventional method of measuring temperature s has found to be insufficient in accordance with the real data recorded by fiber optic sensors [14], [15]. Blume et al [16], [17] noted that there's still a time difference between the rising in top-oil temp as well as the rising in duct oil temp under dynamic loading.…”