Heat transfer Quiz 1

Question 1

A liquid of transfer area $$20{{m}^{2}}$$  and the temperature difference between the hot and cold surfaces be $$46\,K$$, has a convective heat transfer per unit time equal to $$1.3	imes {{10}^{5}}W$$. Calculate its convective heat transfer coefficient?

Accepted Answer

$$141W{{m}^{-2}}{{K}^{-1}}$$

Answer

$$114W{{m}^{-2}}{{K}^{-1}}$$

Answer

$$117W{{m}^{-2}}{{K}^{-1}}$$

Answer

$$185W{{m}^{-2}}{{K}^{-1}}$$

Question 2

Consider a metal rod with its tip placed in a fireplace, the other end of the rod gradually gets heated. What is the phenomenon that explains this?

Accepted Answer

Conduction

Answer

Convection

Answer

Radiation

Answer

None of the above

Question 3

The conductivity of the three states of matter i.e. solid, liquid and gas in descending order is,

Accepted Answer

Solid $$\rangle $$ Liquid $$\rangle $$Gas

Answer

Liquid $$\rangle $$ Gas $$\rangle $$Solid

Answer

Gas $$\rangle $$ Liquid $$\rangle $$Solid

Answer

None of the above

Question 4

Find the convective heat transfer per unit time of a liquid of transfer area $$1.26{{m}^{2}}$$  and the temperature difference between the hot and cold surfaces be $${{38}^{0}}$$C, with a convective heat transfer coefficient of $$185W{{m}^{-2}}{{K}^{-1}}$$ ?

Accepted Answer

$$8.9kW$$

Answer

$$89kW$$

Answer

$$3.2kW$$

Answer

$$8.9W$$

Question 5

A conducting rod of length $$2$$m and cross-section area $$0.4{{m}^{2}}$$ and thermal conductivity $$79.5W{{m}^{-1}}{{K}^{-1}}$$, has the temperature difference between it two ends as $$87K$$, then what is the heat transfer per unit time in this rod?

Accepted Answer

$$1.4kW$$

Answer

$$1.4W$$

Answer

$$5.5kW$$

Answer

$$55kW$$