1

GATE ME 1990

Subjective

+5

-0

A double pipe counter flow heat exchanger is to be designed to cool $$12000$$ $$kg/hr$$ of an oil of specific heat $$1.95$$ $$kJ/kgK$$ from $$\,85{}^ \circ C$$ to $$\,55{}^ \circ C$$ by water entering the heat exchanger at $$\,30{}^ \circ C$$ and leaving at $$\,45{}^ \circ C$$. If the $$OHTC$$ of heat exchanger is $$400$$ $$\,W/{m^2}K.\,$$ Calculate the $$LMTD$$ and the surface area of the heat exchanger

2

GATE ME 1988

Subjective

+5

-0

A shell and tube heat exchanger is to be designed for heating pressurized water by means of hot gasses which get cooled the data are as follows

Temp of water at the inlet $$ = \,80{}^ \circ C$$

Temp of the water at the outlet $$ = \,140{}^ \circ C$$

Temp of hot gasses at the inlet $$ = \,340{}^ \circ C$$

Temp of hot gasses at the outlet $$ = \,180{}^ \circ C$$

Mass flow rate of water $$=12$$ $$kg/s,$$ Specific heat of water $$=4.2kJ/kgK$$

$$OHTC=30$$ $$W/{m^2}K$$,

Correction factor for $$LMTD$$ based on counter flow conditions $$=0.9$$

Calculate the tube surface area required in the heat exchanger and the effectiveness of the heat exchanger.

Temp of water at the inlet $$ = \,80{}^ \circ C$$

Temp of the water at the outlet $$ = \,140{}^ \circ C$$

Temp of hot gasses at the inlet $$ = \,340{}^ \circ C$$

Temp of hot gasses at the outlet $$ = \,180{}^ \circ C$$

Mass flow rate of water $$=12$$ $$kg/s,$$ Specific heat of water $$=4.2kJ/kgK$$

$$OHTC=30$$ $$W/{m^2}K$$,

Correction factor for $$LMTD$$ based on counter flow conditions $$=0.9$$

Calculate the tube surface area required in the heat exchanger and the effectiveness of the heat exchanger.

Questions Asked from Heat Exchangers (Marks 5)

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