Recent content by Askara

whats the the Rayleight number formulae of vertical cylinder in natural convection?

i uploaded an image to explain better. but that information you need? it doesn't have to be a calculation, just a formula will do.

can anyone tell me what formulae i can use to calculate the temperature of two plate? eg i have a cement plate on top of a steel plate. each plate say 0.5cm thick. on one side of the cement plate is at 1000 degree c. in still air of room temperature 20 degree c. what's the temperature of the...

so say i have a nichrom wire of 0.5 mm dia, and pass 230 v through it.and i coil it up, but some part of the coil touched (imagine the wire parallel to each other so basically 2 circle.) will it short the circuit? i have been told that the area they touch is extremely smaller since they are...

but 2*pi*r is the circumference and pi*R^2 is the cross section area of the wire?

hmmm still kinda confused about the formula in excel. i mean i understand what does those number mean? T increase as x increase? should T = 100 at x 0.18 or atleast close? x T dT/dx d^2T/dx^2 0.18 1391.989962 86890.92844 14517931.07 if is possible to write it...

russ_watters thanks, i alway just assumed radiation doesn't matter much but actually as you said, is it much bigger factor than convection. that's why the data i got doesn't match the result from convection

what is the max free air heat transfer coefficient(film coefficient)? at 1000 c? i have a object that is at 1000 degree c by applying 900watt. i model it solid edge and apply heat generation load of 900 watt, from what i research air convection is 5-25 w/m^2/k. but when i apply that in the...

so say i have a cylinder heated 1000 degree c. i use the black body formulae q = σ*(T^4)*A and got a value of say 500 watt. this the the total value of heat transfer from cylinder to surrounding? or use convective heat transfer of say 5watt/m^2/k, so power=h*(delta T)* A. if i got a value of...

the heat transfer by conduction, convection and radiation. so blackbody radiation is not a method that just take into account of radiation. but give you average total heat transfer of a hot body to surrounding? what's the wavelength you use? if possible can i see you working? i mean how do i...

let say a cylinder(steel) is 6 cm diameter and length of 3.5 cm length. and is heated to 1000 degree c. in a room of free air and room temperature of 20. will convective heat transfer dominate? it radiation is negligible? what would the convective heat transfer be? what power(watt)...

why black body radiation? i thought the main heat transfer will be conduction, and heat loss by convection?

the thing is engineering box say 5 and 25 W/m^2.K, i have seen some website say 5 and 50 W/m^2.K, and wikipedia 10-100 W/m^2.K so i don't really know what to chooese. plus onvection heat transfer coefficient increase with temperature, it may be 25 W/m^2.K at 20-200 degree c but it will be...

whats would be typical value for free air convection heat transfer coefficient at high temperature of 1000 degree c? let say i have a vertical cylinder of diameter 5 cm and 3 cm high. and i heat it to 1000 degree c. the room temperature is 20c . what would the convection heat transfer...

the temperature is 20 c, room temperature. and no air flow. so natural convection