1

GATE ME 2014 Set 2

Numerical

+2

-0

In a concentric counter flow heat exchanger, water flows through the inner tube at $${25^ \circ }C$$ and leaves at $${42^ \circ }C$$. The engine oil enters at $${100^ \circ }C$$ and flows in the annular flow passage. The exit temperature of the engine oil is $${50^ \circ }C.$$ Mass flow rate of water and the engine oil are $$1.5kg/s$$ and $$1$$ $$kg/s,$$ respectively. The specific heat of water and oil are $$4178$$ $$J/kg.K$$ and $$2130$$ $$J/kg.K,$$ respectively. The effectiveness of this heat exchanger is _________.

Your input ____

2

GATE ME 2014 Set 3

Numerical

+2

-0

A double-pipe counter-flow heat exchanger transfers heat between two water streams. Tube side water at $$19$$ liter/s is heated from $${10^ \circ }C$$ to $${38^ \circ }C$$. Shell side water at $$25$$ liter/s is entering at $${46^ \circ }C$$. Assume constant properties of water; density is $$1000\,kg/{m^3}$$ and specific heat is $$4186$$ $$J/kg.K.$$ The $$LMTD$$ (in $${}^ \circ C$$) is ____________.

Your input ____

3

GATE ME 2013

MCQ (Single Correct Answer)

+2

-0.6

Water (specific heat, $${c_p} = 4.18\,\,kJ/kgK$$ ) enters a pipe at a rate of $$0.01$$ $$kg/s$$ and temperature of $${20^ \circ }C.$$ The pipe, of diameter $$50$$ $$mm$$ and length $$3$$ $$m,$$ is subjected to a wall heat flux $${q_w}$$ in $$W/{m^2}:$$

If $${q_w}$$ $$=2500x,$$ where $$x$$ is $$m$$ and in the direction of flow ($$x=0$$ at the inlet), the bulk mean temperature of the water leaving the pipe in $$^ \circ C$$ is

4

GATE ME 2013

MCQ (Single Correct Answer)

+2

-0.6

Water (specific heat, $${c_p} = 4.18\,\,kJ/kgK$$ ) enters a pipe at a rate of $$0.01$$ $$kg/s$$ and temperature of $${20^ \circ }C.$$ The pipe, of diameter $$50$$ $$mm$$ and length $$3$$ $$m,$$ is subjected to a wall heat flux $${q_w}$$ in $$W/{m^2}:$$

If $${q_w}$$ $$=5000$$ and the convection heat transfer coefficient at the pipe outlet is $$1000$$ $$W/{m^2}K,$$ the temperature in $$^ \circ C$$ at the inner surface of the pipe at the outlet is

Questions Asked from Heat Exchangers (Marks 2)

Number in Brackets after Paper Indicates No. of Questions

GATE ME Subjects

Engineering Mechanics

Machine Design

Strength of Materials

Heat Transfer

Production Engineering

Industrial Engineering

Turbo Machinery

Theory of Machines

Engineering Mathematics

Fluid Mechanics

Thermodynamics

General Aptitude