The heating capacity of muffle furnace depends on the

The main function of a muffle in the muffle furnace is to

A

Protect the charge from the effects of the products of combustion

B

Smooth out temperature inequalities on the combustion side of the muffle wall

C

Both A & B

D

Neither A nor B

In a muffle furnace, the muffle

A

Retards the heat transfer

B

Assists in temperature equalisation in the charge

C

Permits the use of controlled atmosphere for the protection of stock

D

All of the above

Because of its very high refractoriness of the order of __________ °C, silicon carbide refractories are used in zinc smelting furnace, muffle furnace and for supporting the wares in tunnel kilns.

A

1800

B

2200

C

2400

D

2700

The muffle furnace is

A

used for laboratory purpose to do the heat treatment of materials

B

Used to make steel

C

Used to make iron

D

Used to make coke

The bypass factor (B.P.F.) in case of sensible heating of air is (Where td₁ = Dry bulb temperature of air entering the heating coil, td₂ = Dry bulb temperature of air leaving the heating coil and td₃ = Dry bulb temperature of heating coil)

A

$$\frac{{{\text{t}}{{\text{d}}_2} - {\text{t}}{{\text{d}}_3}}}{{{\text{t}}{{\text{d}}_3} - {\text{t}}{{\text{d}}_1}}}$$

B

$$\frac{{{\text{t}}{{\text{d}}_3} - {\text{t}}{{\text{d}}_2}}}{{{\text{t}}{{\text{d}}_3} - {\text{t}}{{\text{d}}_1}}}$$

C

$$\frac{{{\text{t}}{{\text{d}}_3} - {\text{t}}{{\text{d}}_1}}}{{{\text{t}}{{\text{d}}_2} - {\text{t}}{{\text{d}}_3}}}$$

D

$$\frac{{{\text{t}}{{\text{d}}_3} - {\text{t}}{{\text{d}}_1}}}{{{\text{t}}{{\text{d}}_3} - {\text{t}}{{\text{d}}_2}}}$$

The heating capacity of continuous reheating furnace depends upon the

A

Hearth area and furnace temperature

B

Emissivity of the stock

C

Ratio of wall surface to stock surface

D

All of the above

Two long rods A and B of the same diameter have thermal conductivities k and 4k and have one of their end inserted into a furnace at 400 K. At 9.5 m away section from the furnace, the temperature of rod B is120 degree Celsius. So find out at what end from the furnace end, the same temperature would be reached in the rod A?

A

0.25 m

B

0.75 m

C

0.15 m

D

0.50 m

A cylindrical stainless steel (k = 25 W/m K) ingot, 10 cm in diameter and 25 cm long, passes through a heat treatment furnace which is 5 meter in length. The initial ingot temperature is 90 degree Celsius, the furnace gas is at 1260 degree Celsius and the combined radiant and convective surface coefficient is 100 W/m2 K. Determine the maximum speed with which the ingot moves through the furnace if it must attain 830 degree Celsius temperature. Take thermal diffusivity as 0.45 * 10 -5 m2/s

A

. 000116 m/s

B

.000216 m/s

C

. 000316 m/s

D

. 000416 m/s

Combustion of furnace oil in a furnace (soaking pit) with preheated combustion air at 400°C results in saving of about __________ percent furnace oil as compared to its combustion with atmospheric air, if the flue gas outlet temperature from the soaking pit is 1200°C.

A

5

B

60

C

20

D

40

During the winter season, a room is heated by central heating furnace which delivers the 750 W of heat energy by burning wood pellets. How much power can be saved if heat pump with a COP of 3 is used instead of furnace?

A

100 W

B

500 W

C

1000 W

D

1500 W

The heating capacity of muffle furnace depends on the

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