cold water inlet and outlet

hot medium inlet and outlet

hot medium outlet and cold water inlet

hot medium outlet and cold water outlet

both the fluids at inlet (of heat ex¬changer where hot fluid enters) are in their coldest state

both the fluids at inlet are in their hot¬test state

both the fluids .at exit are in their hottest state

one fluid is in hottest state and other in coldest state at inlet

better insulation should be put over pipe and better one over it

inferior insulation should be put over pipe and better one over it

both may be put in any order

whether to put inferior OIL over pipe or the better one would depend on steam temperature

one dimensional cases only

two dimensional cases only

three dimensional cases only

regular surfaces having non-uniform temperature gradients

ratio of emissive power to absorptive power for all bodies is same and is equal to the emissive power of a perfectly black body.

emissive power depends on temperature

emissive power and absorptivity are constant for all bodies

ratio of emissive power to absorptive power is maximum for perfectly black body