ELECTRICAL HEATING - PART - 03 - THREE PROBLEMS IN DESIGN OF HEATING ELEMENT

ELECTRICAL HEATING - PART – 03 - THREE PROBLEMS IN DESIGN OF HEATING ELEMENT
PROBLEM – 01 – A 40 kW, single phase, 220 V, resistance Oven employs circular Nichrome wire for its heating element. If the wire temperature is not to exceed 1127 degree centigrade and temperature of charge is to be 427 degree centigrade. Calculate the size and length of wire required. Assume emissivity = 0.9, radiation efficiency 0.6 and resistivity of the wire is 1.09^-6. What would be the temperature of the wire when the charge is cold?

PROBLEM – 02 – A 10 kW, 220 V, single phase resistance Oven is to employ nickel-chrome strip 0.025 cm thickness. If the wire temperature is not exceed 1200 degree centigrade and the temperature of the charge is to be 600 degree centigrade. Calculate the width of the strip. Assume emissivity = 0.9, radiation efficiency 0.6 and resistivity of the wire is 1.03^-6.

PROBLEM – 03 – A 50 kW, 400 V resistance oven is to employ nickel-chrome strip 0.025 cm thick for the three phase star connected heating element. If the wire temperature is to be 1000 degree centigrade and that of charge is to be 627 degree centigrade. Calculate a suitable width of the strip. Assume emissivity = 0.9, radiation efficiency 0.6 and resistivity of the wire is 1.03^-6.