Hot water (0.01 m³ /min) enters the tube side of a counter current shell and tube heat exchanger at 80°C and leaves at 50°C. Cold oil (0.05 m³/min) of density 800 kg/m³ and specific heat of 2 kJ/kg.K enters at 20°C. The log mean temperature difference in °C is approximately

Heat Transfer
Hot water (0.01 m³ /min) enters the tube side of a counter current shell and tube heat exchanger at 80°C and leaves at 50°C. Cold oil (0.05 m³/min) of density 800 kg/m³ and specific heat of 2 kJ/kg.K enters at 20°C. The log mean temperature difference in °C is approximately

50

32

45

37

50

32

45

37

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Heat Transfer
Which has the lowest Prandtl number?

Liquid metal

Water

Lube oil

Aqueous solution

Liquid metal

Water

Lube oil

Aqueous solution

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Heat Transfer
A composite wall consists of two plates A and B placed in series normal to the flow of heat. The thermal conductivities are kA and kB and the specific heat capacities are CPA and CPB for plates A and B respectively. Plate B has twice the thickness of plate A. At steady state, the temperature difference across plate A is greater than that across plate B, when

KA < 0.5kB

CPA < CPB

KA>2 kB

CPA > CPB

KA < 0.5kB

CPA < CPB

KA>2 kB

CPA > CPB

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Heat Transfer
In a single evaporator system, the steam economy __________ by creating vacuum in the evaporator.

Decreases

Remains constant

Increases

May increase or decrease, depends on the vacuum

Decreases

Remains constant

Increases

May increase or decrease, depends on the vacuum

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Heat Transfer
The Nusselt number for fully developed (both thermally and hydrodynamically) laminar flow through a circular pipe whose surface temperature remains constant is

88.66

1.66

Dependent on NRe only

3.66

88.66

1.66

Dependent on NRe only

3.66

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Heat Transfer
Fouling factor

None of these

Does not provide a safety factor for design

Is a dimensionless quantity

Accounts for additional resistances to heat flow

None of these

Does not provide a safety factor for design

Is a dimensionless quantity

Accounts for additional resistances to heat flow

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Heat Transfer

Heat Transfer Hot water (0.01 m³ /min) enters the tube side of a counter current shell and tube heat exchanger at 80°C and leaves at 50°C. Cold oil (0.05 m³/min) of density 800 kg/m³ and specific heat of 2 kJ/kg.K enters at 20°C. The log mean temperature difference in °C is approximately

Heat Transfer Which has the lowest Prandtl number?

Heat Transfer In a single evaporator system, the steam economy __________ by creating vacuum in the evaporator.

Heat Transfer The Nusselt number for fully developed (both thermally and hydrodynamically) laminar flow through a circular pipe whose surface temperature remains constant is

Heat Transfer Fouling factor

Heat Transfer
Hot water (0.01 m³ /min) enters the tube side of a counter current shell and tube heat exchanger at 80°C and leaves at 50°C. Cold oil (0.05 m³/min) of density 800 kg/m³ and specific heat of 2 kJ/kg.K enters at 20°C. The log mean temperature difference in °C is approximately

Heat Transfer
Which has the lowest Prandtl number?

Heat Transfer
In a single evaporator system, the steam economy __________ by creating vacuum in the evaporator.

Heat Transfer
The Nusselt number for fully developed (both thermally and hydrodynamically) laminar flow through a circular pipe whose surface temperature remains constant is

Heat Transfer
Fouling factor