1
GATE ME 1989
Subjective
+5
-0
Two black plates, each one meter square, are placed parallel to each other in such a way that the radiation shape factor for the system is $$0.4.$$ If the plates are maintained at $${800^ \circ }C$$ and $${400^ \circ }C$$ respectively, determine the net radiant heat transfer between the plates. Also calculate the net heat exchange if the plates were infinite in size. Stephen Boltzmann constant $$ = 5.67 \times {10^{ - 8}}\,\,W/{m^2}{K^4}$$
2
GATE ME 1989
Subjective
+5
-0
The total efficiency, $${\eta _t}$$ for a finned surface may be defined as the ratio of the total heat transferred by the combined area of the fins, $${A_r},$$ and the exposed surface to that by the total area, $$A$$, if it were maintained at the base temp, $${T_0}.$$ Assuming uniform heat transfer coefficient over the entire surface, derive an expression for the relationship between efficiency and effectiveness of the fin.
3
GATE ME 1989
MCQ (Single Correct Answer)
+1
-0.3
The heat transfer process between a body and its ambient is governed by an internal conductive resistance $$\left( {{\rm I}CR} \right)$$ and an external convective resistance $$(ECR).$$ The body can be considered to be a lumped heat capacity system if
A
$${\rm I}CR > ECR$$
B
$${\rm I}CR$$ is marginally smaller than $$ECR$$
C
$${\rm I}CR = ECR$$
D
$${\rm I}CR$$ is negligible.
4
GATE ME 1989
MCQ (Single Correct Answer)
+2
-0.6
Which of the following is a technique for forecasting?
A
Exponential smoothing
B
$$PERT/CPM$$
C
Gantt chart technique
D
Control charts
EXAM MAP