When the temperature of the surrounding is higher than the temperature of the body, then the heat loss by convection from the body to the surrounding will be

Nusselt number (N_N) is given by

A. $${{\text{N}}_{\text{N}}} = \frac{{{\text{h}}l}}{{\text{k}}}$$

B. $${{\text{N}}_{\text{N}}} = \frac{{\mu {{\text{c}}_{\text{p}}}}}{{\text{k}}}$$

C. $${{\text{N}}_{\text{N}}} = \frac{{\rho {\text{V}}l}}{\mu }$$

D. $${{\text{N}}_{\text{N}}} = \frac{{{{\text{V}}^2}}}{{{\text{t}}{{\text{c}}_{\text{p}}}}}$$

In case of sensible heating of air, the coil efficiency is given by (where B.P.F. = Bypass factor)

A. B.P.F. - 1

B. 1 - B.P.F.

C. $$\frac{1}{{{\text{B}}{\text{.P}}{\text{.F}}{\text{.}}}}$$

D. 1 + B.P.F.

The undesirable property of a refrigerant is

A. Non-toxic

B. Non-flammable

C. Non-explosive

D. High boiling point

The desirable property of a refrigerant is

A. Low boiling point

B. High critical temperature

C. High latent heat of vaporisation

D. All of these